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Application of Wood Vinegars Prepared from Branches and Tree Tops of Cryptomeria japonica at Different Collection Temperatures to Evaluate their Fungi Resistance for Moso Bamboo Material

Source: OAI

ABSTRACT In this study, wood vinegars were collected from the chimney outflow of earthen kiln at 6 different temperatures (80-159, 80-90, 91-100, 101-120, 121-140 and 141-159°C) during the charcoal preparation from the branches and tree tops of Cryptomeria japonica. These vinegars were used to evaluate the fungi resistance of airborne fungi particles, Aspergillus niger, Aspergillus flavus and Trichoderma viride after they as well as acetic acid and tap water (as the controls) were used to impregnate Moso bamboo specimens for 240 min using the vacuum method. The basic properties of the wood vinegars obtained were: pH value of 2.54 to 3.45, specific gravity ranging from 1.006 to 1.008, contents of organic acid ranged between 1.75 and 3.03%, soluble tar content was from 0.186 to 0.629%, and the color difference (\Delta E*) ranged from 8.37 to 14.36. The absorption by the bamboo specimens after having been processed with the various vinegars using the vacuum method ranged from 10.85 to 19.35 mg/$cm^3$. The results of the macro-observation showed that after 70 days the growth rate of airborne fungi particle on the surface of bamboo specimens impregnated with vinegar at 80 to 159°C range between 10% and 15%, but it was close to 100% for either of the controls after only about 30 days. The FTIR analysis showed that the specimens treated with vinegar at 80 to 159°C did not contain the fungal chemical compounds, at 1654 $cm^{-1}$ (C = O) and 1552 $cm^{-1}$ (N-H), while the acetic acid and the tap water both showed absorbance peaks. The C/N ratio of the airborne fungi particles of the specimen treated with vinegar at 80 to 159°C was 131.4%, but it was only about 90.5 to 102.8% for the controls. These results suggest that the compositions of the wood vinegars collected at different temperatures affect the fungi resistance of the bamboo material.

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