Preparation Of DDAC-OMMT Compound Preservative And Its Application In Wood

In order to overcome the shortage of plantation-grown wood such as low density and ease of decay, wood samples were treated with didecyldimethylammonium chloride (DDAC)/orgnic montmorillonite (OMMT) in this study. The optimal variables in proparing the compound preservative treated wood were selected by orthogonal test and the properties of the treated wood samples were tested or characterized. From the experimental data and analysis we draw the following conclusions:1. The tensile stress relaxation of wood vacuum treated with DDAC and OMMT solutions became gradual and the most obvious effect appears at an OMMT concentration of 3%. Moisture condition also played an important role in the stress relaxation of the treated wood.The wet wood appeared the most obvious stress relaxation compared to the air-dried and oven-dry wood.2. The sequence of factors influencing the total weight gain of wood after vacuum-pressure impregnation was OMMT concentration> treatment temperature> DDAC concentration. The OMMT concentration and treatment temperature affected extremely significantly or significantly. The optimal parameter of compound preservative treated wood was selected as DDAC concentration of 2.1%, OMMT concentration of 3%, temperature 40℃.3. OMMT entered into the inner cell cavities of wood throuh vacuum-pressure impregnation observed by SEM-EDXA. Most of OMMT clusters infiltrating into wood distributed in wood cell lumen. A few small clusters and exfoliated layers could pass through the pits, but could hardly infiltrate into the wood cell wall.4. The preservative treatment appeared little influence on the stress relaxation of poplar wood.The compression strength perpendicular to grain of the samples treated with the compound preservative (OMMT+DDAC+PVA) improved 27% than the distilled water treated samples, and the decay resistance of OMMT treated samples also improved compared to DDAC treated samples.5. The sequence of the percentage of weight gain after preservative treatment for different wood species was Cunninghamia lanceolate Hook.> Populus tomentosa Carr.> Populus cathayana Rehd.>Pinus spp.. The compression strength perpendicular to grain and parallel to grain both improved compared to water treated control samples and the increase of the former is··higher than the latter. Preservative treatment has very little influence on stress relaxation of Populus cathayana Rehd.,but has obvious influence on that of Cunninghamia lanceolate Hook. The addition of PVA suspension made the stress relaxation increased slightly. The decay resistance of preservative treated samples improved greatly. More OMMT entered into hardwood and well distributed, so its fungicidal effect is more obvious.