The crystal modulus of ultra high modulus linear polyethylenes

Attempts have been made to determine the longitudinal crystal modulus for linear polyethylene by studying the change in the 0 0 2 reflection with load for a series of uniaxially oriented films. The specimens examined covered a wide range of draw ratios, and included a number of ultra high modulus films. In low draw ratio specimens, the assumption of homogeneous stress gave a value for the crystal modulus in good agreement with previous work. The results for the ultra high modulus specimens, on the other hand, were more consistent with continuity of strain, although there were still discrepancies which require further study.