Features of thermomechanical properties of radiation-modified blends of high-density polyethylene with liquid-crystalline copolyester

The present paper surveys the investigation results of gamma-irradiated blends of high-density polyethylene (PE) with thermotropic liquid-crystalline polymer (LCP). The LCP used was a liquid crystalline copolyester of 40% poly(ethyleneterephthalate) with 60% p-(hydroxybenzoic acid). The LCP content in the blends was 0,5, and 10 wt.%. The constituents were blended with the use of a single-screw extruder. The samples were prepared by compression molding and irradiated by a Co60 γ-radiation source in an inert atmosphere (argon) to relatively low absorbed doses (up to 200 kGy; 1 Mrad=10 kGy). Morphological, thermal, and mechanical properties in a wide temperature range were investigated for the irradiated and nonirradiated samples. The effects of gamma-irradiation and LCP addition on the thermomechanical behavior of PE are discussed. It was found that the LCP addition affected significantly the stress-strain behavior of PE at temperatures above the melting point. The features of thermorelaxation properties of the PE/LCP blends previously irradiated and oriented, particularly thermorelaxation and residual shrinkage stresses at isometric heating and cooling, were also established. The results obtained testify that the LCP addition makes it possible to improve considerably the thermosetting properties of irradiated PE.