INFLUENCE OF NETWORK ON THE INTERFACIAL DIFFUSION OF MULTILAYER POLYETHYLENE BLENDS

Abstract

Ultrahigh molecular mass polyethylene(UHMWPE) and statistical copolymer of ethylene and 1-hexene(PEH) were used to prepare UHMWPE/PEH blends with relatively low UHMWPE concentrations.UHMWPE forms network structure in the blends with UHMWPE concentrations above a critical value of c=1 wt%.The influence of the formed UHMWPE network on the interfacial diffusion behaviors of multilayer UHMWPE/PEH blends was investigated by applying small oscillatory shear rheology.The interfacial diffusion coefficients of multilayer UHMWPE/PEH blends were obtained from the rheological data.It is found that the diffusion coefficients are time-dependent and two diffusion regions are distinct before the diffusion reaches the plateaus according to the changes of diffusion exponent n in the relation of D-t n,which implies an approximate Fickian diffusion behavior in region Ⅰ(c 1.0 wt%) and an obvious deviation from the Fickian diffusion behavior in region Ⅱ(c1.0 wt%).With the formation of UHMWPE network in the UHMWPE/PEH blends,deviation from the Fickian behavior for diffusion of multilayer UHMWPE/PEH blends becomes significant.The above results help facilitate the industrial processing of multilayer polyolefins,which is related to the interfacial diffusion.