Key Takeaways & Executive Findings
- •• • The novel epoxy cured compound TC/BP-CA/PA-F@Al(np) achieves a tensile strength of 72.41 MPa and elongation at break of 4.81%, meeting engineering-grade epoxy requirements for structural applications. • • Incorporation of polyether segments reduces minimum ignition energy by 28.1% compared to TC-CA, and closed bomb peak pressure increases by 3.8%, indicating enhanced ignitability and energy release. • • Addition of fluoropolymer-coated nano-aluminum (F@Al(np)) further boosts peak pressure by 3.2% relative to TC-CA-F@Al(np), demonstrating synergistic energy release enhancement. • • The material exhibits a thermal decomposition onset of ~273 °C and a maximum pressure rise rate of 0.407 MPa·ms⁻¹, with peak pressure reaching 5.935 MPa, confirming rapid and substantial energy release suitable for reactive warhead casings.
Abstract
To address the issue that resin matrices in carbon fiber reinforced polymer (CFRP) composites cannot participate in explosive energy release when used in warhead casings, an epoxy resin cured compound with both high mechanical properties and high energy-release characteristics was prepared by introducing more easily pyrolyzable polyether segments and fluoropolymer-coated nano-aluminum powder into a high-rigidity epoxy cured compound. The crosslinked network structure, mechanical properties, thermal decomposition characteristics, ignition and combustion characteristics, and energy-release performance were characterized using infrared spectroscopy, quasi-static mechanical testing, TG-DSC, laser ignition testing, and closed bomb testing. Results show that the cured compound has a well-formed crosslinked network, a tensile strength of 72.41 MPa, an initial thermal decomposition temperature of approximately 273 °C, a minimum ignition energy reduced to 1.77 J, a maximum pressure rise rate of 0.407 MPa·ms⁻¹, and a peak pressure increased to 5.935 MPa in closed bomb tests. The introduction of polyether segments and fluoropolymer-coated nano-aluminum enhances the energy release rate and total energy release, making the material a potential resin matrix for CFRP-based reactive structural materials.
1. Introduction
Carbon fiber reinforced polymer (CFRP) composites are increasingly used in small warhead casings for weight reduction due to their high specific strength and stiffness. However, conventional resin matrices such as epoxy, phenolic, and polyether ether ketone are inert and difficult to ignite, failing to contribute to explosive energy release during detonation. This limitation has hindered the development of CFRP-based reactive structural materials (RSM) that can simultaneously bear mechanical loads and release chemical energy. The challenge lies in modifying the resin matrix to achieve both high mechanical integrity and rapid, sustained energy release.
This study addresses this bottleneck by designing a novel epoxy crosslinked network that incorporates polyether segments, which introduce weaker C–O bonds that break preferentially at lower temperatures, and fluoropolymer-coated nano-aluminum (F@Al(np)) particles that act as localized heat sources upon ignition. This dual modification aims to lower the thermal decomposition temperature, enhance the fragmentation of the network, and increase the energy release rate. The resulting material, TC/BP-CA/PA-F@Al(np), demonstrates a tensile strength of 72.41 MPa and significantly improved ignition and energy release characteristics, offering a promising resin matrix for CFRP-based RSM applications.
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ZHANG Wen-feng, WU Zhi-han, LI Bing-zhe, LEI Si-yang, DUAN Ke, ZHANG Jian-wei, JU Su, LIU Jun, HE Yong-lv (2026). Preparation and Performance of Epoxy Resin Cured Compounds with High Mechanical Strength and Energy-release Capability for Reactive Warhead Casings. Chinese Journal of Energetic Materials (含能材料). https://doi.org/10.11943/CJEM2026036
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Frequently Asked Questions
What is the failure mechanism under high strain rates, and how does the material's tensile strength of 72.41 MPa translate to impact resistance in warhead casings?
The study reports a tensile strength of 72.41 MPa and elongation at break of 4.81%, indicating a balance between strength and ductility. While high-strain-rate behavior was not directly measured, the material's crosslinked network with polyether segments may provide energy-absorbing mechanisms. For warhead casings, this strength level is comparable to engineering epoxies, but further dynamic testing (e.g., split Hopkinson bar) is required to validate performance under blast loading.
How does the addition of fluoropolymer-coated nano-aluminum affect the processing and scalability of the epoxy system?
The F@Al(np) particles are incorporated via solid-liquid blending and multi-stage curing. The specific formulation (Al:fluororubber:PTFE = 10:1:1) requires careful dispersion to avoid agglomeration. Scalability is feasible as the process uses standard mixing and curing equipment, but quality control of nanoparticle dispersion is critical to maintain consistent mechanical and energetic properties.
What is the cost parity of this modified epoxy system compared to conventional epoxy matrices used in CFRP?
The additional cost arises from the polyether epoxy (BPE) and polyetheramine (PA) monomers, as well as the fluoropolymer-coated nano-aluminum. While exact pricing is not disclosed, these specialty chemicals are more expensive than standard epoxy resins. However, the enhanced energy release may justify the premium for specific military applications where structural and energetic performance are critical.
How does the thermal decomposition onset of ~273 °C affect the processing window and long-term stability of the cured compound?
The decomposition onset at 273 °C is lower than typical engineering epoxies due to the polyether segments. This limits the maximum service temperature and requires careful control during curing and any subsequent high-temperature processing. However, for warhead applications, the material is not expected to experience prolonged high temperatures, and the lower decomposition temperature is beneficial for rapid energy release upon initiation.
What is the reproducibility of the closed bomb test results, and how does the peak pressure of 5.935 MPa compare to existing reactive materials?
The study reports a maximum pressure rise rate of 0.407 MPa·ms⁻¹ and peak pressure of 5.935 MPa. While statistical variability is not detailed, the results indicate a significant improvement over the baseline TC-CA. Compared to other reactive materials, this performance is promising, but direct comparison requires standardized testing conditions. Further studies should include multiple trials to assess reproducibility.
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