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Cure kinetics and catalyzed effect of hydroxyl group of LC diglycidyl ether of bisphenol-S with aromatic diamines



The curing reactions of liquid crystalline 4,4′-bis-(2,3-epoxypropyloxy)-sulfonyl-bis(1,4-phenylene) (p-BEPSBP) with 4,4′-diaminodiphenylmethane (DDM) and 4,4′-diaminodiphenylsulfone (DDS) were investigated by nonisothermal differential scanning calorimeter (DSC). The relationships of Ea with the conversion α in the curing process were determined. The catalyzed activation of hydroxyl group for curing reaction of epoxy resins with amine in DSC experiment was discussed. The results show that these curing reactions can be described by the autocatalytic Šesták-Berggren model. The curing technical temperature and parameters were obtained, and the even reaction orders m, n, and ΔS for p-BEPSBP/DDM and p-BEPSBP/DDS are 0.35, 0.92, −81.94 and 0.13, 1.32, −24.45, respectively. The hydroxyl group has catalyzed activation for the epoxy–amine curing system in the DSC experiment. The average Ea of p-BEPSBP/DDM is 67.19 kJ mol−1 and is 105.55 kJ mol−1 for the p-BEPSBP/DDS system, but it is different for the two systems; when benzalcohol as hydroxyl group was added to the curing system, the average Ea of p-BEPSBP/DDM decreases and increases for p-BEPSBP/DDS. The crystalline phase had formed in the curing process and was fixed in the system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

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