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Delaminating Metal–Polymer Composites through CO2 Bubble Nucleation and Crystallization for Material Recycle in Electric Vehicles
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Delaminating Metal–Polymer Composites through CO2 Bubble Nucleation and Crystallization for Material Recycle in Electric Vehicles
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  • Rajesh Kumar Sharma
    Rajesh Kumar Sharma
    School of Frontier Engineering, College of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
    More by Rajesh Kumar Sharma
    Orcidhttps://orcid.org/0000-0001-6285-4317
  • Yuto Mori
    Yuto Mori
    School of Mechanical Science, Graduate School of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
    More by Yuto Mori
  • Soichiro Kishimoto
    Soichiro Kishimoto
    School of Mechanical Science, Graduate School of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
    More by Soichiro Kishimoto
  • Ryotaro Okuda
    Ryotaro Okuda
    Graduate School of Organic Material Science, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
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  • Hiroshi Ito
    Hiroshi Ito
    Graduate School of Organic Material Science, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
    More by Hiroshi Ito
    Orcidhttps://orcid.org/0000-0001-8432-8457
  • Kentaro Taki*
    Kentaro Taki
    School of Frontier Engineering, College of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
    *Email: [email protected]
    More by Kentaro Taki
    Orcidhttps://orcid.org/0000-0002-6019-3110
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ACS Applied Polymer Materials

Cite this: ACS Appl. Polym. Mater. 2024, 6, 16, 9627–9634
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https://doi.org/10.1021/acsapm.4c01463
Published August 12, 2024

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Abstract

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Recycling metal–polymer composites in electric vehicles (EVs) is a complex but crucial aspect of achieving sustainability in the automotive industry. To enable effective recycling of multimaterials in EVs, it is essential to ensure the thorough separation of all constituent materials. In this study, we demonstrated the effectiveness of bubble nucleation at higher saturation pressure, followed by subsequent heating, in achieving nearly complete delamination of the metal–polymer interface. A lap-shear assembly comprising aluminum alloy (Al) and 40 wt % glass fiber-reinforced polycarbonate (PCGF40) with a joined strength of 20 MPa as a test piece of EV part were impregnated with CO2 at a saturation pressure of 12.5 MPa and a temperature of 80 °C for 24 h. Subsequently, the impregnated samples were heated at different temperatures (110–150 °C) for 3 min to induce bubble nucleation at atmospheric pressure. The presence of crystallinity in the impregnated samples due to high saturation pressure was confirmed through differential scanning calorimetry (DSC) data. Tensile lap-shear strength tests were conducted on all samples to determine the maximum separation load, as per ISO19095-3 fixture standards. The results indicated a decrease in the maximum separation load with increasing the heating temperature, attributed to the presence of bubbles at the interface and fractures in the polymer matrix, as clarified by X-ray computed tomography (X-ray CT). Cohesive failure was observed at the temperature of 150 °C. The smallest maximum separation load and polymer residue were achieved for the sample heated at 140 °C. Through the crystallization of polycarbonate and bubble nucleation processes, the findings of this study demonstrate a successful reduction of approximately 95% in the maximum separation load compared to the control sample, showcasing an effective strategy for achieving nearly complete delamination of metal/semicrystalline polymers.

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1. Introduction

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As the global community seeks greener and more affordable transportation solutions, the demand for electric vehicles (EVs) continues to rise. (1) A key focus in the development of EVs is the need to keep them lightweight and energy-efficient, enhancing their range and performance. To achieve these goals, many components in EVs, including batteries and structural parts, are manufactured from composite materials. (1−3) Multimaterials are indeed valuable across various industries (e.g., automobile, electronics, aerospace) due to their ability to combine different materials with complementary properties to achieve enhanced performance and functionality. (1,4−7) These composites offer a unique balance of strength, weight, and versatility, making them invaluable in the design and manufacturing of EVs. Certain metal–polymer composites exhibit excellent thermal conductivity and heat dissipation, which is vital for managing the heat generated by EV batteries and electric motors. (1) The ability to join metals and polymers in innovative ways is a versatile and increasingly important process in materials engineering and manufacturing. A notable method for achieving this is metal–polymer direct joining (MPDJ) technology, which uses an injection molding machine for adhesive-free bonding of metal and polymer materials. (8−12) This technique is significant in the automotive industry, particularly in EVs, where there is a high demand for lightweight yet strong materials and efficient manufacturing processes. (11) Although MPDJ technology joins metals and polymers firmly due to the anchoring effect, (8) the ability to recycle materials at the end of their life cycle remains a unique and challenging requirement in engineering and manufacturing.
The development of effective recycling methods for metal–polymer composites is a crucial area of research as the industry seeks to maintain sustainability throughout the life cycle of EVs. Earlier, various methods were employed to recycle multimaterials such as chemical (13,14) and mechanical recycling (e.g., milling, shredding, or grinding) (15−17) processes. Nevertheless, these methods are not without their drawbacks. Chemical recycling, while effective in some respects, often leads to the production of considerable waste byproducts, which require additional treatment and disposal. The use of harsh chemicals and high-energy processes results in substantial greenhouse gas emissions and environmental pollution. (17) Furthermore, mechanical recycling methods demand high energy consumption and expensive machinery, adding to the overall cost of the recycling process. (15) Additionally, these recycling approaches often struggle to preserve the integrity of the original materials. The interfacial separation of multimaterials is indeed a significant consideration in recycling processes, especially when dealing with products or materials that are made from a combination of metals and polymers. The interfacial strength between these two materials can present challenges when it comes to efficiently and effectively recycling them.
Recently, Mori et al. (18) have developed a method for metal–polymer interfacial separation using microcellular foaming technology where CO2 gas is impregnated through the polymer and bubbles are nucleated at the interface with subsequent heating. This method not only enhances the feasibility of recycling of metal–polymer composites but also lowers the overall energy consumption. The reduction in energy consumption contributes to cost savings, making the process economically viable for large-scale industrial applications. They have successfully reduced the metal–polymer interfacial separation load by 50% at a saturation pressure of 10 MPa and a heating temperature of 130 °C. Achieving a 50% reduction in the separation load indicates a promising step forward in the efficiency of the separation process of the multimaterials. However, if the goal is to achieve complete separation of the multimaterials, further reductions in the interfacial separation load are necessary.
In our current research, which builds upon our previous work, (18) we have effectively reduced the interfacial separation load between the metal and polymer, allowing for easier delamination, by implementing a microcellular foaming technique. (19−22) The glass fiber-reinforced polycarbonate (PCGF40) was joined with a laser-engraved microstructured aluminum (Al) alloy through an injection molding process employed in this study. The CO2 gas was impregnated through the PCGF40 resin of the specimen at a high saturation pressure at constant temperature. CO2 is a preferred choice because it is nontoxic, nonflammable, cost-effective, naturally abundant, and environmentally friendly; has a moderate critical temperature (31.1 °C) and pressure (7.38 MPa); and exhibits high solubility in polymers. (23−25) The Al/PCGF40 specimen was subsequently subjected to high temperatures for a specific duration to induce the nucleation of CO2 gas bubbles at the interface of the Al/PCGF40. The high saturation pressure-induced crystallinity in the polymer matrix was confirmed by the DSC measurement. Afterward, lap-shear tensile strength measurements were conducted to determine the maximum interfacial separation load between PCGF40 and Al. The X-ray CT imaging technique was utilized to visualize voids at the interface. The outcomes of this study have significant implications for the automotive industry, particularly EVs, where lightweight yet strong materials and efficient recycling processes are paramount.

2. Experimental Section

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2.1. Materials

Polycarbonate, a thermoplastic polymer reinforced with 40 wt % glass fiber (PCGF40; Panlite G-3440LIBK, Teijin), was directly bonded with a 5 mm-long laser-engraved area of Al alloy through an injection molding process. The specimens were acquired from Daicel Miraizu Ltd., Japan. The Al substrate possessed dimensions of 45 mm in length, 10 mm in width, and 1.5 mm in thickness. The PCGF40 had dimensions of 45 mm in length, 10 mm in width, and 3 mm in thickness. The total surface area of the joint was measured to be 50 mm2. The specimen’s geometry adhered to the ISO 19095-2:2015, 4.2 standard. All specimens were utilized in their original state for further experimentation.

2.2. CO2 Gas Impregnation

The CO2 gas impregnation process in this study was executed in accordance with the procedure outlined in our earlier research. (18) The impregnation process was conducted at a saturation pressure of 12.5 MPa while maintaining a constant temperature of 80 °C for 24 h. After the sorption time, the pressure was released within 5 min. Subsequently, the CO2 bubbles were induced to nucleate by heating the samples on a heating plate at a high temperature for 3 min. The CO2 gas concentration was calculated as per our previous study, (18) determining the weight difference of the specimen before and after CO2 gas impregnation prior to the 3 min heating process. The foaming magnification (X), indicating the volume expansion or density reduction of the resin, was also calculated as per our previous study based on Archimedes' principle. (18)

2.3. Tensile Lap-Shear Strength

We utilized a mechanical tensile test machine (AGS-5kNX, Shimadzu Corporation, Japan) to determine the maximum separation load between Al and PCGF40 after CO2 bubble nucleation occurred at the interface. The sample was securely clamped in accordance with the ISO 19095-3:2015, 5.2 standard fixture, enabling the measurement of tensile lap-shear strength. The displacement rate for all measurements remained constant at 1 mm/s. All measurements were conducted under room temperature (23 °C) conditions and were repeated a minimum of three times to calculate the average value.

2.4. Residual Resin Area Ratio Measurement

After measuring the tensile strength, microscopic images of the engraved area on the Al substrate were captured using a digital microscope (VHX-7000, Keyence, Japan) to assess the residual PCGF40 resin. The residual PCGF40 resin area ratio on the engraved surface of the aluminum substrate was calculated using ImageJ software, following the methodology outlined in our previous study. (18)

2.5. X-ray Computed Tomography (X-ray CT)

The morphological investigation of CO2 bubble nucleation at the interface between Al and PCGF40 was conducted utilizing the X-ray CT imaging technique. The X-ray CT imaging was carried out at the BL8S2 beamline of the Aichi Synchrotron Radiation Center in Nagoya, Japan. Prior to the X-ray CT imaging, all specimens were cut into 2 mm squares to capture high-resolution images (with a voxel size of 1.33 μm). When the specimen demonstrated high joint strength, a grinder was employed for cutting; however, in cases of low strength, a diamond wire saw was utilized for the cutting process. The sample, heated at 130 °C, was cut into dimensions of 1 × 1 × 10 mm3. White X-rays with 5× magnification and an exposure time of 20 ms were employed to capture all the images.

2.6. Differential Scanning Calorimetry (DSC)

The thermal behavior of the control and sample impregnated at 5, 7.5, 10, and 12.5 MPa at a constant temperature of 80 °C was analyzed by using a DSC (PerkinElmer, DSC 8000) under a nitrogen environment at the rate of 10 °C/min. The calibration was performed with the Indium standard.

3. Results and Discussion

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3.1. CO2 Gas Dissolution in the PCGF40 Resin under a Pressure of 12.5 MPa Followed by Subsequent Heating

The foaming magnification (X) and CO2 gas concentration in the PCGF40 under a pressure of 12.5 MPa were plotted in Figure 1, with a comparison to our earlier study. (18) The CO2 gas concentration in the PCGF40 resin was measured at different pressures while maintaining a constant temperature of 80 °C for 24 h, as depicted in Figure 1a. Mori et al. (18) previously demonstrated a linear increase in gas concentration with pressure (5 < 7.5 < 10 MPa).

Figure 1

Figure 1. (a) CO2 gas concentration under pressures of 5, 7.5, 10, and 12.5 MPa at a saturation temperature of 80 °C. (b) Foaming magnification (X) under pressures of 5, 7.5, 10, and 12.5 MPa at a saturation temperature of 80 °C followed by subsequent heating at various temperatures (110–150 °C).

