Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2023
Abstract
The dimensional stabilisation of wood using thermosetting resins relies on the resin uptake into the cell walls. This study tested if a conditioning step after the impregnation and before the final heat-curing enhances the cell wall uptake to improve dimensional stabilisation without increasing the chemical consumption. Small blocks of Scots pine sapwood were vacuum-impregnated with an aqueous melamine formaldehyde solution and conditioned at 33, 70, or 95 % RH for up to 1 week before drying and curing the blocks at 103 °C. However, the conditioning step decreased the cell wall bulking and the moisture exclusion effect compared to the immediate heat curing of the impregnated samples. Analyses of the resin-treated samples by scanning electron microscopy, IR spectroscopy and confocal Raman microspectroscopy provided evidence of wood hydrolysis and polycondensation of the resin within the cell lumen during the conditioning step. Hydrolysis and removal of wood constituents may have counterbalanced the cell wall bulking of the resin. Polycondensation of the resin in the lumen increased its molecule size, which could have hindered the cell wall diffusion of the resin.
Authors
Michael Altgen Michael Fröba Julius Gurr Andreas Krause Martin Ohlmeyer Uta Sazama Wim Willems Martin NopensAbstract
Water-sorption studies and certain organic chemistry reactions require water removal from cellulosic samples. This is hindered by the strong interaction of cellulosic materials with water, and it remains uncertain if a completely anhydrous state can be reached under common drying conditions. Here, different drying conditions were applied to wood and cellulose, and the residual moisture contents were quantified either gravimetrically or by coulometric Karl-Fischer titration. Vacuum-drying at 103 °C and ≤ 1 mbar for at least 360 min decreased the moisture content to ≤ 0.04%. However, in automated sorption balances, drying at atmospheric pressure under dry air or nitrogen flow left some samples with more than 1% moisture content. The residual moisture content obtained under dry gas flow was temperature dependent. Increasing the temperature up to 55 °C decreased the residual moisture content and cooling resulted in a moisture re-uptake, presumably due to small quantities of water vapor in the surrounding atmosphere. These effects must be considered in fundamental studies on water interactions of cellulosic materials.
Abstract
No abstract has been registered
Authors
Zoé Cord'homme Nils Maximilian Dittrich Kristina Bringedal Gedde Romain Guillaume Billy Daniel Beat MuellerAbstract
No abstract has been registered
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No abstract has been registered
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No abstract has been registered
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No abstract has been registered
Abstract
Modifying natural polymers with silicones gives new possibilities for packaging products and waste management. In this study, the innovative papers produced were altered following the reaction of polysaccharides and organosilicon compounds. The susceptibility of the studied material to biodegradation caused by a brown-rot fungus was assessed. Strength properties by tensile strength and dynamic mechanical analysis and hydrophobic properties by water uptake test and water contact angle analysis were evaluated. Moreover, elemental analysis by ICP method was controlled. The durability against fungi and the hydrophobic properties were increased by the modification. The fungal decay resistance of the silanized paper was reduced by water storage, which allows for managing paper waste. Cellulose-based paper treated with starch-modified methyltrimethoxysilane showed potential as a packaging material due to its reduced water uptake. Possible application areas could be corrugated boxes, cellulose thermoformed products for electronics, and food packaging. However, the water-repellent effect is limited to short-term exposure in humid conditions.
Abstract
No abstract has been registered
Abstract
No abstract has been registered