Polyamide 12 PA12, nylon 12, also known as polydodecalactam and polylactam, is a long carbon chain nylon. There are non-polar methylene groups in nylon 12, and the number is large, which makes the flexibility of nylon 12 molecular chain larger; the amide group in nylon 12 is polar, and the cohesion energy is large, and it can form hydrogen bonds between molecules, which makes the arrangement of molecules more regular. Therefore, the crystallinity of nylon 12 is high, and the strength is also higher. Nylon 12 (PA12) has low water absorption, good low temperature resistance, good air tightness, excellent alkali resistance, grease performance, medium resistance to alcohols and inorganic dilute acids and aromatics, good mechanical properties and electrical properties, and is a self-extinguishing material. 1) Density The relative density of nylon 12 is only 1.01-1.03, which is the smallest among all engineering plastics, which has a certain effect on reducing the mass of the car and lowering the fuel consumption. If compared by unit volume, nylon 12 has advantages in price and performance. 2) Melting point The melting point of nylon 12 is 172-178℃, which is slightly lower than that of nylon 11, and it can fully meet the working temperature requirement of automobile fuel and air brake pipes. 3）Water absorption As we all know, the biggest drawback of nylon products is the large water absorption, and it is difficult to ensure the dimensional stability. However, due to the increase of methylene molecules in nylon 12, the influence of hydrophilic groups is greatly reduced, therefore, nylon 12 has the lowest water absorption rate among nylon products, which reduces the change of performance and size of products caused by water absorption, which makes nylon 12 have great advantages. After water absorption, the tensile strength of nylon 12 decreases very little, while nylon 66 and nylon 6 have great changes. 4) Impact strength Impact strength is an important technical index, and it is especially important for nylon 12 tubes that are often exposed to air. Nylon 12 at -20 ℃ and -40 ℃ according to the standard test, no fracture phenomenon, fully meet the requirements of use. Nylon 12 impact resistance is very good. 5）Low temperature performance Nylon 12 has the lowest brittleness temperature of -70 degrees Celsius, so it can be widely used for parts with low temperature resistance. 6) Flexibility The effect of plasticizers on the physical properties of nylon 12 is concentrated on the elastic modulus of the resin. There are three basic types of nylon 12 resins, the main difference between them is the different plasticizer content and the formation of different flexibility. As the content of plasticizer extractable components increases, the elastic modulus of the resin decreases. 7）Low abrasion and low friction properties Nylon 12 has excellent low-wear and low-friction properties and self-lubricating properties, so the frictional noise of Nylon 12 products is very low. 8）Fuel resistance In the automobile, the current use of oxygenated fuel, high aromatic fuel and alcohol mixed fuel will lead to the decomposition of many hose materials. Only nylon 11, nylon 12 and fluorocarbon elastomers have been tested for use in this environment. Under the action of motor fuels, all nylons dissolve, resulting in dimensional changes, especially in methanol-containing gasoline, where nylons containing large amounts of amide groups such as nylon 6 dissolve much more than nylons containing small amounts of amide groups such as nylon 12 %. It is found that the fuel containing 15% methanol has a great effect on nylon. 9) Resistant to zinc chloride solution Zinc chloride will appear in the environment under the car. Under certain temperature and humidity, the salt on the road reacts with galvanized steel or zinc-containing primer to form a small amount of zinc chloride. Zinc chloride is highly corrosive, but Nylon 12 is highly resistant to zinc chloride solutions. Ozone aging, UV exposure, temperature conditions, etc., can bring varying degrees of damage to parts and reduce service life. Since nylon 12 does not contain the + 2 3 2 + unsaturated double bond, which is susceptible to ozone attack, it does not suffer from ozone aging. In addition, the high crystallinity of nylon 12 and its high melting temperature make it more stable in terms of heat resistance, and the addition of heat stabilizers increases its heat resistance exponentially. When exposed to sunlight, its energy can cause the chemical bonds of organic materials to break. The bonding energy of C-H, C-O and C-N bonds in nylon 12 is so large that UV light is not enough to break them, but only the C-C bonds with smaller bonding energy; therefore, after adding appropriate anti-aging agents to the raw materials, the UV resistance of nylon 12 is excellent. Polyamide 12 - Long carbon fiber In the modified engineering plastics industry, long fiber reinforced composites are composites made fr...