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Untersuchungen zum Effekt von Dichte auf mechanische und hygrische Eigenschaften von Spanplatten und Massivholz am Beispiel von Paulownia

dc.contributor.advisorMai, Carsten Prof. Dr.
dc.contributor.authorNelis, Philipp Alexander
dc.titleUntersuchungen zum Effekt von Dichte auf mechanische und hygrische Eigenschaften von Spanplatten und Massivholz am Beispiel von Paulowniade
dc.title.translatedStudies about the effect of density on mechanical and hygrical properties of particleboards and solid wood using the example of Paulowniade
dc.contributor.refereeMai, Carsten Prof. Dr.
dc.description.abstractengThe scope of this study was to investigate the effect of density on mechanical and hygrical properties of particleboards varying particle mixtures and utilizing raw materials of different densities in surface and core layers. The objective was to gain application- and fundamentals-oriented knowledge. Furthermore, a characterization of kiri wood (Paulownia elongata x fortunei) was conducted, including physical and mechanical properties, as well as mycological examinations to determine its durability classes. Against the background of material shortage of wood assortments for the wood-based panel industry and the current competitive situation of energetic and material use of wood, an evaluation of the fast-growing, low-density species Paulownia as potential raw material for the wood and wood-based panel industry was carried out to uncover its potentials. Paulownia has been recognized as an excellent species for short-term cultivations on agricultural areas throughout Europe to produce quality timber. It was shown that the low-density kiri wood can be used to produce particleboards of different panel densities. In particular light particleboards with densities of 500 kg/m3 showed excellent mechanical and hygrical properties. Despite a low panel density, a high compaction ratio is achieved. This improves the efficiency of the glue utilization. The assumption that a higher compaction ratio leads to higher thickness swelling was rejected. The release of high stresses initiated through the compaction process during pressing was counteracted with high internal bonding between the particles. Bending strength and internal bond strength could be significantly improved through admixing of kiri particles (KP) to commonly used industrial mixtures. The use of small amounts of KP had the greatest relative effect on bending and internal bond strength. Properties could be significantly improved through usage of KP in surface or core layers. Furthermore, it was discovered that as much as 50 % of resin could be saved without reduction of bending strength and about 30 % without reducing internal bond strength when using KP instead of Norway spruce particles. Two effects, the density effect (effect of the raw material density) and the compaction effect (effect of a more efficient glue utilization due to a higher compaction ratio) could be identified when using low- and high-density wood species in surface or core layers, respectively. With changing the panel density, a shift of the occurring effects was observed. Interpreting the results of strength properties of particleboards produced by raw material of different densities in surface and core layers, these two effects must always be considered in order to avoid misunderstandings. Within the characterization of kiri wood, generally low mechanical strength values were obtained. A statement saying that kiri shows a particularly good strength-to-weight ratio could not be verified by these results. Light blockboards with kiri wood as core layer material could be produced without problems and showed a more evenly distributed density than those with spruce wood as middle layer. Mycological examinations revealed that kiri wood is not durable against white-rot (Trametes versicolor) and soft-rot, but very durable against brown-rot (Coniophora puteana). The latter should be verified again due to conspicuous differences within the
dc.contributor.coRefereeZhang, Kai Prof. Dr.
dc.contributor.thirdRefereeKharazipour, Alireza Prof. Dr.
dc.subject.engMechanical propertiesde
dc.subject.engHygrical propertiesde
dc.subject.engSolid woodde
dc.affiliation.instituteFakultät für Forstwissenschaften und Waldökologiede
dc.subject.gokfullForstwirtschaft (PPN621305413)de

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