ADHESIVES MADE FROM INTERPENETRATING POLYMER NETWORKS FOR BONDING RUSTED IRON WITHOUT PRETREATMENT

Adhesives made from two types of room-temperature-cured interpenetrati ng polymer network (IPN) based on (1) castor oil polyurethane (PU)/vin yl or acrylic polymer and (2) PU/(unsaturated polyester and vinyl or a crylic polymer) were studied. The effects of NCO/OH molar ratio, PU co ntent, type of vinyl or acrylic monomer and weight ratio of monomer/po lyester on the adhesive properties of IPNs between rusted iron plates were investigated. The results showed that, for the first type of IPN, the lap-shear strength of the IPN between rusted iron plates exhibite d a maximum value at 60-80% PU content and increased with NCO/OH molar ratio. For different monomers, the lap-shear strength of the IPNs dec reased with decreasing glass transition temperature (T-g) of the vinyl or acrylic polymer. For the second type of IPN, acrylonitrile seemed to be the best monomer. Optimum lap-shear strength occurred at about 8 8 wt% acrylonitrile content in the acrylonitrile/(polyester + monomer) . (C) 1997 Elsevier Science Ltd.