Im Rahmen des Forschungsprojektes wurden zwei Verfahren zur Herstellung thermisch modifizierter Furniere entwickelt. Nach Verfahren 1 erfolgt die Herstellung von Furnier durch Messern von thermisch modifizierten Blöcken, wobei der Hauptanteil der Untersuchungen an längs gemesserten Furnieren durchgeführt wurde. Ein Industrieversuch belegt die Machbarkeit der Herstellung thermisch modifizierter Furniere aus modifizierten Blöcken durch quer messern, also nach dem üblichen Verfahren zur Herstellung dekorativer Furniere. Nach Verfahren 2 erfolgt die Herstellung von thermisch modifizierten Furnieren durch thermische Modifizierung handelsüblicher dünner Messerfurniere (d=0,5...0,6 mm). Parameter für eine thermische Modifikation sind im Wesentlichen die Dauer der Behandlung sowie die Temperatur. Die Temperatur wurde im Bereich zwischen 170°C und 210°C variiert, die Dauer der Hochtemperaturbehandlung zwischen 2 h und 4 h. Als Holzarten wurden Rotbuche, Ahorn, Birke, Pappel und Esche untersucht. Die hergestellten Furniere wurden hinsichtlich verschiedener mechanischer Eigenschaften, farblicher Eigenschaften sowie verarbeitungstechnischer Eigenschaften untersucht und bewertet.

Bestimmte Extraktstoffe aus thermisch modifizierter Buche weisen fungizide Eigenschaften auf. Methanol-Extrakte aus thermisch modifizierter Buche, die in Propanon wieder aufgelöst wurden, wiesen eine leichte pilzwachstumshemmende Wirkung auf. Die getränkten Prüfkörper aus Buche erreichten eine Zuordnung zur Dauerhaftigkeitsklasse 4, d. h. nicht dauerhaft. Prüfkörper, die mit anderen Extrakten aus thermisch modifizierter Buche getränkt wurden, dabei insbesondere Wasser-Extrakte, weisen dagegen keine signifikante Resistenzverbesserung auf. Die Analyse der Methanol-Extrakte mittels Gaschromatografie mit Massenspektrometrie-Kopplung (GC-MS) ließ einen erhöhten Anteil bestimmter phenolischer Verbindungen erkennen, die teilweise Resistenz fördernde Wirkungen haben. Das Vorhandensein dieser Verbindungen kann somit als Begründung der Verbesserung der Resistenz entsprechend imprägnierter Prüfkörper herangezogen werden. Die Endfassung des Artikels ist auf www.holztechnologie.de verfügbar. / Certain extractives from thermally modified beech have fungicidal properties. Methanol extracts, resolubilized in propanone, caused a significant retardation of fungal growth on native beech specimen. Beech specimen impregnated with these extractives could be assigned to the durability class 4, i. e. not permanent. Other extracts of thermally modified beech, in particular water extracts, did not show significant improvement in resistance. The analysis of methanol extracts using gas chromatography coupled with mass spectrometry (GC-MS) showed an increased amount of phenolic compounds known to increase resistance. Their presence in organic extracts of thermally modified wood may explain the improvement of the resistance of the impregnated specimen. The original publication is available at www.holztechnologie.de.

Bestimmte Extraktstoffe aus thermisch modifizierter Buche weisen fungizide Eigenschaften auf. Methanol-Extrakte aus thermisch modifizierter Buche, die in Propanon wieder aufgelöst wurden, wiesen eine leichte pilzwachstumshemmende Wirkung auf. Die getränkten Prüfkörper aus Buche erreichten eine Zuordnung zur Dauerhaftigkeitsklasse 4, d. h. nicht dauerhaft. Prüfkörper, die mit anderen Extrakten aus thermisch modifizierter Buche getränkt wurden, dabei insbesondere Wasser-Extrakte, weisen dagegen keine signifikante Resistenzverbesserung auf. Die Analyse der Methanol-Extrakte mittels Gaschromatografie mit Massenspektrometrie-Kopplung (GC-MS) ließ einen erhöhten Anteil bestimmter phenolischer Verbindungen erkennen, die teilweise Resistenz fördernde Wirkungen haben. Das Vorhandensein dieser Verbindungen kann somit als Begründung der Verbesserung der Resistenz entsprechend imprägnierter Prüfkörper herangezogen werden. Die Endfassung des Artikels ist auf www.holztechnologie.de verfügbar. / Certain extractives from thermally modified beech have fungicidal properties. Methanol extracts, resolubilized in propanone, caused a significant retardation of fungal growth on native beech specimen. Beech specimen impregnated with these extractives could be assigned to the durability class 4, i. e. not permanent. Other extracts of thermally modified beech, in particular water extracts, did not show significant improvement in resistance. The analysis of methanol extracts using gas chromatography coupled with mass spectrometry (GC-MS) showed an increased amount of phenolic compounds known to increase resistance. Their presence in organic extracts of thermally modified wood may explain the improvement of the resistance of the impregnated specimen. The original publication is available at www.holztechnologie.de.

