Influence of drawing conditions on the ultradrawing properties of film specimens of ultrahigh molecular weight polyethylene and low molecular weight polyethylene blends

The influence of the drawing temperature and rate on the ultradrawing properties and deformation mechanisms of a series of film specimens prepared from varying concentrations of gel solutions of ultrahigh molecular weight polyethylene (UHMWPE) and low molecular weight polyethylene (LMWPE) blends is reported. The maximum achievable draw ratio was obtained when each UHMWPE/LMWPE film specimen was drawn at an optimum temperature (T-op), wherein the T-op values of each UHMWPE/LMWPE film specimen increased consistently with the drawing rate. The temperature dependence of the apparent elongational viscosity (eta(epsilona)) revealed two distinguishable intervals with different activation energies. Coincidentally, the transition temperature (T-r) obtained from the intersection of the two straight lines drawn parallel to the two distinct intervals is approximately equal to the T-op value found for the film sample drawn at the same rate. Dynamic mechanical analysis of the film samples exhibited an extraordinary high alpha transition peaked at temperatures near 95-115 degreesC, which are again very close to the T-op and T-r values found for the film samples drawn at varying rates, and increases significantly with the testing frequencies. Possible mechanisms accounting for these interesting deformations, temperature dependence of the apparent elongational viscosity and dynamic mechanical properties are suggested in this study.