TENSILE-STRENGTH OF SOLUTION-SPUN, ULTRA-DRAWN ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE FIBERS .2. INFLUENCE OF PROPYLENE COMONOMER CONTENT

The effect of copolymerization with propylene on the fracture behaviour of solution-spun ultra-drawn, ultra-high molecular weight polyethylene (UHMW-PE, M(w) > 10(3) kg mol-1) fibres was investigated. UHMW-PE grades with virtually identical molecular weight and varying comonomer content (0.5-13.5 CH3/1000 C atoms) were used. It is shown that the tensile strength of drawn UHMW-PE fibres, at a constant Young's modulus, is independent of the comonomer content of the polymer. Apparently, the methyl side-groups hardly influence the fracture behaviour of the fibres. In combination with the experimental observation that methyl side-groups decrease intermolecular chain slippage (creep), this indicates that the failure process of solution-spun, drawn UHMW-PE fibres is mainly controlled by chain scission.