Isocyanate cross-linked polybutadiene

Low-molecular-weight (3,000-10,000) versions of such elastomers are used to produce liquid rubbers which can be shaped more easily than the conventional high-viscosity elastomers. The liquid rubbers can be vulcanized by reactions of their specific end groups. Hydroxyl-ended polybutadienes can be caused to grow in molecular size and to cross-link, for example, by reaction with isocyanates with functionalities > 2 (cf. reaction 1-12). 

Thermo-oxidative breakdown of the cross-linked polymer derived from toluene-2,4-di-isocyanate, methylene bis(4-amino-3-chloroph0iyl), and a hydroxy-terminated polybutadiene occurred, however, by a radical mechanism... 

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