Curing of Epoxy Resins with In Situ-Generated Substituted Ureas

D.P. FASCE; M.J .GALANTE; R.J.J. WILLIAMS

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 1990 vol. 39 p. 383 - 394

0021-8995

An epoxy resin based on bisphenol-A diglycidylether (DGEBA) was cured with a substitutedurea generated in situ from the reaction of piperidine with an equivalent amount of toluenediisocyanate(TDI). Curing at 100°C or higher temperatures, during 24 h, led to a complete conversionof epoxy groups and the appearance of aliphatic ethers and oxazolidone rings as revealed by IRspectra. The epoxy conversion was proportional to the oxazolidone concentration. The reactionheat was (-AH) = 61 kJ/eq. The maxim 'uTm was 102OC, e.g., the same value as the oneobtained with piperidine alone. Thus, the cure with the substituted urea leads to a similarnetwork but has the following advantages: increase in the latency of the initial formulation,absence of secondary amine volatilization (reproducible curing schedule), and decrease in thereaction heat per epoxy equivalent.