Fire resistance is a critical requirement in military environments. Armored vehicles, aircraft, naval platforms, shelters, and other defense systems may be exposed to explosions, fuel fires, ballistic impacts, and intense heat. Under these conditions, materials that ignite easily or rapidly lose their structural integrity can threaten personnel safety and reduce operational survivability.
Conventional military materials such as metals, ceramics, and synthetic fiber-reinforced composites have long been used because of their strength and thermal performance. However, each material also presents limitations. Metals are relatively heavy and conduct heat efficiently, ceramics can be brittle under dynamic loading, and some synthetic composites rely on petroleum-based materials and flame retardants that may produce toxic emissions during combustion.
Biocomposites reinforced with natural fibers are emerging as a potential alternative. Fibers from bamboo, kenaf, flax, hemp, and coconut coir are renewable, lightweight, and potentially less environmentally damaging than some conventional materials. The major challenge is that natural fibers contain cellulose and hemicellulose, which can degrade at relatively low temperatures and release combustible gases that accelerate ignition and flame spread.
Review Maps the Development of Sustainable Defense Materials
To examine the current state of the technology, the authors conducted a narrative review of peer-reviewed journal articles, books, international standards, and technical reports covering composite materials, fire science, defense engineering, and sustainable materials.
The reviewed literature focused on natural fiber-reinforced composites, flame-retardant technologies, thermal degradation, military fire safety requirements, ballistic protection, electromagnetic interference shielding, and sustainability. The authors then synthesized the findings to identify technological developments, performance characteristics, limitations, and future research opportunities.
The review shows that the fire performance of biocomposites depends on several factors, including fiber composition, polymer matrix selection, flame-retardant technology, and the overall architecture of the material.
Flame-Retardant Technology Is Central to Fire Protection
One of the review's key findings is the importance of advanced flame-retardant systems. Phosphorus-based flame retardants can promote the formation of protective char layers that act as barriers against heat and oxygen. Nitrogen-based additives can release inert gases during heating, helping dilute combustible gases.
The combination of phosphorus and nitrogen can provide a synergistic effect by protecting the material through both condensed-phase and gas-phase mechanisms. The review also highlights nanomaterials such as nanoclay, graphene, and carbon nanotubes, which can reduce heat transfer and limit the movement of combustible volatile products.
Bio-based flame retardants derived from lignin, phytic acid, chitosan, and biochar are also gaining attention. These materials could improve char formation and thermal stability while supporting the broader goal of developing more sustainable fire-resistant materials.
Bamboo and Coconut Coir Show Strong Thermal Potential
The type of natural fiber used significantly affects the performance of a fire-resistant biocomposite. The review indicates that fibers with higher lignin content, including bamboo and coconut coir, generally demonstrate stronger thermal stability and char-forming capabilities.
Bamboo, with a lignin content of approximately 20–30 percent, is associated with high thermal stability and fire performance. Coconut coir, which contains approximately 30–45 percent lignin, also shows high potential for insulation and fire-resistant applications.
Flax and hemp, meanwhile, offer valuable mechanical properties but generally provide moderate fire resistance. This means that fiber selection must be matched to the intended application, whether the material is designed for structural panels, thermal barriers, insulation systems, or other military components.
One Material Could Provide Multiple Protection Functions
The development of military biocomposites is increasingly moving beyond fire resistance alone. Researchers are exploring multifunctional materials that can provide several protective capabilities within a single structure.
The review highlights the possibility of combining fire resistance with reduced weight, thermal insulation, ballistic protection, and electromagnetic interference (EMI) shielding. Such materials could potentially be used in military vehicle interior panels, insulation systems, modular shelters, aircraft cabins, and other non-primary structural components.
Hybrid composites that combine natural fibers with synthetic reinforcements may also improve impact and ballistic performance. This approach could allow natural-fiber-based materials to contribute to defense applications while maintaining a lower weight and potentially reducing environmental impacts.
However, the authors emphasize that fire-resistant biocomposites cannot yet completely replace conventional materials in all military applications, particularly in primary structural components exposed to extreme conditions. Moisture sensitivity, long-term durability, compliance with military fire-safety standards, and large-scale manufacturing remain major challenges.
Future Military Materials Must Balance Safety and Sustainability
The review points to a future in which military materials are designed to perform several functions simultaneously. Flame retardants, nanomaterials, and bio-based additives must be carefully combined to improve fire resistance without significantly reducing mechanical strength, increasing weight, or making manufacturing impractical.
Future research should also test biocomposites under conditions that more closely resemble real military environments, including simultaneous exposure to heat, impact, and ballistic loading. Researchers must further improve resistance to moisture, repeated thermal cycles, and long-term environmental stress.
The authors conclude that multifunctional biocomposites combining fire resistance, ballistic protection, EMI shielding, and sustainable material design could become an important direction for future defense technology. If the remaining durability, standardization, and manufacturing challenges can be addressed, these materials could help create lighter, safer, and more environmentally responsible military systems.
Author Profiles
Rizky Dwiandra Putra, Dangan Waluyo, Timbul Siahaan, Nurul Ilmi, and Nurrudin Ahmad are affiliated with the Defense Industry Study Program, Faculty of Defense Engineering and Technology, The Republic of Indonesia Defense University, Bogor, Indonesia.
Alvin Muhammad Savero is affiliated with the Research Center for Biomass and Bioproducts, National Research and Innovation Agency (BRIN), South Tangerang, Indonesia. The authors' research backgrounds cover defense industry studies, defense technology, sustainable materials, biomass, and biocomposite development.
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