The foam is both hard and soft.
1. The rigid foam is the crystalline or amorphous form of the foam at room temperature, and their glass transition temperature is higher than normal temperature. Therefore, the texture of the foam is hard at normal temperature.
2. The flexible foam, that is, the polymer constituting the foam has a melting point lower than normal temperature or the glass transition temperature of the amorphous polymer is lower than normal temperature, and the material is soft at room temperature.
Third, semi-rigid (or semi-soft) foam is a foam between the above two categories.
You are talking about soft foam.
Foam plastics can also be classified into low foaming and high foaming. Generally, the expansion ratio (a multiple after the expansion is increased more than the volume before foaming) of less than 5 is called low foaming, and the ratio of more than 5 is called high foaming.
Foam plastic is a kind of polymer material formed by dispersing a large amount of gas micropores in solid plastic. It has the characteristics of light weight, heat insulation, sound absorption, shock absorption, etc., and its dielectric property is superior to matrix resin, and its application is wide. Almost all kinds of plastics can be made into foam, and foam molding has become an important field in plastic processing.
Foam is also called porous plastic. A resin made of resin as the main raw material with numerous micropores inside. Light weight, heat insulation, sound absorption, shockproof and corrosion resistant. There are soft and hard points. Widely used as insulation, sound insulation, packaging materials and car shells.
Compared with pure plastics, foams have low density, light weight, high specific strength, increased strength with increasing density, ability to absorb shock loads, excellent cushioning and shock absorption properties, sound insulation and sound absorption properties, and thermal conductivity. Low, good thermal insulation performance, excellent electrical insulation performance, corrosion resistance and mold resistance. Flexible foam has excellent properties such as elasticity.
A plastic with many tiny pores inside. It is prepared by a mechanical method (with air or carbon dioxide foamed while mechanically stirring) or by a chemical method (with a blowing agent). There are two types of closed-cell type and open-hole type. The pores in the closed-cell type are isolated from each other and are floating; the pores in the open-hole type are connected to each other and have no floating property. It can be made of resin such as polystyrene, polyvinyl chloride or polyurethane. It can be used as insulation and sound insulation material and has a wide range of uses.
(1) The weight is very low, which can reduce the weight of the package and reduce the transportation cost;
(2) It has excellent impact and vibration energy absorption, which can greatly reduce the damage of the product by buffering the shockproof packaging;
(3) It has strong adaptability to changes in temperature and humidity and can meet the requirements of general packaging conditions;
(4) Low water absorption, low hygroscopicity, good chemical stability, no corrosion to the contents, and strong resistance to chemicals such as acid and alkali;
(5) Low thermal conductivity, can be used for thermal insulation packaging, such as ice cream cups, fast food containers and insulated fish boxes;
(6) The molding process is convenient, and various foam cushions, foam blocks, sheets, and the like can be formed by molding methods such as molding, extrusion, and injection. It is easy to carry out secondary molding processing, for example, foam sheets can be made into various fast food containers by thermoforming. In addition, the foam block can be bonded to another material by an adhesive or bonded to other materials to form various cushioning sheets and the like.