A number of polyurethanes (PU) were synthesized by reacting castor oil with hexamethylene di-isocyanate and varying the NCO/OH ratio. All polyurethanes were reacted with acrylamide using EGDM cross-linker and benzoyl peroxide initiator. Thermogravimetric analyses of the polymers were followed, using a computer analysis method, the LOTUS package, for assigning the kinetic mechanism. Various kinetic equations have been used to evaluate the kinetic parameters. The suggested mechanism of degradation of the interpenetrating polymer networks (IPN) are based on the kinetic parameters.