Synthesis and Elastomeric Properties Study of GAP-PB-GAP Energetic Tri-Block-Polymer

The binder is an essential ingredient of solid composite propellants. Today, the industrial military scientists have been focused on finding and developing the new energetic binders to enhance the performance of composite propellants. In this research, triblock hydroxyl-terminated polybutadiene (HTPB) with Glycidyl azide polymer (GAP) was synthesized as a new energetic binder. In the first step, PECH-PB-PECH copolymer was synthesized from the reaction of epichlorohydrin (ECH) with HTPB as a macro initiator in the presence of boron trifluoride etherate as catalyst; which then was characterized by FTIR, 1H-NMR spectroscopies. In the second step, the GAP-PB-GAP copolymer was synthesized by azidation of the triblock polyepichlorohydrin (PECH) and HTPB in the presence of sodium azide and mixed solvents of dimethyl acetamide and toluene at 70OC (90% yield). The effects of monomer, catalyst, and solvents on molecular weight, as well as the yield of copolymer (GAP-PB-GAP) were studied. The synthesized copolymers were identified by IR, NMR, GPC, DSC, TGA, viscosity and TLC (tin layer chromatography) methods. In addition, after finding the curing conditions, the mechanical properties of polyurethane-based GAP-PB-GAP (such as tensile strength and strain) were investigated.