TY - JOUR A1 - Bücker, Michael A1 - Jäger, Christian A1 - Pfeifer, Dietmar A1 - Unger, Brita T1 - Evidence of Si-O-C bonds in cellulosic materials modified by sol-gel-derived silica N2 - The present study contributes to the controversial discussion in the literature whether Si–O–C bonds in wood–silica–gel composites exist. 13C NMR is a suitable method to proof such bonds. Because of the low concentration of 13C isotopes in natural wood, 13C cellulose was used as 13C-enriched substitute. A tailored sol for the impregnation of that cellulose was chosen by liquid 29Si NMR pre-investigations of various sols whose reactivity and stability were time-dependently analysed. It is based on a sub-stoichiometric hydrolysis of tetraethoxysilane (TEOS) with 1 mol water per mol TEOS. Thermal analyses were performed to show a comparability of the thermal behaviour of wood–silica–gel and cellulose–silica–gel composites. There are two strong hints of the existence of stable Si–O–C bonds: (1) by thermal analysis, a shift in the fire behaviour of 100 K can be observed with a change in pyrolysis behaviour of the composite and (2) the proof by REDOR NMR that a dipolar coupling between 1329Si and 13C nuclei exists. KW - Silica-cellulosic composites KW - Sol-gel derived silica KW - Si-O-C bonds KW - 13C NMR KW - 29Si NMR PY - 2014 UR - http://link.springer.com/article/10.1007/s00226-014-0657-9/fulltext.html DO - https://doi.org/10.1007/s00226-014-0657-9 SN - 0043-7719 SN - 1432-5225 VL - 48 IS - 5 SP - 1033 EP - 1047 PB - Springer CY - Berlin AN - OPUS4-31223 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hübert, Thomas A1 - Unger, Brita A1 - Bücker, Michael T1 - Sol-gel derived TiO2 wood composites N2 - The sol–gel process was applied to enhance properties of pine sapwood. For this purpose wood prisms were soaked in nanoscaled precursor solutions prepared from titanium(IV) n-butoxide and titanium(IV) iso-propoxide, respectively, using vacuum impregnation technique. The wet composites were cured by special program with final heat treatment at 103 °C. Weight percent gains (WPG) of the wood specimen in the range of 19-25% were obtained due to these procedures. SEM investigations show that precursor solutions penetrate into the whole wood body and the titania formed after heat treatment in the composites is deposited in the pores (lumen) and partly in the cell walls of the wooden matrix. The moisture sorption was investigated in long term tests for a period of some months by storage at 20-23 °C in humid air (relative humidity of 99%) and ambient atmosphere (relative humidity 40-60%), respectively. For untreated reference samples the moisture sorption results in increasing of mass and volume according to saturation values of 24 and 13%, respectively, after about 15 days. The incorporation of titania reduces the saturation values of the moisture sorption by up to 12% in mass and by up to 5% in volume at a relative humidity of 99%. Thus, an enhancement of the dimensional stability of about 60% is obtained at best. The results demonstrate that modification of wood with sol-gel derived precursors can enhance its dimensional stability, which prevents the formation of cracks. Because of that reduced moisture sorption biological attacks should be delimited. Additionally, thermal analyses show a retarded combustion of the wood matrix due to titania infiltration. KW - Titania KW - Sol-gel KW - Nanocomposites KW - Wood protection KW - Water sorption PY - 2010 DO - https://doi.org/10.1007/s10971-009-2107-y SN - 0928-0707 SN - 1573-4846 VL - 53 IS - 2 SP - 384 EP - 389 PB - Kluwer Academic Publ. CY - Dordrecht AN - OPUS4-20892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Brita T1 - Imprägnierung von Holz mit SiO2- und/oder SiO2-Solen: Fixierung der anorganischen Komponente im Holz T2 - XXXI. Tagung des Arbeitskreises "Nichtkristalline und partiellkristalline Strukturen" der DGK CY - Wolfersdorf (Berga), Germany DA - 2010-10-11 PY - 2010 AN - OPUS4-22327 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raedel, Martina A1 - Bücker, Michael A1 - Unger, Brita T1 - Historische und moderne Goldmosaike im Vergleich KW - Historische und moderne Goldmosaike KW - Aufbau KW - Besonderheiten KW - Herstellungstechnik KW - Glaszusammensetzung KW - EDX-Analyse KW - Viskositäts-Temperatur-Verhalten KW - Ausdehnungskoeffizient PY - 2010 SN - 0947-6229 IS - 3 SP - 184 EP - 185 PB - Dt. Bergbau-Museum CY - Bochum AN - OPUS4-22707 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bücker, Michael A1 - Böcker, Wolfgang D. G. A1 - Reinsch, Stefan A1 - Unger, Brita T1 - Holzmodifikation durch Tränkung mit Nanopartikeln T2 - Tagung "Rosenheimer Fenstertage 2004" CY - Rosenheim, Deutschland DA - 2004-01-01 KW - Holzmodifikation KW - Sol-Gel KW - Tränkverfahren KW - Holzschutz PY - 2004 SP - 23 EP - 26 PB - Institut für Fenstertechnik CY - Rosenheim AN - OPUS4-4487 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bücker, Michael A1 - Böcker, Wolfgang D. G. A1 - Reinsch, Stefan A1 - Unger, Brita T1 - Alternativer Holzschutz KW - Holzschutz KW - Kieselsol KW - Biozide KW - Sol-Gel-Prozess PY - 2004 SN - 1435-1854 IS - 11 SP - 77 EP - 80 PB - Verl. f. Fachpublizistik CY - Stuttgart AN - OPUS4-6333 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bücker, Michael A1 - Böcker, Wolfgang D. G. A1 - Reinsch, Stefan A1 - Unger, Brita ED - Acker, J. V. T1 - Wood Modification by Sol-Gel Derived Precursors T2 - 1st European Conference on Wood Modification ; 1st ECWM 2003 CY - Ghent, Belgium DA - 2003-04-03 KW - Silica-sol treatment KW - Wood-inorganic composite KW - Water repellency KW - Environmental stability PY - 2003 SN - 90-806565-2-6 SN - 1018-5593 SP - 255 EP - 259 PB - Univ., Laboratory of Wood Technology CY - Ghent AN - OPUS4-2521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Brita T1 - Sol-gel-Chemie und Werkstoffverbunde T2 - Abteilungsseminar, Abteilung VI, BAM CY - Berlin, Germany DA - 2003-09-04 PY - 2003 AN - OPUS4-5413 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Böcker, Wolfgang D. G. A1 - Bücker, Michael A1 - Reinsch, Stefan A1 - Unger, Brita T1 - Abschlussbericht zum Vorhaben Verbundwerkstoff - Mineralisiertes Holz - FKZ: 033 9829 - Förderschwerpunkt "Integrierter Umweltschutz im Bereich der Holzwirtschaft" des Bundesministeriums für Bildung, Wissenschaft, Forschung und Technologie, BMBF - Projektlaufzeit: 1.10.2000-30.9.2003 KW - Mineralisiertes Holz KW - Sol-Gel KW - Holz KW - Vakuumtränkung KW - Holzschutz KW - Biozide PY - 2004 SP - 1 EP - 94 CY - Berlin AN - OPUS4-12055 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Brita A1 - Jancke, Harald A1 - Müller, Renate A1 - Peplinski, Burkhard A1 - Hähnert, Manfred ED - Rüssel, C. T1 - Sol-gel derived precursors for cordierite glass-ceramics T2 - 5th International Otto Schott Colloquium ; 5. Internationales Otto-Schott-Kolloquium CY - Jena, Germany DA - 1994-07-10 PY - 1994 SN - 0946-7475 N1 - Serientitel: Glass science and technology – Series title: Glass science and technology IS - 67 SP - 448 EP - 451 PB - Verl. Dt. Glastechn. Ges. CY - Frankfurt/Main AN - OPUS4-12598 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Brita T1 - Sintering and crystallization of amorphous cordierite powders prepared by sol-gel technique T2 - 11th Conference on Glass and Ceramics CY - Varna, Bulgaria DA - 1993-10-21 PY - 1993 AN - OPUS4-12616 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Brita T1 - Sol-Gel derived precursors for cordierite glass-ceramics T2 - 5th International Otto-Schott-Colloquium CY - Jena, Germany DA - 1994-07-11 PY - 1994 AN - OPUS4-12620 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bücker, Michael A1 - Unger, Brita T1 - Holzmodifikation durch Tränkung mit Nanopartikeln T2 - Ausstellung: "Versteinertes Arboretum - Versteinertes Holz", Naturkundemuseum CY - Gera, Germany DA - 2007-04-25 PY - 2007 AN - OPUS4-14841 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Brita A1 - Bücker, Michael A1 - Reinsch, Stefan A1 - Hübert, Thomas T1 - Chemical aspects of wood modification by sol-gel-derived silica N2 - It has been shown that tetraethoxysilane-derived precursors are suitable solutions for impregnating pine sapwood to improve its dimensional stability. Tailored sol–gel syntheses result in precursors with nano-scaled silica species which are able to penetrate into the cell walls of wood. The physical fixation of those species inside the cell walls was verified by ESEM/EDX investigations. There is evidence that the silica species are chemically bonded to wood components. Nonreacted alkoxy groups can exist in the wood composites after impregnation. The amount of these organic residues depends on the composition of the precursors, especially their condensation degree and reactivity. Treatments for finishing the composites