PA-polyamide, also known as nylon, is a general term for a large class of amide polymers. The most common are PA6, PA66, PA1010. Recently, with the development of the IT industry, the use of a new type of polyamide-PA46 has increased dramatically, which is used to replace LCP (liquid crystal polymer) in the production of plug-ins on computers. Because PA has good mechanical properties, good toughness, impact resistance, wear resistance, self-lubricating, flame retardant, insulation and other characteristics, it is widely used in automobile, machinery, electronics, instrumentation, chemical and other fields, such as gears, pulleys, bearings, impellers, bushings, containers, brushes, zippers, etc. PA6, PA66, PA46 are aliphatic polyamide, is a linear polymer, its molecular structure has a strong polar amide group, so it has a high degree of crystallization ability. The properties of PA products depend on their crystalline morphology and crystallinity. However, the processing conditions have an effect on the crystalline morphology and crystallinity. The crystalline change of PA products can reach 40% under different processing conditions, the cooling of the products is slow, the crystallinity is high, and the crystalline morphology with larger size is formed. Water absorption also has an effect on its crystallinity. In addition, PA in the processing process due to flow, shear will produce a certain degree of orientation, resulting in anisotropy of product performance, the strength along the orientation direction is better than the non-orientation direction, orientation is also conducive to the crystallization process, in the mold design to consider this factor. The performance and physical properties of PA are non-※, tasteless, non-mildew, translucent or transparent in appearance, Milky White or light yellow, with a density of 1.04-1.36. When burning, it emits a special protein smell, and the flame is blue and yellow at the top. Good mechanical properties, good toughness, resistance to repeated impact vibration, the use of temperature -40-100 ℃, friction resistance, wear resistance, self-lubrication, but poor creep resistance, poor dimensional stability, can be reinforced by adding glass fiber or blend with other materials to overcome this shortcoming. Chemical resistance and weather resistance PA has few organic solvents and good chemical properties. PA's organic solvents are formic acid and phenolic compounds. Different concentrations of inorganic acids, bases, and salts can cause PA to swell, dissolve, or hydrolyze. Under the condition of not being exposed to sunlight, its anti-aging performance is good, but under the conditions of heat, light and radiation, the aging is fast, the product changes color and the performance decreases.