Tensile strength of highly oriented polyethylene. II. Effect of molecular weight distribution

Abstract

Abstract The tensile strength of oriented polyethylene filaments is discussed in relation to molecular weight. Short‐term tensile properties at room temperature were obtained in our laboratory and from the literature for polymer samples covering the molecular weight ( M w ) range from 54 × 10 3 to 4 × 10 6 , and polydispersities ranging from 1.1 to 15.6, oriented by solid‐state extrusion, melt spinning/drawing, solution spinning/drawing, and “surface growth.” It was found that both the molecular weight and its distribution markedly affected tensile strength. The breaking stress σ of highly oriented fibers varied with molecular weight roughly as σ ∝, M 0.4 , at constant M w / M n over the entire range studied. Reduction of polydispersity from 8 to 1.1 by an increase of M n with M w approximately constant at 10 5 increased tensile strength of oriented polyethylene filaments by a factor of nearly 2.