Glass transitions of polyolefins by inverse gas chromatography

The glass transition temperatures of polypropylene, poly‐1‐butene, polyisobutylene, and an ethylene‐propylene (EP) copolymer have been determined by inverse gas chromatography. The results are consistent with those determined by other procedures. When applied to low‐, medium‐ and high‐density polyethylene, values of −35, −25, and −18°C, respectively, were obtained. Because of the fact that the chromatographic technique involves essentially a sensitive detection of free volume in a polymer, it is suggested that these values represent T g if it is defined as an iso‐free volume state of the amorphous phase of the polyethylene.