CONDUCTIVE RUBBERS.

Acetylene black was compounded into eleven rubbers, and the resulting vulcanisates were found to be highly conductive to electricity. Electrical properties, tensile strength, elongation at break, and hardness were measured also the effects of compression, tensile strain, flexing, and shelf ageing on their electrical resistances were studied. Different proportions of acetylene black were added to natural rubber and the resulting physical properties were measured. Various other materials were added to natural rubber such as high abrasion furnace black, two special conducting furnace blacks, graphite, carbon fibres, barium ferrite, aluminium staple, copper powder, and iron powder. Properties of these filled vulcanisates were compared with those containing acetylene black. It was found that natural rubber filled with acetylene black to the weight ratio 10070 produced a good processable rubber with high conductivity and that similar vulcanisates of a polysulphide rubber, a fluorinated elastomer, and a synthetic polyisoprene showed even higher conductivity. The two special furnace blacks were superior to acetylene black in physical and electrical properties. The other fillers did not show high conductivity. Author