Effects of micro and nano fillers on the mechanical and thermal properties of hydroxyl‐terminated polybutadiene‐polyurethane based rocket motor liner

Abstract Case bonded solid rocket motors hold significant importance in both the defense and aerospace industries which typically consist of an insulating layer, a solid propellant, and a liner layer serving as an adhesive between the insulator and solid propellant. In this investigation, the aim was to assess the critical mechanical properties of five different HTPB based liner formulations under ambient conditions, as well as at elevated and reduced temperatures. The liner formulations incorporated micro carbon black, nano carbon black, nano silica, and nano titania as fillers. A comprehensive characterization study encompassing mechanical and thermal properties was conducted to evaluate the performance of these potential rocket motor liners. Mobility reduction of polymer chains and bond strengthening at lower temperatures led to the enhancement in mechanical properties of all filled and unfilled liners with decline in temperature. All mechanical properties of filled liner formulations increased significantly compared to unfilled formulation at all temperatures. Enhancements in mechanical properties were more pronounced with carbon blacks as fillers. Thermal analyses of each formulation revealed that there were improvements in the thermal properties of filled liners compared to unfilled one.