Transport of organic solvents through coir-fiber-reinforced natural rubber composites: a method for evaluating interfacial interaction

Use is made of the transport of organic solvents such as benzene, toluene and xylene to understand the interfacial interaction in cross-linked coir-fiber-reinforced natural rubber composites. Attempts were made to analyze the interfacial bonding in the composites containing coir fibers subjected to different chemical treatments. Based on experiments, a probable mechanism of transport is suggested. The diffusion coefficient and solubility in the rubber compound-solvent system have been evaluated. The swelling of composites containing untreated and NaOH-treated coir increased initially with fiber loading, but decreased at higher levels of fiber loading. But the swelling of composites which contained coir fiber treated with solutions of NaOH, toluene diisocyanate and natural rubber decreased gradually with fiber loading. It was also found that the swelling of this composite was the least. This is due to the high inter-facial interaction between the fiber and the matrix which resists the uptake of organic solvents. It was seen that silica was not a necessary constituent of the bonding system for coir fiber reinforced natural rubber composites.