A series of castor oil-based polyurethane (PU)/poly (methyl methacrylate-butyl methacrylate-styrene) (PA) grafted interpenetrating polymer networks (IPNs) were prepared. The effect of composition of the IPNs on the damping, thermal and mechanical properties were studied systematically. PU/PA (60:40, weight ratio) IPNs with methyl methacrylate/butyl methacrylate/styrene (MMA/BMA/St = 80/10/10, weight ratio). In the paper castor oil (CO) was used as PU’s branch units, the damping properties affected by the branch units ratio (ρ) were studied. Mechanical tests showed the tensile strength of the IPNs was improved after increasing the ρ value and PA content. The thermal stability was improved by incorporating heterocyclic imide rings into the PU molecular chains using isocyanate reacting with pyromellitic dianhydride (PMDA). It was found that the IPN composition with ρ value = 0.2 and PU/PA = 60:40 would be useful as structural damping materials, having tanδ values higher than 0.3 for a temperature range of 102°C (5.0-106.9°C).
