FAST CRYSTALLIZATION OF POLY(ETHYLENE-TEREPHTHALATE)

The crystallization of poly(ethylene terephthalate) (PET) was studied in the presence of nucleating agents and promoters. The effect of both by themselves and in concert was investigated using differential scan ning calorimetry. The aim of this work is to find conditions of fast c rystal lization of PET. Sodium benzoate(SB) and Surlyn(R) (S) substant ially increase the crystallization rate of PET at higher temperature o wing to a reduction in the energy barrier towards primary nucleation, but they accelerate crystallization even more al lower temperature wit h an additional improvement of the molecular mobility of PET chains. C hain scission of PET caused by the reaction with the nucleating agents was proven by determination of molecular weight. The addition of S al one led to a lower reduction in molecular weight. A series of N-alkyl- p-toluenesulfonamides (ATSAs) were shown to effectively promote molecu lar motion of the PET chains, leading to an increase in crsytallizatio n rate at lower temperature. A remarkable acceleration of crystallizat ion of PET was attained at lower temperature when S and ATSA were adde d together. When the content of ATSA is low, S has the dominant influe nce due to its dual effect of decreasing energy barrier towards nuclea tion and promoting molecular motion of PET chains. A further increase of crystallization rate of PET was found only after an addition of ATS A of above 5 wt. %.