Influence of Carbon Nanofibers on Thermal and Mechanical Properties of NC‐TEGDN‐RDX Triple‐Base Gun Propellants

Abstract

Triple‐base gun propellants composed of nitrocellulose (NC), triethylene glycol dinitrate (TEGDN) and cyclotrimethylenetrinitramine (RDX) with carbon nanofibers (CNFs) were studied to explore the effects of CNFs on the thermal and mechanical properties. The results indicated that CNFs with less than 0.50 wt % were evenly and randomly dispersed in the propellant, otherwise there existed obvious aggregation. Temperatures of initial decomposition and exothermic peak reduced with the increase of NCFs from 0.00 to 3.00 wt %. Decomposition enthalpy of the composites with 0.50 wt % NCFs was 1214.6 J g−1, increased by ∼131.4 J g−1 compared to that of NC‐TEGDN‐RDX propellants. Moreover, the mechanical properties were effectively tailored by varying the amount of CNFs added to the composition. Decomposition enthalpy of the propellant with 0.25 wt % CNFs were hardly compromised for achieving enhancement in the compressive and impact properties, while the tensile strengths decreased slightly compared to that of the propellants.

Carbon Fibers Enhance the Propagation of High Loading Nanothermites: In Situ Observation of Microscopic Combustion

“…In principle, the addition of carbon fibers might also affect the heat transfer in the composites. − The thermal conductivity of carbon fiber can vary widely from ∼10 to ∼1000 W·m –1 ·K –1 , while the value of carbon fibers used in this study is estimated to be ∼10–20 W·m –1 ·K –1 . , A ∼2.5 wt % addition of the carbon fibers, however, should not appreciably increase the calculated overall thermal conductivity/diffusivity, until a fiber conductivity of at least ∼250 W·m –1 ·K –1 (∼aluminum’s thermal conductivity), as shown in Figure S3 and Table S4. Although the addition of carbon fibers might not increase the overall thermal conductivity of the composites, conductive heat transfer from hot burned/burning particles to the unburnt materials via these fibers might be quite efficient, especially in the case where the carbon fibers themselves create a connective network (Figure d) .…”

“…Although the addition of carbon fibers might not increase the overall thermal conductivity of the composites, conductive heat transfer from hot burned/burning particles to the unburnt materials via these fibers might be quite efficient, especially in the case where the carbon fibers themselves create a connective network (Figure d) . However, while the average conductivity might not be substantially impacted (because of its small mass fraction in the composite), the fact remains that the fibers have a much higher thermal conductivity (>10 W·m –1 ·K –1 ) than the polymer matrix (∼0.2 W·m –1 ·K –1 ) and the surrounding gas (∼0.02 W·m –1 ·K –1 ), ,− which provides 10× higher overall thermal conductivity (see detailed calculations in Figure S4 and Table S5) through the gas/carbon fiber combination route (0.17 W·m –1 ·K –1 , Table S5), compared to those via just gas heat transfer (0.017 W·m –1 ·K –1 , Table S5). It is also reasonable to expect that the fibers provide a local path for hot spots perhaps penetrating deep into the preheat zone of the composite.…”

Temperature Sensitivity Coefficients of RDX‐Based Propellants and Their Mixed Charges

“…Addition of RDX into propellants [33] can enhance the energy output of the propellants [34][35][36]. Due to weak adhesion between RDX and the binder, voids and exposure of the RDX surfaces increase the burning surface and controlled combustion performances are obtained [37,38]. Taking full advantage of this characteristic, the burning surface increases further at low temperature, and the low temperature sensitivity coefficient of the propellant may be obtained.…”

Kinetic Modeling of Liquid Phase RDX Thermal Decomposition Process and its Application in the Slow Cook‐Off Test Prediction

“…Hexahydro-1,3,5-trinitro-s-triazine (RDX) is an extremely important explosive component with its high energy density, high detonation velocity, and pressure. Recently, RDX has also been widely used in propellants as a high-energy component [5][6][7][8][9][10]. In order to better understand its decomposition characteristics, many detailed researches on its thermal decomposition products and initial reaction pathways have been carried out since 20th century.…”

“…Figure6. Apparent activation energy, ln(A α f(α)) vs. conversion for RDX (Note: the calculation of activation energy does not include the melting process).…”