Claus Behn

Effect of some treatments on emission of volatile organic compounds (VOC) from chips used in pellets making processes

Abstract Emission of volatile organic compounds (VOC) from wood during processing to pellets – significance of wood extractives. Cellulose, hemicelluloses and lignin are the main components of the cell wall in wood. Moreover, wood contains different amounts of extractives, depending on the wood species. Extractives in softwoods play an important role during processing of wood to different wood products. This work studies the influence of storage on the change of extractives as well as on the emission of monoterpenes (primary emission) and aliphatic aldehydes, as degradation products of fats and fatty acids (secondary emission). In case of pine wood storage for 2 days at 80°C proved to be more efficient in the reduction of emissions of terpenes and aldehydes than 4 weeks at 40°C. Quantitative differences between pine (Pinus sylvestris) and spruce (Picea abies) wood chips in the emission were evaluated and discussed. Pinewood emits about 10 times higher amounts of terpenes and aldehydes than spruce wood. The results indicate that the intense of change in primary and secondary emissions due to storage depends on the wood species as well as on the boundary conditions under which storage is carried out. In general, storage at high temperature (80°C) is much more effective than at low temperature (40°C). The results also reveal that removal of wood extractives from pine wood by extraction with ethanol-cyclohexane or treatment with sodium hydroxide decreases the emission of primary and secondary volatile organic compounds drastically. Nevertheless, after such treatments minute amounts of volatile organic compounds are still detectable.

Benetzung von TMP und CTMP aus Holz sowie gebrauchten mitteldichten Faserplatten (MDF)

AbstractTMP (thermo-mechanical pulps) and CTMP (chemo-thermo-mechanical pulps) were made from pine wood and recycling MDF, which has been prepared from pine wood too. The fibres were tested for their wettability using the method developed by Roffael et al (2002). The results reveal that TMP are much less wettable in comparison to CTMP from the same wood. Moreover, fibres made from UF-bonded MDF by the TMP- and CTMP-process are of much higher wettability compared to TMP and CTMP prepared directly from wood. No significant difference in the wettability between TMP and CTMP from UF-bonded MDF was detected. This behaviour has been attributed to the fact that the UF-resin in MDF degrades during thermohydrolytic pulping leading to the formation of ammonia and free urea. Therefore, pulping of UF-bonded boards takes place under chemo-thermo-mechanical conditions (CTMP).

Benetzbarkeit von Recyclingspänen und ,,frischen“ Holzspänen mit verschiedenen Bindemitteln

Nach allen Messzeiten zeigten die „frischen“ Holzspane eine bessere Benetzung mit UF-Harz, PF-Harz und PMDI-Klebstoff als die Recyclingspane. Besonders durch mechanische Zerklei- nerung gewonnene R ...

Wasserrückhaltevermögen von Recyclingspänen und von direkt aus Holz gewonnenen Spänen

Das Wasserruckhaltevermogen nimmt mit Verlangerung der Lagerungsdauer im Wasser zu, wobei die Zunahme im Falle der mechanisch gewonnenen Recyclingspane (M) besonders ausge- pragt und im Falle der t ...

Einfluss der Alterung UF-Harz gebundener Holzspanplatten auf die Abgabe flüchtiger Säuren : [Influence of aging of UF-bonded Particleboards on the release of volatile organic acids]

ZusammenfassungDie Abgabe an flüchtigen Säuren von UF-Harz gebundenen Kiefernholzspanplatten wurde nach der Herstellung sowie nach einer Alterungsdauer von 13 Jahren bestimmt. Die Ergebnisse lassen erkennen, dass die Abgabe an Ameisensäure durch die Alterung der Platten deutlich abgenommen hat, während die Abgabe an Essigsäure signifikant zugenommen hat. Auf diesen Zusammenhang scheint der bei der Plattenherstellung verwendete Härtertyp (Ammoniumnitrat, Ammoniumchlorid) und die eingesetzte Härtermenge keinen entscheidenden Einfluss zu nehmen. AbstractThe release of volatile organic acids from UF-bonded particleboards made from Scots pine was assessed after production as well as after aging for 13 years. The results reveal that aging significantly decreased the release of formic acid and substantially increased the emanation of acetic acid. The change in the release of volatile acids by aging seems to be highly independent of the hardener type used (ammonium chloride, ammonium nitrate) as well as of the amount of added hardener.

Über den Einfluss des Bindemittels auf das Wasserrückhaltevermögen (WRV-Wert) von Recyclingfasern und Recyclingspänen

ZusammenfassungDer hydrophobierende Einfluss des in Gebrauchspänen und -fasern vorhandenen Bindemittels ist bekannt (vgl. Roffael und Schneider 1978, 1979). Erste Untersuchungsergebnisse deuten darauf hin, dass dieser Einfluss durch die ohne großen Aufwand durchführbare Messung des WRV-Wertes erfasst werden kann.AbstractThe hydrophobing influence of binders on the equilibrium moisture content (EMC) of wood and fibers is well known in the literature (Roffael und Schneider 1978, 1979). Preliminary experiments reveal, that this effect can be assessed by measuring the water retention value (WRV) of glued recycling fibers and chips.