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Polymer Foam Material Sourcing, Industrial Foam Sourcing - Sourcebook
Conversely, open-cell foams do not possess cells that are entirely closed. The cells in open-cell foams have gaps in them that allows air (or gas) to flow in between the structures. Open-cell foams have greater vapor permeability, water absorption, and are more conformable than closed-cell foams. A sub-type of open-cell foams are reticulated foams. Reticulated foams are foams in which the cell membranes (windows) are removed, creating an open foam of high porosity. Originally, the foam will start out as a closed-cell foam, but will undergo thermal reticulation or quenching (also known as chemical etching) to have the cell membranes removed.
To further control the characteristics of reticulated foam, various factors within both the quenching and thermal reticulation process can be controlled. For example, during quenching, the length of time the foam is exposed to the solution can be regulated to produce a foam of specific characteristics.
During the slabstock manufacturing process, the liquid mixture is poured onto a traveling belt that is walled off on both sides to form a channel that allows the mixture to temporarily settle. During this time, the chemicals within the liquid mixture undergo a chemical reaction, eventually resulting in a slab of foam.
The molding manufacturing process is similar to the slabstock process in that a liquid, chemical mixture is poured into a mold to undergo a chemical reaction. However, unlike slabstock, where rectangular or square foams are produced, the molding process allows for more versatile shapes. Depending on the desired final geometry, a variety of mold shapes can be utilized to produce foams of specific shapes.