Studies on Urethane Elastomers - 1.

The fundamental chemistry of preparation of urethane elastomers has been reviewed and the authors' experimental results presented. It has been shown that the influence of NCO to OH molar ratio and of chain extender on the network structure of elastomers can be investigated by Veisfeld's method. The crosslinking of urethane oligomers with free isocyanate groups in the presence of Li-organic catalysts has been studied. It has been found that the cyclopolymerization of free NCO groups is responsible for the crosslinking and formation of isocyanuric rings. Cyclohexanone-formaldehyde resin as a chain extender has also been studied. The formation of urethane, amide, allophane and N-acyl derivative of urea links has been proved.