CORRELATIONS BETWEEN ORIENTATION AND SOME PROPERTIES OF POLYMER FILMS AND SHEETS*

ABSTRACT: The orientation effects of biaxially stretched polystyrene (PS) sheets and polyethylene (PE) blown films were investigated. The study mainly focused on the relationships between orientation of amorphous PS and semi-crystalline PE and their shrinkage, tensile properties and tear resistance. For low orientations, it was found that the stress and strain (shrinkage in films) can be simply related to birefringence for both PS and PE. For tear properties of PE films, better correlations were observed with crystalline orientation factors. KEY WORDS: polystyrene, LDPE, biaxially oriented, thermal shrinkage, tensile properties, birefringence, blown films, cast sheet, elmendorf tear, dra