Abstract: The invention relates to polyurethanes obtainable by reaction of (a) polyisocyanates A selected from modified or unmodified 4,4?-methanediphenyl diisocyanate, higher nuclear homologs of 4,4?-methanediphenyl diisocyanate, isocyanated groups containing prepolymers based on 4,4?-methanediphenyl diisocyanate, and mixtures thereof, with (b) compounds having at least two isocyanate-reactive hydrogen atoms, comprising (b1) block copolymers formed from a polybutadienol and a cyclic ester as component B1, and (b2) low molecular weight extenders or crosslinkers each having a molecular weight of 62 to 500 g/mol as component B2.

Abstract: A crosslinked polyurethane obtainable by a process is disclosed wherein polyisocyanates are mixed with polymeric compounds having at least two hydrogen atoms reactive toward isocyanate groups and comprising at least one diene block copolymer which has at least two hydrogen atoms reactive toward isocyanate and has a polydiene main chain and at least one side chain or terminal chain composed of a polyether and/or a polyester, where the proportion by weight of the polydiene main chain is, based on the total weight of the diene block copolymer, from 25 to 95% by weight, to give a reaction mixture that is cured. Composites and blends composed of crosslinked polyurethane and rubber are also disclosed, as well as the use of crosslinked polyurethane in the production of tires or parts of tires, cable sheathing, shoe sole, roller or hose.

Abstract: The invention relates to polyurethanes obtainable by reaction of (a) polyisocyanates A selected from modified or unmodified 4,4?-methanediphenyl diisocyanate, higher nuclear homologs of 4,4?-methanediphenyl diisocyanate, isocyanated groups containing prepolymers based on 4,4?methandiphenyl diisocyanate, and mixtures thereof, with (b) compounds having at least two isocyanate-reactive hydrogen atoms, comprising (b1) block copolymers formed from a polybutadienol and a cyclic ester as component B1, and (b2) low molecular weight extenders or crosslinkers each having a molecular weight of 62 to 500 g/mol as component B2.