INTERACTIONS OF ORGANIC SOLVENTS WITH POLYURETHANE

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Abstract
Polyurethane elastomers [1] are linear block copolymers of the type in which one of the two blocks is typically a polyether or a polyester diol with a molar mass between 300 to 6000. These blocks comprise the soft segments because at the service temperature they exist in a rubbery or a viscous state and impart elastomeric properties. The other segments are composed of aromatic diisocyanates extended with low diols to produce blocks with molar mass ranging from 500 to 3000. These blocks comprise the hard segments because at the service temperature they exist in the glassy (or semicrystalline) state. Dimensional stability is imparted through microphase separation of the hard segments into domains which act as a reinforcing filler and multifunctional crosslinks. Polyurethanes are mainly thermoplastics because heating above the hard segment glass transition temperature (Tg) will allow the material to flow.