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However, in this study, the gas concentration at 12.5 MPa was observed to be lower than that obtained at 10 MPa. This reduction in the gas concentration at 12.5 MPa pressure can be attributed to the crystallization of PCGF40 resin at high pressure. (26−28) The solubility of CO2 in amorphous polycarbonate increases linearly with saturation pressure and decreases with rising temperature, accompanied by an increase in the diffusivity. (26) Nevertheless, beyond a certain threshold pressure, solubility decreases, leading to crystallization due to the plasticization effect imposed by CO2 molecules. Consequently, CO2 molecules are expelled from the crystalline area of PCGF40 resin (26−28) and the CO2 concentration dropped. Furthermore, it was noted that the foaming magnification exhibited a slight increase with temperature, as shown in Figure 1b. Specifically, for samples impregnated at 12.5 MPa, the foaming magnification was slightly higher up to 130 °C compared to those observed at 10 MPa, with a subsequent slight decrease beyond 130 °C. As the heating temperature rises, there is a slight increase in foaming magnification due to the rapid nucleation of CO2 gas in the amorphous regions. However, the presence of crystalline regions continues to impose a restriction on cell growth.

3.2. CO2 Gas Bubble Visualization Using X-ray CT

After CO2 saturation at 12.5 MPa and the heating process, the specimens underwent X-ray CT imaging to visualize bubbles at the interface as well as within the PCGF40 resin, as shown in Figure 2. Figure 2a shows the X-ray CT images of the control sample, revealing no evidence of gas bubbles at the interface and no cracking in the PCGF40 matrix, and the sample impregnated at 12.5 MPa with subsequent heating at 140 °C shows numerous gas bubbles at the interface, accompanied by cracking in the matrix. Samples impregnated at 12.5 MPa, both without and with subsequent heating at various temperatures (110–150 °C), are shown in Figure 2b. We observed that the specimen impregnated under a pressure of 12.5 MPa at a temperature of 80 °C, without subsequent heating, exhibited bubbles at the Al/PCGF40 interface, along with observable fracture in the resin. Additionally, small amounts or negligible bubbles were observed within the polymer resin. This observation can be attributed to the presence of the crystalline phase in the polymer matrix, where the polymer chains fold and more closely align to form highly ordered regions, consequently reducing the available free volume for the dissolution of gas molecules, as depicted schematically in Figure 4. As a result of this, CO2 gas migrates from the crystalline region to the amorphous region of the polymer matrix. The X-ray CT images reveal the existence of an amorphous region at the interface, characterized by a large number of bubbles. Furthermore, upon heating the Al/PCGF40 samples, bubble nucleation at the interface was observed, as discussed in our previous study. (18) However, the fracture area of the PCGF40 matrix increased with higher heating temperatures. Numerous small bubbles were observed at the interface in the sample heated at 110 °C. Conversely, large and numerous bubbles were evident at the interface in the sample heated at 140 °C. Samples heated at 120 and 150 °C exhibit large fractures in the polymer matrix near the interface, which might be the cause of the lower separation load. The fracture in the polymer at the interface might be due to the increasing bubble nucleation, resulting in the coalescence of the bubbles.

Figure 2

Figure 2. X-ray CT images of (a) the control sample and impregnated sample under 12.5 MPa pressure, followed by heating at 140 °C, and (b) the lap-shear specimen impregnated at 12.5 MPa without subsequent heating and heating at 110–150 °C (bubbles at the interface indicated by white triangles and the cracking indicated by red arrows).

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3.3. Crystallinity in the PCGF40 at Various Saturation Pressures and a Constant Temperature of 80 °C

The DSC curves for the control sample and samples impregnated at 5, 7.5, 10, and 12.5 MPa saturation pressures, at a constant temperature of 80 °C, were depicted in Figure 3. No melting peaks were observed for the control sample, as well as for samples saturated at 5 and 7.5 MPa; instead, only a glass transition temperature (Tg) pattern at around 140 °C was evident. For the sample saturated under 10 MPa pressure at 80 °C, a small endothermic melting (Tm1) peak at approximately 169.4 °C along with Tg, was observed, indicating the presence of confined secondary crystallization in the sample. Two distinct melting temperature peaks were observed for the sample saturated at a higher pressure of 12.5 MPa, at a constant temperature of 80 °C, without subsequent heating, suggesting increased mobility of polymer molecular chains and more stable crystallization in the PCGF40 resin. The higher temperature peak, Tm2 (224.3 °C), is associated with primary crystals, while the lower temperature peak, Tm1 (166.6 °C), is associated with secondary crystals. The higher temperature peak appeared slightly broader than the lower temperature peak, indicating a higher fraction of primary crystals. A subtle effect of subsequent heating on the crystallization of the impregnated samples was observed. The lower endothermic melting (Tm1) peaks were observed at 169.6, 169.5, 167.3, 171.4, 171.1, and 171.9 °C, while the higher endothermic melting (Tm2) peaks were recorded at 220.6, 221.3, 222.1, 223.0, 224.7, and 223.7 °C for the samples heated at 100–150 °C, respectively. The lower endothermic melting peaks observed in the heated samples were sharp and slightly shifted toward higher temperatures compared to the sample without heating, indicating the presence of stable secondary crystals. However, the higher endothermic melting peaks in the heated samples were broader and appeared at slightly lower temperatures than those of the sample without heating, suggesting that the sample without heating possesses stable primary crystals compared to the heated samples. A slight shift toward higher temperatures was observed in both the lower endothermic melting (Tm1) and higher endothermic melting (Tm2) peaks with subsequent heating of the impregnated samples, indicating a subtle increase in crystallization. The degree of crystallinity (χ) of each sample was calculated using eq 1 and is listed in Table 1.
χ(%)=ΔHfΔHf°×100
(1)
where ΔHf and ΔHf° are the enthalpy of fusion of the samples and pure crystalline polycarbonate (ΔHf° = 109.7 J/g), respectively. (28,29) ΔHf was determined from the DSC thermogram by calculating the peak area corresponding to each Tm.

Figure 3

Figure 3. DSC thermogram for the control sample and samples impregnated under saturation pressures of 5, 7.5, 10, and 12.5 MPa (with and without subsequent heating), at a constant temperature of 80 °C.

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Table 1. Crystallization Behavior of PCGF40 Impregnated at 5, 7.5, 10, and 12.5 MPa at a Constant Saturation Temperature of 80 °C
     enthalpy of fusion% crystallinitytotal crystallinity
saturation pressure Psat (MPa)heating temperature (°C)glass transition temperature Tg (°C)Tm1 (°C)Tm2 (°C)ΔHf1 (J/g)ΔHf2 (J/g)χ1χ2χ (%)
control 140       
5 135       
7.5 139       
10 140169.4 1.9 1.7 1.7
12.5  166.6224.36.613.76.012.518.5
12.5100 169.6220.612.07.511.06.817.8
12.5110 169.5221.37.89.27.28.415.6
12.5120 167.3222.18.614.17.912.920.8
12.5130 171.422310.39.59.48.618.0
12.5140 171.1224.76.811.66.210.616.8
12.5150 171.9223.79.111.38.310.318.6
Analysis of the crystallinity data reveals that the sample impregnated at 10 MPa exhibited a lower degree of crystallinity (1.7%), primarily attributable to secondary crystals. Conversely, samples impregnated at 12.5 MPa demonstrated enhanced crystallinity compared to the 10 MPa counterparts, indicative of the presence of both primary and secondary crystals. The sample impregnated at 12.5 MPa without subsequent heating exhibits a degree of crystallinity of 18.5%, nearly 10 times higher than that of the sample impregnated at 10 MPa. Furthermore, upon subsequent heating at temperatures ranging from 100 to 150 °C, the degree of crystallinity ranged from 15.5 to 20.7%, indicating slight differences.

3.4. Mechanism of Crystallization and Cracking in PCGF40

The process of crystallization and cracking, attributed to the plasticization effect due to CO2 molecules, is elucidated in Figure 4. Initially, under high pressure, the saturation process occurs, leading to the dissolution of CO2 molecules within the PCGF40 resin. This initiates a series of molecular rearrangements within the polymer chains, which in turn triggers the formation of a crystalline structure. Concurrently, as the polymer chains undergo rearrangement, CO2 gas molecules begin to migrate toward the amorphous regions within the PCGF40 matrix, as shown in Figure 4a. (26−28,30) However, it is notable that the saturation temperature exerts a greater influence on inducing crystallization compared to saturation pressure. (28) Due to the migration of CO2 gas molecules toward the amorphous regions, a significant portion of these molecules tends to accumulate between the spherulites─the spherical crystalline structures that form during the crystallization process. The interface between spherulites and the amorphous region functions as a heterogeneous nucleation site with a low Gibbs free energy barrier, promoting cell nucleation. (25,31) Furthermore, not only do the spherulites serve as nucleation sites but also the surfaces of the glass fibers within the matrix act as heterogeneous nucleation sites, facilitating cell nucleation. As the saturation process progresses, additional CO2 gas continues to diffuse into the amorphous regions situated between the spherulites and the glass fibers of the PCGF40 matrix. This influx of CO2 exerts extensional forces toward the spherulites and glass fibers, which results in stress accumulation within the amorphous regions. Eventually, this stress surpasses the material’s threshold, leading to cracking within the amorphous area as shown in Figure 4b.

Figure 4

Figure 4. Mechanisms of (a) crystallization and (b) cracking in PCGF40 resin under high-pressure CO2 dissolution.

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3.5. Tensile Lap-Shear Strength

The maximum separation load [N] for the Al/PCGF40 sample, impregnated under a saturation pressure of 12.5 MPa and subsequently heated at various temperatures (110–150 °C), was determined through a tensile lap-shear strength test, as shown in Figure 5. Figure 5a displays the load–displacement curves for the control and the samples impregnated at 12.5 MPa without subsequent heating and with heating at 140 °C. It is evident that the maximum separation load was reduced by approximately half (∼511 N) for the sample only impregnated without further heating, whereas an extensive reduction (∼58 N) was observed for the sample impregnated under a pressure of 12.5 MPa subsequently heated at 140 °C, as compared to the control sample (1250 N).

Figure 5

Figure 5. (a) Load (N)–displacement (mm) curves of control and impregnated (12.5 MPa without heating and with heating at 140 °C) samples. (b) Maximum separation load (N) of the control (*), samples only impregnated (**), and samples impregnated with subsequent heating at 110–150 °C.

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Figure 5b illustrates the maximum separation load (N) for the control and the samples impregnated at 12.5 MPa without subsequent heating and with heating at various temperatures (110–150 °C). The maximum separation load was observed to decrease when impregnating the Al/PCGF40 sample at a saturation pressure of 12.5 MPa, attributed to the presence of bubbles at the interface and the fracture of polymer matrix induced by crystallization at high saturation pressure, as depicted in the X-ray CT images (Figure 2). Upon heating the impregnated samples at temperatures ranging from 110 to 150 °C, a significant decline in the maximum separation load was noted. This reduction can be attributed to bubble nucleation at the interface and the widening of the fractured area in the polymer matrix. The substantial decrease in the maximum separation load of the lap-shear Al/PCGF40 specimen under a saturation pressure of 12.5 MPa with subsequent heating can prove to be highly advantageous for the effortless separation of multilayered materials.

3.6. Remaining Residual Resin at the Aluminum Surface

Measuring the remaining residual polymer on the engraved surface of the Al after the tensile lap-shear strength test can serve as evidence of the complete separation of the multimaterials. The remaining residue of the PCGF40 on the Al surface is depicted in Figure 6. Microscopic images (Figure 6a) of the engraved area of the Al for the samples impregnated with subsequent heating clearly indicate that the maximum residue of the PCGF40 was observed for the sample heated at 150 °C compared to those obtained at lower temperatures (120–140 °C). In Figure 6b, the residual resin area ratio for the control and the samples impregnated at 12.5 MPa without further heating and with heating at 110–150 °C clearly demonstrates a decrease in the residual resin area ratio on heating from 110 to 140 °C, followed by an increase at 150 °C, consistent with the microscopic images. As the heating temperature increases, bubbles nucleate at the interface and between the spherulites. Consequently, at high temperatures, cohesive failure in PCGF40 resin becomes predominant. (18) The sample only impregnated without further heating exhibits slightly higher residue than the control sample. Samples heated at 120 and 150 °C show high residue but demonstrate a small maximum separation load, which might be attributed to cohesive failure resulting from the fracture in the polymer matrix. The smallest residue is observed for the sample heated at 140 °C.

