The Role of Alumina Trihydrate Filler on semiflexible unsaturated polyester resin‐4 and inhibition of double‐base rocket propellants

Abstract

Abstract The use of unsaturated polyesters for inhibition of double‐base rocket propellants has become popular in recent years. A direct bonding inhibition system termed as semiflexible unsaturated polyester resin‐4 has been recently developed and reported by us. It has been reported in literature that the use of some fillers such as antimony trioxide, titanium dioxide, lithophone, alumina trihydrate etc. impart better mechanical and heat resistance properties. The effect of 10% to 60% of alumina trihydrate (Al 2 O 3 · 3 H 2 O) on semiflexible unsaturated polyester resin‐4 in respect of gel time, exotherm peak temperature, tensile strength, %‐elongation, nitroglycerin absorption, water absorption, heat resistance and flame retardance has been studied and the result obtained have been discussed. It is observed that 30% of alumina trihydrate imparts desirable properties. The 108 mm and 148 mm‐diameter propellant sustainers inhibited with resin‐4 containing 30% alumina trihydrate and conditioned at ambient, sub‐zero temperature (−40°C for 18 hr) and high temperature (+50°C for 18 hr) were statically evaluated. The pressure‐time profiles at all temperatures have been found to be flat and neutral which infer that the inhibition system works satisfactorily.