The Interaction between Crystallization Behavior and Foaming Performance in the Foamed Polypropylene

By : Jinsong Wen , Lirong Chen , Xianwu Cao , Yijun Zhang

Page No: 513-524

Abstract
Three types of polypropylene, namely homo-polypropylene (HPP), block copolymer of propylene with ethylene (CPP-B) and random copolymer of propylene with ethylene (CPP-R) were melted and foamed in a self-designed vessel under supercritical carbon dioxide (Sc-CO2 ) atmosphere. The melting behavior, crystalline forms and foaming performance of foamed samples were investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscope (SEM). The results showed that foaming process parameters greatly influence the crystallization behavior and foaming performance of samples. With the increasing of polypropylene contents, crystallinity, cell density was increased. Furthermore, under the certain critical condition, CO2 can induce the change of crystal structure and b- crystals were obtained. In addition, it was observed that g-crystals could be obtained in the foamed CPP-R under Sc-CO2 , while no g-crystals were formed in the other two samples.

Authors :
Jinsong Wen, Lirong Chen, Xianwu Cao and Yijun Zhang : National Engineering Research Center of Novel Equipment for Polymer Processing, The Key Laboratory of Polymer Processing Engineering of Ministry of Education, South China University of Technology, Guangzhou, China