Figure 6

Figure 6. (a) Microscopic images of engraved surface of aluminum substrate after a tensile lap-shear strength measurement for 12.5 MPa with subsequent heating at 120–150 °C. (b) Residual resin area ratio on aluminum substrate for the control (*), samples only impregnated at 12.5 MPa (**), and samples impregnated with subsequent heating at 110–150 °C.

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3.7. Relationship between Residual Resin Area and Relative Maximum Separation Load

The relationship between residual resin and relative maximum separation load is illustrated in Figure 7. A significant reduction in the maximum separation load of 12.5 MPa is evident across all samples compared to those obtained for the control sample. A sample only impregnated without further heating exhibits the highest maximum load, with residual resin even surpassing that of the control sample. Samples subjected to heating after impregnation show reduction in both maximum load and residual resin. The lowest maximum separation load, accompanied by the lowest residual resin, is observed for the sample heated at 140 °C.

Figure 7

Figure 7. Relative maximum load (N) and residual resin area ratio for the control (intersection point of black lines), and samples impregnated at 12.5 MPa with subsequent heating at 110–150 °C and without heating.

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In our previous study, we achieved the smallest maximum load and residue at a saturation pressure of 10 MPa with subsequent heating at 130 °C, amounting to just half (∼600 N) of the control sample. (18) We have achieved a remarkable reduction of approximately 95% (∼58 N) in the maximum separation load at a saturation pressure of 12.5 MPa with subsequent heating at 140 °C, in comparison to the control sample.

4. Conclusions

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An extensive reduction in the maximum separation load for the easy delamination of Al/PCGF40 was successfully achieved by impregnating CO2 gas at a saturation pressure of 12.5 MPa and a constant temperature of 80 °C, followed by subsequent heating at 140 °C. We observed that at a pressure of 12.5 MPa, there was a decrease in gas concentration in the PCGF40 resin during the saturation process. This reduction was attributed to crystallinity occurring at high saturation pressure due to the plasticization effect, as confirmed by the DSC data. The crystallization led to the fracture of the polymer matrix, causing CO2 bubbles to expel into the amorphous region, particularly at the interface side, as confirmed by X-ray CT images. With an increase in heating temperature, the bubbles started to nucleate, resulting in a small maximum separation load, as confirmed by the tensile lap-shear strength data. The smallest maximum separation load (∼58 N) and residue were obtained for the sample impregnated with subsequent heating at 140 °C. We achieved a substantial reduction of approximately 95% in the maximum separation load compared to the control sample, which could significantly improve the recyclability of EVs. Although this method achieves nearly complete delamination of metal–polymer composites, there are still a few challenges. Long saturation time and high saturation pressure could pose significant issues for industrial applications.

Author Information

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  • Corresponding Author
  • Authors
    • Rajesh Kumar Sharma - School of Frontier Engineering, College of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan;  Orcidhttps://orcid.org/0000-0001-6285-4317
    • Yuto Mori - School of Mechanical Science, Graduate School of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
    • Soichiro Kishimoto - School of Mechanical Science, Graduate School of Science and Engineering, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
    • Ryotaro Okuda - Graduate School of Organic Material Science, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
    • Hiroshi Ito - Graduate School of Organic Material Science, Yamagata University, Yonezawa, Yamagata 992-8510, Japan;  Orcidhttps://orcid.org/0000-0001-8432-8457
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The current study received support through a grant (JPMJCR21L3) from JST-CREST, Japan. The authors express gratitude to the Aichi Synchrotron Radiation Center, Nagoya, Japan, for providing access to their X-ray CT facility at the BL8S2 beamline. The authors are also very grateful to Professor Katsuhisa Tokumitsu and Dr. Takumitsu Kida for generously allowing the use of the DSC facility at the University of Shiga Prefecture, Japan.

References

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This article references 31 other publications.

