The effect of chitosan loading on the curing characteristics, mechanical and morphological properties of chitosan-filled natural rubber (NR), epoxidised natural rubber (ENR) and styrene-butadiene rubber (SBR) compounds

Chitosan-filled rubber compounds were prepared using a laboratory sized two-roll mill. The effect of chitosan loading on three different types of rubber (STR 5L, ENR-25 and SBR) was investigated. The results indicate that, overall, the scorch time (tS2), cure time (t90), tensile strength and elongation at break (Eb) decrease with chitosan loading, whereas an increment was observed in the maximum torque (MH) and the tensile modulus (M100 and M300) of all three types of rubber. At a similar chitosan loading, the cure characteristics of SBR were found to be longer (for tS2 and t90) and higher (for MH) than those of STR 5L and ENR-25. The tensile properties of SBR were found to be the lowest of the three rubbers at a similar chitosan loading. The rubber-filler interaction for all three types of rubber decreases with chitosan loading. Morphological studies of the tensile fractured surface of the vulcanisates using scanning electron microscopy (SEM) indicated that chitosan interacts less well with SBR than STR 5L and ENR-25.