Polycarbonate foams with tailor-made cellular structures by controlling the dissolution temperature in a two-step supercritical carbon dioxide foaming process |
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| Affiliation: | 1. Department of Biotechnology and Department of Zoology, Sri Venkateswara University, Tirupati, India;2. Embryo Biotechnology Laboratory, Department of Physiology, College of Veterinary Science, S.V. Veterinary University, Tirupati 517502, India;1. Microcellular Plastics Manufacturing Laboratory, Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada;2. School of Chemical Engineering and Technology, Xi’an Jiaotong University, 710049, Xi’an, PR China;1. Key Laboratory of Carbon Fiber and Functional Polymers, Beijing University of Chemical Technology, Ministry of Education, China;2. State Key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China;1. Dpto. de Química Física I, Universidad Complutense, E-28040 Madrid, Spain;2. Chemistry Department, Faculty of Science, Helwan University, El Cairo, Egypt |
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| Abstract: | Closed-cell polycarbonate foams were prepared using a two-step foaming process, which consisted of the initial dissolution of supercritical CO2 (scCO2) into PC foaming precursors and their later expansion by heating using a double contact restriction method. The effects of the parameters of both CO2 dissolution and heating stages on the cellular structure characteristics as well as on the physical aging of PC in the obtained foams were investigated. A higher amount of CO2 was dissolved in PC with increasing the dissolution temperature from 80 to 100 °C, with similar CO2 desorption trends and diffusion coefficients being found for both conditions. PC foams displayed an isotropic-like microcellular structure at a dissolution temperature of 80 °C. It was shown that it is possible to reduce their density while keeping their microcellular structure with increasing the heating time. On contrary, when dissolving CO2 at 100 °C and later expanding, PC foams presented a cellular morphology with bigger cells and with an increasingly higher cell elongation in the vertical growth direction with increasing the heating time. Comparatively, PC foams obtained by dissolving CO2 at 100 °C presented a more marked physical aging after CO2 dissolution and foaming, although this effect could be reduced and ultimately suppressed with increasing the heating time. |
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| Keywords: | Polycarbonate foams Supercritical carbon dioxide Two-step foaming Tailor-made cellular structure Physical aging |
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