  1. 1
    Wazeer, A.; Das, A.; Abeykoon, C.; Sinha, A.; Karmakar, A. Composites for Electric Vehicles and Automotive Sector: A Review. Green Energy Intell. Transp. 2023, 2, 100043  DOI: 10.1016/j.geits.2022.100043
    Google Scholar
    There is no corresponding record for this reference.
  2. 2
    Azzopardi, B.; Hapid, A.; Kaleg, S.; Sudirja; Onggo, D.; Budiman, A. C. Recent Advances in Battery Pack Polymer Composites. Energies. 2023, 16, 6223,  DOI: 10.3390/en16176223
    Google Scholar
    There is no corresponding record for this reference.
  3. 3
    Delogu, M.; Zanchi, L.; Dattilo, C. A.; Pierini, M. Innovative Composites and Hybrid Materials for Electric Vehicles Lightweight Design in a Sustainability Perspective. Mater. Today Commun. 2017, 13, 192– 209,  DOI: 10.1016/j.mtcomm.2017.09.012
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    3
    Innovative composites and hybrid materials for electric vehicles lightweight design in a sustainability perspective
    Delogu, M.; Zanchi, L.; Dattilo, C. A.; Pierini, M.
    Materials Today Communications (2017), 13 (), 192-209CODEN: MTCAC7; ISSN:2352-4928. (Elsevier Ltd.)
    Lightwt. design and electrified powertrain have become important strategies in the automotive industry to reduce fuel demand and break down emissions resp. Lightweighting of Elec. Vehicles (EVs) is considered a step forward because advantages of both EVs and lightwt. design could be combined to reduce environmental impacts even further. This paper would contribute to the advancement of knowledge in this field and it deals with the environmental anal., by means of Life Cycle Assessment (LCA), of composite-based and hybrid material lightwt. solns. for EVs modules in comparison with the corresponding ref. ones, by assuming no changes in the powertrain system (e.g. battery resizing). Particular attention is given to primary data collection to build the environmental eco-profiles of four innovative composites. Then, a four-level approach to interpret LCA outcomes in a clear and comprehensive way is proposed in this paper. Despite the relevant mass redn., environmental benefits are not registered for all the analyzed solns., and the main reason is the large impact from the prodn. stage of the new materials, raw materials particularly. Outcomes from this paper showed that Abiotic Depletion Potential (ADPel.) generally had a different trend if compared to Global Warming Potential (GWP) and Primary Energy Demand (PED) so their evaluation in parallel is recommended. Overall, the innovative materials that have a high impact in the prodn. stage could not be suitable in the case of EVs where the emission rate in the use stage is lower than the one of traditional vehicle, so a different application should be also evaluated.
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  4. 4
    Melentiev, R.; Yudhanto, A.; Tao, R.; Vuchkov, T.; Lubineau, G. Metallization of Polymers and Composites: State-of-the-Art Approaches. Mater. Des. 2022, 221, 110958  DOI: 10.1016/j.matdes.2022.110958
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    4
    Metallization of polymers and composites: State-of-the-art approaches
    Melentiev, Ruslan; Yudhanto, Arief; Tao, Ran; Vuchkov, Todor; Lubineau, Gilles
    Materials & Design (2022), 221 (), 110958CODEN: MADSD2; ISSN:0264-1275. (Elsevier Ltd.)
    A review. Polymers and their composites are widely used for designing structures in aerospace, automotive, electronic, sport industries due to their lightwt., cost, and processing advantages. However, the surface of polymeric materials typically exhibits intrinsic deficiencies, limiting their durability and functionalities, e.g., low wear resistance, low thermal and elec. cond., low adhesion, low bioactivity, low reflectiveness, and weak photochem. resistance. Polymer metalization is an emerging concept that addresses these deficiencies by forming a metallic skin on polymeric surfaces. Herein, the working principles, recent advances, challenges, functional capabilities, and applications of the state-of-the-art polymer metalization methods in the fields of additive manufg., coating technologies, and material science are reviewed on nano-, micro-, and macroscales. The polymer metalization methods applied to polymeric and polymer composite substrates are phys. vapor deposition, electrochem. plating, a family of thermal spray methods (such as flame spaying, arc spraying, plasma spraying, and cold spraying), and a series of polymer-metal direct bonding methods (such as adhesive bonding, injection overmolding, and fusion joining techniques, including ultrasonic joining, friction spot joining, electromagnetic induction joining, and laser joining). Understanding the key aspects within these approaches would guide scientist and engineers for optimizing the design and durability of structural materials made of polymers/composites.
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  5. 5
    Nazir, A.; Gokcekaya, O.; Md Masum Billah, K.; Ertugrul, O.; Jiang, J.; Sun, J.; Hussain, S. Multi-Material Additive Manufacturing: A Systematic Review of Design, Properties, Applications, Challenges, and 3D Printing of Materials and Cellular Metamaterials. Mater. Des. 2023, 226, 111661  DOI: 10.1016/j.matdes.2023.111661
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    There is no corresponding record for this reference.
  6. 6
    Blanco, D.; Rubio, E. M.; Marín, M. M.; Davim, J. P. Advanced Materials and Multi-Materials Applied in Aeronautical and Automotive Fields: A Systematic Review Approach. Procedia CIRP. 2021, 99, 196– 201,  DOI: 10.1016/j.procir.2021.03.027
    Google Scholar
    There is no corresponding record for this reference.
  7. 7
    Huang, Y.; Gao, X.; Zhang, Y.; Ma, B. Laser Joining Technology of Polymer-Metal Hybrid Structures - A Review. J. Manuf. Process. 2022, 79, 934– 961,  DOI: 10.1016/j.jmapro.2022.05.026
    Google Scholar
    There is no corresponding record for this reference.
  8. 8
    Kajihara, Y.; Tamura, Y.; Kimura, F.; Suzuki, G.; Nakura, N.; Yamaguchi, E. Joining Strength Dependence on Molding Conditions and Surface Textures in Blast-Assisted Metal-Polymer Direct Joining. CIRP Ann. 2018, 67 (1), 591– 594,  DOI: 10.1016/j.cirp.2018.04.112
    Google Scholar
    There is no corresponding record for this reference.
  9. 9
    Taki, K.; Nakamura, S.; Takayama, T.; Nemoto, A.; Ito, H. Direct Joining of a Laser-Ablated Metal Surface and Polymers by Precise Injection Molding. Microsyst. Technol. 2016, 22 (1), 31– 38,  DOI: 10.1007/s00542-015-2640-2
    Google Scholar
    9
    Direct joining of a laser-ablated metal surface and polymers by precise injection molding
    Taki, Kentaro; Nakamura, Shuhei; Takayama, Tetsuo; Nemoto, Akihiko; Ito, Hiroshi
    Microsystem Technologies (2016), 22 (1), 31-38CODEN: MCTCEF; ISSN:0946-7076. (Springer)
    The joining of metal and polymer surfaces is a promising technol. to reduce the total wt. of parts and to improve interface reliability. In this study, a micro square grid (200 μm × 200 μm) was fabricated on an aluminum surface using laser ablation. Molten glass-reinforced poly(butylene terephthalate), poly(styrene) and acrylonitrile-butadiene-styrene were introduced to the micro square grids by a precise injection molding machine. The max. load tensile test was used as a measure of the joining strength between aluminum and the polymer. The tensile strength tests assisted in the differentiation of three modes of sepn.: interface-peeling, cohesive failure and matrix fracture. The max. load increased with the effective joined area where interface-peeling was obsd. The max. load ceased at a certain effective joined area, and matrix fracture occurred. Cohesive failure was obsd. where the effective joined area was smaller than the area for which matrix fracture was obsd., and the joined strength was larger than that obsd. for interface-peeling. The max. stress, which was calcd. by dividing cross-sectional area by the max. load, at the matrix fracture was proportional to the polymer tensile strength.
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  10. 10
    Ramani, K.; Moriarty, B. Thermoplastic Bonding to Metals via Injection Molding for Macro-Composite Manufacture. Polym. Eng. Sci. 1998, 38 (5), 870– 877,  DOI: 10.1002/pen.10253
    Google Scholar
    10
    Thermoplastic bonding to metals via injection molding for macro-composite manufacture
    Ramani, Karthik; Moriarty, Brendan
    Polymer Engineering and Science (1998), 38 (5), 870-877CODEN: PYESAZ; ISSN:0032-3888. (Society of Plastics Engineers)
    In this work, we explore a new method of in-situ joining of polymers to metals in injection molding to allow direct bonding between thermoplastic and metal parts. Such a method can integrate several downstream steps in product manuf., allow optimal design of products and joints, and avoid adhesive application, assembly, and assocd. difficulties. A variety of process parameters and their effects upon the interface tensile strengths were examd. A full-factorial expt. was conducted involving four of the crit. process parameters identified. The effects upon tensile strength at break of the following process parameters were studied: 1) adherend surface temp., 2) screw linear velocity, 3) bondline thickness, and 4) pack and hold pressure. The fracture surfaces and the thermoplastic metal interfaces were analyzed. The bonds fabricated with higher adherend surface temps. have increased mean tensile strength and less adhesive failure. This increase in mean bond tensile strength and less adhesive failure was due to increased polymer penetration of the adherend surface roughness, at the micrometer level, as shown in the anal. of the polymer-metal interface by a scanning electron microscope (SEM). Polycarbonate bonded to aluminum is used to illustrate.
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  11. 11
    Grujicic, M.; Sellappan, V.; Omar, M. A.; Seyr, N.; Obieglo, A.; Erdmann, M.; Holzleitner, J. An Overview of the Polymer-to-Metal Direct-Adhesion Hybrid Technologies for Load-Bearing Automotive Components. J. Mater. Process. Technol. 2008, 197 (1–3), 363– 373,  DOI: 10.1016/j.jmatprotec.2007.06.058
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    11
    An overview of the polymer-to-metal direct-adhesion hybrid technologies for load-bearing automotive components
    Grujicic, M.; Sellappan, V.; Omar, M. A.; Seyr, Norbert; Obieglo, Andreas; Erdmann, Marc; Holzleitner, Jochen
    Journal of Materials Processing Technology (2008), 197 (1-3), 363-373CODEN: JMPTEF; ISSN:0924-0136. (Elsevier B.V.)
    A review. The work published in the open literature dealing with various polymer metal hybrid (PMH) approaches used to promote direct (adhesive-free) adhesion between metal and injection-molded thermoplastics is reviewed and critiqued. Different approaches are categorized as follows: (a) micro-scale polymer-to-metal mech. interlocking; (b) in-coil or stamped-part pre-coating for enhanced adhesion; and (c) chem. modifications of the injection-molded thermoplastics for enhanced polymer-to-metal adhesion. For each of these approaches their suitability for use in load-bearing body-in-white (BIW) components is discussed. In particular, the compatibility of these approaches with the BIW manufg. process chain (i.e. pre-coated metal component stamping, BIW construction via different joining technologies, BIW pre-treated and painting operations) is presented. It has been found that while considerable amt. of research has been done in the PMH direct-adhesion area, many aspects of these technologies which are crit. from the standpoint of their use in the BIW structural applications have not been addressed (or addressed properly). Among the PMH technologies identified, the one based on micro-scale mech. inter locking between the injection-molded thermoplastic polymer and stamped-metal structural rib component appears to be most promising.
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  12. 12
    Zhao, S.; Kimura, F.; Kadoya, S.; Kajihara, Y. Experimental Analysis on Mechanical Interlocking of Metal-Polymer Direct Joining. Precis. Eng. 2020, 61, 120– 125,  DOI: 10.1016/j.precisioneng.2019.10.009
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    There is no corresponding record for this reference.
  13. 13
    Samorì, C.; Cespi, D.; Blair, P.; Galletti, P.; Malferrari, D.; Passarini, F.; Vassura, I.; Tagliavini, E. Application of Switchable Hydrophilicity Solvents for Recycling Multilayer Packaging Materials. Green Chem. 2017, 19, 1714– 1720,  DOI: 10.1039/C6GC03535C
    Google Scholar
    13
    Application of switchable hydrophilicity solvents for recycling multilayer packaging materials
    Samori, Chiara; Cespi, Daniele; Blair, Paola; Galletti, Paola; Malferrari, Danilo; Passarini, Fabrizio; Vassura, Ivano; Tagliavini, Emilio
    Green Chemistry (2017), 19 (7), 1714-1720CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)
    A new procedure based on switchable hydrophilicity solvents (SHS) was proposed for polyethylene and aluminum recovery from food aseptic packaging. Treatment with N,N-dimethylcyclohexylamine (DMCHA) allowed very high material recovery (>99% for aluminum and >80% for polyethylene), without compromising the quality in terms of oxidn. or polymer degrdn. Moreover, the results from a simplified and preliminary life cycle anal. confirm the potential environmental benefits of a SHS approach compared with other treatment and disposal scenarios.
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  14. 14
    Zhang, S.; Luo, K.; Zhang, L.; Mei, X.; Cao, S.; Wang, B. Interfacial Separation and Characterization of Al-PE Composites During Delamination of Post-Consumer Tetra Pak Materials. J. Chem. Technol. Biotechnol. 2015, 90 (6), 1152– 1159,  DOI: 10.1002/jctb.4573
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    14
    Interfacial separation and characterization of Al-PE composites during delamination of post-consumer Tetra Pak materials
    Zhang, Sufeng; Luo, Ke; Zhang, Lulu; Mei, Xingxian; Cao, Shumiao; Wang, Baiji
    Journal of Chemical Technology and Biotechnology (2015), 90 (6), 1152-1159CODEN: JCTBED; ISSN:0268-2575. (John Wiley & Sons Ltd.)
    In order to understand Al-PE composite delamination during the sepn. process, interfacial sepn. and characterization of Al-PE composites during delamination were analyzed. The aim was to enrich the present theor. anal. of Al-PE sepn. and to provide new ideas for the recycling and reuse of post-consumer Tetra Paks. The composites delaminated into three layers, but the times for delamination of the two plastic layers were different. After sepn., some plastics were present in the sepn. solvents analyzed by FTIR. Bright spots of unregular particles with scattered distribution on the surfaces of the three layers were Al, O and C, detected by SEM-EDS. During the sepn. reaction a mixed soln. permeates into the interfaces of Al-PE composites; adhesive structures of the PE layers were destroyed and even dissolved into particles, thus interfacial adhesive failure and Al-PE sepn. occurred. However the different properties of the adhesive layers and the oxidn. degree of PE fragments cause different sepn. speeds of the two interfaces adhered to each side of the Al foil.
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  15. 15
    Yang, Y.; Boom, R.; Irion, B.; van Heerden, D. J.; Kuiper, P.; de Wit, H. Recycling of Composite Materials. Chem. Eng. Process. 2012, 51, 53– 68,  DOI: 10.1016/j.cep.2011.09.007
    Google Scholar
    15
    Recycling of composite materials
    Yang, Yongxiang; Boom, Rob; Irion, Brijan; van Heerden, Derk-Jan; Kuiper, Pieter; de Wit, Hans
    Chemical Engineering and Processing (2012), 51 (), 53-68CODEN: CENPEU; ISSN:0255-2701. (Elsevier B.V.)
    A review. Composite materials are used in a wide range of applications such as automotive, aerospace and renewable energy industries. But they have not been properly recycled, due to their inherent nature of heterogeneity, in particular for the thermoset-based polymer composites. The current and future waste management and environmental legislations require all engineering materials to be properly recovered and recycled, from end-of-life (EOL) products such as automobiles, wind turbines and aircrafts. Recycling will ultimately lead to resource and energy saving. Various technologies, mostly focusing on reinforcement fibers and yet to be commercialized, have been developed: mech. recycling, thermal recycling, and chem. recycling. However, lack of adequate markets, high recycling cost, and lower quality of the recyclates are the major commercialization barriers. To promote composites recycling, extensive R&D efforts are still needed on development of ground-breaking better recyclable composites and much more efficient sepn. technologies. It is believed that through the joint efforts from design, manufg., and end-of-life management, new sepn. and recycling technologies for the composite materials recycling will be available and more easily recyclable composite materials will be developed in the future.