Im Rahmen des Forschungsprojektes wurden zwei Verfahren zur Herstellung thermisch modifizierter Furniere entwickelt. Nach Verfahren 1 erfolgt die Herstellung von Furnier durch Messern von thermisch modifizierten Blöcken, wobei der Hauptanteil der Untersuchungen an längs gemesserten Furnieren durchgeführt wurde. Ein Industrieversuch belegt die Machbarkeit der Herstellung thermisch modifizierter Furniere aus modifizierten Blöcken durch quer messern, also nach dem üblichen Verfahren zur Herstellung dekorativer Furniere. Nach Verfahren 2 erfolgt die Herstellung von thermisch modifizierten Furnieren durch thermische Modifizierung handelsüblicher dünner Messerfurniere (d=0,5...0,6 mm). Parameter für eine thermische Modifikation sind im Wesentlichen die Dauer der Behandlung sowie die Temperatur. Die Temperatur wurde im Bereich zwischen 170°C und 210°C variiert, die Dauer der Hochtemperaturbehandlung zwischen 2 h und 4 h. Als Holzarten wurden Rotbuche, Ahorn, Birke, Pappel und Esche untersucht. Die hergestellten Furniere wurden hinsichtlich verschiedener mechanischer Eigenschaften, farblicher Eigenschaften sowie verarbeitungstechnischer Eigenschaften untersucht und bewertet.

Abstract The present thesis exploits advanced liquid and gas NMR methods for the characterization of various interesting materials. The methods used to study the structural properties of thermally modified wood, ionic liquids, cements, shales, and porous organic cages include MRI, NMR cryoporometry, Laplace NMR, multidimensional Laplace NMR, as well as ¹²⁹Xe and ¹⁹F NMR. The commonality factor in all the studies is the usage of either inherent or introduced liquid or gas molecules to probe the topical materials. The MRI method was utilized to visualize the water absorption phenomena in the thermally modified pine wood. High-resolution images made it possible to observe the spatial distribution of free water and the changes in the rate of absorption of water in wood samples modified at different temperatures. The images also helped to resolve the individual resin channels. T₂ maps enabled us to observe the changes in the relaxation values of free water in thermally modified wood as compared to their unmodified reference wood samples. The multidimensional Laplace NMR methods were exploited to study the structural and dynamical properties of a novel halogen-free, boron-based ionic liquid (hf-BIL). NMR self-diffusion (D) experiments showed the presence of two coexisting dynamic phases in hf-BIL. Multidimensional D − T₂ correlation experiments made it possible to determine the T₂ relaxation times of the slow and fast diffusing phases. T₂ − T₂ relaxation exchange measurements allowed quantifying the exchange rates of anions and cations between the phases. Moreover, the theoretical modeling of the experimental data revealed that the slow diffusing phase was composed of anion-cation aggregates, while the fast diffusing phase was comprised of free anions and cations. ¹²⁹Xe NMR analysis of the xenon adsorbed in the cements and shales helped us to determine their porous structures. The method exploits the high sensitivity of the chemical shift of ¹²⁹Xe to its local environment. The chemical shift value of ¹²⁹Xe enabled us to estimate the size of the mesopores in the cement samples. The exchange spectroscopy (EXSY) measurements were used to determine the exchange rates between the free gas and mesopores of the cement samples. ¹²⁹Xe NMR spectra of the shale samples provided information about pore sizes and paramagnetic compounds. ¹H NMR cryoporometry measurements of the shale samples immersed in acetonitrile made it possible to analyze the pore size distribution ranging from 10 to over 100 nm. Moreover, T₂ − T₂ exchange measurements helped us to quantify the exchange rates of acetonitrile in the shale samples. Xenon and SF₆ were used as internal reporters to gain versatile information on adsorption phenomena in the cage and window cavities of the crystalline porous organic cages. ¹²⁹Xe NMR analysis of the adsorbed xenon helped us to determine the diffusion coefficients and activation energy of diffusion as well as thermodynamic parameters. With the help of T₂ relaxation time values, it was possible to estimate the exchange rates between cage and window cavities. Chemical exchange saturation transfer (CEST) experiments resolved a window cavity site, which arises from crystal defects in porous organic cages. In addition, ¹⁹F NMR analysis made it possible to estimate the relaxation rates and diffusion coefficients of SF₆ gas in porous organic cages. Modelling of the T₁, T₂ and diffusion data confirmed that the cage to window exchange is the completely dominating mechanism for ¹²⁹Xe T₂ relaxation. T₁ relaxation is dominated by diffusion modulated dipole-dipole relaxation (DDinter) and chemical shift anisotropy (CSA) relaxation due to local cavity mobility. Whereas, in case of SF₆ T₂ data, the dominating mechanism is diffusion modulated dipole-dipole relaxation and for T₁ the local tumbling of SF₆ in cage cavity is the key dynamics behind the dipole-dipole and CSA mechanisms. / Original papers The original publications are not included in the electronic version of the dissertation. Javed, M. A., Kekkonen, P. M., Ahola, S., & Telkki, V.-V. (2015). Magnetic resonance imaging study of water absorption in thermally modified pine wood. Holzforschung, 69(7), 899–907. https://doi.org/10.1515/hf-2014-0183 Javed, M. A., Ahola, S., Håkansson, P., Mankinen, O., Aslam, M. K., Filippov, A., … Telkki, V.-V. (2017). Structure and dynamics elucidation of ionic liquids using multidimensional Laplace NMR. Chem. Commun., 53(80), 11056–11059. https://doi.org/10.1039/c7cc05493a http://jultika.oulu.fi/Record/nbnfi-fe2017102750335 Javed, M. A., Komulainen, S., Daigle, H., Zhang, B., Vaara, J., Zhou, B., & Telkki, V.-V. (2019). Determination of pore structures and dynamics of fluids in hydrated cements and natural shales by various ¹H and ¹²⁹Xe NMR methods. Microporous and Mesoporous Materials, 281, 66–74. https://doi.org/10.1016/j.micromeso.2019.02.034 http://jultika.oulu.fi/Record/nbnfi-fe2019041712678 Komulainen, S., Roukala, J., Zhivonitko, V. V., Javed, M. A., Chen, L., Holden, D., … Telkki, V.-V. (2017). Inside information on xenon adsorption in porous organic cages by NMR. Chemical Science, 8(8), 5721–5727. https://doi.org/10.1039/C7SC01990D http://jultika.oulu.fi/Record/nbnfi-fe201709288804 Håkansson, P., Javed, M. A., Komulainen, S., Chen, L., Holden, D., Hasell, T., … Telkki, V.-V. (2019). NMR relaxation and modelling study of the dynamics of SF₆ and Xe in porous organic cages. Manuscript.

