Morphological changes during stretching of two PET samples (S and T) with different crystallization rate have been studied by means of SALS

solvent etching and polarizing microscope techniques. Results show that under the same drawing conditions larger and more perfect rod-like and spherulitic superstructures were formed more easily in the sample with higher crystallization rate (sample S). The amount of less compact regions which may be easily attacked by the vapor of allyl amine decreases more rapidly insample S than in sample T during stretching

and these regions are more randomly distributed in sample T especially at low elongations.The difference of the two samples in morphological changes is coincident with their differece in tensile behavior.