PA66 Nylon Of Glass Fiber Reniforced Quality Concern

PA66 Nylon has a series of excellent properties such as high mechanical strength, chemical resistance, oil resistance, wear resistance, self-lubricating, and easy processing and forming. It has become one of the widely used thermoplastic engineering plastics at home and abroad.

However, in practical applications, the performance requirements of PA66 nylon are different under different conditions of use or environments.For example, components such as electric drills and motor housings, pump impellers, bearings, diesel engines and air-conditioning all-plastic fans require nylon materials to have high strength, high rigidity and high dimensional stability; due to the poor low temperature toughness of nylon, it needs to be toughened and modified at this time; in some outdoor applications, nylon materials must be modified for weather resistance in long-term outdoor environments and so on.

The reinforcing materials used in reinforced PA66 nylon are mainly fibrous substances such as glass fiber, carbon fiber, and whiskers, and among them, glass fiber reinforcement is the most widely used.The rigid strength and hardness of the material can be significantly improved by glass fiber reinforcement, and the dimensional stability and heat resistance of the material can be significantly improved.

Since PA66 nylon itself is not strong enough, its strength is increased by adding 10-30% fiber.In particular, the strength of 30% is recognized as the most appropriate ratio.It can also be increased to 40-50%. According to the specific requirements of different products, coupled with the appropriate formula, it can be successful.

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Production Process of Glass Fiber Reinforced PA66 Nylon

Generally speaking, there are two production processes for glass fiber reinforced nylon: long fiber method and short fiber method.

The long fiber method, that is, nylon and other components are added to the hopper after being premix, while the glass fiber is rotated from the inlet of the glass fiber through the screw to bring it into the screw, and then mixed with the nylon resin.

The staple fiber method is to force the chopped glass fiber to the barrel through the side feeding, and then mix it with nylon.

Factors Affecting the Performance of Glass Fiber Reinforced PA66 Nylon

First of all, the interfacial bonding between glass fiber and PA66 nylon resin has the most important influence on glass fiber reinforced nylon.If the combination between the two is not good, the strengthening effect will be greatly reduced.At this time, the surface treatment of glass fiber is particularly important.Nowadays, glass fiber manufacturers have been able to produce glass fiber models with different surface treatments for different materials for use by modified plastic manufacturers, as long as they are selected properly.

Secondly, the length of glass fiber in PA66 nylon material is another major factor affecting its performance.Generally speaking, whether it is tensile strength, bending strength and modulus, or notch impact strength, long glass fibers are better than short glass fibers.

At the same time, the dispersion of glass fiber in the material cannot be ignored.The dispersion of glass fiber mainly depends on the proper shear effect of the twin screws and the kneading effect of the material, which involves the combination and speed of the screws.The choice of screw speed is related to the content of additives such as glass fiber in the formula.For flame-retardant reinforced nylon, since the flame retardant has been thermally decomposed, low speed is appropriate.

In addition, the processing temperature, glass fiber diameter, and glass fiber type will also affect the final performance of the material, so we will not repeat them here.

Glass Fiber Reinforced PA66 Nylon Ages with Heat and Oxygen during Processing

Glass fiber is easy to squeeze and rub against the PA66 nylon material, screw and inner wall of the barrel in the barrel of a twin-screw extruder, and produces a lot of friction heat, which often makes the actual temperature of the material in the barrel of the extruder much higher than the displayed temperature of the extruder. Such high temperature can easily lead to thermal and oxygen aging and degradation of nylon 66, and the mechanical properties of composite materials are reduced. The below table shows the effects of different antioxidant systems on the initial mechanical properties of glass fiber reinforced nylon 66 composite materials.

From the data in the table, it can be seen that the tensile strength, bending strength and notch impact strength of the 1# samples without added antioxidants are lower than the corresponding properties of the 2# and 3# samples, which shows that adding antioxidants can effectively block the thermal oxygen aging and degradation of nylon 66 during processing, and significantly improve the mechanical properties of composite materials.It shows that a suitable antioxidant system can play a better role in stabilizing the initial processing.

