TGMDA resins impurities

The effects of impurities, or synthesis byproducts, and stoichiometry on the cure kinetics of N,N -tetraglycldyl methylene dianiline (TGMDA) resins formulated with dlaminodiphenyl sulfone (DDS) are evaluated using gel permeation chromatography and differential scanning calorimetry. 

Both GPC and DSC show that impurities or reaction byproducts in commercial TGMDA resins increase the rate of reaction. This effect is illustrated in Figures 8 and 9 where the epoxy/amine equivalent ratios are held constant. Impurities also tend to lower g, reduce the gelation time, increase M at g, and increase Ofjnai The magnitude of these effects are particularly notable upon comparing the DSC parameters of the TGMDA and Residue formulations (Table IV). 

Results obtained by the GPC and DSC studies are in excellent agreement. Correlations between GPC and DSC data provide a better understanding of epoxy resin cure behavior and are useful In assessing the effects of stoichiometry and impurities. Simple amine-to-epoxy addition is the predominant reaction between TGMDA and DDS during the early stages of cure. This reaction is adeguately described by a third-order rate expression (Eg. 10). 

---