Carbonization Reactions in Novolac Resins, Hexamethylenetetramine, and Furfuryl Alcohol Mixtures

The carbonization process of novolac resins cured by hexamethylenetetramine (HMTA) in the presence of furfuryl alcohol (FA) was studied by a high-resolution solid-state NMR technique. Most reactions occur below 600 °C, and aliphatic species disappear above 800 °C. Nitrogen (2−3%) is present in the carbon materials obtained. The process can be influenced by the starting novolac structures, ca. the ratio of ortho/para reactive sites, and the FA content in the systems. When a novolac resin contains a high ratio of para-reactive sites, the carbonization reaction occurs at relatively lower temperatures, and the rate is relatively fast. High FA content slows down the carbonization process, and reactions occur at relatively high temperatures. Starting novolac structures and FA content in the systems also vary the nitrogen structures during the process and the structure distribution in the carbon materials at 800 °C.