Network regulation and properties optimization of glycidyl azide polymer-based materials as a candidate of solid propellant binder via alternating the functionality of propargyl-terminated polyether

A kind of glycidyl azide polymer (GAP)-based composite has been fabricated using propargyl-terminated ethylene oxide-tetrahydrofuran copolymer (PPET) with two (p-) and three (t-) alkyne functionalities via Huisgen reaction. Independent upon the PPET functionality, both crosslink densities and mechanical properties for two GAP/PPET systems showed a positive-interrelation changes of initial increase and subsequent decrease with an increase of azide/alkyne molar ratios. At equivalent of azide/alkyne molar ratios, the composites containing t-PPET with higher alkyne functionality exhibited better mechanical properties, while those with two alkyne functionality presented lower glass transition. Under the regulation of alkyne functionality as 3 and azide/alkyne molar ratio as 3:1, the tensile strength, Young's modulus and breaking elongation could simultaneously reach the maximum values of 1.38 MPa, 4.07 MPa, and 122.5%, which was ascribed to optimal participation of azide/alkyne reaction into network construction. Overall, this study provides an additional optimization route for network-structured binders in solid propellant system. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48016.