Transition Regions and Surface Melting in Partially Crystalline Polyethylene: A Raman Spectroscopic Study

Abstract

Structures of semi crystalline high-molecular weight polyethylene and their changes with temperature were studied by analysis of Raman spectra. Decomposition of spectra into contributions of an orthorombic crystalline phase, a meltlike phase, and two kinds of transition regions yields the respective mass fractions. The result of temperature dependent measurements is indicative of a largely reversible surface melting process, the transition regions being located at the crystal surfaces. As-polymerized samples show a large fraction of the intermediate phase. Annealing leads to a reduction of this phase.