Preparation and characterization of novolac phenol–formaldehyde resins with enzymatic hydrolysis lignin

Abstract

Enzymatic hydrolysis lignin (EHL) derived from bio-ethanol production is attracting increased attention for use as a substitute for petroleum-based phenol in phenolic resins. In this work, EHL was successfully liquefied into small phenolic compounds catalyzed by oxalic acid in the presence of phenol. Experiments were designed to determine the effects of different replacement percentages of phenol by EHL on the residue content (RC) and the combined phenol (CP). Up to a 55% weight of phenol was substituted by liquefied EHL to formulate a novolac bio-based phenolic resin (EHL–PF). The differences between EHL and liquefied EHL, PF and EHL–PF were studied by Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), 1H NMR spectroscopy, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). RC was found to increase with the increasing replacement percentage, while CP was found to increase at a lower replacement percentage and decrease at a higher replacement percentage. EHL–PF possessed comparable properties to those of commercial products.