Foam is a plastic containing a myriad of micropores as a whole, which is a two-phase system in which a continuous phase is formed of plastic and a gas is used as a dispersed phase. Different resins and foaming methods can be used to produce foams of various properties. Due to the presence of the gas phase, the foam has the advantages of low density, heat insulation, sound absorption, and shock resistance. However, there are many ways to classify foam. Below the Jiuzhi Plastics Network Xiaobian take everyone to look at the classification of plastic foam:
Foams can be divided into open-cell foams and closed-cell foams according to their structure. The individual pores in the foam are interconnected and called open-cell foam. If the foams are separated from each other, they are called closed-cell foams.
According to their density, foams can be divided into low foaming, medium foaming and high foaming foams. A density of less than 0.1 g/cm3 is called a high foamed foam, a density of between 0.1 and 0.4 g/cm3 is called a medium foamed foam, and a density of more than g/cm3 is called a low foamed foam.
Foam plastics can be divided into soft foam, semi-rigid foam and rigid foam according to their hardness. For example, according to the elastic modulus, at 23 ° C and 5% relative humidity, the elastic modulus is higher than 686 MPa, which is called rigid foam, and the elastic modulus is between 68.6 and 686 MPa, which is called semi-rigid foam. A flexible modulus of less than 68.6 MPa is called a flexible foam.
In addition, there are structural foams and combination foams. The former has a non-foamed or less foamed skin layer and a foamed core layer, while the latter adds tiny hollow glass and ceramic microspheres to the already cured. The resin of the agent is then solidified and molded.
At present, polyethylene, polystyrene, polyurethane and other thermoplastic resin foams are widely used in the industry. Thermosetting resin foams also have a certain yield, but the flexibility is poor, mainly used for high strength and good flame retardancy. Foam products.
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