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  16. 16
    Knappich, F.; Schlummer, M.; Mäurer, A.; Prestel, H. A New Approach to Metal- and Polymer-Recovery from Metallized Plastic Waste using Mechanical Treatment and Subcritical Solvents. J. Mater. Cycles Waste Manag. 2018, 20, 1541– 1552,  DOI: 10.1007/s10163-018-0717-6
    Google Scholar
    There is no corresponding record for this reference.
  17. 17
    Krauklis, A. E.; Karl, C. W.; Gagani, A. I.; Jørgensen, J. K. Composite Material Recycling Technology─State-of-the-Art and Sustainable Development for the 2020s. J. Compos. Sci. 2021, 5, 28,  DOI: 10.3390/jcs5010028
    Google Scholar
    There is no corresponding record for this reference.
  18. 18
    Mori, Y.; Kishimoto, S.; Sharma, R. K.; Taki, K. Bubble Nucleation-Induced Interfacial Delamination of a Lap-Shear Aluminum/Glass Fiber-Reinforced Polycarbonate Specimen by CO2 Gas Impregnation and Subsequent Heating. Ind. Eng. Chem. Res. 2023, 62 (39), 15919– 15927,  DOI: 10.1021/acs.iecr.3c02107
    Google Scholar
    There is no corresponding record for this reference.
  19. 19
    Taki, K.; Yanagimoto, T.; Funami, E.; Okamoto, M.; Ohshima, M. Visual Observation of CO2 Foaming of Polypropylene-Clay Nanocomposites. Polym, Eng. Sci. 2004, 44 (6), 1004– 1011,  DOI: 10.1002/pen.20093
    Google Scholar
    19
    Visual observation of CO2 foaming of polypropylene-clay nanocomposites
    Taki, Kentaro; Yanagimoto, Tatsunori; Funami, Eita; Okamoto, Masami; Ohshima, Masahiro
    Polymer Engineering and Science (2004), 44 (6), 1004-1011CODEN: PYESAZ; ISSN:0032-3888. (John Wiley & Sons, Inc.)
    Using a newly developed high-pressure autoclave, which has two sapphire windows on the walls, we visually obsd. the batch phys. foaming of polymer-clay nanocomposites to understand the effect of nano-sized clay on the initial stage of foaming. With CO2 as a phys. foaming agent, polypropylene-montmorillonite clay nanocomposites were foamed at 150°C. A high-speed digital camera with a microscope could observe the bubble nucleation and bubble growth behavior of the early stage of foaming in situ. The series of micrographs was analyzed in order to investigate the effect of clay content on bubble nucleation and growth. The expts., together with CO2-soly. and diffusivity data, show that the clay enhances bubble nucleation as a nucleation agent and retards the growth of bubbles at the early stage of foaming.
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  20. 20
    Ito, A.; Semba, T.; Taki, K.; Ohshima, M. Effect of the Molecular Weight Between Crosslinks of Thermally Cured Epoxy Resins on the CO2-Bubble Nucleation in a Batch Physical Foaming Process. J. Appl. Polym. Sci. 2014, 131 (12), 40407,  DOI: 10.1002/app.40407
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    20
    Effect of the molecular weight between crosslinks of thermally cured epoxy resins on the CO2-bubble nucleation in a batch physical foaming process
    Ito, Akihiro; Semba, Takeshi; Taki, Kentaro; Ohshima, Masahiro
    Journal of Applied Polymer Science (2014), 131 (12), 40407/1-40407/8CODEN: JAPNAB; ISSN:0021-8995. (John Wiley & Sons, Inc.)
    Epoxy resins (bisphenol A type epoxy resins/2-ethyl-4-methylimidazole) consisting of oligomers with different mol. wts. were foamed using a temp.-quench phys. foaming method with CO2. The resulting cell morphologies could be classified into four types: non-foamed structure, cracked structure, star-shaped structure, and sphere-shaped structure. The effects of the gel fraction and mol. wt. between crosslinks (MC) on the cell morphol. were investigated for the prepn. of microcellular epoxy foams. MC was calcd. by measuring the plateau rubber modulus of the rheol. properties and the wt. uptake of acetone. By varying the mol. wt. of the epoxy oligomers and the cure time, the MC of the epoxy was controlled to modulate the cell morphol. The expts. elucidated the threshold MC value that permits CO2-bubble nucleation: CO2-bubble nucleation in the epoxy resin could be induced when the distance between the crosslinking points exceeded the crit. size of bubble nucleus. Based on this information, the microcellular epoxy foam was prepd. by maintaining MC above 104g mol-1 and the complex modulus above 6 × 108 Pa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40407.
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  21. 21
    Taki, K.; Kitano, D.; Ohshima, M. Effect of Growing Crystalline Phase on Bubble Nucleation in Poly(L-Lactide)/CO2 Batch Foaming. Ind. Eng. Chem. Res. 2011, 50 (6), 3247– 3252,  DOI: 10.1021/ie101637f
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    21
    Effect of Growing Crystalline Phase on Bubble Nucleation in Poly(L-Lactide)/CO2 Batch Foaming
    Taki, Kentaro; Kitano, Daisaku; Ohshima, Masahiro
    Industrial & Engineering Chemistry Research (2011), 50 (6), 3247-3252CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)
    Creating a high-efficiency bubble nucleation agent for a polymer foaming process is essential for increasing bubble d. as well as decreasing bubble size. Spherulites (cryst. phase) grown in a semicryst. poly(L-lactide) (PLLA) matrix enhanced carbon dioxide (CO2) bubble nucleation in a batch foaming process. Several sites for PLLA spherulite formation were obsd. at a hold-temp. of 110°C after CO2 satn. in molten PLLA, which was heated to 180°C at 11 MPa. By depressurizing the system from 11 MPa to atm. pressure, the dissolved CO2 in the PLLA matrix became supersatd., and CO2 bubbles nucleated around growing PLLA spherulites. The no. of nucleating bubbles increased as a function of increasing spherulite quantity and area. A faster linear spherulite growth rate and a lower hold-temp. created more bubbles around the spherulites. From these observations, it was concluded that the growing spherulites expelled CO2 from the advancing spherulite-amorphous phase interface and that CO2 accumulated at the interface. Then, the increase in the concn. of CO2 led to an increase in the nucleation of bubbles around the spherulites.
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  22. 22
    Chai, J.; Wang, G.; Zhao, J.; Zhang, A.; Shi, Z.; Wei, C.; Zhao, G. Microcellular PLA/PMMA Foam Fabricated by CO2 foaming with Outstanding Shape-Memory Performance. J. CO2 Util. 2021, 49, 101553  DOI: 10.1016/j.jcou.2021.101553
    Google Scholar
    22
    Microcellular PLA/PMMA foam fabricated by CO2 foaming with outstanding shape-memory performance
    Chai, Jialong; Wang, Guilong; Zhao, Jinchuan; Zhang, Aimin; Shi, Zhanlin; Wei, Chao; Zhao, Guoqun
    Journal of CO2 Utilization (2021), 49 (), 101553CODEN: JCUOAJ; ISSN:2212-9839. (Elsevier Ltd.)
    Porous shape memory polymers (SMPs) are attracting people's attention due to their extensive application prospect. Herein, a novel and flexible method to produce bio-friendly polylactic acid (PLA)/polymethyl methacrylate (PMMA) shape memory foam by a two-step CO2 microcellular foaming is proposed. The achieved foams exhibit outstanding shape memory performance, such as a max. shape fixity ratio of 98 %, a max. shape recovery ratio of 86 %, and further the recovery ratio remaining more than 75 % even after 10 compression-recovery cycles. The additive PMMA phases uniformly disperse with spherical morphol. in nanoscale, and they result in the greatly decreased crystallinity and crystal size of PLA. Meanwhile, the extensive interfaces lead to increased crystal d. In this context, more amorphous mol. chains left in the cell wall act as reversible segments, and more numerous denser crystals act as net points, which together can decrease the resistance in the shape memory process, thus, facilitating the significant promotion of shape memory capability of the as-achieved PLA/PMMA foams. Therefore, it exhibits a promising future to produce environmentally friendly SMPs by a simple, cost-efficient, and clean microcellular foaming technol.
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  23. 23
    Liao, X.; Wang, J.; Li, G.; He, J. Effect of Supercritical Carbon Dioxide on the Crystallization and Melting Behavior of Linear Bisphenol A Polycarbonate. J. Polym. Sci. B Polym. Phys. 2004, 42 (2), 280– 285,  DOI: 10.1002/polb.10597
    Google Scholar
    There is no corresponding record for this reference.
  24. 24
    Cooper, A. I. Polymer Synthesis and Processing using Supercritical Carbon Dioxide. J. Mater. Chem. 2000, 10, 207– 234,  DOI: 10.1039/a906486i
    Google Scholar
    24
    Polymer synthesis and processing using supercritical carbon dioxide
    Cooper, Andrew I.
    Journal of Materials Chemistry (2000), 10 (2), 207-234CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)
    This review with 271 ref. focuses on recent advances in polymer synthesis and processing using liq. and supercrit. CO2. The synthetic techniques discussed include homogeneous soln. polymn., pptn. polymn., dispersion and emulsion polymn., and bulk polycondensation. The formation of porous polymers and polymer blends is also considered, and the specific advantages of CO2 in these processes are evaluated in each case. The use of CO2 as a solvent for polymer processing is reviewed from a materials perspective, with particular attention being given to the formation of polymers with well defined morphologies. The variable solvent strength assocd. with supercrit. fluids has been utilized in areas such as polymer fractionation and polymer extn. Plasticization phenomena have been exploited for the impregnation and heterogeneous chem. modification of polymeric materials. The formation of microcellular polymer foams by pressure induced phase sepn. is considered, as is the use of CO2 for polymer particle formation, spray coating, and microlithog. The aim of the review is to highlight the wide range of opportunities available to the materials chemist through the use of carbon dioxide as an alternative solvent.
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  25. 25
    Yang, Y.; Li, X.; Zhang, Q.; Xia, C.; Chen, C.; Chen, X.; Yu, P. Foaming of Poly(Lactic Acid) with Supercritical CO2: The Combined Effect of Crystallinity and Crystalline Morphology on Cellular Structure. J. Supercrit. Fluids 2019, 145, 122– 132,  DOI: 10.1016/j.supflu.2018.12.006
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    25
    Foaming of poly(lactic acid) with supercritical CO2: The combined effect of crystallinity and crystalline morphology on cellular structure
    Yang, Yongchao; Li, Xiangyu; Zhang, Qingqing; Xia, Chenghao; Chen, Chikunya; Chen, Xuhuang; Yu, Peng
    Journal of Supercritical Fluids (2019), 145 (), 122-132CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)
    Using a batch foaming technique, the effects of supercrit. carbon dioxide on the formation of crystals under different satn. conditions (i.e. temp. or pressure) and subsequently on the cellular structure of the PLA foams were investigated. The crystallinity decreased with increasing annealing temp. or pressure, meanwhile, crystal morphologies were varied by controlling the temp. or pressure. It was found that a uniform closed cell structure was obtained by specifically controlling the foaming temp. in the range of (80-100) °C, in which only the ring-banded spherulites were formed. A suitable foaming window as a function of temp. was proposed. A no. of stamen-like cell structure was obsd. because of formation of irregular-banded spherulites under 8 MPa. However, an opened and interconnected cell structure was obtained at 24 MPa. The results indicated that not only the crystallinity but also the cryst. morphol. played an important role in the cellular structure.
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  26. 26
    Lan, Q.; Yu, J.; Zhang, J.; He, J. Enhanced Crystallization of Bisphenol A Polycarbonate in Thin and Ultrathin Films by Supercritical Carbon Dioxide. Macromolecules 2011, 44 (14), 5743– 5749,  DOI: 10.1021/ma102797r
    Google Scholar
    26
    Enhanced Crystallization of Bisphenol A Polycarbonate in Thin and Ultrathin Films by Supercritical Carbon Dioxide
    Lan, Qiaofeng; Yu, Jian; Zhang, Jun; He, Jiasong
    Macromolecules (Washington, DC, United States) (2011), 44 (14), 5743-5749CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
    The crystn. behavior of thin bisphenol A polycarbonate (PC) films after treatment in supercrit. CO2 (ScCO2) was investigated by using polarized optical microscopy (POM) and at. force microscopy (AFM). Exptl. results indicated that the crystn. ability in thin PC film of 259 nm thick was higher than that in the bulk in a much wider temp. range, and the crystn. window was further broadened when the thickness of samples decreased. The 15 nm film crystd. under 20 MPa CO2 at 60 °C, i.e., more than 90 K below the glass transition temp. of the bulk at ambient pressure, while the 259 nm film remained amorphous under the same treatment condition. The results further revealed that cryst. morphol. was affected by the CO2 treatment condition and film thickness. And the 7 nm film dewetted the substrate in the treatment at 20 MPa/60 °C instead of crystn. It was indicated that chain mobility of the polymer was strongly increased in ScCO2 when the film thickness was decreased to the scale of radius of gyration (ca. 6 nm) of the polymer. A modified three-layer model was proposed to explain these findings by introducing the effect of CO2 adsorption. The excess CO2 adsorbed at the free surface and polymer/substrate interface enlarged portions of these two layers and enhanced the polymer mobility therein, which took effect in thin films with thickness from hundreds down to several nanometers.
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  27. 27
    Sun, Y.; Matsumoto, M.; Kitashima, K.; Haruki, M.; Kihara, S.; Takishima, S. Solubility and Diffusion Coefficient of Supercritical-CO2 in Polycarbonate and CO2 Induced Crystallization of Polycarbonate. J. Supercrit. Fluids 2014, 95, 35– 43,  DOI: 10.1016/j.supflu.2014.07.018
    Google Scholar
    27
    Solubility and diffusion coefficient of supercritical-CO2 in polycarbonate and CO2 induced crystallization of polycarbonate
    Sun, Ying; Matsumoto, Miki; Kitashima, Kota; Haruki, Masashi; Kihara, Shin-ichi; Takishima, Shigeki
    Journal of Supercritical Fluids (2014), 95 (), 35-43CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)
    The soly. and diffusion coeff. of supercrit. CO2 in polycarbonate (PC) were measured using a magnetic suspension balance at sorption temps. that ranged from 75 to 175°C and at sorption pressures as high as 20 MPa. Above certain threshold pressures, the soly. of CO2 decreased with time after showing a max. value at a const. sorption temp. and pressure. This phenomenon indicated the crystn. of PC due to the plasticization effect of dissolved CO2. A thorough investigation into the dependence of sorption temp. and pressure on the crystallinity of PC showed that the crystn. of PC occurred when the difference between the sorption temp. and the depressed glass transition temp. exceeded 40°C (T - Tg≥40°C). Furthermore, the crystn. rate of PC was detd. according to Avrami's equation. The crystn. rate increased with the sorption pressure and was at its max. at a certain temp. under a const. pressure.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXhtlOlt7zK&md5=d8094ae4ff910256cacac7109a25dd16
  28. 28
    Li, G.; Park, C. B. A New Crystallization Kinetics Study of Polycarbonate under High-Pressure Carbon Dioxide and Various Crystallinization Temperatures by using Magnetic Suspension Balance. J. Appl. Polym. Sci. 2010, 18 (5), 2898– 2903,  DOI: 10.1002/app.32697
    Google Scholar
    There is no corresponding record for this reference.
  29. 29
    Monnereau, L.; Urbanczyk, L.; Thomassin, J.-M.; Alexandre, M.; Jérôme, C.; Huynen, I.; Bailly, C.; Detrembleur, C. Supercritical CO2 and Polycarbonate Based Nanocomposites: A Critical Issue for Foaming. Polymer 2014, 55 (10), 2422– 2431,  DOI: 10.1016/j.polymer.2014.03.035
    Google Scholar
    There is no corresponding record for this reference.
  30. 30
    Reignier, J.; Tatibouet, J.; Gendron, R. Batch Foaming of Poly(ε-Caprolactone) using Carbon Dioxide: Impact of Crystallization on Cell Nucleation as Probed by Ultrasonic Measurements. Polymer 2006, 47 (14), 5012– 5024,  DOI: 10.1016/j.polymer.2006.05.040
    Google Scholar
    There is no corresponding record for this reference.
  31. 31
    Sarver, J. A.; Kiran, E. Foaming of Polymers with Carbon Dioxide–The Year-in-Review– 2019. J. Supercrit. Fluids 2021, 173, 105166  DOI: 10.1016/j.supflu.2021.105166
    Google Scholar
    There is no corresponding record for this reference.

