Improvement in the Mechanical Properties of Paraffin-Based Propellant

Abstract

The hybrid rocket has been in use due to a super level of safety, low cost than the conventional type of rocket fuels. Normally hybrid propellant-based rocket engine not well appreciated due to the low rate of regression and poorly efficient combustion. The solution was sought in the use of low-melting solid fuel-like paraffin wax. A total of eight compositions of fuels were processed using paraffin wax, stearic acid Araldite, hardener, LDPE, EVA and carbon black. These fuel compositions were subjected to stress–strain analysis using universal testing machine INSTRON-model no: 1133. Based on mechanical strength, three samples, i.e. wax, one which has lower mechanical strength and one has higher mechanical strength were further studied for calorific value and regression rate. For sample-1 (P.W-100%) and sample-2 (P.W-90% + S.A-10%), the stress–strain curve is in a zigzag pattern like a brittle material. The maximum value of stresses is 1.003 and 1.176 MPa with corresponding maximum per cent strains are 4.064 and 3.098, respectively. For this particular type of paraffin wax, Young’s modulus is of 109.52 MPA. For sample-2, Young’s modulus is of 157.72 MPa. For sample-4(P.W85.47% + S.A8.54% + Araldite4% + Hardener(epichlorohydrin)0.85% + C.B0.85%), sample-5(P.W93.45% + Araldite4.67% + Hardener(epichlorohydrin)-0.93% + C.B-0.93%) the stress–strain curve pattern is like an elastic materials. For sample-3, 4 and 5, the maximum value of stresses is 0.656, 0.791, 0.547 MPa and corresponding maximum per cent strains are 2.653, 2.576, 1.93, respectively. For the three samples, 3, 4 and 5 the Young’s moduli are, respectively, 136.51, 75.52 and 56.41 MPa. Sample-6(P.W-81.87% + SA-8% + Araldite-4% + Hardener-0.81% + C.B-1% + LDPE-4%), sample-7(P.W-81.87% + SA-8% + Araldite-4% + Hardener-0.81% + C.B-1% + EVA-4%), sample-8(P.W-78.36% + SA-7.83% + Araldite-3.91% + Hardener-0.78% + C.B-1% + LDPE-4% + EVA-4%) the stress–strain curve is following the nature of an elastic materials but necking point. For sample-6, 7 and 8, the maximum value of stresses is 0.806, 1.132, 1.386 MPa and corresponding maximum per cent strains are 2.498, 9.704, 1.981, respectively. Similarly, the Young’s modulus is, respectively, 50.990, 22.62 and 225.62 MPa. Highest Young’s modulus has observed for sample-8 for sample dimension \(8 \times 2.5 \times 0.5\,{\text{cm}}\).