Effect of natural and expanded vermiculite clays on the properties of eco-friendly biopolyethylene-vermiculite clay biocomposites

In this work, the effect of natural (NV) and expanded (EV) vermiculite clays on the properties of biopolyethylene (BioPE)-vermiculite clay biocomposites was investigated. It was observed that the addition of NV and EV clays to BioPE increased the Heat Deflection Temperature (HDT) and improved the fire retardance. In general, the degree of crystallinity (X-c) of BioPE decreased with the increase in the NV clay content, whereas in the presence of EV clay, the decrease in the X-c was only observed for the EV clay content above 3 phr. From optical microscopy (OM) it was observed that EV clay particles were better dispersed in the BioPE matrix, whereas many NV clay agglomerates were formed. SEM micrographs showed a lack of adhesion between the BioPE matrix and the NV or EV clay, resulting in a decrease of tensile and impact strength. Rheological measurements under oscillatory shear flow indicated the formation of a percolated network structure in the BioPE-NV and BioPE-EV biocomposites containing 5 and 10 phr of NV or EV clay. The biocomposite containing 10 phr of EV clay presented the higher melt yield stress value. Rheological measurements at high shear rates showed that the processability of the biocomposites will be similar to that of neat BioPE.