| Abstract: | 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 Tg if it is defined as an iso-free volume state of the amorphous phase of the polyethylene. |
