| Abstract: | The kinetics of the thermal cure reaction of Bisphenol A dicyanate (BACY) in presence of various transition metal acetyl acetonates and dibutyl tin dilaurate (DBTDL) was investigated using dynamic differential scanning calorimetry (DSC). The cure reaction involved a pregel stage corresponding to around 60% conversion and a postgel stage beyond that. Influence of nature and concentration of catalysts on the cure characteristics was examined and compared with the uncatalyzed thermal cure reaction. The activation energy (E), preexponential factor (A), and order of reaction (n) were computed by the Coats–Redfern method. A kinetic compensation correction was applied to the data in both stages to normalize the E values. The normalized activation energy showed a systematic decrease with increase in catalyst concentration. The exponential relationship between E and catalyst concentration substantiated the high propensity of the system for catalysis. At fixed concentration of the catalyst, the catalytic efficiency as measured by the decrease in E value showed dependency on the nature of the coordinated metal and stability of the acetyl acetonate complex. Among the acetyl acetonates, for a given oxidation state of the metal ions, E decreased with decrease in the stability of the complex. A linear relationship was found to exist between activation energy and the gel temperature for all the systems. Manganese and iron acetyl acetonates were identified as the most efficient catalysts. In comparison to DBTDL, ferric acetyl acetonate proved to be a more efficient catalyst. The activation parameters computed using the Coats–Redfern method agreed well with the results from two other well known integral equations. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1103–1114, 1999 |
