Optimization of Triblock Copolymerization Conditions of Propylene OxideTetrahydrofuran-Propylene Oxide and Properties Investigation of its Elastomers

Binders are one of the most key components of solid composite propellants used in the military and space research industries. In present research, a PPG-PTHF-PPG triblock copolymer was synthesized as a binder using polytetrahydrofuran as an initiator and propylene oxide monomer through the cationic ring-opening mechanism with suitable molecular weight and high efficiency. The synthesized copolymer was investigated and identified with tools such as IR, NMR, GPC, and DSC. In the next, the optimal conditions for copolymer synthesis, including the choice of solvent type, the amount of solvent and catalyst, and the duration of the reaction, were investigated. After taking steps of copolymer synthesis, the curing of the copolymer was tested by different isocyanate curing agents, so the optimal amounts of curing catalyst, chain extender, and R ( mixture of N-100 and IPDI isocyanate agents) were obtained. The mechanical properties of elastomers were also evaluated through preparing dumbbell-shaped elastomers, which showed an 80% increase in elongation compared to the HTPB sample.