Modified nylon is an engineering plastic obtained by modifying nylon through physical or chemical methods. It has excellent comprehensive properties, mainly including thermal properties, mechanical properties, and other properties.
Temperature Properties
Temperature properties include glass transition temperature (Tg) and melting point (Tm); high heat distortion temperature (HDT), usually between 180°C and 250°C; high long-term service temperature (UL-746B); wide service temperature range; and low coefficient of thermal expansion.
Mechanical Properties
Mechanical properties include high strength, high mechanical modulus, low creep, strong wear resistance, and fatigue resistance. For example, nylon 66 with 30% glass fiber has a tensile strength of up to 185 MPa and a flexural strength of up to 260 MPa. Toughened modified nylon has good toughness and impact resistance and can maintain good impact resistance at low temperatures, such as -30°C. The tensile and flexural strength of aramid fiber reinforced nylon 6 composites are improved, but the impact performance is slightly reduced. Other properties include chemical resistance, electrical conductivity, flame retardancy, weather resistance, and excellent dimensional stability. Modified nylon exhibits good corrosion resistance to a variety of chemicals, particularly acids, alkalis, and oils, and can be used outdoors for extended periods without being affected by UV radiation or climate change.
Due to the strong polarity of PA, it has high hygroscopicity and poor dimensional stability, but this can be improved through modification.
Performance characteristics and process requirements of different modification types: Flame-retardant PA contains flame retardants, most of which decompose easily at high temperatures, releasing acidic substances that corrode metals. Therefore, plasticizing components require hard chrome plating, and the process necessitates controlling barrel temperature and injection speed. Weather-resistant PA incorporates UV-absorbing additives such as carbon black, which increases wear on metals.
Therefore, it requires a combination of screws and barrels with high feeding capacity and high wear resistance. Transparent PA possesses good tensile strength and impact resistance, high light transmittance, and a processing temperature of 300-315℃. Strict control of barrel temperature and a low mold temperature are necessary.
Modified cast nylon materials exhibit significant plastic deformation after tensile yielding without brittle fracture. High aspect ratio modified sericite-reinforced nylon 6 shows significantly improved mechanical properties. Potassium titanate whiskers, after surface modification with elastomers, effectively toughen nylon 66. DSP cord exhibits superior heat resistance and dimensional stability compared to modified nylon 66 cord; compared to high-modulus, low-shrinkage polyester cord, modified nylon 66 cord has higher strength and strength retention, but slightly lower dimensional stability. It exhibits good low-temperature performance, with an unnotched impact strength ≥55kJ/m² (ISO 179-1) and tensile strength retention ≥88% at -35℃. The nylon toughening technology developed by Beijing University of Chemical Technology uses maleic anhydride-grafted polyolefins or olefin copolymers as toughening agents. Adding 8% to 10% to nylon can significantly improve its toughness, and when the addition amount is 15% to 20%, it can meet the performance requirements of ultra-tough nylon.