Influence of sequence of chemical reactions on kinetics and solid state behavior for bisphenol A diglycidyl ether – bisphenol A – sulfanilamide ternary blends

The kinetics of reaction of ternary blends based on Bisphenol A diglycidyl ether, Bisphenol A and sulfanilamide curing agent was investigated using FTIR, HPLC, SEC following two different synthesis paths. Four the same initial composition prepolymers differing by the cross-link point distribution and the chain length between cross-links have been synthesized and their solid state behavior has been studied. For the formulation DGEBA:SAA:BA = 4.0:1.25:1.5 mol (catalyst - 0.005 e.e.w. DGEBA), though the schedules have different kinetics, finally the prepolymers with equal conversion of epoxy groups and mass-average molar mass were obtained by both schedules. The dynamic mechanical spectroscopy performed in the glass transition region displays the evolution of the viscoelastic characteristics as a function of cross-link density. For similar formulations networks obtained by schedule 1 have higher values of T _g and σ _y than networks obtained by schedule 2, perhaps due to a higher real cross-link density. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000