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1	Stanovení kinetiky polymerace propenu na Zieglerových-Nattových katalyzátorech metodami násadové polymerace a Stopped-Flow za průmyslových podmínek / Determination of propene polymerization kinetics on Ziegler-Natta catalysts by methods of batch and Stopped-Flow polymerization performed under industrial conditions Tvrdý, Michal January 2019 (has links) This thesis is focused on the determination of the propene polymerization kinetics on phthalate and nonphthalate diester Ziegler-Natta MgCl2-supported catalysts under the industrial conditions. The kinetic profiles were determined by various laboratory techniques for propene polymerization. For assessing the profiles were utilized batch gas and liquid polymerization modes in 2-litre and 4-litre reactors. Finally, the results were complemented with the runs performed in a unique Stopped-Flow apparatus, which allows polymerization of liquid propene at very short polymerization times. The kinetics profiles of both catalysts were determined and compared by combination of experimental data of these techniques. The basic properties of the synthesized polymeric powders were measured, such as the melt flow index, bulk density and amount of polypropene fraction soluble in cold xylene.
2	Influence of Humidity Over the Properties of Wood Fiber-based Biocomposites / Fuktighetens Inverkan på Egenskaperna hos Träfiberbaserade Biokompositer Hedin, Arvid, Kudinova, Anna, Masso, Linnea January 2022 (has links) The project aims to develop a methodology to study the variation in properties of wood polymer composites (WPC’s) with/without surface treatment at different humidity conditions. The project aims to investigate the behavior of biocomposites at 50%, 80%and 100% relative humidity (RH). Also to clarify if the hydrophilization effect helps to preserve the structural integrity of the materials for longer periods at these conditions. The comparison between biocomposites comprising polypropylene (PP) with both untreated wood fibers (WF) or FibraQ (hydrophobic surface-treated wood fibers from Biofiber Tech) was made. The focus was on the mechanical properties, water absorption, macro- and microstructures. The results show that PP comprising FibraQ exhibits lower moisture uptake than the PP comprising untreated WF at high relative humidity conditions. The mechanical properties did not seem significantly affected by the surface treatment at high relative humidity conditions. It is also concluded that since the study only ran for four weeks, there was not enough time to fully understand the influence of moisture uptake over the materials’ properties. Wood Polymer Composite WPC Relative Humidity RH Tensile Testing Polypropene FibraQ Wood Fiber Surface Treatment Mechanical Properties Materials Chemistry Materialkemi Polymer Technologies Polymerteknologi Composite Science and Engineering Kompositmaterial och -teknik Bearbetnings-, yt- och fogningsteknik

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Influence of Humidity Over the Properties of Wood Fiber-based Biocomposites / Fuktighetens Inverkan på Egenskaperna hos Träfiberbaserade Biokompositer