Wednesday, July 10, 2013

polyurethane

A polyurethane (PUR and PU) is any polymer composed of a chain of organic units joined by carbamate (urethane) links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer (with at least two isocyanate functional groups) with another monomer (with at least two hydroxyl or alcohol groups) in the presence of a catalyst.

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Nine holes

  Nine holes is a two-player abstract strategy game from different parts of the world and is centuries old. It was very popular in Englan...