Interaction of Hexamethylenetetramine with Phenol-Formaldehyde Resin during Simultaneous Curing of Novolac and Resole.

This work is focused on the analysis of the curing process of phenol-formaldehyde resins using hexamethylenetetramine. Most of the recent studies address the curing of either liquid resole or powdered novolac resin. However, there are no published studies concerning their mixture despite the fact that this material is commonly used in the abrasive industry. In the presented study, the curing mechanism of a resole-novolac mixture in the presence of hexamethylenetetramine was investigated using simultaneous thermal analysis combined with FTIR spectroscopy. This approach enabled the qualitative and quantitative identification of volatile compounds released over a wide temperature range (40-300 °C) as well as a comparison of the curing processes of resole, novolac, and their mixtures. The results show that when both types of resins are combined, hexamethylenetetramine reacts with water produced during the curing of the resole resin, thereby altering the course of the novolac cross-linking process.