Statistical treatment of allophanate crosslinking in the formation of polyurethane networks

Summary Crosslinking of polyurethanes by a reaction of isocyanate groups with urethane groups leading to trifunctional allophanate branch points is treated statistically using the theory of branching processes. The occurrence of gelation in the diol — diisocyanate system and its dependence on the excess of isocyanate groups and the intensity of allophanate formation is discussed.