Protection of epoxy resin against thermo-oxidation via co-curing epoxy/resole (I)

Co-cured materials based on 100/0, 50/50 and 0/100 weight ratios of resole/ epoxy were prepared by using NaOH and 4,4'-diaminodiphenylmethane (MDA) as curing agents. Samples were spin-coated on Al plates and were subjected to accelerated aging at 150 degrees C in air for 49 days. The functional group changes during thermal oxidation were monitored with FT-IR at various time s. Difference spectra were obtained by using aromatic absorption at 1608 cm (-1) as internal standard. Kinetic study was performed, and a first order o f degradation was demonstrated. Experimental results revealed that the degr adation rate constants for pure epoxy, 50/50 of resole/epoxy and pure resol e are 9.32x10(-3), 4.29x10(-3) and 2.03x10(-3) h(-1), respectively, indicat ing a significant protection of epoxy against thermal oxidation via co-curi ng resole/epoxy. (C) 2000 Elsevier Science Ltd. All rights reserved.