1) Component-B in SPF. This component contains a polyol, catalyst, blowing agent, fire retardant, and surfactants. It is mixed with the A component to form polyurethane. 2) General term applied to a wide variety of more or less transparent and fusible products, which may be natural or synthetic. Higher molecular weight synthetic resins are referred to as polymers. 3) Any polymer that is a basic material for coatings and plastics.