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  • Abstract

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    Figure 1

    Figure 1. (a) CO2 gas concentration under pressures of 5, 7.5, 10, and 12.5 MPa at a saturation temperature of 80 °C. (b) Foaming magnification (X) under pressures of 5, 7.5, 10, and 12.5 MPa at a saturation temperature of 80 °C followed by subsequent heating at various temperatures (110–150 °C).

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    Figure 2

    Figure 2. X-ray CT images of (a) the control sample and impregnated sample under 12.5 MPa pressure, followed by heating at 140 °C, and (b) the lap-shear specimen impregnated at 12.5 MPa without subsequent heating and heating at 110–150 °C (bubbles at the interface indicated by white triangles and the cracking indicated by red arrows).

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    Figure 3

    Figure 3. DSC thermogram for the control sample and samples impregnated under saturation pressures of 5, 7.5, 10, and 12.5 MPa (with and without subsequent heating), at a constant temperature of 80 °C.

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    Figure 4

    Figure 4. Mechanisms of (a) crystallization and (b) cracking in PCGF40 resin under high-pressure CO2 dissolution.

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    Figure 5

    Figure 5. (a) Load (N)–displacement (mm) curves of control and impregnated (12.5 MPa without heating and with heating at 140 °C) samples. (b) Maximum separation load (N) of the control (*), samples only impregnated (**), and samples impregnated with subsequent heating at 110–150 °C.

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    Figure 6

    Figure 6. (a) Microscopic images of engraved surface of aluminum substrate after a tensile lap-shear strength measurement for 12.5 MPa with subsequent heating at 120–150 °C. (b) Residual resin area ratio on aluminum substrate for the control (*), samples only impregnated at 12.5 MPa (**), and samples impregnated with subsequent heating at 110–150 °C.

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    Figure 7

    Figure 7. Relative maximum load (N) and residual resin area ratio for the control (intersection point of black lines), and samples impregnated at 12.5 MPa with subsequent heating at 110–150 °C and without heating.

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  • References

    This article references 31 other publications.

