梯形聚甲基倍半硅氧烷对脱醇型RTV-1硅橡胶性能的影响

Effect of Polymethylsilsesquioxane on Properties of Dealcoholized RTV-1 Silicone Rubber

以甲基三氯硅烷为主要原料,乙二胺为梯形控制剂,合成了梯形聚甲基倍半硅氧烷(PMSQ);以八甲基环四硅氧烷(D4)为原料,采用碱催化平衡聚合法,制备了α,ω-二羟基聚二甲基硅氧烷(107硅橡胶);采用107硅橡胶、交联剂、PMSQ等制备了脱醇型单组分室温硫化(RTV-1)导热硅橡胶。探讨了PMSQ用量对RTV-1硅橡胶导热、绝缘、物理性能、阻燃和热稳定性的影响。结果表明,温度高于90℃时,随PMSQ用量的增加,硅橡胶的热导率增大;当其用量为2.5 g(以50 g 107硅橡胶为基准)时,硅橡胶在30～150℃具有较好的导热性能。随PMSQ用量的增加,硅橡胶的拉伸强度、断裂伸长率均逐渐下降;硅橡胶的体积电阻率随PMSQ的增加先增后减,添加量为1.5 g时,体积电阻率增大了1.68倍。PMSQ能提高RTV-1硅橡胶的阻燃性能,并且能提高硅橡胶的热稳定性,减轻了RTV-1硅橡胶高温下迅速分解的状况,延缓了热失重的速度,PMSQ的较佳用量为2.5 g,此时,硅橡胶的热导率为0.425 W/m·K,拉伸强度为3.5 MPa,拉断伸长率为188%,体积电阻率为4.0×1015Ω·cm。

Ladder polymethylsilsesquioxane （PMSQ） was synthesized using methyhrichlorosilane as the raw material and an organic amine as the trapezium control agent. The preparation of a, to -dihydroxyl polydimethylsiloxane （107 rubber） by equilibrium polymerization using an alkali catalyst. A thermally con- ductive, electrically insulated and dealcoholized RTV - 1 silicone rubber was prepared with 107 rubber, cross- linking agent and PMSQ. The effect of PMSQ on the thermal conductivity, electrical insulation and other phys- ical properties, as well as the thermal stability of the RTV - 1 silicone rubber was studied. The results showed that the silicone rubber had good thermal conductivity with adding 2.5 g PMSQ （50g 107 rubber as basis）, from 30 ~C to 150 ~C. When the temperature was over 90 ~C, the thermal conductivity of the RTV - 1 silicone rubber was increased along with the increase of PMSQ. With the increase of amount of PMSQ, the tensile strength and elongation were decreased. Volume resistivity was increased with increasing the loadings of PMSQ first, and then decreased. Adding 1.5g PMSQ, volume resistivity was increased to 1.68 times. PMSQ could improve the flame retardant properties of the RTV - 1 silicone rubber. Furthermore, the thermal stability was improved by reducing the speed of decomposition. The silicone rubber has thermal conductivity of 0. 425 W/re.K, tensile strength of 3.5 MPa, elongation at break of 188% and volume resistivity of 4.0×10^15Ω .cm when 2.5 g PMSQ was added.