Abstract
The impurities present in the commercial (Ciba-Geigy) N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane (TGDDM) resins MY720 and MY72I and a purified TGDDM resin were studied using high-performance liquid chromatography and infrared spectroscopy. The cure kinetics for the three resins cured with 27% 4,4'-diaminodiphenylsulfone (DDS) were described using a previously developed kinetic model and near-infrared spectroscopy with the catalysis of epoxide reactions by impurity hydroxyl groups being seen to have a large effect on the initial rate of epoxide reaction. The gel times were determined using the crossover point between storage and loss moduli (i.e. tan (= 1) as measured using dynamic rheometry. An impurity effect on the-degree of epoxide reaction necessary for gelation to occur was identified and an empirical relationship was developed to quantify this effect. An approach was proposed for the prediction of gel times for TGDDM resins of any purity cured with DDS combining the use of the kinetic model and empirical gel time function.
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