Abstract: Improved radiation curable polyurethanes are provided that are polymerizable crystalline polymers having terminal ethylenic unsaturation, relatively low molecular weights and that rapidly crystallize, are prepared from the reaction product of (1) certain polyester glycols and diisocyanates to form an isocyanate-terminated prepolymer that is then reacted with an ethylenic unsaturated alcohol to form the ethylenic unsaturated crystallizable polymer, or in the alternative, (2) the polyester glycol is reacted with an ethylenic unsaturated monoisocyanate to form the polymerizable crystallizable polymer, that can be used as such for example in preparing magnetic tape, as such, or in admixture with other materials, and which can be applied to a substrate from a melt, or formed by molding, extrusion, and then cured with appropriate energy as an electron beam.

Abstract: Improved thermoset or vulcanized polyurethane elastomers are obtained by adding to liquid polyurethane reactants, prior to reaction to form the polyurethane, organic peroxides having a half-life value of greater than one hour at 100.degree. C. Such mixtures may be heated to form the polyurethane article and thereafter thermoset or vulcanized, or the polyurethane containing the unactivated peroxide may be provided in sheet, crumbs, granules or otherwise and then formed and heated to thermoset or vulcanize the polyurethane.

Abstract: Viscosity stable polyurethane solutions in polar solvents as N,N-dimethylformamide are obtained when such solutions contain small amounts of ammonium salts of strong acids, such salts include ammonium chloride and nitrate.