Rapid Prototyping involved creating a working model of various parts of the system at a very early stage, after a relatively short investigation. The method used in building it is usually quite informal, the most important factor being the speed with which the model is provided.
There are water-and solvent-based -- also called oil-based -- polyurethane varnishes. Water-based polyurethanes are more environmentally friendly and safer to use than solvent-based, but they are not as resistant to wear and tear as solvent-based products.
Polyurethane synthesis, wherein the urethane groups â NH-(C=O)-O-link the molecular units. Polyurethane (PUR and PU) is a polymer composed of organic units joined by carbamate (urethane) links.olyurethane foams are now used in high-temperature oil filter applications. Polyurethane foam (including foam rubber) is sometimes made using small amounts of blowing agents to give less dense foam, better cushioning/energy absorption or thermal insulation.