Preparation and properties of block copolymerization thermoset polyurethane elastomers prepared in situ

Polyurethane elastomers are commonly employed as binder in propellant propellants and explosives due to their excellent mechanical properties. In-situ block copolymer synthesis of polyurethane for several advantages, including the elimination of the need for solvents in the reaction process, avoidance of excessive reaction steps, and minimizing the generation of byproducts. On the other hand, the in-situ method utilizes a low-cost prepolymer, making it highly suitable for large-scale production. Polyethylene glycol is currently one of the most widely used prepolymer in polymerization. PCL possesses favorable solubility and exhibits hydrophobicity with a low melting point, remarkably noteworthy are its thermoplastic properties, including a high decomposition temperature and a low glass transition temperature. This work employed an in-situ block copolymerization method to synthesize polyurethane elastomers and subsequently investigated their mechanical properties, surface structure, evolution over time, and thermal decomposition process. Polyurethane elastomers exhibited favorable mechanical properties, the elongation properties of these polyurethane systems herein are influenced by the proportion of hydrogen-bonded carbonyl groups within the urethane. The thermal decomposition of polyurethane elastomers can be divided into two distinct processes. Random scission of the polyurethane yielding PCL occurs under low-temperature conditions, while specific cleavage events take place at higher temperatures.