Chemical Modification of Hydroxyl-Terminated Polybutadiene and Its Application in Composite Propellants

Abstract

In this article, hydroxyl-terminated polybutadiene (HTPB) was chemically transformed into multiamine, hydroxy polybutadiene (AEHTPB) by the adoption of appropriate synthesis strategies. The structure of AEHTPB was confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). The modification degree was altered by adjusting reaction conditions to find out the effect of structural change on various physical properties, including the viscosity and glass transition temperature (Tg) of AEHTPB. Adding AEHTPB to the HTPB binder system could improve the cross-link density and strength of the polyurethane elastomer. Meanwhile, the experiment results indicated that AEHTPB could inhibit the low-temperature decomposition of ammonium perchlorate (AP) by forming a dense coating on the surface of AP. Then, the propellant level studies were conducted with the use of AEHTPB/HTPB mixture as a binder. As a result, the burning rate of propellant containing AEHTPB (5 wt %) was found to be reduced by 10.8% compared to HTPB-based propellant, and the mechanical properties of the propellant were superior to those of HTPB-based propellant with an improvement of 46.2% in tensile strength and 35.1% enhancement in elongation at break. Finally, tensile testing and observation of fracture surface morphology further demonstrated that AEHTPB had a significant bonding effect on AP-based propellant.