English Abstract

Influence of Surface Migration of 6PPD as an Amine Type Antioxidant on Ozone Resistance of Vulcanized Rubber

Hiroaki KONDO
Yoshito OHTAKE
Chemicals Evaluation and Research Institute, Japan, Kitakatsusika-gun, Saitama, Japan
Nippon Gomu Kyokaishi,(2019),92(1),3-9 Original Paper in Japanese

Ozone resistance of vulcanized isoprene rubber containing 6PPD as an amine type antioxidant was investigated at temperatures between -30 °C and 55 °C. Both pure gum compound and carbon black filled compound were prepared by mixing isoprene rubber with zinc oxide, stearic acid, sulfur, accelerator and 6PPD. Ozone exposure tests of the vulcanized rubber after 20% straining were carried out under 50 pphm ozone at -30 °C, 40 °C and 55 °C for 48 hours, respectively. Ozone cracks and surface morphology of the rubber were observed with a digital microscope and a scanning electron microscope. The crack propagation of the vulcanized rubber took place at 40 °C, whereas it was suppressed at -30 °C and 55 °C, even though the amount of 6PPD bloomed on the surface of the rubber at 40 °C was higher than that at -30 °C. It was found that the ozone resistance of rubbers containing 6PPD depends markedly on the surface morphology of rubbers blooming 6PPD, that is, the temperature under ozone exposure.

Keywords: Ozone Degradation, Amine Type Antioxidant, 6PPD, Melting Point, Bloom, Bleed, Migration