Higher‐order transitions in poly(4‐methyl‐1‐pentene)

Abstract

Abstract Dilatometric data for the glass transition temperature T g of poly(4‐methyl‐1‐pentene) (PMP) have been extended to more crystalline samples and rendered more precise. T g is definitely shown to decrease with increasing degree of crystallinity, an effect which tentatively is related to increasing free volume of the amorphous part of the polymer as the less dense crystalline phase increases and pulls apart the polymer chains in the amorphous regions. T g is determined to be 14 ± 2°C. for 78% crystalline PMP, and 25 ± 2°C., for amorphous polymer. The existence of a higher‐order transition at 125 ± 10°C. is confirmed by x‐ray measurements and ascribed to transverse chain segment motion.