EFFECT OF SODIUM BENZOATE UPON THE NUCLEATION OF POLY(ETHYLENE TEREPHTHALATE) CRYSTALLIZATION
Liu Youxi, Wu Limin and Xie Weijun (Institute of Polymer Science, Zhongshan University, Guangzhou)
PET formulations containing small amounts of sodium benzoate were prepared by extrusion from melt. In the presence of sodium benzoate with various particle diameter and content, it has been stated that the T∝, the peak temperature value of cold crystallization, the crystallinity and decomposition of PET are dependent on the molecular numbers of sodium benzoate, not the particle diameter and the grain numbers. The increase of the content of sodium benzoate can decrease the peak temperature value of cold crystallization and crystallinity of PET. The molecular weight of PET cuts down with the increase of the content of sodium benzoate and the extrusion time. Atomic absorption showed that at least 65% of initial sodium ions take part in the reaction with PET and become PET-sodium salt. DSC analyses of PET before and after extracting the reaidual sodium benzoate showed that the main effect on PET crystallization is from PET-sodium salt, not sodium benzoate itself. Homogeneous nucluation was thought dominative.