Effects of Benzenesulphonylhydrazide Concentration on Curing Characteristics, Morphology and Expansion Ratio of Natural Rubber (NR) Foam

摘要

The effect of the concentration of the chemical blowing agent, benzenesulphonyl hydrazide (BSH), on the curing characteristics, morphology and expansion ratio of NR foam for thermal insulation was investigated in the concentration range of 2 to 10 parts per hundred of rubber (phr). The NR compound was prepared on a two-roll mill and vulcanised in a hot mould at 150 degrees C. The results indicated that the cure time, scorch time and cure index increased with increasing BSH loading, whereas the maximum torque of the NR foam exhibited a decreasing trend. Both the number of cells per unit volume and the density of the NR foam reduced with increasing BSH content in the NR compound. Furthermore, the average expansion ratio of the NR foam increased. The recommended expansion ratio and concentration for BSH were 2.31 and 6 phr, respectively, to optimise the manufacture of thermal insulation in either refrigeration or air conditioning systems.