Kinetics of an Anhydride-Epoxy Polymerization as Determined by Differential Scanning Calorimetry
The use of differential scanning calorimetry (DSC) to study the thermal behavior of polymers has developed to the point where it is now used to establish the kinetics of polymer phase transformations, including polymerization reactions. We will describe the use of DSC to determine the polymerization kinetics of the anhydride-epoxy system, bisphenol A diglycidyl ether (DGEBA)-”nadic” methyl anhydride (NMA). This polymerization reaction, catalyzed by benzyldimethyl amine (BDMA) is generally viewed as a very complex curing process but the data here were fitted to a two stage model utilizing a single reaction order of n=2 and (only) two activation energies. Namely, in dynamic scans, after the reaction had proceeded with an activation of about 15 kcal/mole for about 12% completion, the rate increased until completion but with a higher activation energy of about 38 kcal/mole. Such an increase in rate was verified qualitatively by an isothermal run. Other workers studying similar systems have reported the lower activation energy. However, scrutiny of their data indicates a similar increase in rate.
KeywordsDifferential Scanning Calorimetry Base Line Differential Scanning Calorimetry Data Polymerization Kinetic Fast Heating Rate
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