EFFECT OF ZONE DRAWING ACCOMPANIED WITH CROSS-LINKING ON THE STRUCTURE AND PROPERTIES OF ULTRAHIGH MOLECULAR-WEIGHT POLYETHYLENE GEL FILM

To enhance the thermal properties of ultrahigh molecular weight (UHMW) (viscosity-average molecular weight of 6 x 10(6)) polyethylene (PE) g el film, this was crosslinked by dicumyl peroxide (DCP) during a high- temperature zone drawing, which is effective to orient film. Through a series of experiments, it turned out that crosslinking actualized by an optimum amount of DCP and high-temperature zone drawing technique c aused significant changes in the structure and properties of UHMW PE g el film. That is, crosslinking increased storage modulus of UHMW PE ge l film at 25 degrees C, resulting in improving thermal properties of t he film. On the contrary, the crosslinking effect played a hindering r ole in raising the draw ratio of UHMW PE gel film. Maximum storage mod ulus of 165 GPa at 25 degrees C could be obtained at the draw ratio of 324 of uncrosslinked homo-PE gel film. In the case of crosslinked PE gel film, the highest storage modulus at 25 degrees C reached 65 GPa a t maximum draw ratio of 150. Crosslinked film exhibited high modulus, even at 190 degrees C, to some extent, while uncrosslinked homo-PE gel film was molten completely at 150 degrees C. (C) 1997 John Wiley & So ns, Inc.