| abstract |
Polyurethanes having a two phase morphology and characterized by high impact strength and, optionally, high modulus are obtained by reaction of 4,4'-methylenebis(phenyl isocyanate) and modified forms thereof with an aliphatic glycol extender and a blend of at least two polyoxypropylene-polyoxyethylene polyols both of which have average functionalities in the range of 2 to 4, one of which has a molecular weight in the range of about 3000 to 10,000 and contains at least 23 percent by weight of ethylene oxide residues and the other has a molecular weight in the range of about 750 to about 2000 and contains at least 45 percent by weight of ethylene oxide. The two or more such polyols are employed in proportions such that the aliphatic glycol extender is completely miscible with said polyols if blended together. |