POSS杂化聚硅氧烷复合材料的制备与热性能研究

以八乙烯基多面体低聚倍半硅氧烷（OVPOSS）和含氢硅氧烷为单体，通过硅氢加成反应制备了一种新型POSS交联剂V2-POSS。将V2-POSS加入到聚甲基硅氧烷中，制备了一系列不同POSS含量的聚甲基硅氧烷。采用热重分析（TGA）、热重-红外联用（TGA-IR）、裂解气相色谱-质谱（PyGC-MS）等手段对POSS杂化聚甲基硅氧烷的热性能、热分解动力学及动态热解性能进行研究，结果表明：V2-POSS在聚甲基硅氧烷中均匀分散，POSS纳米结构的引入可显著提高聚甲基硅氧烷的热性能；V2-POSS添加量（V2-POSS占聚甲基硅氧烷的质量分数）为10%时，氮气氛5%热失重温度从纯树脂的442.2℃提高至469.4℃；热失重率为15%时，热解表观活化能由纯树脂的87.53 kJ/mol提高至杂化树脂的251.12 kJ/mol。POSS杂化聚甲基硅氧烷的热解机理主要包括聚硅氧烷主链的断裂、高分子链回咬、含硅基团的重排、碳氢化合物的形成以及小分子的逸出。

Preparation and thermal properties of a functionalized polyhedral oligomeric sitsesquioxane and its methyl polysiloxane hybrid materials

A novel polyhedral oligomeric silsesquioxane (POSS) cross-linker V2-POSS has been synthesized by hydrosilylation of octavinyl-POSS and a hydrogen terminated siloxane (H2) and incorporated into methyl polysiloxane resins in different ratios by thermal curing technology. The thermal properties, thermal degradation kinetics and pyrolysis behavior of the POSS hybrid methyl polysiloxane were investigated by TGA, TGA-IR, and PyGC-MS. The experimental results showed that V2-POSS could be homogeneously dispersed in the methyl polysiloxane matrix. The thermal properties of methyl polysiloxane were significantly improved by addition of V2-POSS. The 5% weight loss temperature of methyl polysiloxane with 10% V2-POSS increased to 469.4℃ in N₂, 27.2℃ higher than the corresponding value for the pure methyl polysiloxane resin. The thermal decomposition activation energy of the POSS hybrid methyl polysiloxane increased to 251 kJ/mol compared to a value of 88 kJ/mol for the pure methyl polysiloxane resin when the weight loss ratio was 15%. The thermal degradation mechanism of the methyl polysiloxane includes main chain scission, end-initiated unzipping, rearrangement of silicon-containing groups, formation of hydrocarbons and escape of small molecules.