Production of Novolac Resin after Partial Substitution of Phenol from Bio-Oil

Abstract

Highlights Bio-oil was used to produce novolac resin. Bio-oil interacted with phenol and altered the reaction rate and equilibrium. Comparable performance was observed with a low amount of substitution. Abstract. Commercially produced bio-oil with a high content of pyrolytic lignin was substituted for phenol in novolac phenol-formaldehyde (PF) resin production. The reaction progress was tracked, and products were analyzed. Bio-oil substitution resulted in lower conversion rates for both formaldehyde and phenol. Substitution higher than 10 mol% increased the ortho to para ratio and enhanced thermal decomposition of resin by providing an oxidative environment, while 10 and 20 mol% of substitution did not reduce the shear strength of the novolac resin. When mixed with hexamethylenetetramine (HMTA), the bio-oil substituted resins precipitated quickly around char particles, which allowed more resin application on the wood bonding surface. Further investigation found that bio-oil substitution (higher than 10 mol%) might have changed the reaction equilibrium and promoted reverse reactions releasing formaldehyde. Overall, less than 20 mol% phenol substitution by bio-oil with a high content of pyrolytic lignin can be effective in producing novolac resin. Keywords: Bio-oil, Formaldehyde, Lignocellulosic biomass, Novolac, Phenol, Pyrolysis.