PROPERTIES OF 2 KINDS OF ROOM-TEMPERATURE CURED INTERPENETRATING POLYMER NETWORKS BASED ON CASTOR-OIL POLYURETHANE

Mechanical properties and adhesive strength of two kinds of room tempe rature cured interpenetrating polymer networks (IPNs) based on castor oil polyurethane were studied. The first IPNs (IPNs-I) were synthesize d from castor oil, toluene diisocyanate (TDI) and vinyl or acrylic mon omer. The second IPNs (IPNs-II) were prepared from castor oil, TDI, un saturated polyester and vinyl or acrylic monomer. For IPNs-I made from different monomers, both maximum tensile strength and maximum lap she ar strength between rusted iron plates decreased in almost the same or der as the decreasing order of T(g) of the vinyl or acrylic polymer. T he apparent crosslink density and tensile strength of the IPNs increas ed with NCO/OH molar ratio. The lap shear strength of IPN-I exhibited a maximum at 70-80% polyurethane (PU) content and increased with NCO/O H ratio up to 1.92. For IPNs-II, acrylonitrile seems to be the best mo nomer. Optimum properties occurred at a weight ratio of acrylonitrile/ polyester of about 8, a molar ratio of NCO/OH about 1.9 and at 65% PU content.