CURE CHARACTERIZATION OF TRIGLYCIDYL EPOXY AROMATIC AMINE SYSTEMS

The curing of triglycidyl para-aminophenol (TGPAP) epoxy resin with th ree aromatic amine hardeners, diaminodiphenye sulphone (DDS), pyridine diamine (PDA), and toluenediamine (TDA), has been investigated. A seri es of isothermal cures was conducted and analyzed by Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry (D SC). The chemical reactions occurring during cure were monitored at di fferent temperatures by qualitative and quantitative estimation of dif ferent groups in the IR spectra, and the ratio of rate constants (k(2) /k(1)) were evaluated. Dynamic DSC analysis of TGPAP/TDA resulted in t wo exothermal peaks, indicating cure kinetics different from those of TGPAP/DDS and TGPAP/PDA systems, which gave a single exothermal peak. Various kinetic parameters such as total heat of reaction Delta H', ac tivation energy E(a). Frequency factor z, and order of reaction n were evaluated for all the three systems. From the initial kick-off temper atures and activation energy values it was concluded that the rate of curing followed the order TDA > PDA > DDS. The reaction conversions du ring cure, evaluated from IR analysis, were exactly the same as those obtained from DSC Borchardt-Daniels kinetics. Using this model, the pl ots of time vs. temperature for different conversions were constructed for all the three systems; on the basis of these, the cure cycles can be fixed. (C) 1995 John Wiley and Sons, Inc.