Preparation and properties of a pre-coated solvent-free adhesive for EPDM insulation bonding

Epoxy-modified HTPB (ETPB), acrylate-modified HTPB (ATPB) and epoxy acrylate (EA), were synthesized from hydroxyl-terminated polybutadiene (HTPB) and epoxy resin E-51 as the main raw materials. These three kinds of synthetic resins were mixed with epoxy resin E-51 and additives in a certain mass ratio to prepare a solvent-free adhesive for bonding ethylene propylene diene monomer (EPDM) insulation and solid rocket motor case. For the convenience of storage and pasting, the adhesive was pre-coated on the surface of an EPDM sheet and irradiated by ultraviolet light to form a kind of pressure sensitive adhesive sheet with EPDM as the substrate. This pressure sensitive adhesive sheet is stable at room temperature and could be cured at high temperature. Based on orthogonal experiment, the proportions of the four main components in the adhesive were optimized. The results show that the bonding performance of the solvent-free adhesive is the best when the addition amounts (mass content) of epoxy resin E-51, ETPB, ATPB and EA are 39.0%, 23.5%, 23.5% and 6.0%, respectively. The ring initial adhesion of the pressure sensitive adhesive sheet is 8.33 N. The peel strengths of pressure sensitive adhesive sheet bonded with carbon fiber composite and aluminum material after thermal curing are 4.32 kN/m and 4.49 kN/m respectively.