Synthesis and thermal properties of novel room temperature vulcanized (RTV) silicone rubber containing POSS units in polysioxane main chains

Ethyoxyl-phenyl polyhedral oligomeric silsesquioxane (DOPO) was synthesized at first and then copolymerized with polydimethylsiloxane (PDMS) and finally cured to prepare room temperature vulcanized (RTV) silicone rubber (b-POS-SiR). Their structures and properties are characterized and evaluated by fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), wide angle X-Ray diffraction (WAXD), and dynamic mechanical analysis (DMA). The thermal degradation mechanisms are investigated via thermal gravimetric analysis (TGA) coupled with FTIR analyses. The results show, that the thermal degradation temperatures (5 mass % loss) of the b-POS-SiR are significantly improved with addition of DOPO, e.g., 60 °C and 20 °C higher in nitrogen and in air, respectively, for the b-POS-SiR with 5 wt% DOPO compared that of PDMS rubber (PSiR). The variety of degradation mechanisms in the different atmospheres are also studied by using TGA coupled with FTIR.