Abstract: Poly(silphenylene-dimethyl siloxane)s (PTMPS-DMS) containing crosslinkable vinyl groups were synthesized through the Si—H/Si—OR polycondensation process. The crosslinked PTMPS-DMS networks were prepared by hydrosilation and the BPO thermal crosslink process respectively. TG，DSC and isothermal gravimetric analysis at 300℃ showed that the crosslink process had great impact on the thermal properties of the crosslinked networks. The BPO thermal crosslinked network，which began to degrade at 480℃ in air，possessed much higher thermo-oxidation stability than that crosslinked by the hydrosilation process，which began to degrade at 368℃ in air. The Tgs of these two networks had no significant difference，which were －55℃ and －49℃，respectively. It showed that the catalyst H2PtCl6 greatly decreased the thermo-oxidation stability of the PTMPS-DMS networks.

摘要： 用Si—H/Si—OR缩聚的方法制备了含可交联乙烯基的聚亚苯基硅氧烷-二甲基硅氧烷共聚物（PTMPS-DMS），用硅氢加成、BPO热交联两种方法进行交联得到交联网络，并用热重分析（TG）、300 ℃恒温热分析和DSC等方法对其热性能进行了研究。结果表明，交联方法对PTMPS-DMS交联网络的热稳定性影响很大，BPO热交联网络的热稳定性远远高于硅氢加成交联网络，两种交联网络在空气中的5％热失重温度分别是480℃和368℃，Tg则没有显著差异，分别是－55 ℃和－49 ℃。H2PtCl6能显著降低PTMPS-DMS及其交联网络在空气中的热稳定性。