What is Polyurethane Foam?

Polyurethane is a type of polymer created by joining various monomers by urethane. One of the most important aspects of polyurethane is its ability to create foams, which can have various structural and chemical properties. These foams can be used for many purposes, including cushioning and insulation.

Identification

Polyurethane is a generic term that is given to any compound that is made up of various organic monomers that are connected by the chemical group urethane. The basic polyurethane model can be tweaked in many ways, by adding other reactants that can include surfactants, flame retarding agents and pigments. This polymer can then be modified to create a foam.

Features

Polyurethanes are part of a group of compounds called reaction polymers. Other reaction polymers are phenolics, polyesters and epoxies. Polyurethane is made by combining monomers with two or more isocyanate groups with another monomer with at least two alcohol groups. The two monomers are then fused with a urea group, and extending this reaction, often with a catalyst, yields a polyurethane polymer.

Effects

One of the most important aspects of polyurethane is its ability to be turned into foam. Water and certain other reactants, such as specific halocarbons and hydrocarbons (n-pentane, for example) can be blown into the polyurethane. Water and these other reactants will interact with the polyurethane, causing the formation of carbon dioxide, which will cause small cells to form and expand in this process. Once the polyurethane hardens, a foam is created. Surfactants can be used to alter the size of these foam cells and to modify their structure and to prevent collapse.

Types

Softer foam, such as that used for spandex and soft rubber parts, can be created by using polyether compounds as the source of the alcohols (alcohols are necessary for reaction with the isocyanate groups). More rigid polyurethane can be created by using special catalysts which give the matrix of the foam a cyclic structure, giving it a stronger structure. Finally, careful manipulations of the monomers and the catalysts can be used to create memory foam, which is softer when exposed to temperatures near the temperature of the skin compared to room temperature.

Benefits

The fact that polyurethane foam can have differing properties based on the reaction conditions makes it widely useful for commercial purposes. It can be used as a form of support behind other structures, or as cushioning as insulation. The ability to change its response to temperature allows for careful and easy molding, even allowing it to retain the shape of body parts that are pressed to it, which allows for the creation of form-fitting structures.