Effect of ionomeric compatibilizer on clay dispersion in polyethylene/clay nanocomposites

Linear low-density polyethylene (LLDPE)/clay nanocomposites are obtained and studied by using a zinc-neutralized carboxylate ionomer as a compatibilizer. LLDPE-g-MA is used as a reference compatibilizer. Two different clays, natural montmorillonite (Closite Na+) and a chemically modified clay Closite 20A have been used. Nanocomposites are prepared by melt blending in a twin-screw extruder using two mixing methods: two-step mixing and one-step mixing. The relative influence of each compatibilizer is determined by wide-angle X-ray diffraction structural analysis and mechanical properties. The results are analyzed in terms of the effect of the compatibilizing agent and incorporation method in the clay dispersion, and the mechanical properties of the nanocomposites. Experimental results confirm that the film samples with ionomer show a good mechanical performance only slightly below that of the samples with maleic anhydride (MA). The two-step mixing conditions result in better dispersion and intercalation for the nanofillers than one-step mixing. The exfoliation of clay platelets leads to an improved thermal stability of the composite. The oxygen permeability of the clay nanocomposites, using ionomer as a compatibilizer, is decreased by the addition of the clay.