Determination of Unsaturation of Synthetic and Natural Rubbers by Means of Iodine Monochloride

Abstract The unsaturation of GR-S at various conversions corresponds to the spectrophotometrically determined styrene content. It is concluded that GR-S at various conversions has the theoretical unsaturation. Emulsion polybutadiene was found to have 97 to 98 per cent of the theoretical unsaturation, emulsion polyisoprene 97 per cent. Sodium polybutadiene and polyisoprene had unsaturations which were considerably less than theoretical. The unsaturation of sodium polybutadiene was 92 per cent and that of sodium polyisoprene was 85 per cent. Sodium copolymer of butadiene (75) and styrene (25) also had an unsaturation considerably less than the theoretical value.