| Abstract: | Certain homopolymer–polyol mixtures, after treatment with a free-radical generating agent or ionizing radiation, will produce polyurethane elastomers of nearly twice the stiffness and tensile properties compared to control elastomers made with untreated mixtures. Specific examples of these mixtures include the homopolymers of acrylonitrile and vinyl chloride with a poly(oxypropyl) triol of about 3000 molecular weight as the polyol in each case. The marked improvement in the stiffness and tensile properties of elastomers made with the treated mixtures over those of the untreated controls indicates a grafting process occurring between the polyol and homopolymer upon the generation of free radicals. In the present work, grafting could occur by a chain-transfer hydrogen-abstraction mechanism, whereby a free-radical site is generated on both the homopolymer and polyol chains. Coupling of these two free-radical sites would thus result in the establishment of a polymer–polyol graft bond. |
