Sustainable glucose-based phenolic resin and its curing with a DGEBA epoxy resin

A sustainable novolac-type resin – phenol–hydroxymethylfurfural (PHMF) resin was prepared by reacting phenol with HMF, in-situ derived from glucose, at 120 °C by acid catalysis. Bisphenol A type epoxy resin, i.e. bisphenol A diglycidyl ether (DGEBA), was used as a formaldehyde-free curing agent by substituting conventional formaldehyde-based hexamethylene tetraamine (HMTA) to crosslink the PHMF resin. Curing mechanism was probed and the curing proceeded likely with the ring opening reaction between the DGEBA and reactive hydroxyl groups. DGEBA not only made this system truly formaldehyde-free but also helped form a void-free matrix which is an important merit for composites. The kinetic parameters of the curing reaction were evaluated with model-free and model-fitting methods using exothermal peak data from the curing process. The thermo-mechanical characterization of the cured resin and fiber reinforced bio-composites showed good heat resistance and mechanical performance, suggesting its potential for producing void- and formaldehyde-free composite materials. © 2016 Taiwan Institute of Chemical Engineers