Synthesis and Properties of Phenyl Silicone Resin Reinforced Addition Type Liquid Phenyl Silicone Rubber

Phenyl silicone resin reinforced addition type liquid phenyl silicone rubber was prepared by vulcanization of vinyl end-capped polymethylphenylsiloxane (PVPS), phenyl MT resins and hydrogen end-capped polydiphenylsiloxane (PHPS) under Pt catalysis at 150°C for 4h. The effects of the proportion and the vinyl content of phenyl MT resins on the mechanical properties of cured products were investigated. The thermal stability was explored by thermogravimetric analysis. The changes of mechanical properties were also studied before and after irradiation. Phenyl silicone rubber with good performance was obtained when the phenyl MT resin content was 50~60 wt% and the vinyl content was at 5.5~6.6 wt%. The onset temperature of thermal degradation and the center temperature of thermal degradation were 443.7°C and 502°C, respectively. When the radiation dose increased from 0 to 300 KGy, the tensile strength decreased from 4.1MPa to 2.3MPa and the tearing strength decreased from 8.9MPa to 5.1MPa. When the radiation dose continues to increased from 300 to 900 KGy, the tensile strength increased from 2.3MPa to 6.4MPa and the tearing strength increased from 5.1MPa to 6.5MPa. During the process of radiation, the elongation at break had been kept down from 96% to 52%, and the hardness increased from 80A to 90A.