EFFECT OF ANNEALING ON THE STRUCTURE OF CRAZES IN ISOTACTIC POLYPROPYLENE DEFORMED IN LIQUID-MEDIA

The structure of crazes in isotactic PP deformed in adsorption-active media by the mechanism of classical and delocalized crazing was studie d. It was shown that the structure of crazes in annealed PP deformed i n a liquid medium by the mechanism of delocalized crazing is character ized by smaller diameters of pores and fibrils. The nature of the medi um affects the structure of crazes depending on the variation of the s urface tension of a polymer, and this effect is more clearly pronounce d for the unannealed PP. It is suggested that the difference in the st ructure of crazes med in annealed and unannealed PP upon the subsequen t (post-drawing) change of the medium is related to different flexibil ity of fibrils in crazes.