Summary
Sapwood of Scots pine (Pinus silvestris L.) was acetylated with 14C- and 3H-labelled acetic anhydride.
The distribution of acetyl groups was investigated with microautoradiography and microautoradiographs
were evaluated with ESEM, Environmental Scanning Electron Microscopy.
The investigation showed that the impregnation of wood with radioisotope-labelled substances provides
a good opportunity to investigate the location of substances covalently bonded to the wood material.
Introduced 14C-labelled acetyl groups show an even distribution in the wood cell wall, with no discernible
concentration gradients at acetylation levels of about 5, 15 and 20% weight gain. 3H-labelled
acetyl groups show an even distribution in the wood cell wall at 15 and 20% weight gain, with no discernible
concentration gradients. At the 5% weight gain level, however, an uneven distribution of 3H-labelled
acetyl groups over the cell wall is observed. Nevertheless, the unevenness is random and no concentration
gradient is discernible at this level.
3H with a relatively high resolution, 0.5–1 μm, compared to 14C with a resolution of 2–5 μm, gives
more accurate information about where exactly the acetyl groups are situated in the wood cell wall.
Acetic anhydride was evenly distributed when a full impregnation procedure was used. The chemical and
physical properties of acetic anhydride allow a uniform penetration into the pine cell wall and a complete
acetylation takes place when the specimens are heated.
Enhancement of the physical and mechanical properties of wood using a novel organo-montmorillonite/hyperbranched polyacrylate emulsion
