Engineering biomass into formaldehyde-free phenolic resin for composite materials

The use of formaldehyde to prepare phenol-formaldehyde (PF) resins is one of the primary challenges for the world-wide PF industry with respect to both sustainability and human health. This study reports a novel one-pot synthesis process for phenol-5-hydroxymethylfurfural (PHMF) resin as a formaldehyde-free phenolic resin using phenol and glucose, and the curing of the phenolic resin with a green curing agent organosolv lignin (OL) or Kraft lignin (KL). Evidenced by ¹³C NMR, the curing mechanism involves alkylation reaction between the hydoxyalkyl groups of lignin and the ortho- and para-carbon of PHMF phenolic hydroxyl group. The curing kinetics was studied using differential scanning calorimetry and the kinetic parameters were obtained. The OL/KL cured PHMF resins were tested in terms of thermal stability, and mechanical properties for their applications in fiberglass reinforced composite materials. The results obtained demonstrated that OL/KL can be promising curing agents for the PHMF resins. © 2015 American Institute of Chemical Engineers.