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Gewählte Master / Diploma Thesis:

Alfred Andreas Hummer (2009): Production of hardboards made with tannic acid and phenol-oxidizing enzymes.
Master / Diploma Thesis, BOKU-Universität für Bodenkultur, pp 86. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Abstract:
Fibres derived from three different wood mixtures were used to produce hardboards. The fibres were obtained from an industrial manufacturing process and formed into fibre mats. The mats were impregnated according to two different laboratory scale methods (conventional and non-conventional). In the conventional method the fibres were suspended in water and a solution of tannic acid and/or laccase was added to the suspension. The fibres were formed into mats and subsequently pressed into hardboards on a laboratory press. In the non-conventional method fibre mats were formed and in a second step impregnated with tannic acid and/or laccase solution. The mats were incubated/dried in an oven at 40°C until a moisture content of about 50% was reached and then pressed into hardboards. The hardboards were tested for internal bond strength (IB), modulus of elasticity (MOE), modulus of rupture (MOR) and thickness swell after 24h of water immersion. The effects of laccase dose, tannin concentration, pH of impregnation solution, mat moisture content before pressing, press temperature and board density on board properties were investigated. The best results were achieved with a laccase dose of 500 nkat/g d.f., tannic acid concentration of 10%/g d.f. and pH 6 of the impregnation solution. An addition of Hydrowax to the impregnation solution was beneficial for the dimensional stability but not for the mechanicl one. Press temperatures above 190°C and moisture contents below 50% of the fibre mat before pressing had an adverse effect on board parameters. Even the fibre mixture was an issue, the best results were achieved with mixtures rich in softwood.

Beurteilende(r): Teischinger Alfred

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