Fabrication of highly stable and durable furfurylated wood materials. Part II: the multi-scale distribution of furfuryl alcohol (FA) resin in wood

The aim of this investigation was mainly to evaluate the multi-scale distribution of furfuryl alcohol (FA) resin in modified Chinese fir and poplar wood. C-13 CP/ MAS NMR, Scanning Electron Microscopy (SEM), Confocal Laser Scanning Microscopy (CLSM), Nanoindentation and Imaging Fourier transform infrared microscopy (Imaging FT-IR) were applied to describe the FA resin distribution in wood from bulk to cell wall scale. The results showed that FA resin were mainly located in the cell cavity of Chinese fir tracheids. For poplar, FA resin was mostly deposited in the cavity of fibers and ray cells, while little was found in the adjacent vessels. Lots of pits of wood cells were covered with FA resin which implied a higher risk of drying after wood furfurlation in practical production. Nanoindentation demonstrated that FA resin could easily infiltrate into the wood cell wall because both reduced modulus and hardness of the modified wood cell walls were significantly improved. This conclusion was further supported by the results of imaging FT-IR.