Evaluation of torrefaction condensates as phenol substitutes in the synthesis of phenol-formaldehyde adhesives suitable for plywood

The last decades, investigators have been striving to find alternatives to materials and products from fossil sources in response to the need to get independent from petroleum. So far, the most attractive renewable source has been found to be biomass and especially wood that is easily accessible and offers a wide range of building blocks with diverse chemistries and structures that can then be used to build materials for the modern world. In this study, wood from Aspen, Pine and Birch as well as a mixture of Spruce and Pine was subjected to torrefaction and the fraction of the condensables with a dew point above 140 °C was used for the partial replacement of phenol (up to 40% wt) in the synthesis of resol phenol-formaldehyde resins suitable to be used as adhesives in the manufacturing of plywood panels. The condensables and the resins were subjected to typical lab analysis and thermal study with TGA and DSC while the plywood panels were tested and evaluated according to the European standards used by the relative industry. It was found that the studied torrefaction condensables may be successfully used in this application while the one from pine was the best performed overall.