Twenty Kinds of Plastics and Their Properties—(3) PA12
3.PA12 polyamide 12 or nylon 12
Typical application range:
Water meter and other commercial equipment, cable sleeve, mechanical cam, sliding mechanism and bearing and so on.
Injection molding process conditions:
Drying process: the humidity should be less than 0.1% before processing. If the material is stored in the air, it is recommended to dry for 4~5 hours at 85 centigrade. If the material is stored in a closed container, it can be used directly after 3 hours of temperature balance.
Melting temperature: 240~300 °C; do not exceed 310 °C for ordinary characteristic materials, and do not exceed 270 °C for flame retardant material.
Mould temperature: 30~40 °C for unreinforced material, 80~90 °C for thin-walled or large area components, and 90~100 °C for reinforced material. Increasing the temperature will increase the crystallinity of the material. It is important for PA12 to control the temperature of the die accurately.
Injection pressure: maximum can be reached to 1000bar (it is recommended to use low pressure pressure and high melting temperature).
Injection speed: high speed (better for materials with glass additives).
Runner and gate: for material without additive, the diameter of the channel should be around 30mm because of the low viscosity of the material. For reinforced materials, the diameter of the large flow channel of 5~8mm is required. The shape of the channel should be all round. The injecting mouth should be as short as possible.
Chemical and physical properties:
PA12 is a linear, semi crystalline – crystalline thermoplastic material from butadiene. Its characteristics are similar to PA11, but the crystal structure is different. PA12 is a good electrical insulator and, like other polyamides, does not affect insulation due to moisture. It has good anti shock chemical stability. PA12 has many improved varieties in the aspects of plasticization and enhancement. Compared with PA6 and PA66, these materials have lower melting point and density, and have very high moisture regain. PA12 has no resistance to strong oxidizing acid. The viscosity of PA12 depends mainly on the humidity, temperature and storage time. It has a good fluidity. The shrinkage rate is between 0.5% and 2%, which depends mainly on the variety of materials, the thickness of the wall and other technological conditions.