What are the characteristics of PMI foam?
1. Compression performance. The compressive strength of cross-linked polyethylene foam is higher than that of soft polyester polyurethane foam, but lower than that of polystyrene foam, which is a semi-rigid foam. The cross-linked polyethylene foam has excellent resistance to repeated compression. After 105 times of compression (50% compression deformation each time), the permanent deformation is about 15010, and the change in compression strength (deformation 25%) is also quite small. This shows that cross-linked polyethylene foam is an ideal packaging material. The disadvantage of cross-linked polyethylene foam is that it does not recover immediately after the compressive force is removed, and can only return to its original state after being placed for one week.
2. Water vapor transmission rate. The water vapor transmission rate of cross-linked polyethylene foam is much lower than that of polystyrene and rigid polyurethane foam. Thermal performance. The thermal conductivity of cross-linked polyethylene foam is roughly the same as that of polystyrene and rigid polyurethane foam, and is higher than that of non-cross-linked polyethylene foam. Its maximum use temperature is 80°C, and it will gradually shrink above this temperature. The short-term use temperature is 100aC. The lowest operating temperature is -84°C, but the foam will become brittle at this time.
3. Water absorption. The water absorption of cross-linked polyethylene foam is worse than that of polystyrene foam. Chemical resistance performance. The cross-linked polyethylene foam has excellent chemical resistance. It will swell slightly after being immersed in carbon tetrachloride, aromatic hydrocarbon, gasoline or other similar substances for a long time. Long-term immersion in acid and alkali will have no effect and the strength will not change. PMI foam has excellent aging resistance.
Performance advantages of PMI foam packaging:
The mechanical strength, heat resistance, solvent resistance, chemical stability, and shape stability of plastic parts of PMI foam packaging are all higher than those of linear polymers. Therefore, in some aspects of strength, temperature, creep, etc. In high-demand occasions, body-shaped polymers are widely used. In order to improve the performance of certain thermoplastic polymer foam packaging to meet certain special performance requirements, radiation crosslinking (physical crosslinking) can be used to generate a certain crosslinked structure between molecular chains. For example, the long-term use temperature of high-density polyethylene is about 100°C. After radiation cross-linking, the use temperature can be increased to 135. C (up to 200-300. C under anaerobic conditions), the cross-linking reaction is difficult to complete.
A plastic with numerous micropores inside, made from resin as the main raw material. Lightweight, heat-insulating, sound-absorbing, shock-proof and corrosion-resistant. There are soft and hard points. It is widely used as heat insulation, sound insulation, packaging materials and car and ship shells. Plastic with many tiny pores inside. It is made by mechanical method, in which air or carbon dioxide is blown into foam while mechanical stirring, or by chemical method (adding foaming agent). There are two types: closed cell type and open cell type. The pores in the closed cell type are isolated from each other and have floating properties; the pores in the open cell type are connected to each other and have no floating properties. It can be made of polystyrene, polyvinyl chloride, polyurethane and other resins. It can be used as heat insulation and sound insulation material and has a wide range of uses.
Foam plastic is a type of polymer material formed by a large number of gas micropores dispersed in solid plastic. It has the characteristics of light weight, heat insulation, sound absorption, shock absorption, etc., and its dielectric performance is better than that of matrix resin, and it has a wide range of uses. Almost all kinds of plastics can be made into PMI foam, and foam molding has become an important field in plastic processing. The structural foam plastic developed in the 1960s is characterized by foaming of the core layer and non-foaming of the skin layer. It is hard on the outside and tough on the inside. It has high specific strength (strength per unit mass), low consumption of materials, and is increasingly replacing wood. Used in the construction and furniture industry.