Influence of Furfuryl Alcohol on the Cross-Linking Process of Selected Industrial Phenol-Formaldehyde Resins

Furfuryl alcohol (C5H6O2, FA) is commonly used as a modifier for phenol-formaldehyde (PF) resins and has been reported to influence their curing behavior and processing performance. Comparative analysis of commercial resin systems with and without FA suggested that the presence of FA influences the distribution of methylene bridge linkages formed during curing. FT-IR spectra indicated an increased contribution of para-para linkages in FA-containing resins, with this tendency becoming more pronounced at elevated temperatures. MAS-NMR spectra revealed differences in local methylene bridge environments, supporting the conclusion that FA influences the organization of the cross-linked network. XPS analysis revealed differences in the chemical structure of the cured resins, including a higher contribution of oxygen-containing functional groups in the FA-modified systems. STA-FT-IR results showed that FA-containing resins exhibited a more gradual curing process accompanied by a more uniform release of volatile products. Dynamic viscosity measurements demonstrated a substantial reduction in viscosity after FA addition, from 1051 to 228 mPa s for the F110-based resin system and from 1104 to 144 mPa s for the MC-05-based system. The results suggest that FA influences the cross-linking pathway, curing behavior and processing properties of PF resins. Improved understanding of these effects may support advanced PF-based composites manufacture.