Abstract:

Vinyl MQ silicone resin(M and Q respectively represent R₃SiO_1/2 and SiO_4/2)was synthesized via the hydrolytic condensation of hexamethyldisiloxane,1,3-divinyl-1,1,3,3 tetramethyldisil0xane and tetraethyl orthosi-licate,and the effects of polymerization conditions on the properties of the product were investigated.Then,a series of room-temperature vulcanizing(RTV)silicone rubbers reinforced with vinyl MQ silicone resin were prepared from vinyherminated polydimethylsiloxane(PVMS)cured with organohydrogenpolysiloxane under the catalysis of Pt cata-lyst.Finally,the effects of the preparation process on the mechanical properties and transparency of the cured sili-cone rubbers were investigated.The results show that the synthesized MQ silicone resin is of the best reinforcement effeet when HCl and ethanol contents are respectively 4.0% and 1.6% and when the M/Q molar ratio is 0.75,and that,when the mass ratio of PVMS to MQ silicone resin is 1,the molar ratio of Si-H to Si-Vi is 1.4,the catalyst dosage is 10μg/g and the inhibitor dosage is 0.3 m/g,the cured silicone rubbers are of a tensile strength being up to 7.2 MPa and of excellent transparency owing to the reinforcement of MQ silicone resin.

Key words: MQ silicone resin, room temperature vulcanization, silicone rubber, reinforcement