Views: 1 Author: Site Editor Publish Time: 2024-04-01 Origin: Site
With the development of industries such as automobiles, machinery, electronics, and aerospace, the requirements for material properties are becoming increasingly high. Developing high-performance and multifunctional modified nylon (PA) special materials has become a major research and development topic.
01 Glass fiber reinforced PA
Adding glass fiber to PA significantly improves its mechanical properties, dimensional stability, heat resistance, and aging resistance. The molding process of glass fiber reinforced PA is roughly the same as that of unreinforced PA, but due to poor flow compared to before reinforcement, the injection pressure and injection speed should be appropriately increased, and the barrel temperature should be increased by 10-40 ℃.
Due to the orientation of fiberglass along the flow direction during injection molding, the mechanical properties and shrinkage rate are enhanced in the orientation direction, resulting in deformation and warping of the product.
Therefore, in mold design, the position and shape of the gate should be reasonable, and the temperature of the mold can be raised in the process. After the product is taken out, it should be slowly cooled in hot water.
In addition, the larger the proportion of fiberglass added, the greater the wear on the plasticizing components of the injection molding machine. It is best to use bimetallic screws and machine barrels.
02 Flame retardant PA
Due to the addition of flame retardants in PA, most flame retardants are prone to decomposition at high temperatures, releasing acidic substances that have a corrosive effect on metals. Therefore, plasticized components (screws, rubber heads, rubber rings, rubber gaskets, flanges, etc.) need to be plated with hard chromium.
In terms of technology, try to control the temperature of the barrel as much as possible and the injection speed should not be too fast to avoid discoloration and mechanical performance degradation of the product caused by the decomposition of the rubber material due to high temperature.
03 Transparent PA
Transparent PA has good tensile strength, impact resistance, rigidity, wear resistance, chemical resistance, surface hardness and other properties. It has a high transmittance, similar to optical glass, and a processing temperature of 300-315 ℃. During molding and processing, the barrel temperature must be strictly controlled. If the melt temperature is too high, the product will discolor due to degradation, and if the temperature is too low, the transparency of the product will be affected due to poor plasticization. Try to keep the mold temperature as low as possible, as high mold temperatures can reduce the transparency of the product due to crystallization.
04 Weather resistant PA
Weather-resistant modification is the addition of UV absorbing additives such as carbon black to PA, which greatly enhances its self-lubricating properties and metal wear. During forming and processing, it can affect the cutting and wear of machine parts. Therefore, it is necessary to use a combination of screw, barrel, rubber head, rubber ring, and rubber washer with strong feeding capacity and high wear resistance.
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