Effect of filler dispersion degree on the Joule heating stimulated recovery behaviour of nanocomposites

Composites based on highly branched ethylene-1-octene copolymer (EOC) and carbon black (CB) with different dispersion degree of CB were prepared. The method of the online measured electrical conductance/resistance was used to monitor the change of the electrical conductance/resistance of the composites during the preparation processes, i.e. mixing and cross-linking. It was found that the kinetics of thermally stimulated shape-memory recovery of CB filled EOC is strongly influenced by the filler dispersion degree, which actually affects the heat transfer in the composites. Using a special arrangement of experiments the Joule heating stimulated shape-memory behaviour was quantified. CB dispersion degree and related electrical resistivity determine the extent of the Joule heating stimulated shape-memory behaviour. Composite collected at the maximum in the online measured conductance-time characteristics showed the best shape-memory effect owing to the highest electrical conductivity in the solid state. The CB filled EOC showed a negative thermal coefficient of resistivity (NTC) effect, which accelerates the temperature increase and shape-memory recovery of the composites when applying a voltage.