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Controlling sandwich‐structure of PET microcellular foams using coupling of CO 2 diffusion and induced crystallization
Author(s) -
Li Dachao,
Liu Tao,
Zhao Ling,
Yuan Weikang
Publication year - 2012
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.12764
Subject(s) - crystallization , crystallinity , materials science , amorphous solid , diffusion , fourier transform infrared spectroscopy , chemical engineering , sorption , diffusion process , composite material , saturation (graph theory) , thermal diffusivity , crystallography , adsorption , thermodynamics , chemistry , knowledge management , physics , innovation diffusion , mathematics , combinatorics , computer science , engineering
Controlling sandwich‐structure of poly(ethylene terephthalate) (PET) microcellular foams using coupling of CO 2 diffusion and CO 2 ‐induced crystallization is presented in this article. The intrinsic kinetics of CO 2 ‐induced crystallization of amorphous PET at 25°C and different CO 2 pressures were detected using in situ high‐pressure Fourier transform infrared spectroscopy and correlated by Avrami equation. Sorption of CO 2 in PET was measured using magnetic suspension balance and the diffusivity determined by Fick's second law. A model coupling CO 2 diffusion in and CO 2 ‐induced crystallization of PET was proposed to calculate the CO 2 concentration as well as crystallinity distributions in PET sheet at different saturation times. It was revealed that a sandwich crystallization structure could be built in PET sheet, based on which a solid‐state foaming process was used to manipulate the sandwich‐structure of PET microcellular foams with two microcellular or even ultra‐microcellular foamed crystalline layers outside and a microcellular foamed amorphous layer inside. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2512–2523, 2012