Effects of crosslinking degree and carbon nanotubes as filler on composites based on glycidyl azide polymer and propargyl‐terminated polyether for potential solid propellant application

Abstract

Triazole crosslinked polymers were prepared by reacting glycidyl azide polymer (GAP) with the propargyl-terminated poly(tetramethylene oxide) (PTMP) at different molar ratios of azide versus alkyne. Based on the optimum mechanical properties of the GAP/PTMP-2.5, a series of GAP/PTMP nanocomposites reinforced by either multi-walled carbon nanotubes (MWCNTs) or carboxyfunctionalized multiwalled carbon nanotubes (MWCNTs-COOH) were prepared with different mass ratios. The glass transition temperatures (T g, PTMP ) assigned to PTMP of the GAP/PTMP composites almost kept at a constant range when the molar ratio of azide versus alkyne was from 1.0 to 2.5. When the loading MWCNTs was 1.0 wt %, the tensile strength and elongation at break achieved a maximum of 1.77 MPa and 36.3%, respectively. The nanocomposites with nearly similar T g, PTMP indicated no phase separation in the crosslinked polymers. The results revealed that the improved properties of GAP-based materials could be achieved by changing the molar ratio of azide versus alkyne and the nanofillers content.

Glycidyl Azide Polymer and its Derivatives-Versatile Binders for Explosives and Pyrotechnics: Tutorial Review of Recent Progress

“…A different method of producing GAP/carbon nanotube composites is reported by Wang et al [26] who cross-linked GAP with a propargyl-terminated polymeric curing agent (CA9) in MWCNT and carboxyl-functionalised MWCNT dispersions. As such, the authors chose to rely on occlusion as means of "trapping" the nanotubes in the solidifying cross-linked polymer matrix rather than using direct chemical linkage, as in the abovementioned case of GAP-MWCNT/HTPB-MWCNT networks.…”

Recent advances on graphene microstructure engineering for propellant‐related applications

“…In order to achieve the high performances, recently, carbon nanomaterials, such as carbon black, 2 graphite, 3 fullerenes, 4 and carbon nanotubes (CNTs), 5,6 have been efficiently used as catalysts or additives for composite propellants because of their notable physical and chemical properties. [7][8][9][10][11][12] Graphene, as an exciting carbon material, has aroused much interest owing to its unique electrical, thermal, and mechanical properties, and so on. [13][14][15][16][17][18] In recent years, researchers have tried to evaluate the feasibility of the application of graphene in composite propellant.…”

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

“…On the other hand, the application of alkyne‐terminated polymers, instead of alkyne‐containing small‐molecules, might contribute to higher elongation of the GAP‐based binder systems due to long‐chain flexibility. Many kinds of hydroxy‐terminated polymers involving hydroxyl‐terminated polybutadiene (HTPB) and polytetramethylene oxide (PTMO), which have traditionally been used to fabricate polyurethane‐type binders via isocyanate‐curing system, could be chemically modified to give terminal alkyne groups and hence compounded with GAP to produce the triazole‐based binder systems. Usually, the binder systems based on GAP and alkyne‐terminated polymers presented the glass transition assigned to long‐chain polymers at lower temperature region.…”

“…15,[26][27][28] The crosslink density of the GAP-based binder systems cured with alkyne-terminated polymers still more presented a nonlinear changes with an increase of azide/alkyne reaction ratio. [30][31][32] Ethylene oxide-tetrahydrofuran copolymer (Poly(THF-co-EO)) is a nontoxic and highly flexible copolyether. 33 Because of excellent mutual compatibility with nitrate plasticizers, Poly[THF-co-EO] has been commonly used to prepare polyurethane-type binders in nitrate ester plasticized polyether (NEPE) propellants.…”

“…Thus, the crosslink density, which dominates mechanical properties of the network‐structured GAP‐based binders, failed to be effectively regulated by rule even though some GAP‐based binder systems cured with alkyne‐containing small molecules showed monotonic dependence of the crosslink density upon the feeding molar ratio of azide versus alkyne . The crosslink density of the GAP‐based binder systems cured with alkyne‐terminated polymers still more presented a nonlinear changes with an increase of azide/alkyne reaction ratio …”