Comparison of model-fitting kinetics for predicting the cure behavior of commercial phenol-formaldehyde resins

Abstract

Phenol-formaldehyde (PF) resins have been the subject of many model-fitting cure kinetic studies, yet the best model for predicting PF dynamic and isothermal cure has not been established. The objective of this research is to compare and contrast several commonly used kinetic models for predicting degree of cure and cure rate of PF resins. Toward this objective, the nth-order Borchardt-Daniels (nthBD), ASTM E698 (E698), autocatalytic Borchardt-Daniels (Auto-BD), and modified autocatalytic methods (M-Auto) are evaluated on two commercial PF resins containing different molecular weight distributions and thus cure behaviors. The nth-BD, E698, and M-Auto methods all produce comparable values of activation energies, while Auto-BD method yields aberrant values. For dynamic cure prediction, all models fail to predict reaction rate, while degree of cure is reasonably well predicted with all three methods. As a whole, the nth-BD method best predicts degree of cure for both resins as assessed by mean squared error of prediction. © 2007 Wiley Periodicals, Inc.