Tensile Tests of Paraffin Wax for Hybrid Rocket Fuel Grains

Abstract

The tensile strength, elastic modulus and percent elongation of paraffin wax doped with small concentrations of low density polyethylene (LDPE) where measured. The centrifugal casting process was used to create paraffin wax / LDPE wax hybrid rocket motors. Tensile tests were then performed on samples taken from these test motors. Concentrations from 0 % to 4 % LDPE added to the paraffin wax were tested. The tensile strength, and elastic modulus increased with increasing concentration of LDPE. The results show that paraffin wax motors can be created that have a greater elastic modulus and similar tensile strengths compared to current solid rocket motors based on HTPB rubber motors. However the paraffin wax motors were found to be less elastic than HTPB with a much lower percent elongation. Void formation, tiny bubbles in the paraffin wax created during the casting process, were found to affect the tensile properties measured.