The catalysis effects of acetylacetone complexes on polymer matrix of HTPB-based fuels

Abstract

The slow regression rate caused by the difficulty of pyrolysis can not meet the practical application requirements of hydroxyl-terminated polybutadiene (HTPB)-based fuels in hybrid rocket propulsion. Accelerating the decomposition of polymer matrix has become a new method to enhance the regression rate of HTPB fuels. For determining the difference of combustion performance between different acetylacetone (acac) complex loaded HTPB-based fuels, Fe(acac)3, Ni(acac)2, and Cu(acac)2 are introduced into the HTPB matrix with 5 wt%, respectively. The experimental results reveal that the acetylacetone complexes can catalyze the pyrolysis of HTPB matrix hence increasing the regression rate of fuel grains: 5 wt% Fe, Ni, and Cu acetylacetone enhance the regression rate of HTPB fuels by 13.8%, 15.5%, and 11.4% at Gox = 50 kg/m2s. And the gap in regression rate between three complex loaded fuels is originated from the influence of many factors such as catalytic effect, combustion heat, and combustion products, etc. This study compares the regression rate of different acetylacetone complex loaded fuels for future catalyst selection, and explains the corresponding combustion mechanism.