At present, China is the world's largest producer of bulletproof vests. The material technology of bulletproof vests has been constantly improving, and the level is also in the forefront.
There are only three manufacturing countries that can independently complete the whole process from the research and development of the materials of bulletproof clothing to the completion of the production, namely, China, the United States and the Netherlands.
The bulletproof vest in China is mainly made of UHMWPE, that is, ultra-high molecular weight polyethylene. This kind of material has good protection effect and low cost. At present, the mainstream bulletproof vest, bulletproof insert plate and other bulletproof equipment are made of UHMWPE.
It is reported that 70% of UHMWPE fibers in the United States are used in bulletproof clothing, bulletproof helmets, bulletproof armor for military facilities and equipment, aerospace and other military fields. The development of high-performance fibers is the embodiment of a country's comprehensive strength and an important material foundation for building a modern power.
At present, China strongly supports and accelerates the development of production and application of UHMWPE fiber, and domestic UHMWPE fiber has occupied a pivotal position in the world.
Ultra high molecular weight polyethylene (UHMWPE) is polyethylene with a molecular weight of 1 million to 5 million. The molecular weight of ordinary polyethylene ranges from hundreds of thousands to hundreds of thousands.
Therefore, UHMWPE has excellent characteristics that ordinary polyethylene cannot match, such as extremely high abrasion resistance, higher strength than most metals, and excellent impact resistance. It is a widely used engineering plastic.
Excellent performance of UHMWPE
Excellent friction resistance
The friction resistance of UHWMPE is in direct proportion to its molecular weight, exceeding that of conventional materials such as carbon steel and PA66
Strong impact resistance
The impact resistance increases with the increase of molecular weight, and reaches the maximum value at the molecular weight of 5 million and then decreases. It is particularly noteworthy that it can also maintain excellent impact strength at low temperatures
Excellent self lubrication
The friction coefficient under water lubrication is about twice that of dry friction, which is one third of that of PA66 under the same conditions
Low temperature resistance
The embrittlement temperature is generally below – 80 ℃, and it can still maintain high impact strength and other mechanical properties between 0 ℃ and – 40 ℃
High tensile strength
The fiber product through gel spinning has a tensile strength of 3-15GPa, a tensile elastic modulus of 100-125GPa, which is 4 times that of carbon fiber and 10 times that of steel wire
Main application fields of UHWMPE
Due to its excellent mechanical properties, UHMWPE has been used in national defense and military, medical and health care, aerospace, marine industry, etc. Its products also include pipes, films, medical implantable bones, fibers.
UHWMPE was first developed by Hoechst Company in Germany in 1958 and has been industrialized. Later, Hercules of the United States, Mitsui Chemical of Japan and DMS of the Netherlands achieved large-scale industrial production.
In the 1980s, China began to research and develop UHMWPE fiber. At present, it has become the third largest UHMWPE fiber production.
The scientific research achievements of SHDH Chemical Fiber Research Institute enable China to apply this ultra-high strength fiber to the recovery system of the Shenzhou spaceship. The UHMWPE fiber products developed by SHDH Chemical Fiber Research Institute are widely used in bulletproof, helmet and other defense and military industries.
At the same time, SHDH has developed high concentration spinning technology and built a single line production line with an annual output of 250T, making China a country with independent intellectual property rights to produce UHMWPE fibers after the United States and the Netherlands.
At present, there are dozens of enterprises producing UHMWPE fiber and its products in China.
Among them, SDAD Polymer Material Technology Corporation (DSM joint venture) is the largest one
BJTYI High Performance Fiber Technology Development Corporation
NBDC Advanced Materials Technology Corporation
HNZT High Performance Protective Equipment Technology Corporation
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Anti cutting gloves, national defense and military supplies equipment (lightweight high-performance bulletproof plates, bulletproof helmets, soft bulletproof clothing, stab resistant clothing) can also be used in aerospace composites, ocean going ships, naval ship ropes, ocean fishing trawls, deep-sea anti wind and wave cages, sports equipment, building engineering reinforcement and other high-performance composites