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.