SORPTION CHARACTERISTICS OF DYNAMICALLY VULCANIZED POLYPROPYLENE/EPOXIDIZED NATURAL RUBBER BLENDS FILLED WITH CARBONIZED DIKA NUTSHELL (Irvialgia Gabonensis)

The sorption characteristics of dynamically vulcanized polypropylene/epoxidized natural rubber blends filled with carbonized Dika nutshell have been investigated with special reference to the effects of filler carbonization temperature and dosage of cross-linking agent. Toluene, an aromatic solvent commonly used in the rubber industry, was chosen as the solvent in this investigation. The filled blends were prepared by compression moulding using maleic anhydride-graft-polypropylene as a compatibilizer. The blend morphology was studied using Scanning Electron Microscope (SEM). Both the SEM and dynamic vulcanization studies indicate that the non-compatibilized/ non-vulcanized blends are immiscible and form twophase structures, accompanied by high solvent (toluene) uptake. Resistance to toluene sorption increased with increase in the dosage of cross-linking agent due to increase in cross-link density as a result of increase in network formation. This behaviour is supported by SEM micrographs of vulcanized and non-vulcanized blends, which reveal restriction to swelling of vulcanized blends due to increase in network formation. Resistance to toluene sorption with increase in filler carbonization temperature was also observed. This is attributed to increase in surface area of the filler due to the elimination of volatile matter that are deleterious to the blend-filler interfacial interaction.