PREPARATION OF EPOXY HARDENERS FROM WASTE RIGID POLYURETHANE FOAM ANDTHEIR APPLICATION

Aliphatic amines were used as decomposer to decompose waste rigid poly urethane and polyisocyanurate foams, and the obtained decomposed produ cts were directly used as curing agent of epoxy resin. Effects of the decomposing condition including amine type, foam-decomposer ratio, and reaction temperature on the decomposition reaction and properties of the decomposed products were investigated. Using amines with low molec ular weight could enhance decomposition reaction rate and total amine number and lessen viscosity of the obtained decomposed products. Visco sity of the decomposed products decreased with increase of reaction te mperature, but increased with increment of foam-decomposer ratio. Shea r strength of adhesives consisting of decomposed products and epoxy re sin was measured, and their thermal properties were analyzed. The adhe sives could be cured completely over 60 degrees C and their shear stre ngth enhances with adding coupling agent in the adhesive system. The a dhesives have goad thermal stability and show satisfactory shear stren gth with more than 15, 15, 7, and 3 MPa at 25, 60, 100, and 150 degree s C, respectively. The results demonstrate that the obtained adhesive systems can be used as structural adhesive. (C) 1995 John Wiley and So ns, Inc.