Abstract: Interpenetrating polymer networks(IPN) were formed by simultaneous polymerization of castor oil, toluene diisocyanate and vinyl monomers using redox initiator and dibutyl tin dilaurate as catalyst at room temperature. The effect of composition of the IPNs on lap shear strength of the IPN between iron plates without rust removal has been studied. The results showed that the lap shear strength increases with increasing glass transition temperature of the polymer prepared. The higher the molar ratio of NCO/OH, the higher the lap shear strength. The coating formed by the castor oil polyurethane/poly(styrene-acryloni-trile) IPN on the iron plate without rust removal showed very good properties with respect to adherence, impact strength, flexibility and resistance to oil, dilute acid, alkali and brine.The surface of the rusted iron plate and the coated film were examined by SEM.

Key words: interpenetrating polymer network, coating, adhesive, castor oil, polyurethane