Flexibilized novolac epoxy resin for inhibition of composite propellants

The effect of variation of polyamide hardener (EH411) on a novolac epoxy resin (Dobeckot E4) has been studied in terms of tensile strength and percent elongation. Based on a combination of tensile strength and percent elongation, formulation 9 (Dobeckot E4 : 100 + hardener EH411 : 50) has been selected for studying the effect of liquid polysulfide rubbers (LP-32 and LP-33). The data indicate that gel time, tensile strength, heat resistance, and flame retardance decrease, whereas elongation and dioctyl adipate absorption increase as the proportion of liquid polysulfide rubbers increases. The effect of antimony trioxide and alumina trihydrate fillers on formulation 20 (Dobeckot E4: 100 + hardener EH411: 50 + LP-33: 20) and formulation 21 (Dobeckot E4: 100 + hardener EH411: 50 + LP-33 :30) has also been studied. Based on tensile strength, elongation, dioctyl adipate absorption, heat resistance, and flame retardance data, formulation 27 (Dobeckot E4 : 100 + hardener EH411:50 + LP-33:30 + Sb2O3 :40) has been selected for inhibition followed by static evaluation of hydroxy-terminated-polybutadine- (HTPB-) based tubular composite propellants. The pressure-time profiles from -40 to 50 degreesC indicate that the formulation 27 (Dobeckot E4: 100 + hardener EH411:50 + LP-33:30 + Sb2O3 :40) is a viable inhibition system for inhibition of HTPB-based composite propellants.