COMPARISONS OF THE CURE OF PHENOL-FORMALDEHYDE NOVOLAC AND RESOL SYSTEMS BY DIFFERENTIAL SCANNING CALORIMETRY

Comparisons were made of differential scanning‐calorimetric (DSC) thermograms of both liquid and powdered commercial phenol–formaldehyde resins. By a combination of the results from analyses under a variety of conditions, such as ambient pressure, high pressure, using freeze‐dried samples, and also by direct observation of the resin‐curing process in wood‐veneer assemblies, the curing reactions of phenol–formaldehyde resins were found to differ for resol and novolac systems. At a heating rate of 10°C/min, the resol resin showed endothermic curing reactions at temperatures of about 150°C, while the novolac‐type resin showed an exothermic peak maximum at about 160°C. Results are presented to show how DSC can be used to differentiate between a resol and novolac system. Copyright © 1979 John Wiley & Sons, Inc.