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91	Dřevostavby s použitím přírodních tepelných a zvukových izolací / Wooden buildings using natural thermal and acoustic insulation Ambrožová, Elena January 2016 (has links) Dissertation deals with the technical parameters of natural thermal insulation. In addition, there is a global trend in the construction of reducing energy consumption for heating, air conditioning, or with operating facilities in buildings and the use of perspective and efficient building materials with a negligible negative impact on the environment. Therefore, the attention not only professionals are increasingly turning to alternative materials, such as natural insulation, the material can be drawn from local sources and whose production is energy-saving and leaving a small ecological footprint. As part of the doctoral thesis were tested short term water absorption, measurements were made of the thermal conductivity and its change after the test short term water absorption. Was determined dependence of thermal conductivity on humidity and heat resistance was determined. Moreover a natural insulation applications in building construction with a comparison of the various technical parameters and environmental footprint. At the conclusion was made by acoustic insulation in timber construction and price analysis.
92	Wheat Straw-Clay-Polypropylene Hybrid Composites Sardashti, Amirpouyan 23 September 2009 (has links) The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix. Biocomposite Biodegradable Natural Fiber Natural Filler Wheat Straw Polypropylene Clay Coupling Agent Automotive Construction Extrusion Injection Molding Particle Size Solvent Extraction Particle Density Scanning Electron Microscopy Thermo Gravimetric Analysis Differential Scanning Calorimetry Flexural Strength Flexural Modulus Water Absorption Melt Flow Index X-Ray Diffraction Chemical Engineering
93	Wheat Straw-Clay-Polypropylene Hybrid Composites Sardashti, Amirpouyan 23 September 2009 (has links) The preparation of polymeric hybrid composite consisting of organic and inorganic fillers is of interest for industries like automotive, construction and packaging. In order to understand and predict the physical and chemical properties of these hybrid composites, it is necessary to fully understand the nature and properties of the employed fillers. In this study, the preparation of polypropylene hybrid composite consisting of wheat straw and clay was investigated. A detailed study was performed on wheat straw from South Western Ontario region. The effect of grinding the straw and compounding it with polypropylene was investigated. Experiments were carried out to identify the thermal stability of the ground wheat straw with respect to their size and composition. It was important to identify a correlation between these properties in order to minimize the straw degradation by processing and also to improve the final properties of the hybrid composite. The composite samples were prepared through melt blending method using a co-rotating twin-screw extruder. Sample test bars were prepared by injection moulding. The composition of the constituents of the hybrid composite; percentages of wheat straw, clay and coupling agent, were varied in order to investigate their influence on thermal stability, water resistance and mechanical properties. The results of the study indicated that grinding the wheat straw with a hammer mill produced particles with different sizes and shapes. It was found that through the grinding system all particles, regardless of their size, had a multi-layered structure similar to the plant structure. Further hammer milling did not produce plant particles with long aspect ratios that would be expected in a defibrillation process. Analysis of the chemical composition of wheat straw particles of different sizes and shapes was used to measure the ratio of hemicelluloses: lignin and the ash content. It was found that the large particles contained more amount of lignin whereas smaller particles had larger amount of ash content. The thermal stability of the particles was found to be a function of particle size rather than the lignin content. Particle size analysis on the wheat straw particles after the extrusion process indicated a reduction in the particle length and aspect ratio. The thermal stability of the composites was found to be enhanced by the addition of clay particles at higher temperature and the addition of coupling agent at lower temperatures. Increasing the amount of wheat straw and clay content increased the flexural modulus and reduced the resistance for water absorption. Increasing the amount of coupling agent also increased the flexural modulus and resistance for water absorption. The morphological study by scanning electron microscopy revealed that coupling agent increased the interfacial interaction between the particles and the polymer matrix. Biocomposite Biodegradable Natural Fiber Natural Filler Wheat Straw Polypropylene Clay Coupling Agent Automotive Construction Extrusion Injection Molding Particle Size Solvent Extraction Particle Density Scanning Electron Microscopy Thermo Gravimetric Analysis Differential Scanning Calorimetry Flexural Strength Flexural Modulus Water Absorption Melt Flow Index X-Ray Diffraction Chemical Engineering
94	Recyklované kamenivo do pozemních komunikací / Recycled aggregate to pavement constructions of roads Antošová, Klára January 2015 (has links) The diploma thesis deals with using of recycled aggregate of concrete for base layers of pavement. The work is divided into practical and theoretical part. The theoretical part deals with basic concepts of construction and demolition waste, production, development and management of this waste in the Czech Republic. It also focuses on the principle of recycling and the use of recycled concrete in the Czech Republic and abroad. The practical part of the thesis deals with laboratory testing and assessment of recycled aggregates in bound, unbound and grouted courses layers of the base layers of roads.
