DAMPING MATERIALS BASED ON SIMULTANEOUSLY GRAFTED INTERPENETRATING POLYMER NETWORKS FROM CASTOR-OIL

Four kinds of grafted interpenetrating polymer networks (IPNs) were sy nthesized from castor oil (CAS), toluene diisocyanate (TDI), monohydro xy terminated acrylic (or methacrylic) prepolymer and/or acrylic (or m ethacrylic) monomer in the presence of dibutyltin dilaurate and redox initiators. Formation rates of soluble and insoluble polymers were inv estigated in the course of synthesis of the grafted IPN from NCO-termi nated CAS precursor, butyl acrylate prepolymer, CAS and ethyl methacry late monomer. Mechanical properties of the IPNs were studied as well. Studies of the dynamic mechanical properties of the various grafted IP Ns showed that certain IPNs (from CAS/TDI/butyl methacrylate and butyl acrylate prepolymers, CAS/TDI/butyl acrylate monomer/ethyl methacryla te prepolymer, CAS/TDI/ethyl methacrylate monomer/butyl methacrylate p repolymer) exhibit high damping behavior over wide temperature ranges for tan delta > 0.3 (DELTAT(hd) from 88-degrees-C up to 133-degrees-C) and maximum tan delta values higher than 1.1.