Toughening liquid-crystalline polymers with polyethylenes containing epoxy functionality

To improve toughness, a liquid-crystalline polymer (LCPs) was blended with polyethylenes containing epoxy functionality in concentrations of 2, 6, and 15 wt %. The blends were prepared with a corotating twin-screw extruder and were injection-molded into specimens for mechanical testing. The effect of the amount of the epoxy-functionalized polyethylenes on the morphology and mechanical and thermal properties was studied. The toughness improved with increasing amount of functionalized polyethylene, and the blend containing 15 wt % epoxy-functionalized polyethylene had the best toughness properties. Impact strength values up to three times higher than those of the neat LCP were achieved. However, the stiffness of the LCP concurrently decreased substantially. The morphology became much more uniform, and the melting behavior changed. The results show that considerable improvements in the toughness properties of LCPs can be achieved with epoxy-functionalized polyethylenes. (C) 2002 Wiley Periodicals, Inc.