Glass Fiber Enhances the Fluidity of PA66 Nylon

The fluidity of glass fiber reinforced nylon is poor, and it is prone to problems such as high injection pressure, high injection temperature, dissatisfied injection, and poor surface quality during the injection molding process, which seriously affects the appearance of the product and leads to a high product defect rate.Especially in the production process of injection molded products, lubricants cannot be directly added to solve the problem, and can only be improved on raw materials. In general, this requires the addition of lubricating ingredients to the modified formula.

Resistance to High Temperature and Xxygen Aging of Glass Fiber Reinforced PA66 Nylon

In some application fields such as bearings and diesel engine fans, glass fiber reinforced nylon often faces the problem of long-term high-temperature thermal oxygen aging.Although the enhancement and modification of nylon with glass fiber can moderately improve the heat resistance of nylon, it cannot solve the problem well. Better results can be obtained by adding suitable anti-thermal and oxygen aging additives to the glass fiber reinforced nylon composite material. Follow the picture above.

After the three samples were aged by 1000h thermal oxygen, the tensile strength retention rate of the 1# sample (no antioxidant) was 58.0%, the tensile strength retention rate of the 2# sample (generally commonly used antioxidant system) was 77.4%, and the corresponding performance of the 3# sample (improved antioxidant system) was 88.0%.It can be seen that a suitable antioxidant system can effectively delay the thermal oxygen aging and degradation of glass fiber reinforced nylon, so as to exert a better high-temperature thermal oxygen aging protection effect.

The weather resistance of glass fiber reinforced PA66 nylon

PA66 Nylon is affected by external conditions such as sunlight, temperature changes, wind and rain, etc., and will experience a series of aging phenomena such as fading, discoloration, cracking, chalking, and decreased strength. Among them, ultraviolet light is the key factor to promote aging. .Weather-resistant nylon is currently mainly a black product, that is, its weather resistance is solved by adding carbon black and other additives that absorb ultraviolet rays to nylon.However, in addition to black products, natural or light-colored nylon often faces aging problems when used outdoors, mainly due to yellowing of parts.

Application of Nylon with Different Fiber Proportions

1.High-strength Glass Fiber Reinforced Products.

Reinforced nylon material with a glass fiber addition ratio of 40-50% is mainly suitable for the manufacture of high-strength gears and high-strength parts of professional equipment.

Various Precision Gears

2. Medium-strength Glass Fiber Reinforced Products.

Reinforced nylon material with a glass fiber addition ratio of 25-35% is mainly suitable for the manufacture of medium-strength parts such as auto parts, power tool housings, electrical blades, wind wheels, tableware, toys, etc.

Application 1: Auto Parts

Automotive PA66+GF materials can be used in engine intake pipes, engine covers, automobile chassis, engine fan blades, automobile air conditioning evaporator condensers, etc.

1) Start the intake pipe PA66+30%GF, long-term temperature resistance of 140℃ for more than 2000 hours.

2) Automobile chassis mudguards, engine fan blades PA66+30%GF, require excellent toughness and strength, as well as low deformation and dimensional stability.

3) Automobile air-conditioning evaporators need good warping, long-term heat resistance, hydrolysis resistance, high dimensional stability, high strength and toughness, PA66+15% GF+10% talcum powder.

Application 2: Various Connectors for Electronic Accessories

This is halogen-free flame-retardant PA66+35% GF, which is used in various electronic connectors.Electronic connectors need to have high fluidity, dimensional stability, good electrical properties, and some also need flame retardant properties. At this time, only modified materials can completely replace them.

Application 3: Various High-power Fan Blades and Impellers

High steel, high toughness, low warping, creep resistance, hydrolysis resistance modified PA66+30% GF material.

Application4: Cookware：
High temperature resistance, food grade, high fluidity, enhanced, PA66+30%GF.

Application 5: Toy Field
Toy gun holders, drone propellers, and motor brackets generally use medium and high-strength modified plastics, PA66+30% GF and PA66+30% carbon fiber.

3. Low-strength Glass Fiber Reinforced Products

Reinforced nylon material with a glass fiber addition ratio of 10-20% is mainly suitable for the manufacture of connectors, touch switches, medical equipment and other parts in electronic and electrical products.

Application: Medical Equipment Field

Nylon material has mechanical strength and skin-friendly feel that ordinary materials do not have, while medical equipment, foot drop correction devices, rehabilitation wheelchairs, and medical nursing beds usually require parts with a certain load-bearing capacity, so PA66+15%GF is generally selected.