Effect of high‐pressure annealing on the structure of oriented polyethylene

The effect of annealing at different temperatures and pressures of 3000, 5000, and 7000 kg/cm 2 on the structure of oriented films of linear polyethylene has been studied. It has been established that for each of the above pressures there is an optimal temperature of annealing at which the maximum crystallinity of the sample is achieved. The results obtained by wide and small angle x‐ray diffraction, infrared spectroscopy, electron microscopy, and density show that annealing at the optimal temperature leads to extended‐chain crystallites in the sample. Orientation of crystallites remains largely unchanged.