Morphology studies of the liquid-induced crystallization of poly(ethylene terephthalate): Effects of polymer blending,nucleating agents,and molecular weight

The morphology associated with the liquid-induced crystallization of poly(ethylene terephthalate) (PET) blended either with poly(tetramethylene terephthalate) (PTMT), atactic polystyrene (APS), or polycarbonate of bisphenol A (PC) was studied, along with the effects of nucleating agents and polymer molecular weight on this type of crystallization in PET. It was found that melt-mixed blends of PET and either PTMT or PC led to an apparent well-mixed, two-component material in which some copolymer formation may be in evidence judging from the material superstructure. Blending PET with APS appeared to produce distinctly phase-separated materials in which PET could be crystallized and APS dissolved out of the structure as a result of treatment of the blend with certain types of liquid. The incorporation of nucleating agents into PET was shown to measurably influence the spherulitic character of the subsequently liquid-induced crystallized polymer. Finally, it was determined that liquid-induced crystallized PET samples with number-average molecular weights of 18,000 and 30,000 had identical characteristic morphology and apparent crystallization kinetics.