(1) In spray polyurethane foam roofing, the B-component (B-side). This component contains a catalyst, blowing agent, fire retardants, surfactants and polyol. It is mixed with the A-component (A-side) to form polyurethane; (2) in plastics manufacturing, any polymer that is a basic material for plastics; (3) in grouting, a material that usually constitutes the base of an organic grout system.
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