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Abstract
With the help of DSC, WAXS, and SAXS techniques highly oriented PE samples produced in six different ways in the range of draw ratios from 25 up to 300 have been investigated. The decrease of melting interval up to zero and the significant increase of melting temperature up to its equilibrium value are observed with draw ratio. The analysis of DSC data enabled us to calculate the thermodynamical parameter of intrachain cooperativity of melting which was found to be equal to v≍2×103 nm. Although the observed thermodynamical characteristics corresponded to those expected for hypothetical macroscopic single crystals of PE, the combining of DSC and X-ray data allow to consider ultraoriented PE as consisting almost entirely of very extended (up to v≍2×103 nm) straightened chain sections, each of which going through dozens of small crystallites and intercrystalline regions containing defects of disclinational type. As a result, the linear correlation between the parameter v and the mechanical strength [sgrave] of oriented PE has been revealed.
