Preparation of ultra-high modulus materials from metallocene based linear polyethylenes

In this communication we report the preparation of new ultrahigh modulus ta pes from metallocene-based Linear polyethylene (LPE) using tensile drawing. Samples have been prepared with a draw ratio in excess of 50 and a room te mperature Young's modulus of 103 GPa. The findings represent a natural exte nsion of the previously reported universal relationship between the modulus and the draw ratio. WAXS measurements suggest that the crystal size in the chain direction is as high as 460 Angstrom while SAXS measurements indicat e a long period of about 200 Angstrom. This apparent contradiction is resol ved by the inter-crystalline bridge model which correlates the modulus with the degree of crystal continuity determined from the longitudinal crystal thickness and the long period. The increase in modulus is attributed to an increase in crystallinity and crystal continuity along the draw direction w ithout any extended chain crystallisation. (C) 2001 Elsevier Science Ltd. A ll rights reserved.