foamed thermoset

Foamed thermosets are a type of plastic that, once processed, cannot be reshaped by reheating. This is because they undergo a chemical reaction during their initial molding that creates a permanent, insoluble network structure, essentially forming one large molecule.1

These foams are created by incorporating a volatile liquid into the reactive mixture. As the mixture heats up during the reaction, the liquid evaporates, creating gas bubbles that expand the material into a foam. The properties of the resulting foam, such as flexibility or rigidity, depend on the specific components used in the mixture. For example, using hydroxyl-terminated polyethers results in flexible foams, often used for cushioning, while hydroxyl-terminated polyesters create rigid foams suitable for packaging. Phenol-formaldehyde resins are another type of rigid thermoset that can be foamed in place.2

Foamed plastics, in general, offer advantages like lower thermal conductivity and increased rigidity for their weight compared to solid polymers. Their ability to absorb energy when compressed also makes them useful for protective packaging.3