| abstract |
The invention is achieved by a polyurethane that is the reaction product of 4,4'-diphenylmethane diisocyanate (MDI), poly(oxyethylene)glycol (PEG), and 1,4-butane diol (BDO). The equivalents of each reactant in the polyurethane is 4:1:3. Polyethylene glycol 1450 is preferred. The amount of hard segment (made up of chain extender and MDI) is about 46 weight percent. The polymer is unusually tough and has good tensile strength and wet strength. |