95	Recyklované kamenivo do asfaltových směsí pozemních komunikací / Recycled aggregates to asphalt mixtures of the flexible pavements Kropáč, Pavel January 2013 (has links) This thesis deals with the theoretical part of the creation, distribution and recycling of construction and demolition waste. Subsequently covers made from these recycled construction and demolition waste and its potential application in structural layers of the pavement. In the practical part of the thesis deals with monitoring the overall properties of nine asphalt mixtures with different proportion of recycled concrete aggregate and asphalt binder, which are designed and intended for bed asphalt pavement. The recycled concrete aggregate and asphalt are performed various laboratory tests, the results are subjected to a comparison with the relevant standards and TP 210. The conclusion is made price comparisons of asphalt mixtures.
96	Einfluss der Material- und Verarbeitungseigenschaften von Phenolharzformmassen auf die Qualität spritzgegossener Bauteile Höer, Martin 23 October 2014 (has links) Spritzgießbare Duroplaste zeichnen sich durch hohe thermo-mechanische Beständigkeit, geringe Schwindung und niedrige Materialkosten aus. Damit können die Anforderungen an spritzgegossene Präzisionsbauteile für den Automobilbau erreicht werden. Im Rahmen der vorliegenden Arbeit werden unterschiedliche Novolak-Phenolformmassen hinsichtlich ihres hygroskopischen Verhaltens und dessen Auswirkung auf die Spritzgießverarbeitung und die Bauteilqualität untersucht. Das Absorptionsverhalten kann mithilfe der Fick’schen Diffusionsgesetzte näherungsweise beschrieben werden. Auf Basis von mechanischen Untersuchungen sowie der Beurteilung der Maßhaltigkeit eines Präzisionsdemonstrators hinsichtlich Schwindung und Verzug wird zudem der Einfluss der Prozessparameter beim Spritzgießen bestimmt. Die vorgestellten Untersuchungen zeigen die Grenzen der Verarbeitung und der realisierbaren Bauteilqualität auf, die auf die großserientaugliche Verarbeitung von duroplastischen Bauteilen übertragen werden können. / Injection moldable thermosetting materials show excellent material properties, e.g. high thermo-mechanical resistance and reduced shrinkage in combination with low material cost. Thus, technical requirements for high performance parts for automotive applications can be achieved. In the scope of this work different phenolic novolac compounds were investigated regarding their hygroscopic behavior with its influence for injection molding and product quality. The absorption can be approximately described by Fick’s-Diffusion-Model. The interrelationship of injection molding parameters and the thermo-mechanical behavior is examined on the basis of mechanical testing and the assessment of the dimensional accuracy for a thermoset high precision part. The presented investigations point to the limit of processing and realizable part quality which can be transferred for high performance parts molded in mass production. info:eu-repo/classification/ddc/600 ddc:600 info:eu-repo/classification/ddc/620 ddc:620
97	Ausgewählte Eigenschaften des Sporopollenins der Kiefer Bohne, Guido 27 February 2007 (has links) Gegenstand der Arbeit sind Zusammenhänge zwischen physikochemischen Eigenschaften und Funktionen der Exine bei Ausbreitung, Bestäubung und Befruchtung. Dabei bewährte sich der Einsatz der 3-kammrigen Sporopolleninkapseln (Zentralkapsel und Sacci) in der Permeationschromatographie. Sowohl kinetisch bedingte chromatographische Dispersion kleiner Moleküle als auch Konzentrationsänderungen von Zuckern und Dextranmolekülen im Medium wurden zur Bestimmung von Permeabilitätskoeffizienten der Nexine genutzt. Die Wasserabsorptionskapazität von Exinefragmenten und die hydraulische Leitfähigkeit der Nexine wurden anhand von Konzentrationsänderungen ausgeschlossener Dextranmoleküle ermittelt. Das Tectum der saccalen Sexine ist eine Mikrofiltermembran mit scharfer Trenngrenze im Submikrometerbereich; daher werden an den Sacci nur Hydrokolloide mit Stokes''schen Radius über 100 nm (z.B. aus nativem Dextran) ausgeschlossen. Die Nexine ist eine nicht-ideale Umkehrosmose-Membran, die in Zucker- und Salzlösungen