Studies on Nonaluminized High Burning Rate AP-Composite Propellants

Abstract

This paper discusses the effect of replacement of hydroxyl terminated poly butadiene (HTPB) by butacene on the burning rates of a nonaluminized ammonium perchlorate (AP)–based composite propellant. A remarkable burning rate enhancement (60–100%) was observed on replacement of HTPB by butacene to the extent of 25%. Replacement of 50–75% HTPB by butacene led to further increase in burning rate by merely 10–20%, and no incremental effect was observed on complete replacement of HTPB. Butacene-based propellants also exhibited a lower pressure exponent (n) of the burning rate. The results obtained are in line with the findings of other researchers on aluminized AP composite propellants. Addition of transition metal oxides, ferric oxide (FO), and copper chromite (CC) to butacene-based formulations led to further enhancement of the burning rates, albeit to a less extent than in the case of HTPB-based systems. However, the burning rates of the former were higher than those of the latter in the case of ballistically modified compositions as well. DSC results for butacene-based formulations revealed lower activation energy (Ea) for decomposition than that for HTPB-based propellants. TGA studies brought out that butacene-based compositions decompose following a pattern similar to that of HTPB-based formulations. However, lower decomposition temperatures (1st and 2nd stages) were observed for butacene-based propellants.