What is Closed Cell Foam?

Closed-cell foam plastics Almost all cells in foam are surrounded by complete cell walls, and the cells are not connected to each other.

Closed-cell foam plastics Almost all cells in foam are surrounded by complete cell walls, and the cells are not connected to each other.

Chinese name

Closed cell foam

Foreign name

Closed-cell foam plastics

Structure

Closed structure of bubble wall and bubble siege

Corresponding

Open cell foam

Definition of closed-cell foam material

Cells of closed-cell foam plastic are closed structures composed of foam walls and foam siege walls. The structure is complete, and the cells encourage each other and are not connected with each other. However, in practice, the open-cell structure and the closed-cell structure may coexist in foam plastics, but the probability of appearance is different ^[1] . Therefore, according to the proportion of the open-cell structure and the closed-cell structure in the foam, the foam with a closed-cell structure of more than 90% is defined as a closed-cell foam; otherwise, it is defined as an open-cell foam.

Factors affecting closed-cell foam

The closed cell ratio of foam plastic is related to many factors, not only related to the type of matrix polymer, but also closely related to the material formula, foaming method, and process control.

In the general foam plastic preparation process, the closed-cell ratio of the kettle method is high, and the open-cell ratio of extrusion foaming is relatively high; the foaming agent uses a physical foaming agent with a higher closed-cell ratio; when the foaming ratio is low, the The closed cell ratio is high; the higher the melt strength of the foamed raw material is, the higher the closed cell ratio is.

Properties and uses of closed-cell foam

Cell structure has a significant impact on the performance of foam plastics. Generally, closed-cell foams have higher mechanical strength, better thermal insulation and cushioning properties, and lower water absorption. Open-cell foams are softer and more flexible. Flexible and good sound insulation. In addition to the general foam characteristics, closed-cell foams also have low thermal conductivity and water absorption. Styrofoam is usually rigid, closed-celled. The density of domestic polystyrene closed-cell foam is 0.015 ~ 0.030 g / cm, the thermal conductivity is 35 mW / (m · k), and the water absorption is 0.8%. ^[2]

Closed-cell foam is generally used as insulation, insulation, sound insulation, packaging, floating, shock absorption and interior decoration materials. Rigid closed-cell foam can also be used as a structural material. ^[2]