    1. 1
      Wazeer, A.; Das, A.; Abeykoon, C.; Sinha, A.; Karmakar, A. Composites for Electric Vehicles and Automotive Sector: A Review. Green Energy Intell. Transp. 2023, 2, 100043  DOI: 10.1016/j.geits.2022.100043
      There is no corresponding record for this reference.
    2. 2
      Azzopardi, B.; Hapid, A.; Kaleg, S.; Sudirja; Onggo, D.; Budiman, A. C. Recent Advances in Battery Pack Polymer Composites. Energies. 2023, 16, 6223,  DOI: 10.3390/en16176223
      There is no corresponding record for this reference.
    3. 3
      Delogu, M.; Zanchi, L.; Dattilo, C. A.; Pierini, M. Innovative Composites and Hybrid Materials for Electric Vehicles Lightweight Design in a Sustainability Perspective. Mater. Today Commun. 2017, 13, 192– 209,  DOI: 10.1016/j.mtcomm.2017.09.012
      3
      Innovative composites and hybrid materials for electric vehicles lightweight design in a sustainability perspective
      Delogu, M.; Zanchi, L.; Dattilo, C. A.; Pierini, M.
      Materials Today Communications (2017), 13 (), 192-209CODEN: MTCAC7; ISSN:2352-4928. (Elsevier Ltd.)
      Lightwt. design and electrified powertrain have become important strategies in the automotive industry to reduce fuel demand and break down emissions resp. Lightweighting of Elec. Vehicles (EVs) is considered a step forward because advantages of both EVs and lightwt. design could be combined to reduce environmental impacts even further. This paper would contribute to the advancement of knowledge in this field and it deals with the environmental anal., by means of Life Cycle Assessment (LCA), of composite-based and hybrid material lightwt. solns. for EVs modules in comparison with the corresponding ref. ones, by assuming no changes in the powertrain system (e.g. battery resizing). Particular attention is given to primary data collection to build the environmental eco-profiles of four innovative composites. Then, a four-level approach to interpret LCA outcomes in a clear and comprehensive way is proposed in this paper. Despite the relevant mass redn., environmental benefits are not registered for all the analyzed solns., and the main reason is the large impact from the prodn. stage of the new materials, raw materials particularly. Outcomes from this paper showed that Abiotic Depletion Potential (ADPel.) generally had a different trend if compared to Global Warming Potential (GWP) and Primary Energy Demand (PED) so their evaluation in parallel is recommended. Overall, the innovative materials that have a high impact in the prodn. stage could not be suitable in the case of EVs where the emission rate in the use stage is lower than the one of traditional vehicle, so a different application should be also evaluated.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXjtFagu7s%253D&md5=0a380fba4e76e022696e5a279b13d155
    4. 4
      Melentiev, R.; Yudhanto, A.; Tao, R.; Vuchkov, T.; Lubineau, G. Metallization of Polymers and Composites: State-of-the-Art Approaches. Mater. Des. 2022, 221, 110958  DOI: 10.1016/j.matdes.2022.110958
      4
      Metallization of polymers and composites: State-of-the-art approaches
      Melentiev, Ruslan; Yudhanto, Arief; Tao, Ran; Vuchkov, Todor; Lubineau, Gilles
      Materials & Design (2022), 221 (), 110958CODEN: MADSD2; ISSN:0264-1275. (Elsevier Ltd.)
      A review. Polymers and their composites are widely used for designing structures in aerospace, automotive, electronic, sport industries due to their lightwt., cost, and processing advantages. However, the surface of polymeric materials typically exhibits intrinsic deficiencies, limiting their durability and functionalities, e.g., low wear resistance, low thermal and elec. cond., low adhesion, low bioactivity, low reflectiveness, and weak photochem. resistance. Polymer metalization is an emerging concept that addresses these deficiencies by forming a metallic skin on polymeric surfaces. Herein, the working principles, recent advances, challenges, functional capabilities, and applications of the state-of-the-art polymer metalization methods in the fields of additive manufg., coating technologies, and material science are reviewed on nano-, micro-, and macroscales. The polymer metalization methods applied to polymeric and polymer composite substrates are phys. vapor deposition, electrochem. plating, a family of thermal spray methods (such as flame spaying, arc spraying, plasma spraying, and cold spraying), and a series of polymer-metal direct bonding methods (such as adhesive bonding, injection overmolding, and fusion joining techniques, including ultrasonic joining, friction spot joining, electromagnetic induction joining, and laser joining). Understanding the key aspects within these approaches would guide scientist and engineers for optimizing the design and durability of structural materials made of polymers/composites.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XitlCrsbfI&md5=b68c8ccf911578b2d7ba391e21d6939d
    5. 5
      Nazir, A.; Gokcekaya, O.; Md Masum Billah, K.; Ertugrul, O.; Jiang, J.; Sun, J.; Hussain, S. Multi-Material Additive Manufacturing: A Systematic Review of Design, Properties, Applications, Challenges, and 3D Printing of Materials and Cellular Metamaterials. Mater. Des. 2023, 226, 111661  DOI: 10.1016/j.matdes.2023.111661
      There is no corresponding record for this reference.
    6. 6
      Blanco, D.; Rubio, E. M.; Marín, M. M.; Davim, J. P. Advanced Materials and Multi-Materials Applied in Aeronautical and Automotive Fields: A Systematic Review Approach. Procedia CIRP. 2021, 99, 196– 201,  DOI: 10.1016/j.procir.2021.03.027
      There is no corresponding record for this reference.
    7. 7
      Huang, Y.; Gao, X.; Zhang, Y.; Ma, B. Laser Joining Technology of Polymer-Metal Hybrid Structures - A Review. J. Manuf. Process. 2022, 79, 934– 961,  DOI: 10.1016/j.jmapro.2022.05.026
      There is no corresponding record for this reference.
    8. 8
      Kajihara, Y.; Tamura, Y.; Kimura, F.; Suzuki, G.; Nakura, N.; Yamaguchi, E. Joining Strength Dependence on Molding Conditions and Surface Textures in Blast-Assisted Metal-Polymer Direct Joining. CIRP Ann. 2018, 67 (1), 591– 594,  DOI: 10.1016/j.cirp.2018.04.112
      There is no corresponding record for this reference.
    9. 9
      Taki, K.; Nakamura, S.; Takayama, T.; Nemoto, A.; Ito, H. Direct Joining of a Laser-Ablated Metal Surface and Polymers by Precise Injection Molding. Microsyst. Technol. 2016, 22 (1), 31– 38,  DOI: 10.1007/s00542-015-2640-2
      9
      Direct joining of a laser-ablated metal surface and polymers by precise injection molding
      Taki, Kentaro; Nakamura, Shuhei; Takayama, Tetsuo; Nemoto, Akihiko; Ito, Hiroshi
      Microsystem Technologies (2016), 22 (1), 31-38CODEN: MCTCEF; ISSN:0946-7076. (Springer)
      The joining of metal and polymer surfaces is a promising technol. to reduce the total wt. of parts and to improve interface reliability. In this study, a micro square grid (200 μm × 200 μm) was fabricated on an aluminum surface using laser ablation. Molten glass-reinforced poly(butylene terephthalate), poly(styrene) and acrylonitrile-butadiene-styrene were introduced to the micro square grids by a precise injection molding machine. The max. load tensile test was used as a measure of the joining strength between aluminum and the polymer. The tensile strength tests assisted in the differentiation of three modes of sepn.: interface-peeling, cohesive failure and matrix fracture. The max. load increased with the effective joined area where interface-peeling was obsd. The max. load ceased at a certain effective joined area, and matrix fracture occurred. Cohesive failure was obsd. where the effective joined area was smaller than the area for which matrix fracture was obsd., and the joined strength was larger than that obsd. for interface-peeling. The max. stress, which was calcd. by dividing cross-sectional area by the max. load, at the matrix fracture was proportional to the polymer tensile strength.
      >> More from SciFinder ®
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    10. 10
      Ramani, K.; Moriarty, B. Thermoplastic Bonding to Metals via Injection Molding for Macro-Composite Manufacture. Polym. Eng. Sci. 1998, 38 (5), 870– 877,  DOI: 10.1002/pen.10253
      10
      Thermoplastic bonding to metals via injection molding for macro-composite manufacture
      Ramani, Karthik; Moriarty, Brendan
      Polymer Engineering and Science (1998), 38 (5), 870-877CODEN: PYESAZ; ISSN:0032-3888. (Society of Plastics Engineers)
      In this work, we explore a new method of in-situ joining of polymers to metals in injection molding to allow direct bonding between thermoplastic and metal parts. Such a method can integrate several downstream steps in product manuf., allow optimal design of products and joints, and avoid adhesive application, assembly, and assocd. difficulties. A variety of process parameters and their effects upon the interface tensile strengths were examd. A full-factorial expt. was conducted involving four of the crit. process parameters identified. The effects upon tensile strength at break of the following process parameters were studied: 1) adherend surface temp., 2) screw linear velocity, 3) bondline thickness, and 4) pack and hold pressure. The fracture surfaces and the thermoplastic metal interfaces were analyzed. The bonds fabricated with higher adherend surface temps. have increased mean tensile strength and less adhesive failure. This increase in mean bond tensile strength and less adhesive failure was due to increased polymer penetration of the adherend surface roughness, at the micrometer level, as shown in the anal. of the polymer-metal interface by a scanning electron microscope (SEM). Polycarbonate bonded to aluminum is used to illustrate.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXjsFyqtLg%253D&md5=8180d4665f4c89c6f39508b8d3794655
    11. 11
      Grujicic, M.; Sellappan, V.; Omar, M. A.; Seyr, N.; Obieglo, A.; Erdmann, M.; Holzleitner, J. An Overview of the Polymer-to-Metal Direct-Adhesion Hybrid Technologies for Load-Bearing Automotive Components. J. Mater. Process. Technol. 2008, 197 (1–3), 363– 373,  DOI: 10.1016/j.jmatprotec.2007.06.058
      11
      An overview of the polymer-to-metal direct-adhesion hybrid technologies for load-bearing automotive components
      Grujicic, M.; Sellappan, V.; Omar, M. A.; Seyr, Norbert; Obieglo, Andreas; Erdmann, Marc; Holzleitner, Jochen
      Journal of Materials Processing Technology (2008), 197 (1-3), 363-373CODEN: JMPTEF; ISSN:0924-0136. (Elsevier B.V.)
      A review. The work published in the open literature dealing with various polymer metal hybrid (PMH) approaches used to promote direct (adhesive-free) adhesion between metal and injection-molded thermoplastics is reviewed and critiqued. Different approaches are categorized as follows: (a) micro-scale polymer-to-metal mech. interlocking; (b) in-coil or stamped-part pre-coating for enhanced adhesion; and (c) chem. modifications of the injection-molded thermoplastics for enhanced polymer-to-metal adhesion. For each of these approaches their suitability for use in load-bearing body-in-white (BIW) components is discussed. In particular, the compatibility of these approaches with the BIW manufg. process chain (i.e. pre-coated metal component stamping, BIW construction via different joining technologies, BIW pre-treated and painting operations) is presented. It has been found that while considerable amt. of research has been done in the PMH direct-adhesion area, many aspects of these technologies which are crit. from the standpoint of their use in the BIW structural applications have not been addressed (or addressed properly). Among the PMH technologies identified, the one based on micro-scale mech. inter locking between the injection-molded thermoplastic polymer and stamped-metal structural rib component appears to be most promising.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhsVCksrrJ&md5=01a7b0989d87d0b20831dd591806e4a0
    12. 12
      Zhao, S.; Kimura, F.; Kadoya, S.; Kajihara, Y. Experimental Analysis on Mechanical Interlocking of Metal-Polymer Direct Joining. Precis. Eng. 2020, 61, 120– 125,  DOI: 10.1016/j.precisioneng.2019.10.009
      There is no corresponding record for this reference.
    13. 13
      Samorì, C.; Cespi, D.; Blair, P.; Galletti, P.; Malferrari, D.; Passarini, F.; Vassura, I.; Tagliavini, E. Application of Switchable Hydrophilicity Solvents for Recycling Multilayer Packaging Materials. Green Chem. 2017, 19, 1714– 1720,  DOI: 10.1039/C6GC03535C
      13
      Application of switchable hydrophilicity solvents for recycling multilayer packaging materials
      Samori, Chiara; Cespi, Daniele; Blair, Paola; Galletti, Paola; Malferrari, Danilo; Passarini, Fabrizio; Vassura, Ivano; Tagliavini, Emilio
      Green Chemistry (2017), 19 (7), 1714-1720CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)
      A new procedure based on switchable hydrophilicity solvents (SHS) was proposed for polyethylene and aluminum recovery from food aseptic packaging. Treatment with N,N-dimethylcyclohexylamine (DMCHA) allowed very high material recovery (>99% for aluminum and >80% for polyethylene), without compromising the quality in terms of oxidn. or polymer degrdn. Moreover, the results from a simplified and preliminary life cycle anal. confirm the potential environmental benefits of a SHS approach compared with other treatment and disposal scenarios.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXisVeltLo%253D&md5=9efb0ea87dcc2b5278e6cbb04b017a95
    14. 14
      Zhang, S.; Luo, K.; Zhang, L.; Mei, X.; Cao, S.; Wang, B. Interfacial Separation and Characterization of Al-PE Composites During Delamination of Post-Consumer Tetra Pak Materials. J. Chem. Technol. Biotechnol. 2015, 90 (6), 1152– 1159,  DOI: 10.1002/jctb.4573
      14
      Interfacial separation and characterization of Al-PE composites during delamination of post-consumer Tetra Pak materials
      Zhang, Sufeng; Luo, Ke; Zhang, Lulu; Mei, Xingxian; Cao, Shumiao; Wang, Baiji
      Journal of Chemical Technology and Biotechnology (2015), 90 (6), 1152-1159CODEN: JCTBED; ISSN:0268-2575. (John Wiley & Sons Ltd.)
      In order to understand Al-PE composite delamination during the sepn. process, interfacial sepn. and characterization of Al-PE composites during delamination were analyzed. The aim was to enrich the present theor. anal. of Al-PE sepn. and to provide new ideas for the recycling and reuse of post-consumer Tetra Paks. The composites delaminated into three layers, but the times for delamination of the two plastic layers were different. After sepn., some plastics were present in the sepn. solvents analyzed by FTIR. Bright spots of unregular particles with scattered distribution on the surfaces of the three layers were Al, O and C, detected by SEM-EDS. During the sepn. reaction a mixed soln. permeates into the interfaces of Al-PE composites; adhesive structures of the PE layers were destroyed and even dissolved into particles, thus interfacial adhesive failure and Al-PE sepn. occurred. However the different properties of the adhesive layers and the oxidn. degree of PE fragments cause different sepn. speeds of the two interfaces adhered to each side of the Al foil.
      >> More from SciFinder ®
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    15. 15
      Yang, Y.; Boom, R.; Irion, B.; van Heerden, D. J.; Kuiper, P.; de Wit, H. Recycling of Composite Materials. Chem. Eng. Process. 2012, 51, 53– 68,  DOI: 10.1016/j.cep.2011.09.007
      15
      Recycling of composite materials
      Yang, Yongxiang; Boom, Rob; Irion, Brijan; van Heerden, Derk-Jan; Kuiper, Pieter; de Wit, Hans
      Chemical Engineering and Processing (2012), 51 (), 53-68CODEN: CENPEU; ISSN:0255-2701. (Elsevier B.V.)
      A review. Composite materials are used in a wide range of applications such as automotive, aerospace and renewable energy industries. But they have not been properly recycled, due to their inherent nature of heterogeneity, in particular for the thermoset-based polymer composites. The current and future waste management and environmental legislations require all engineering materials to be properly recovered and recycled, from end-of-life (EOL) products such as automobiles, wind turbines and aircrafts. Recycling will ultimately lead to resource and energy saving. Various technologies, mostly focusing on reinforcement fibers and yet to be commercialized, have been developed: mech. recycling, thermal recycling, and chem. recycling. However, lack of adequate markets, high recycling cost, and lower quality of the recyclates are the major commercialization barriers. To promote composites recycling, extensive R&D efforts are still needed on development of ground-breaking better recyclable composites and much more efficient sepn. technologies. It is believed that through the joint efforts from design, manufg., and end-of-life management, new sepn. and recycling technologies for the composite materials recycling will be available and more easily recyclable composite materials will be developed in the future.
