Experimental and computational investigation of EVOH/clay nanocomposites

Abstract

Ethylene-vinyl alcohol copolymer (EVOH)/ organoclay nanocomposites were prepared via a dynamic melt-intercalation process. The effect of compatibilizers on the melt blending torque, intercalation level, and morphology of EVOH/organoclay systems was investigated. Maleic anhydride grafted ethylene vinyl acetate (EVA-g-MA), or maleic anhydride grafted linear low-density polyethylene (LLDPE-g-MA), were used to compatibilize EVOH with clay, at various concentrations (1, 5, and 10 wt %). Computer-simulation techniques are used to predict structural properties and interactions of EVOH with compatibilizers in the presence and absence of clay. The simulation results strongly support the experimental findings and their interpretation. X-ray diffraction shows enhanced intercalation within the galleries when the compatibilizers were added. Interestingly, results were obtained for the EVOH/clay/ compatibilizer systems, owing to a high level of interaction developed in these systems. Thermal analysis shows that, upon increasing the compatibilizer content, lower crystallinity levels result, until at a certain compatibilizer content no crystallization is taking place. Significantly higher mixing viscosity levels were obtained for the EVOH/organoclay blends compared with the neat EVOH polymer. The storage modulus was higher compared with the uncompatibilized EVOH/organoclay blend in the presence of EVA-g-MA compatibilizer (at all concentrations), and only at low contents of LLDPE-g-MA.

A critical appraisal of polymer–clay nanocomposites

“…The simulations used fixed atomic coordinates in the clay sheets and constrained interlayer separations to examine the interactions between the copolymer and clay surfactant, giving insight to aid interpretation of experimental data, including viscosity measurements. 147…”

Controlled migration of antifog additives from LLDPE compatibilized with LLDPE grafted maleic anhydride

“…The compatibility of polar additives with polyolefins can be increased by the addition of compatibilizers, which are usually functionalized grafted polymers . Compatibilizers improve the interfacial adhesion between AF and the apolar LLDPE matrix .…”

Fracture behaviour of poly[ethylene–(vinyl alcohol)]/organo‐clay composites

“…The EWF technique is used widely as a means to quantify the fracture toughness of ductile materials in sheet and film form, because deformation occurs under plane‐stress conditions. Although several studies of how EVOH is affected by organo‐clay in terms of structural, thermal and barrier properties have already been carried out by other researchers,16–18 the fracture behaviour of EVOH composites has not been studied so far. In fact, there are only a few studies that have applied the EWF concept to polymer/organo‐clay composites 19–21…”