Effect of various fibers on the ablation resistance of poly(diaryloxyphosphazene) elastomer

Abstract

ABSTRACTPoly(diaryloxyphosphazene) elastomer (PDPP) is an alternative and promising thermal insulation material to protect the combustion chamber of solid rocket motors. The hybrid inorganic–organic macromolecule with the backbone of alternating nitrogen and phosphorus atoms has good thermal stability and compatibility for inorganic and organic fillers. This article focused on the effect of inorganic and organic fibers on the ablation resistance of PDPP at slow and fast pyrolysis, which was performed by thermogravimetric analysis and oxyacetylene ablation. Two inorganic fibers (alumina and mullite) and two organic fibers (polyimide and phenolic) were introduced into PDPP elastomer. During the process of slow pyrolysis, two inorganic fibers provided higher char yields due to their higher thermal stability. However, SiC in situ formed on the surface of organic fibers effectively improved the ablation resistance of the composites under the process of fast pyrolysis according to the micromorphology and structure analyses of charred layers. In addition, terminal groups of organic fibers affected the in situ formation of SiC. The phenolic/PDPP composite have a better ablation resistance than the other three composites at fast pyrolysis, owing to more in situ formed SiC on its surface and its higher decomposition activation energy. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48534.