Analysis of the crosslinking process of a phenolic resin by thermal scanning rheometry

The curing reaction of a phenolic resin (resole type) carried out in the ab sence of an initiator was studied by thermal scanning rheometry under isoth ermal conditions at temperatures from 70 to 105 degreesC. The same curing r eaction was studied in the presence of an acid as a catalyst in the tempera ture range of 50-80 degreesC. The gel time, which was defined by several cr iteria, was found to be a good parameter to determine the apparent activati on energy of this process. An empirical model was used to predict the chang e in complex viscosity with time until the gel time was reached. If first-o rder kinetics were assumed, the apparent kinetic constant of the curing rea ction could be obtained. Furthermore, the effect that the addition of water and free phenol had on the curing process of this type of resin was studie d. (C) 2002 John Wiley & Sons, Inc.