In this blog post, we’ll examine the characteristics and principles of body armor materials—from the earliest materials used to the high-performance fibers widely used today, and on to the next-generation materials that will drive future body armor technology.
History: Cotton Armor and Early Body Armor Materials
The history of body armor is very long. In Korea, during the Joseon Dynasty, cotton armor—made by layering multiple layers of cotton—was developed to stop bullets from Western-style firearms. It is known that this cotton armor was produced after the Byeongin Expedition and was actually used during the Sinmi Expedition. Historical records indicate that the structure of multiple layers of cotton could partially prevent bullet penetration, and it is said that actual equipment was manufactured based on these test results.
Although the cotton armor was somewhat effective at stopping bullets, it had drawbacks: due to the nature of cotton, it was highly flammable and quite heavy, and its thick structure significantly restricted the wearer’s mobility. Nevertheless, it was a highly innovative piece of defensive equipment for its time, designed to counter firearms, and is regarded as an important milestone in the history of South Korea’s bulletproof equipment development.
Aramid Fiber and Kevlar
Aramid fiber is the most widely used high-performance fiber in modern body armor. Aramid is a high-performance fiber belonging to the aromatic polyamide family, differing in chemical structure from nylon, which is an aliphatic polyamide. While ordinary nylon melts at relatively low temperatures, aramid maintains its stability even at much higher temperatures and exhibits excellent resistance to heat and flame.
Kevlar, developed by DuPont in the United States, is one of the most representative aramid fibers. Kevlar possesses very high tensile strength and excellent heat resistance, and with a relative density of approximately 1.44, it is very lightweight relative to its strength. These characteristics stem from strong hydrogen bonds within its molecular structure and the regular arrangement of aromatic rings. Composed of relatively light elements such as carbon, hydrogen, nitrogen, and oxygen, it maintains high strength while ensuring exceptional lightness.
Kevlar is widely used in various industries, including not only bulletproof vests and helmets but also protective gloves, cut-resistant equipment, industrial protective clothing, optical fiber reinforcements, and the aerospace sector.
In South Korea as well, high-performance aramid fibers such as Hyosung’s Heracron have been developed, securing competitiveness in the global market and expanding their range of applications to include not only bulletproof materials but also various industrial materials.
How Body Armor Stops Bullets
Modern body armor consists of a multi-layered structure of high-strength fabric. When dozens or more layers of high-strength yarns, such as aramid fibers, are stacked together, the kinetic energy of a bullet is rapidly dispersed over a wide area the moment it strikes the armor.
The tightly woven fibers disrupt the bullet’s rotation and trajectory, dispersing the impact energy in multiple directions, while each fiber stretches or interlocks with others to absorb the energy. As this process repeats, the bullet loses speed, and its penetrating power is significantly reduced.
Furthermore, since aramid fibers are highly heat-resistant, they minimize the transfer of frictional heat or instantaneous high temperatures generated during the bullet impact to the wearer.
However, woven body armor may be penetrated if it is struck by a strong impact or high-energy bullet exceeding its designed protection level, causing the fibers to rupture. To overcome these limitations, various new materials and composite structures are continuously being researched and developed.
New Materials and Cutting-Edge Technologies: STF, Carbon Nanotubes, and Graphene
Recently, bulletproof technology utilizing shear-thickening fluids (STF) has been gaining attention. STF is typically a fluid created by dispersing nanoscale silica particles in a liquid; it flows flexibly under normal conditions but rapidly increases in viscosity and solidifies the moment it is subjected to a strong impact or high shear stress.
When STF is impregnated into bulletproof fabric, the material maintains a flexible feel under normal conditions, but the affected area instantly hardens upon impact from high-speed projectiles such as bullets or shrapnel, thereby more effectively dispersing the impact and preventing penetration.
This technology has the advantage of addressing the issue of fiber breakage, which is a weakness of fabric-based body armor. Currently, various research institutions and companies are developing STF-based body armor and have confirmed its potential to improve flexibility and comfort compared to existing body armor. However, manufacturing costs and mass production technology remain challenges to be addressed, and further technological development is required to expand commercialization.
Another next-generation ballistic material is carbon nanotubes (CNTs). Despite their extremely small size, carbon nanotubes possess outstanding strength and stiffness, and are considered a material with high potential to enhance ballistic performance when incorporated into composite materials. However, since manufacturing costs and ensuring consistent quality remain challenging at present, research is currently focused on specific specialized fields.
Graphene is also the subject of ongoing research as a next-generation ballistic protection material. Graphene is a two-dimensional material consisting of a single layer of carbon atoms; it is extremely thin yet possesses high mechanical strength and excellent thermal conductivity. While it is recognized as having great potential as a future ballistic protection material due to its ability to dissipate impact energy very rapidly, large-scale production and ensuring cost-effectiveness remain major challenges at present.
Challenges and Outlook
Body armor is a critical piece of protective equipment that determines the survival of soldiers, police officers, and security personnel. Therefore, it is crucial not only to ensure protective performance that effectively blocks bullets and shrapnel but also to achieve both lightweight design and freedom of movement to minimize discomfort during prolonged wear.
Currently, body armor is manufactured to various levels based on internationally recognized protection ratings, with performance categorized according to the types of projectiles it can defend against and the level of threat. In the future, there will be a continued demand for technologies that reduce weight and improve comfort while maintaining even higher levels of protection.
New materials such as shear-thickening fluids, carbon nanotubes, and graphene demonstrate excellent performance and great potential, but practical challenges—such as manufacturing costs and mass-production feasibility—remain. Therefore, for lighter, safer, and more practical next-generation body armor to become widely adopted, advancements must be made not only in the performance of the materials themselves but also in the efficiency of production processes and technologies to reduce manufacturing costs.
