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Polymer Foam Material Sourcing, Industrial Foam Sourcing - Sourcebook

Foams

A foam also known as polymer and polymeric foam, is defined as a material that is composed of polymers with masses of gaseous air pockets within them. These gas pockets can be closed, forming closed-cell foam, or the air pockets can be open, creating open-celled or reticulated foam.
Foam can either be closed-cell or open cell. Closed-cell foam is a foam that is composed of cells that are entirely closed and separate, preventing air (or other vapors/fluids) from traveling within the material. Consequently, it is much more resistant to permeability than open-cell foams and are not as prone to water absorption. When compression forces are placed on closed-cell foams, the cells full of captured air do not burst and allow the air to escape. Thus, when the compression forces are removed, the foam will return to its original form. As a result, closed-cell foams are considered to be denser and stronger than open-cell foams.

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 formation process, the desired polymers and additives are mixed together, poured, and allowed to cure and rise into its final shape.

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.

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