Abstract
Ultra-high molecular weight polyethylene (UHMWPE) films with a molecular weight of 6×10 were produced by gelation/crystallization from solution with cosolvent mixtures of decalin and p-xylene. Prior to the analysis of mechanical properties of gel films, sol-gel transition temperature was measured, being dependent on the volume fraction of mixed solvents and polymer concentration. Critical polymer concentration where there is an abrupt change in the concentration dependence of sol-gel transition temperature was higher for xylene-rich solution than for decalin-rich solution. Young's modulus and tenacity of gel films increased with the increase of draw ratio, but were not affected significantly by the volume fraction of mixed solvents. Bire-flingence of gel films increased initially with the increase of draw ratio, but reached an equilibrium value above some critical draw ratio. Critical draw ratio and equilibrium hire-flingence of gel fem for xylene-rich solution were higher than those for decalin-rich solution. Young's modulus tended to increase with the birefringence, but did not show any dominant dependence on the crystallinity.