Reducing Activation Energy in Novolac Resins through Bio-Oil Integration: A Sustainable Approach

Author(s): Archana Bansode, Iris Beatriz Vega Erramuspe, Lorena Alexandra Portilla Villarreal, Braden Hahn, Brian K. Via, Allan David, Nicole Labbe?, Maria L Auad

This study presents the development of a bio-oil-enhanced curing system for novolac phenol-formaldehyde (PF) resins, aimed at advancing both the environmental sustainability and efficiency of these materials. By partially substituting phenol with bio-oil derived from the fast pyrolysis of pinewood biomass, we engineered a bio-based novolac resin with significantly improved curing characteristics. The introduction of bio-oil into the resin formulation led to a marked reduction in the curing temperature by approximately 20°C, a change driven by the additional reactive functional groups present in the bio-oil. These groups enhance the crosslinking potential of the resin, facilitating an earlier onset of curing reactions and reducing the overall activation energy required for the process. The study employed dynamic differential scanning calorimetry (DSC) to assess the curing behavior of both conventional and bio-oil-enhanced resins. While the autocatalytic model demonstrated a strong fit for the conventional novolac resin and HMTA mixture, the Kamal model was found to be more appropriate for describing the curing dynamics of the bio-oil-based novolac resin. The Kamal model's effectiveness is attributed to its ability to capture the complex curing mechanism of the bio-based system, which involves an initial autocatalytic stage followed by a reaction governed by nth-order kinetics. This dual-stage mechanism reflects the unique influence of bio-oil on the resin's crosslinking behavior, providing a more accurate representation of the curing process. These findings highlight the potential of bio-oil as a valuable component in novolac PF resins, offering a pathway to more energy-efficient and sustainable materials.