Structure and oxygen-barrier properties of (linear low-density polyethylene/ethylene-vinyl alcohol copolymer)/linear low-density polyethylene composite films prepared by microlayer coextrusion

摘要

Ethylene-vinyl alcohol copolymer (EVOH) and linear low-density polyethylene (LLDPE) blends with 5% LLDPE grafted with 1% maleic anhydride (MAH; EVOH/LLDPE/LLDPE-g-MAH), created to increase the interfacial compatibility, were coextruded with pure LLDPE through the microlayer coextrusion technology. The phase morphology and gas-barrier properties of the alternating-layered (EVOH/LLDPE/LLDPE-g-MAH)/LLDPE composites were studied by scanning electron microscopy observation and oxygen permeation coefficient measurement. The experimental results show that the EVOH/LLDPE/LLDPE-g-MAH and LLDPE layers were parallel to each other, and the continuity of each layer was clearly evident. This structure greatly decreased the oxygen permeability coefficient compared to the pure LLDPE and the barrier percolation threshold because of the existence of the LLDPE/EVOH/LLDPE-g-MAH blend layers, and the LLDPE layers diluted the concentration of EVOH in the whole composites. In addition, the effects of the layer thickness ratio of the EVOH/LLDPE/LLDPE-g-MAH and LLDPE layers and the layer number on the barrier properties of the layered composites were investigated. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42211.