Nano Co-Continuous Structure Poly(imide-siloxane)/Phenolic Hybrid Resin Fabricated by Copolymerization for the Thermal Protection System

Organic-inorganic hybridizationis an importantway to improvethe ablation resistance of phenolic resin (PR). However, it is difficultto form a continuous inorganic liquid film on the resin surface duringablation, thus limiting the further improvement of ablation performance.In this work, a new poly(imide-siloxane) (PIS) was designed by introducingimide rings and terminal ethoxy groups into the main chain of silicone,and then it was introduced into PR. The imide rings can increase thepolarity of the chain, and the terminal ethoxy groups can react withhydroxyl groups in PR, which can improve the compatibility of PISwith PR. SEM and AFM showed that nano co-continuous and sea-islandstructures of hybrid resins were prepared, respectively. Then, theinfluence of different structures on thermal stability and ablation-resistantproperties was investigated by using TGA, tube furnace heat treatment,and oxyacetylene ablation test. Compared to the sea-island structure,the nano co-continuous structure of resin can form a continuous anddense SiO2 film in situ, giving the resin superior thermalstability and ablation-resistant properties. The present work providesan available way to manipulate hybrid resin's phase structureand develop high-performance ablation-resistant resin in aerospaceapplications.

Automated summary

A new poly(imide-siloxane) (PIS) was designed and introduced into phenolic resin (PR) to improve its ablation resistance. The nano co-continuous structure of the hybrid resin exhibited better thermal stability and ablation resistance due to the formation of a continuous and dense SiO2 film. This study provides a feasible approach to manipulate the phase structure of hybrid resins and develop high-performance ablation-resistant resins for aerospace applications.