Richter K, Windeisen E, Özparpucu M 2021: Interactions of wood extractives and structural wood adhesives and their effects on wood bonding performance
国际木文化学会 | 324 view(s) | 2021/06/04
For the development of new advanced wood-based materials and composites, adhesive bonding of wood plays a crucial role. However, wood bonding is challenging due to the inherently complex chemical and structural properties of wood. It is known that in the bonding process, wood extracts can accumulate at the surface and create a chemical boundary layer with different surface permeability, polarity, and wettability as well. Therefore, the quality of wood-adhesive bonds highly depends on the interactions between the wood and adhesives. In our research, to investigate the interactions between the wood adhesives and extractable wood constituents, in-situ FTIR spectroscopy and rheology analysis was performed, which provides simultaneous examination of the progress of chemical reactions and changes in rheological properties by adhesive curing of both pure adhesives and adhesive-extract mixtures. Results show that adhesive curing was affected specifically under the presence of wood extractives in the four structural wood adhesive systems applied. In particular, for the extracts having a high acidity level such as chestnut extract (pH=3.8), the effect on curing was highly significant, eg. for EPI adhesives. For 1c-PUR, however, an influence of specific extracts could not been detected by the proposed in-situ investigation. In summary, fundamental information on the chemical interactions between the extracts and wood adhesives was provided, valuable to support the development of highly durable advanced adhesive bonds with wood.