CURE MONITORING OF AN EPOXY-AMINE SYSTEM BY DYNAMIC MECHANICAL THERMAL-ANALYSIS (DMTA)

A method has been devised to study the cure of epoxy resins using a dynamic mechanical thermal analyzer (DMTA) in combination with differential scanning calorimetry. Special glass fiber braids (25 × 13 × 0.15 mm) were impregnated with the liquid epoxy/amine (DGEBA/m-PDA) mixture at room temperature and subjected to forced oscillations at elevated cure temperatures. The modulus and the tan δ underwent transitions typical of gelation and vitrification. The times to gelation and vitrification were used to generate the well known time-temperature-transformation diagram proposed by J. Gillham on the basis of torsional braid analysis data. DMTA also provides information about the rate of modulus increase during cure, which was compared with theoretical calculations of the rise in crosslink density. © 1990.