Views:2 Author:Site Editor Publish Time: 2022-01-10 Origin:Site
Polyamide (PA, commonly known as nylon) has good comprehensive properties, including mechanical properties, heat resistance, abrasion resistance, chemical resistance and self-lubrication, and has a low coefficient of friction and certain flame retardancy. It is easy to process, suitable for filling and enhancing modification with glass fiber and other fillers, improving performance and expanding the scope of application. Polyamides can be prepared from diamines and dibasic acids, and can also be synthesized with omega-amino acids or cyclic lactams. Depending on the number of carbon atoms contained in diamines and diacids or amino acids, many different polyamides can be prepared. At present, there are dozens of polyamide varieties, among which polyamide-6, polyamide-66 and polyamide-610 are the most widely used.
In order to improve quality and efficiency, some manufacturers make modified nylon modified according to different needs. As a kind of engineering plastics, modified nylon generally includes: reinforced nylon, toughened nylon, wear-resistant nylon, halogen-free flame-retardant nylon, conductive nylon, flame-retardant nylon and so on.
Advantages of modified nylon
①Improve the water absorption of nylon and improve the dimensional stability of products.
②Improve the flame retardancy of nylon to meet the requirements of electronics, electrical, communications and other industries.
③Improve the mechanical strength of nylon to achieve the strength of metal materials and replace metal
④Improve the low temperature resistance of nylon and enhance its ability to withstand environmental strains.
⑤Improve the abrasion resistance of nylon to adapt to the occasions with high requirements for abrasion resistance.
⑥Improve the antistatic property of nylon to meet the requirements of mines and their mechanical applications.
⑦Improve the heat resistance of nylon to adapt to areas with high temperature conditions such as automobile engines.
⑧Reduce the cost of nylon and improve product competitiveness.
Other properties such as chemical resistance, weather resistance, and good dimensional stability are all modified according to the different needs of some manufacturers.
Modified nylon has many characteristics, so it is widely used in automobiles, electrical equipment, mechanical parts, transportation equipment, textiles, and paper machinery.
In short, through the above improvements, we can achieve high performance and functionalization of nylon composite materials.
Several cases of nylon modification
01. Glass fiber reinforced PA
30% glass fiber is added to PA, the mechanical properties, dimensional stability, heat resistance, and aging resistance of PA are significantly improved, and the fatigue strength is 2.5 times that of unreinforced.
The molding process of glass fiber reinforced PA is roughly the same as that when it is not reinforced, but because the flow is worse than before reinforcement, the injection pressure and injection speed should be appropriately increased, and the barrel temperature should be increased by 10-40°C.
Since the glass fiber will be oriented along the flow direction during the injection molding process, the mechanical properties and shrinkage rate will increase in the orientation direction, resulting in deformation and warpage of the product.
Therefore, when designing the mold, the position and shape of the gate should be reasonable, and the temperature of the mold can be increased in the process. After the product is taken out, it is placed in hot water and allowed to cool slowly.
In addition, the greater the proportion of glass fiber added, the greater the wear on the plasticizing components of the injection molding machine. It is best to use bimetallic screws and barrels.
02. Flame retardant PA
Because flame retardants are added to PA, most flame retardants are easy to decompose at high temperature and release acidic substances, which have a corrosive effect on metals. Therefore, the plasticized components (screw, rubber head, rubber ring, rubber gasket, flange, etc.) need to be hard chrome plated. In terms of technology, try to control the temperature of the barrel not to be too high, and the injection speed not to be too fast, so as to avoid decomposition due to the high temperature of the rubber material, which will cause the product to change color and reduce the mechanical properties.
03. Transparent PA
It has good tensile strength, impact resistance, rigidity, abrasion resistance, chemical resistance, surface hardness and other properties, high light transmittance, similar to optical glass, and processing temperature of 300-315 ℃. During the molding process, the temperature of the barrel must be strictly controlled. Too high melt temperature will cause discoloration of the product due to degradation, and too low temperature will affect the transparency of the product due to poor plasticization. The mold temperature should be as low as possible. A high mold temperature will reduce the transparency of the product due to crystallization.
04. Weather resistant PA
Adding carbon black and other ultraviolet absorbing additives to PA, these self-lubricating properties of PA and abrasion to metal are greatly enhanced, and it will affect blanking and wear parts during forming. Therefore, it is necessary to use a combination of screw, barrel, rubber head, rubber ring, and rubber gasket with strong feeding capacity and high wear resistance.
Development Trend of Modified Nylon
①The market demand for high-strength and high-rigidity nylon is increasing. New reinforcement materials such as inorganic whisker reinforcement and carbon fiber reinforced PA will become important varieties, mainly used in automobile engine parts, mechanical parts and aviation equipment parts.
②Nylon alloying will become the mainstream of the development of modified engineering plastics.
Nylon alloying is an important way to realize the high performance of nylon, and it is also the main method to manufacture nylon and nylon special materials and improve the performance of nylon. By blending other polymers, the water absorption of nylon is improved, the dimensional stability of the product, and the low temperature brittleness, heat resistance and abrasion resistance are improved. Therefore, it is suitable for different requirements of vehicle types.
③ The manufacturing technology and application of nano nylon will develop rapidly.
The advantage of nano nylon is that its thermal properties, mechanical properties, flame retardancy, and barrier properties are higher than pure nylon, and the manufacturing cost is equivalent to that of ordinary nylon. Therefore, it has great competitiveness.
④ The flame-retardant nylon used in electronics, electrical and electrical appliances is increasing day by day, and the green flame-retardant nylon is getting more and more attention from the market.
⑤ Antistatic, conductive nylon and magnetic nylon will become the first choice materials for electronic equipment, mining machinery, and textile machinery.
⑥The research and application of processing aids will promote the process of functionalization and high performance of modified nylon.
⑦ The application of comprehensive technology and the refinement of products are the driving force to promote the development of its industry.
Nanjing Haisi Extrusion supply twin screw extruder special for nylon modification and reinforcement, any interest please feel free to contact us!