Effect of dynamic curing time on thermal, mechanical and rheological behavior of organoclay-containing nanocomposite based on ethylene-octene copolymer

Ethylene-octene copolymer (EOC)/organoclay nanocomposite was cured by peroxide in an internal mixer for different time periods. Low angle x-ray diffraction and transmission electron microscopy results revealed that the clay platelets were appeared as large parallel tactoids in the uncross-linked nanocomposite whereas the layers arranged in thinner tactoids in the cross-linked counterpart. Tensile experiments indicated that although the tensile modulus and yield stress were increased for the samples cross-linked for 6 min in comparison with that of the uncross-linked nanocomposite, the values decreased for the samples cross-linked for extra time. The results obtained from the Cole-Cole and tan delta against angular frequency plots showed that the over-cured samples had lower relaxation time and higher damping values, respectively. The average molecular weight between crosslinks for different samples was also estimated using James-Guth theory and the results showed that the molecular weight was increased for the samples cross-linked dynamically for longer than 6 min.