Alkynyl-functionalization of carbon nanotubes to promote anchoring potential in glycidyl azide polymer-based binders via Huisgen reaction for solid propellant application

Abstract

Triazole curing systems based on glycidyl azide polymer (GAP) have been widely used as the binders of solid propellant systems due to moisture insensitivity, high energy density, and room temperature curing. However, the low-flexible molecular structure of GAP usually causes low mechanical properties, and reinforcement fillers may not be suitable in the binder system of propellants because they probably diffuse into other parts of propellants. Thus, we anchored a strong nanomaterial, carbon nanotube (CNT), on GAP to prevent the CNT from diffusing uncontrollably. The anchoring process was based on the alkynylation reaction and the Huisgen reaction, which was confirmed by tests on chemical structure. The reaction process was further adjusted to introduce CNT into the triazole crosslinked network, leading to a 23.6% increase in the elongation at break of the binder. The high rigidity of CNT also improved the Young’s modulus and tensile strength of the binder increased by 107.7% and 199.0%, respectively. Furthermore, the high thermal conductivity of CNT could reduce the thermal resistance index of the binders from 160.4 °C to 151.2 °C, and decrease the carbon residue rate from 17.8% to 10.5%. Such an anchoring modification can thus target the reinforcement region in multi-component systems, which can be used not only in solid propellants, but also in ablative materials.