after the impregnation step to get clean products and stable properties are discussed in this context. An explanation of the complex relationship between solids content in the impregnation solutions and percentage weight gain and bulking of the composites is given. It can be demonstrated that high WPG values (>20 %) are pre-conditions for an effective protection of the resulting composites but they only guarantee efficient improvements if connected with the incorporation of the inorganic component inside the cell walls. Therefore, the sol–gel syntheses have to be carried out in such a manner that very small (<2 nm) as well as reactive species are sufficiently available. This demands syntheses using sub-stoichiometric water contents (H2O/TEOS <4, better <2). KW - Silica-wood composites KW - Sol-gel derived precursors KW - Curing KW - Fixation of silica KW - Dimensional stability PY - 2013 DO - https://doi.org/10.1007/s00226-012-0486-7 SN - 0043-7719 SN - 1432-5225 VL - 47 IS - 1 SP - 83 EP - 104 PB - Springer CY - Berlin AN - OPUS4-26258 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Böcker, Wolfgang D. G. A1 - Bücker, Michael A1 - Reinsch, Stefan A1 - Unger, Brita A1 - Britz, Roswitha T1 - Mineralisiertes Holz - Verbundwerkstoff mit verbesserten Eigenschaften PY - 2001 CY - München AN - OPUS4-1197 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Bücker, Michael A1 - Böcker, Wolfgang D. G. A1 - Reinsch, Stefan A1 - Unger, Brita ED - Wielage, B. ED - Leonhardt, G. T1 - Entwicklung umweltverträglicher Holzverbundwerkstoffe mit verbesserter biologischer und Feuchtebeständigkeit T2 - Tagung "Verbundwerkstoffe und Werkstoffverbunde" CY - Chemnitz, Deutschland DA - 2001-09-05 PY - 2001 SN - 3-527-30319-7 SP - 463 EP - 467 PB - Wiley-VCH CY - Weinheim AN - OPUS4-1160 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Reinsch, Stefan A1 - Böcker, Wolfgang D. G. A1 - Bücker, Michael A1 - Seeger, Stefan A1 - Unger, Brita ED - Specht, K. T1 - Development of wood-inorganic composites with enhanced properties and environmental stability T2 - 4th International Wood and Natural Fibre Composites Symposium CY - Kassel, Germany DA - 2002-04-10 PY - 2002 VL - 4 SP - 50-1-50-6 CY - Kassel AN - OPUS4-1365 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Böcker, Wolfgang D. G. A1 - Bücker, Michael A1 - Reinsch, Stefan A1 - Unger, Brita T1 - Holzverbundwerkstoffe mit verbesserten Eigenschaften N2 - Die offenporige Struktur des Holzes und dessen chemische Zusammensetzung bieten sich an, über Tränkverfahren geeignete Precursoren so an den inneren Oberflächen des Holzes zu fixieren, dass bei anschließender thermischer Behandlung ein umweltfreundlicher anorganisch-organischer Verbundwerkstoff entsteht. Aus der Literatur sind hierzu verschiedene Ansätze bekannt. - Ziel der vorliegenden Arbeit sind Verbesserungen der biologischen Beständigkeit, der Feuchtebeständigkeit unter Beibehaltung bzw. leichter Verbesserung der mechanischen Eigenschaften des Holzes. Dies wird durch eine chemische Verbindung (Haftung) zwischen den verbundbildenden Phasen Holz und Precursor und eventuell zusätzlichen Einbau von funktionellen organischen Gruppen realisiert. Als Precursoren dienen über den Sol-Gel Weg hergestellte Kieselsole, die nach vollständiger thermischer Umsetzung zu rein anorganischen Phasen (SiO2) führen. Die Sol-Gel Synthese konnte so optimiert werden, dass durch die Behandlung eine homogene Beschichtung aller Oberflächen erreicht werden kann. T2 - Integrierter Umweltschutz im Bereich der Holzwirtschaft CY - Göttingen, Deutschland DA - 2002-01-22 PY - 2002 SP - 100 EP - 102 PB - DGfH CY - München AN - OPUS4-1366 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Mosel, Günter A1 - Unger, Brita A1 - Hähnert, Manfred T1 - Zn-K EXAFS investigations of sol-gel derived ZnO-SiO2 powders KW - Zink KW - Erde PY - 1995 SP - 603 EP - 604 PB - Hamburger Synchrotonstrahlungslabor CY - Hamburg AN - OPUS4-599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Brita T1 - Beiträge zur Strukturaufklärung bei der Alterung von Kieselsolen und -gelen - Ein Methodenvergleich T2 - XXIV. Arbeitskreistagung des AK4 der Deutschen Gesellschaft für Kristallographie "Relaxations- und Alterungsprozesse auf verschiedenen Zeitskalen in nichtkristallinen Materialien" CY - Wolfersdorf, Germany DA - 2003-09-08 PY - 2003 AN - OPUS4-3759 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -