Vulcanization and mechanical properties of natural rubber liquid polyisoprene rubber blends

Natural rubber(NR) was blended with liquid polyisoprene rubber (LIR) in order to modify its processability and mechanical properties. Mooney viscosity of the NR/LIR blend was decreased and vulcanization was delayed with increasing LIR content of the blends. After vulcanization, Shore A hardness and rebound properties were decreased with increasing LIR content of the blends. It was found that the value of tan delta in the blends was increased, while glass transition temperatures of the volcanized blends were constant with increasing LIR content of the blends. The decrease of Mooney viscosity with increasing the LIR content of the blends was interpreted to be plasticizing effects of the UR. Delay of the vulcanization with increasing the LIR content of the blends may be due to the decrease of the ingredients of NR which accelerated the curing. Change of mechanical properties of volcanized NR/LIR blends was attributed to the decreased crosslink density of the blends with increasing the LIR content of the blends.