Synthesis of highly branched polymethylphenylsiloxane grafted epoxy resin copolymer for high efficiency ablation thermal protection coating

Highly branched polymethylphenylsiloxane grafted epoxy resin (HBPSE) was synthesized by grafting silicone intermediate onto epoxy resin via the condensation between methoxyl and hydroxyl. The chemical structure of the highly branched copolymer was characterized by FT-IR, 1H-NMR and GPC. The thermal stability of the HBPSE copolymer was characterized by TGA and muffle furnace ablation test. Furthermore, ablation thermal protection coating (ATPC) with HBPSE copolymer was prepared. Compared with classical epoxy based ATPC, the HBPSE based ATPC has better thermal stability and wider pyrolysis temperature range. After oxygen-acetylene test, the micromorphology and chemical composition of the HBPSE based ATPC were characterized by SEM, EDS and FT-IR. Finally, both the HBPSE based ATPC and epoxy based ATPC were assessed under the heat flow of 200 kW/m2 for 320 s, the ATPC with HBPSE matrix has a lower back face temperature and a better surface state.