成核剂和促进剂对聚对苯二甲酸乙二酯结晶的影响

EFFECTS OF NUCLEATING AGENT AND NUCLEATION PROMOTER ON THE CRYSTALLIZATION OF POLYETHYLENE TEREPHTHALATE

研究了一种成核剂和结晶促进剂及其混合物对聚对苯二甲酸乙二酯（ＰＥＴ）结晶过程和熔融行为的影响．结果表明，成核剂的引入降低了ＰＥＴ的结晶成核界面自由能，起到促进ＰＥＴ结晶成核的作用，从而加快了ＰＥＴ的结晶速度．而结晶促进剂对ＰＥＴ的结晶速度影响很小，不能促进ＰＥＴ的成核结晶，但能使ＰＥＴ结晶更完善，使ＰＥＴ的结晶度提高．当两者并用时，ＰＥＴ由熔体降温的结晶行为主要由成核剂控制，而成核促进剂的作用不明显．

The influence of a nucleating agent,a nucleation promoter and their mixture on the crystallization of poly(ethylene terephthalate) (PET) from melt state was studied by different characterization techniques including the measurements of the crystallization temperature in a non isothermal cooling process,halftime in an isothermal crystallization process and the specific surface free energy for nucleus formation during crystallization.The nucleating agent used was a derivative of sodium benzoate while the nucleation promoter was a sort of low molecular weight ester ether copolymer.It was found that the nucleating agent could promote the nucleation and crystallization of PET,reducing the specific surface free energy for nucleus formation during crystallization.However,the nucleation promoter had little influence on the nucleation and crystallization rate of PET in the high crystallization temperature range.The nucleation promoter may slightly increase the degree of crystallinity of PET,when the mixture of the nucleating agent and the nucleation promoter was used,the crystallization behavior of PET from its melt state was mainly controlled by the nucleating agent.