hohe Reflexionskoeffizienten zeigt; zusätzlich besitzt sie wenige große Poren, die den Austausch von Zuckern und selbst kleinen Polymermolekülen ermöglichen. Die hydraulische Leitfähigkeit der Nexine liegt im Größenbereich derjenigen von Plasmamembranen (0,39-0,48 µm s-1 MPa-1); die Ergebnisse zeigen, dass die Exine weder die Nährstoffaufnahme des Sporoplasten aus der lokulären Flüssigkeit noch dessen rasche Rehydratation in der Mikropyle behindert. Die Einfaltungen der distalen Nexine (oberhalb der Sacci) und die Omega-Faltung der Exine zwischen den Sacci (Leptom) bieten beim Quellvorgang Schutz vor zu schneller Flächenausdehnung der Plasmamembran. Der Corpus kann mit konzentrierten Elektrolytlösungen beladen werden. Beim anschließenden osmotischen Schwellen in Wasser reißt die Exine, und der Sporoplast wird mit anhaftender Intine ausgeschleudert. Wasser und andere polare Flüssigkeiten adhärieren stärker als hydrophobe Flüssigkeiten an Sporopollenin. Die Sporopolleninmatrix weist eine hohe Feststoffdichte auf, ist wenig quellfähig (0,18 mL g-1 TM) und deformationsstabil. Dies ermöglicht die Pulverbildung beim Trocknen. / Subject of this thesis are relationships between physicochemical properties and functions of the exine concerning propagation, pollination and fecundation. Here the application of the 3-chambered sporopollenin-microcapsules (central capsule and sacci) in permeation chromatography proved of value. Both the kinetically dependent dispersion of small molecules and changes in concentration of sugars and dextran molecules in the medium were analysed to determine permeability coefficients of the nexine. The water absorption capacity of exine fragments and the hydraulic conductance of the nexine were calculated by means of changes in concentrations of excluded dextran molecules. The tectum of the saccal sexine is a microfiltration membrane with a sharp cut off in the submicrometer range; thus hydrocolloids with Stokes´radii over 100 nm (e.g. from native dextran) are excluded from the sacci. The nexine is a non-ideal reverse osmosis membrane having high reflexion coefficients in sugar and salt solutions; in addition few large pores allow the exchange of sugars and even of small polymers. The hydraulic conductance of the nexine is in the range typically for plasmamembranes (0.39-0.48 µm s-1 MPa-1); the results indicate that the exine does neither obstruct the uptake of nutrients by the sporoplast from the locular fluid nor hinder the rapid rehydration in the micropyle. When rehydrating, the distal foldings of the nexine (above the sacci) and the omega-like folding of the exine between the sacci (leptom), provide protection for the plasmamembrane when its surface area has to increase too rapidly. The corpus can be loaded with a concentrated electrolyte solution. When subsequently transferred into water the exine rupture and the sporoplast along with the intact intine is ejected. Water and other polar liquids adhere stronger to sporopollenin than hydrophobic ones. The matrix of sporopollenin show a high density in its solid content, water absorption capacity is low (0.18 mL g-1 DM) and it is resistant to deformation. This enable the formation of powder while dehydrating. Diffusion Plasmamembran Benetzbarkeit Calcium Chromatographie Deplasmolyse Dextran Evans Blau Exine Exocytose Größenausschluss HETP hydraulische Leitfähigkeit hypo-osmotischer Schock Intine Kiefer Leptom Nexine osmotischer Schock Parenchymzellen Permeabilität Pinus sylvestris L. Pinus nigra Arnold Plasmoptyse Pollen Poren Reflexionskoeffizient Sexine Sporopollenin Ultrafilterkoeffizient Wasserabsorption Wasseraufnahme Zucker diffusion plasma membrane exocytosis Calcium chromatography de-plasmolysis dextran Evans Blue exine HETP hydraulic conductivity hypo-osmotic shock intine leptom nexine osmotic shock parenchyma cells permeability pine Pinus nigra Arnold Pinus sylvestris L. plasmoptysis pollen pores reflection coefficient sexine size exclusion sporopollenin sugars ultrafilter coefficient water absorption water uptake wettability 570 Biowissenschaften, Biologie 32 Biologie WL 7950 WN 7400 ddc:570

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