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The analysis of acoustic properties of innovative wood-based materials
Svojanovský, Jan ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
The content of this work is research of innovative wood-based materials in the acous-tic perspective. Basically, the goal is to determine the influence of the internal structure of the wood-based material on variables, which are sound speed, acoustic resistance, or acous-tic constant. In total were measured 15 samples, each one was made in a different way. Each sam-ple was weighted, and the length of its sides was measured. By using the ultra sonic timer, it was measured the time of the sound impulses, which go through the samples in all of their axes for the purpose of observation the influence the fibers on speed of sound in the materi-al. The next thing to do was to determine another magnitude, which describe acoustic of the material. All measurements were taken in room conditions (room humidity). Six of the sam-ples, which were randomly selected from those 15 samples, were measured once again after two weeks. In those two weeks were all the samples saved in air-conditioned place in which was the room humidity distinct lower. In the end all the samples were compared with each other and they were also com-pared with materials which are commonly used in production of musical instruments or acoustic components. Possible use in the music industry was assigned to each sample.
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Production Concept of Vacuum Mold for Plastic Forming
Tišnovský, Jakub ; Kalivoda, Milan (referee) ; Sedlák, Josef (advisor)
Vacuum plastic forming is method of termoplastic material treatment. This method uses physical and mechanical changes caused in materiál during his heating. Production of final product requires mould. The main advantage of this technology is fact, that manufacturing of mould is not so hard as manufacturing of mould for injection moulding, so mould is signficantly cheaper. Main purpose of this thesis is to propose production concept of this mould. Proposal was solved by SolidWorks and PowerMill software and manufacturing was realized on 3-axis CNC milling machine. Main result of this thesis is a summary of instructions which can be used in proposes of different moulds for vacuum plastic forming.
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MDF composites AC-PVAl with increased moisture resistance
Repka, Martin ; Brandštetr, Jiří (referee) ; Šoukal, František (advisor)
Polymerem impregnované cementové materiály představují zajímavou a perspektivní alternativu klasických portlandských cementových past. Hlavním zástupcem těchto materiálů jsou macrodefect-free (MDF) kompozity, složené z anorganického pojiva a organického polymeru. I přes řadu vynikajících mechanických vlastností je plné zavedení MDF kompozitů na trh omezené především z důvodu jejich relativně nízké odolnosti vůči vlhkosti. Jednou z možností jak zvýšit odolnost výsledného MDF vůči vlhkosti je „in situ“ síťování polymeru. V této práci byla připravena počáteční série MDF kompozitů na bázi hlinitanového cementu a polyvinylalkoholu se třemi typy organo-titanátových síťovacích činidel (Tyzory). Efekt modifikace MDF kompozitů byl hodnocen na základě zkoušek pevnosti v tahu za ohybu po uložení materiálů v různých vlhkostních podmínkách.
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Development of methodology for study of mechanical activation of chemical reactions at phase boundaries
Matoušek, David ; Kalina, Lukáš (referee) ; Šoukal, František (advisor)
This Bachelor thesis deals with impact of mechanochemical activation on a nature of interphase region in macro-defect-free composites (MDF). MDF composites are highly perspective material on a polymer-cement basis. The most significant advantage of this material is high flexural strength (cca 150 MPa). High strength is caused by high-shear mixing of mixture of cement, polymer, water and plasticiser in twin-roll mill. High-shear stress leads to mechanical activation of reactions between cement and polymer and creation of weak or even strong interactions in interphase region. This work aimed on creation of interphase region by contact of surfaces of two moulded tablets – polyvinyl alcohol and monocalcium aluminate. Next step was construction of simple apparatus, able to define the rate of mechanical activation in interphase region. The most important part of this work concentrated on analysis of activated interphase region by XPS.
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Polymer-cement composites of increased refractoriness
Žůrová, Marcela ; Mončeková, Miroslava (referee) ; Šoukal, František (advisor)
The subject of the barchelor thesis is the preparation of high-strength polymer – cement composites based on the calcium aluminate cement and polyvinylalcohol. For macrodefect–free (MDF) composites are characterized by low porosity and the absence of microcracks. The main problem of the MDF composites is decreased resistance to water or moisture, with a decrease in strength. These compounds are interesting with its mechanical properties, which are greater than the strength of common materials (wood, glass, PMMA,…). Represent perspective type of material that could be used for construction purposes. The thermal degradation of the polymer, however, there are changes in the structure of the composite and to the deterioration of mechanical properties. This thesis is focused on characterization of the effect of temperature change on the structure, material composition and mechanical properties. The MDF composites were prepared based on calcium aluminate cement, which was gradually replaced by refractory additives. During the work was carried out tests of bending strength at various temperatures. Changes in the composition and structure were characterized by TG – DTA, XRD and SEM analysis.
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Mechanical activation of chemical reactions at interfaces of MDF composites
Matoušek, David ; Másilko, Jiří (referee) ; Šoukal, František (advisor)
The thesis deals with study of mechnochemical activation of chemical reactions at interphase of MDF composites. MDF composites are high-perspective composite materials on polymer-cement base. They excel especially in terms of flexural strengths. High flexural stregth is caused by binding interactions between the polymer and the cement. This interactions arise due to mechanochemical activation of raw material mixture at the stage of production. This work focuses on the creation of artificial cement-polymer interphase by contacting the surfaces of two molded tablets (polyvinyl alcohol and monocalcium aluminate), activation of chemical reactions at interphase by means of specially designed appartus, which achieves good plane-parallelism of activation surfaces and good definability of activation conditions (shear rate, pressure). After experiments under different conditions, the activated surfaces are analyzed by SEM, EDS, XPS and FT-IR.
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Sketchup Woodworking Plugin
Matěj, Aleš ; Bidlo, Michal (referee) ; Vašíček, Zdeněk (advisor)
Main goals of this work are to understand the SketchUp application, learn the basic tasks of fiberboard furniture design and the design and implementation of tools, which should increase efficacy of these tasks. Tools are created as plug-ins for SketchUp using its Ruby API. The text it self is focused on fundamentals of 3D computer graphics and use of them in SkechtUp, fiberboard furniture design processes and the woodworking plug-in it self. Described tools are used for creation of board models, their management through user interface and generation of edging for boards.
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Polymer-cement composites for refractory aplications
Zbončák, Marek ; Ptáček, Petr (referee) ; Šoukal, František (advisor)
This bachelor thesis deals with preparation of high-strength polymer-cement composites based on the calcium aluminate cement and polyvinylalcohol. MDF composites are interesting because of their mechanical properties which exceed strengths of the common materials based on the cement and inorganic binders. So they represent perspective kind of material which could be used for construction purposes. Thermal degradation of the polymer leads to structure changes of the composite and reduction of mechanical properties. Therefore thesis is aimed to characterize the influence of the temperature on mechanical properties, structural changes and material composition. Temperature dependence of flexural strength was examined during the work. Changes of composition and structure were characterized by XRD, DTA-TGA in combination with EGA, SEM and EDS analyses. Due to requirement of the material refractoriness there were also tested options of preparation of MDF composites based on phosphates binders which are used in refractory manufacture.
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