      >> More from SciFinder ®
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    16. 16
      Knappich, F.; Schlummer, M.; Mäurer, A.; Prestel, H. A New Approach to Metal- and Polymer-Recovery from Metallized Plastic Waste using Mechanical Treatment and Subcritical Solvents. J. Mater. Cycles Waste Manag. 2018, 20, 1541– 1552,  DOI: 10.1007/s10163-018-0717-6
      There is no corresponding record for this reference.
    17. 17
      Krauklis, A. E.; Karl, C. W.; Gagani, A. I.; Jørgensen, J. K. Composite Material Recycling Technology─State-of-the-Art and Sustainable Development for the 2020s. J. Compos. Sci. 2021, 5, 28,  DOI: 10.3390/jcs5010028
      There is no corresponding record for this reference.
    18. 18
      Mori, Y.; Kishimoto, S.; Sharma, R. K.; Taki, K. Bubble Nucleation-Induced Interfacial Delamination of a Lap-Shear Aluminum/Glass Fiber-Reinforced Polycarbonate Specimen by CO2 Gas Impregnation and Subsequent Heating. Ind. Eng. Chem. Res. 2023, 62 (39), 15919– 15927,  DOI: 10.1021/acs.iecr.3c02107
      There is no corresponding record for this reference.
    19. 19
      Taki, K.; Yanagimoto, T.; Funami, E.; Okamoto, M.; Ohshima, M. Visual Observation of CO2 Foaming of Polypropylene-Clay Nanocomposites. Polym, Eng. Sci. 2004, 44 (6), 1004– 1011,  DOI: 10.1002/pen.20093
      19
      Visual observation of CO2 foaming of polypropylene-clay nanocomposites
      Taki, Kentaro; Yanagimoto, Tatsunori; Funami, Eita; Okamoto, Masami; Ohshima, Masahiro
      Polymer Engineering and Science (2004), 44 (6), 1004-1011CODEN: PYESAZ; ISSN:0032-3888. (John Wiley & Sons, Inc.)
      Using a newly developed high-pressure autoclave, which has two sapphire windows on the walls, we visually obsd. the batch phys. foaming of polymer-clay nanocomposites to understand the effect of nano-sized clay on the initial stage of foaming. With CO2 as a phys. foaming agent, polypropylene-montmorillonite clay nanocomposites were foamed at 150°C. A high-speed digital camera with a microscope could observe the bubble nucleation and bubble growth behavior of the early stage of foaming in situ. The series of micrographs was analyzed in order to investigate the effect of clay content on bubble nucleation and growth. The expts., together with CO2-soly. and diffusivity data, show that the clay enhances bubble nucleation as a nucleation agent and retards the growth of bubbles at the early stage of foaming.
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    20. 20
      Ito, A.; Semba, T.; Taki, K.; Ohshima, M. Effect of the Molecular Weight Between Crosslinks of Thermally Cured Epoxy Resins on the CO2-Bubble Nucleation in a Batch Physical Foaming Process. J. Appl. Polym. Sci. 2014, 131 (12), 40407,  DOI: 10.1002/app.40407
      20
      Effect of the molecular weight between crosslinks of thermally cured epoxy resins on the CO2-bubble nucleation in a batch physical foaming process
      Ito, Akihiro; Semba, Takeshi; Taki, Kentaro; Ohshima, Masahiro
      Journal of Applied Polymer Science (2014), 131 (12), 40407/1-40407/8CODEN: JAPNAB; ISSN:0021-8995. (John Wiley & Sons, Inc.)
      Epoxy resins (bisphenol A type epoxy resins/2-ethyl-4-methylimidazole) consisting of oligomers with different mol. wts. were foamed using a temp.-quench phys. foaming method with CO2. The resulting cell morphologies could be classified into four types: non-foamed structure, cracked structure, star-shaped structure, and sphere-shaped structure. The effects of the gel fraction and mol. wt. between crosslinks (MC) on the cell morphol. were investigated for the prepn. of microcellular epoxy foams. MC was calcd. by measuring the plateau rubber modulus of the rheol. properties and the wt. uptake of acetone. By varying the mol. wt. of the epoxy oligomers and the cure time, the MC of the epoxy was controlled to modulate the cell morphol. The expts. elucidated the threshold MC value that permits CO2-bubble nucleation: CO2-bubble nucleation in the epoxy resin could be induced when the distance between the crosslinking points exceeded the crit. size of bubble nucleus. Based on this information, the microcellular epoxy foam was prepd. by maintaining MC above 104g mol-1 and the complex modulus above 6 × 108 Pa. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40407.
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    21. 21
      Taki, K.; Kitano, D.; Ohshima, M. Effect of Growing Crystalline Phase on Bubble Nucleation in Poly(L-Lactide)/CO2 Batch Foaming. Ind. Eng. Chem. Res. 2011, 50 (6), 3247– 3252,  DOI: 10.1021/ie101637f
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      Effect of Growing Crystalline Phase on Bubble Nucleation in Poly(L-Lactide)/CO2 Batch Foaming
      Taki, Kentaro; Kitano, Daisaku; Ohshima, Masahiro
      Industrial & Engineering Chemistry Research (2011), 50 (6), 3247-3252CODEN: IECRED; ISSN:0888-5885. (American Chemical Society)
      Creating a high-efficiency bubble nucleation agent for a polymer foaming process is essential for increasing bubble d. as well as decreasing bubble size. Spherulites (cryst. phase) grown in a semicryst. poly(L-lactide) (PLLA) matrix enhanced carbon dioxide (CO2) bubble nucleation in a batch foaming process. Several sites for PLLA spherulite formation were obsd. at a hold-temp. of 110°C after CO2 satn. in molten PLLA, which was heated to 180°C at 11 MPa. By depressurizing the system from 11 MPa to atm. pressure, the dissolved CO2 in the PLLA matrix became supersatd., and CO2 bubbles nucleated around growing PLLA spherulites. The no. of nucleating bubbles increased as a function of increasing spherulite quantity and area. A faster linear spherulite growth rate and a lower hold-temp. created more bubbles around the spherulites. From these observations, it was concluded that the growing spherulites expelled CO2 from the advancing spherulite-amorphous phase interface and that CO2 accumulated at the interface. Then, the increase in the concn. of CO2 led to an increase in the nucleation of bubbles around the spherulites.
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    22. 22
      Chai, J.; Wang, G.; Zhao, J.; Zhang, A.; Shi, Z.; Wei, C.; Zhao, G. Microcellular PLA/PMMA Foam Fabricated by CO2 foaming with Outstanding Shape-Memory Performance. J. CO2 Util. 2021, 49, 101553  DOI: 10.1016/j.jcou.2021.101553
      22
      Microcellular PLA/PMMA foam fabricated by CO2 foaming with outstanding shape-memory performance
      Chai, Jialong; Wang, Guilong; Zhao, Jinchuan; Zhang, Aimin; Shi, Zhanlin; Wei, Chao; Zhao, Guoqun
      Journal of CO2 Utilization (2021), 49 (), 101553CODEN: JCUOAJ; ISSN:2212-9839. (Elsevier Ltd.)
      Porous shape memory polymers (SMPs) are attracting people's attention due to their extensive application prospect. Herein, a novel and flexible method to produce bio-friendly polylactic acid (PLA)/polymethyl methacrylate (PMMA) shape memory foam by a two-step CO2 microcellular foaming is proposed. The achieved foams exhibit outstanding shape memory performance, such as a max. shape fixity ratio of 98 %, a max. shape recovery ratio of 86 %, and further the recovery ratio remaining more than 75 % even after 10 compression-recovery cycles. The additive PMMA phases uniformly disperse with spherical morphol. in nanoscale, and they result in the greatly decreased crystallinity and crystal size of PLA. Meanwhile, the extensive interfaces lead to increased crystal d. In this context, more amorphous mol. chains left in the cell wall act as reversible segments, and more numerous denser crystals act as net points, which together can decrease the resistance in the shape memory process, thus, facilitating the significant promotion of shape memory capability of the as-achieved PLA/PMMA foams. Therefore, it exhibits a promising future to produce environmentally friendly SMPs by a simple, cost-efficient, and clean microcellular foaming technol.
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    23. 23
      Liao, X.; Wang, J.; Li, G.; He, J. Effect of Supercritical Carbon Dioxide on the Crystallization and Melting Behavior of Linear Bisphenol A Polycarbonate. J. Polym. Sci. B Polym. Phys. 2004, 42 (2), 280– 285,  DOI: 10.1002/polb.10597
      There is no corresponding record for this reference.
    24. 24
      Cooper, A. I. Polymer Synthesis and Processing using Supercritical Carbon Dioxide. J. Mater. Chem. 2000, 10, 207– 234,  DOI: 10.1039/a906486i
      24
      Polymer synthesis and processing using supercritical carbon dioxide
      Cooper, Andrew I.
      Journal of Materials Chemistry (2000), 10 (2), 207-234CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)
      This review with 271 ref. focuses on recent advances in polymer synthesis and processing using liq. and supercrit. CO2. The synthetic techniques discussed include homogeneous soln. polymn., pptn. polymn., dispersion and emulsion polymn., and bulk polycondensation. The formation of porous polymers and polymer blends is also considered, and the specific advantages of CO2 in these processes are evaluated in each case. The use of CO2 as a solvent for polymer processing is reviewed from a materials perspective, with particular attention being given to the formation of polymers with well defined morphologies. The variable solvent strength assocd. with supercrit. fluids has been utilized in areas such as polymer fractionation and polymer extn. Plasticization phenomena have been exploited for the impregnation and heterogeneous chem. modification of polymeric materials. The formation of microcellular polymer foams by pressure induced phase sepn. is considered, as is the use of CO2 for polymer particle formation, spray coating, and microlithog. The aim of the review is to highlight the wide range of opportunities available to the materials chemist through the use of carbon dioxide as an alternative solvent.
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    25. 25
      Yang, Y.; Li, X.; Zhang, Q.; Xia, C.; Chen, C.; Chen, X.; Yu, P. Foaming of Poly(Lactic Acid) with Supercritical CO2: The Combined Effect of Crystallinity and Crystalline Morphology on Cellular Structure. J. Supercrit. Fluids 2019, 145, 122– 132,  DOI: 10.1016/j.supflu.2018.12.006
      25
      Foaming of poly(lactic acid) with supercritical CO2: The combined effect of crystallinity and crystalline morphology on cellular structure
      Yang, Yongchao; Li, Xiangyu; Zhang, Qingqing; Xia, Chenghao; Chen, Chikunya; Chen, Xuhuang; Yu, Peng
      Journal of Supercritical Fluids (2019), 145 (), 122-132CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)
      Using a batch foaming technique, the effects of supercrit. carbon dioxide on the formation of crystals under different satn. conditions (i.e. temp. or pressure) and subsequently on the cellular structure of the PLA foams were investigated. The crystallinity decreased with increasing annealing temp. or pressure, meanwhile, crystal morphologies were varied by controlling the temp. or pressure. It was found that a uniform closed cell structure was obtained by specifically controlling the foaming temp. in the range of (80-100) °C, in which only the ring-banded spherulites were formed. A suitable foaming window as a function of temp. was proposed. A no. of stamen-like cell structure was obsd. because of formation of irregular-banded spherulites under 8 MPa. However, an opened and interconnected cell structure was obtained at 24 MPa. The results indicated that not only the crystallinity but also the cryst. morphol. played an important role in the cellular structure.
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    26. 26
      Lan, Q.; Yu, J.; Zhang, J.; He, J. Enhanced Crystallization of Bisphenol A Polycarbonate in Thin and Ultrathin Films by Supercritical Carbon Dioxide. Macromolecules 2011, 44 (14), 5743– 5749,  DOI: 10.1021/ma102797r
      26
      Enhanced Crystallization of Bisphenol A Polycarbonate in Thin and Ultrathin Films by Supercritical Carbon Dioxide
      Lan, Qiaofeng; Yu, Jian; Zhang, Jun; He, Jiasong
      Macromolecules (Washington, DC, United States) (2011), 44 (14), 5743-5749CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)
      The crystn. behavior of thin bisphenol A polycarbonate (PC) films after treatment in supercrit. CO2 (ScCO2) was investigated by using polarized optical microscopy (POM) and at. force microscopy (AFM). Exptl. results indicated that the crystn. ability in thin PC film of 259 nm thick was higher than that in the bulk in a much wider temp. range, and the crystn. window was further broadened when the thickness of samples decreased. The 15 nm film crystd. under 20 MPa CO2 at 60 °C, i.e., more than 90 K below the glass transition temp. of the bulk at ambient pressure, while the 259 nm film remained amorphous under the same treatment condition. The results further revealed that cryst. morphol. was affected by the CO2 treatment condition and film thickness. And the 7 nm film dewetted the substrate in the treatment at 20 MPa/60 °C instead of crystn. It was indicated that chain mobility of the polymer was strongly increased in ScCO2 when the film thickness was decreased to the scale of radius of gyration (ca. 6 nm) of the polymer. A modified three-layer model was proposed to explain these findings by introducing the effect of CO2 adsorption. The excess CO2 adsorbed at the free surface and polymer/substrate interface enlarged portions of these two layers and enhanced the polymer mobility therein, which took effect in thin films with thickness from hundreds down to several nanometers.
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    27. 27
      Sun, Y.; Matsumoto, M.; Kitashima, K.; Haruki, M.; Kihara, S.; Takishima, S. Solubility and Diffusion Coefficient of Supercritical-CO2 in Polycarbonate and CO2 Induced Crystallization of Polycarbonate. J. Supercrit. Fluids 2014, 95, 35– 43,  DOI: 10.1016/j.supflu.2014.07.018
      27
      Solubility and diffusion coefficient of supercritical-CO2 in polycarbonate and CO2 induced crystallization of polycarbonate
      Sun, Ying; Matsumoto, Miki; Kitashima, Kota; Haruki, Masashi; Kihara, Shin-ichi; Takishima, Shigeki
      Journal of Supercritical Fluids (2014), 95 (), 35-43CODEN: JSFLEH; ISSN:0896-8446. (Elsevier B.V.)
      The soly. and diffusion coeff. of supercrit. CO2 in polycarbonate (PC) were measured using a magnetic suspension balance at sorption temps. that ranged from 75 to 175°C and at sorption pressures as high as 20 MPa. Above certain threshold pressures, the soly. of CO2 decreased with time after showing a max. value at a const. sorption temp. and pressure. This phenomenon indicated the crystn. of PC due to the plasticization effect of dissolved CO2. A thorough investigation into the dependence of sorption temp. and pressure on the crystallinity of PC showed that the crystn. of PC occurred when the difference between the sorption temp. and the depressed glass transition temp. exceeded 40°C (T - Tg≥40°C). Furthermore, the crystn. rate of PC was detd. according to Avrami's equation. The crystn. rate increased with the sorption pressure and was at its max. at a certain temp. under a const. pressure.
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    28. 28
      Li, G.; Park, C. B. A New Crystallization Kinetics Study of Polycarbonate under High-Pressure Carbon Dioxide and Various Crystallinization Temperatures by using Magnetic Suspension Balance. J. Appl. Polym. Sci. 2010, 18 (5), 2898– 2903,  DOI: 10.1002/app.32697
      There is no corresponding record for this reference.
    29. 29
      Monnereau, L.; Urbanczyk, L.; Thomassin, J.-M.; Alexandre, M.; Jérôme, C.; Huynen, I.; Bailly, C.; Detrembleur, C. Supercritical CO2 and Polycarbonate Based Nanocomposites: A Critical Issue for Foaming. Polymer 2014, 55 (10), 2422– 2431,  DOI: 10.1016/j.polymer.2014.03.035
      There is no corresponding record for this reference.
    30. 30
      Reignier, J.; Tatibouet, J.; Gendron, R. Batch Foaming of Poly(ε-Caprolactone) using Carbon Dioxide: Impact of Crystallization on Cell Nucleation as Probed by Ultrasonic Measurements. Polymer 2006, 47 (14), 5012– 5024,  DOI: 10.1016/j.polymer.2006.05.040
      There is no corresponding record for this reference.
    31. 31
      Sarver, J. A.; Kiran, E. Foaming of Polymers with Carbon Dioxide–The Year-in-Review– 2019. J. Supercrit. Fluids 2021, 173, 105166  DOI: 10.1016/j.supflu.2021.105166
      There is no corresponding record for this reference.