No description available.

This paper deals with the determination of the capillary pore-size distribution (CPSD) and equilibrium moisture content (EMC) of untreated and thermally modified (TM) Norway spruce [Picea abies (L.) Karst.] by means of the pressure plate technique (PPT). Desorption experiments were conducted at very high values of relative humidity (RH) in the range between 99.2% and 100%. The thermal modification of spruce results in an alteration of the CPSD, owing to the formation of intercellular cracks in the middle lamella, as a result of cell-wall compression. The desorption curves for both untreated and TM spruce show an extremely upward bend at 99.97% RH. This step reflects an EMC of 38.1% for untreated spruce and 33.8% for TM spruce. None of the samples shrunk during the PPT measurements. Following desorption experiments at 97.4% RH, all samples shrunk. This step reflects an EMC of 27.9% for untreated spruce and 21.7% for TM spruce.

Today there is growing interest within the construction sector to increase the proportion of biobased building materials made from renewable resources. By-products or residuals from wood processing could in this case be valuable resources for manufacturing new types of biocomposites. An important research question related to wood-based biocomposites is how to characterise molecular interactions between the different components in the composite. The hygroscopic character of wood and its water sorption properties are also crucial. Thermal modification (or heat treatment) of wood results in a number of enhanced properties such as reduced hygroscopicity and improved dimensional stability as well as increased resistance to microbiological decay. In this thesis, surface characteristics of thermally modified wood components (often called wood fibres or particles) and influencing effects from moisture sorption have been analysed using a number of material characterisation techniques. The aim is to increase the understanding in how to design efficient material combinations for the use of such wood components in biocomposites. The specific objective was to study surface energy characteristics of thermally modified spruce (Picea abies Karst.) under influences of water vapour sorption. An effort was also made to establish a link between surface energy and surface chemical composition. The surface energy of both thermally modified and unmodified wood components were studied at different surface coverages using inverse gas chromatography (IGC), providing information about the heterogeneity of the surface energy. The water vapour sorption behaviour of the wood components was studied using the dynamic vapour sorption (DVS) method, and their surface chemical composition was studied by means of X-ray photoelectron spectroscopy (XPS). Additionally, the morphology of the wood components was studied with scanning electron microscopy (SEM). The IGC analysis indicated a more heterogeneous surface energy character of the thermally modified wood compared with the unmodified wood. An increase of the dispersive surface energy due to exposure to an increased relative humidity (RH) from 0% to 75% RH at 30 ˚C was also indicated for the modified samples. The DVS analysis indicated an increase in equilibrium moisture content (EMC) in adsorption due to the exposure to 75% RH. Furthermore, the XPS results indicated a decrease of extractable and a relative increase of non-extractable compounds due to the exposure, valid for both the modified and the unmodified wood. The property changes due to the increased RH condition and also due to the thermal modification are suggested to be related to alterations in the amount of accessible hydroxyl groups in the wood surface. Recommendations for future work and implications of the results could be related to knowledge-based tailoring of new compatible and durable material combinations, for example when using thermally modified wood components in new types of biocomposites for outdoor applications. / <p>Forskningsfinansiärer och strategiska forskningsprojekt:</p><p>Nils och Dorthi Troëdssons forskningsfond (Projektnr 793/12 Hydro-termo-mekanisk modifiering av trä).</p><p> KTH Royal Institute of Technology.</p><p> COST Action FP0904.</p><p> KK-Stiftelsen.</p><p>Stiftelsen för strategiskt forskning (SSF). QC 20150908</p>