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Hybrid Blends of Recycled Plastics
Černý, Miroslav ; Lehocký, Marián (referee) ; Balgová,, Vendula (referee) ; Jančář, Josef (advisor)
Work describes the relationship between structure and mechanical properties in case of hybrid mixtures. They are composed from polyurethane matrices (eventually polyurethane-urea or polyurethane-inorganic filler mixtures), different rubber fractions as filler and eventually reinforcement made from PET monofilaments. Mechanical behaviour was studied by tensile testing. Studied mechanical properties include tensile modulus, ultimate strength and strain and also specific energy need neccessary for ultimate strength achievement. Prepared materials are naturally porous. Therefore their mechanical behaviour has to be described generally for porous composites. The porosity occurence means, that it is difficult to describe them by models valid for mechanical behaviour (mainly elastic modulus) of nonporous composites. Models are also based on idealized structures on microscopic level. In case of porous composites, it is very difficult to create any idealized structure. The structure is changed with modifications of composition (change of components or their rates). These conditions have lead to utilizing of different approach how to describe the relationship between structure and mentioned mechanical properties. The chosen approach comes from knewledge about structural parametres coming from porosity. Structural parameters describe the structure on macroscopic level. They include interspace volume (volume lying between filler particles), interspace filling (how the matrix fills the interspace volume) and matrix volume fraction. Proposed parameters are used in relations, where they are fitted by exponents to interlay values of chosen mechanical properties for composites containing discrete matrix and filler. Found exponents are then described by properties of matrices to obtain relations describing properties of filled porous materials. Very similar approach was chosen for description in the case of reinforced composites. Proposed relation are potentially valid for materials containing binding matrix, infinity count of fillers and one kind of reinforcement.
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Polymer nanocomposites with PMMA matrix
Kostková, Jana ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
This bachelor thesis deals with s study of mechanical and viscoelastic properties of nanocomposites with PMMA matrix filled with different types of surface-modified silica, which differed by the specific surface area, surface treatment and particle size. Nanocomposites were prepared by dissolving, where nanofillers were injected into the dissolved matrix. Nanocomposite samples were tested in tensil and viscoelastic properties were determined till the softening point by dynamic-mechanical analysis (DMA). All types of nanofillers had almost no effect on tensile modulus of nanocomposites at room temperature (it was not reduced) one type of silica at a content 2 %, which was also confirmed by the DMA. The temperature DMA measurements showed that samples containing 2 % of silica were generally thermally more stable compared with nanocomposites containing 1 % of silica. Storage modulus of nanocomposites, except two ones, were similar or lower such pure PMMA to temperature 66 C, then the trend reversed. Loss modulus of all samples was one order of magnitude lower then the elastic modulus.
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Thermoplastic composites for automotive applications
Zbončák, Marek ; Pospíšil,, Ladislav (referee) ; Jančář, Josef (advisor)
Diplomová práca sa zaoberá prípravou teromplastických kompzoitov s PMMA a PC matricou s potenciálnym využitím v automobilovom priemysle. Ako výstuž boli použité krátke sklenené, uhlíkové a PBO (poly(p-fenylén benzobisoxazol)) vlákna známe pod obchodným názvom Zylon®. Práve do PBO vlákien boli vkladané veľké nádeje vzhľadom na ich ohromujúce mechanické vlastnosti. Vplyv objemového zlomku vlákien na modulu pružnosti, pevnosť a ťažnosť kompozitov bol skúmaný. Experimentálne zistený modul pružností bol porovnaný so semi-empirickým Halpin-Tsai modelom. Prídavok sklenených a uhlíkových vlákien viedol k značnému zvýšeniu modulu pružnosti. Ukázalo sa, že po istej hodnote objemového zlomku dochádza k poklesu pevností kompozitov v dôsledku zvyšujúceho sa počtu defektov. Prídavok PBO vlákien preukázal len nepatrný vystužujúci efekt. Viskoelastické vlastností kompozitov boli skúmané pomocou dynamicko mechanickej analýzy (DMA). Termogravimetrická analýza (TGA), konfokálna laserová rastrovacia mikroskopia (CLSM) a rastrovacia elektrónová mikroskopia (SEM) boli využité k štúdiu štruktúry kompozitov.
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Hybrid Blends of Recycled Plastics
Černý, Miroslav ; Lehocký, Marián (referee) ; Balgová,, Vendula (referee) ; Jančář, Josef (advisor)
Work describes the relationship between structure and mechanical properties in case of hybrid mixtures. They are composed from polyurethane matrices (eventually polyurethane-urea or polyurethane-inorganic filler mixtures), different rubber fractions as filler and eventually reinforcement made from PET monofilaments. Mechanical behaviour was studied by tensile testing. Studied mechanical properties include tensile modulus, ultimate strength and strain and also specific energy need neccessary for ultimate strength achievement. Prepared materials are naturally porous. Therefore their mechanical behaviour has to be described generally for porous composites. The porosity occurence means, that it is difficult to describe them by models valid for mechanical behaviour (mainly elastic modulus) of nonporous composites. Models are also based on idealized structures on microscopic level. In case of porous composites, it is very difficult to create any idealized structure. The structure is changed with modifications of composition (change of components or their rates). These conditions have lead to utilizing of different approach how to describe the relationship between structure and mentioned mechanical properties. The chosen approach comes from knewledge about structural parametres coming from porosity. Structural parameters describe the structure on macroscopic level. They include interspace volume (volume lying between filler particles), interspace filling (how the matrix fills the interspace volume) and matrix volume fraction. Proposed parameters are used in relations, where they are fitted by exponents to interlay values of chosen mechanical properties for composites containing discrete matrix and filler. Found exponents are then described by properties of matrices to obtain relations describing properties of filled porous materials. Very similar approach was chosen for description in the case of reinforced composites. Proposed relation are potentially valid for materials containing binding matrix, infinity count of fillers and one kind of reinforcement.
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Thermoplastic composites for automotive applications
Zbončák, Marek ; Pospíšil,, Ladislav (referee) ; Jančář, Josef (advisor)
Diplomová práca sa zaoberá prípravou teromplastických kompzoitov s PMMA a PC matricou s potenciálnym využitím v automobilovom priemysle. Ako výstuž boli použité krátke sklenené, uhlíkové a PBO (poly(p-fenylén benzobisoxazol)) vlákna známe pod obchodným názvom Zylon®. Práve do PBO vlákien boli vkladané veľké nádeje vzhľadom na ich ohromujúce mechanické vlastnosti. Vplyv objemového zlomku vlákien na modulu pružnosti, pevnosť a ťažnosť kompozitov bol skúmaný. Experimentálne zistený modul pružností bol porovnaný so semi-empirickým Halpin-Tsai modelom. Prídavok sklenených a uhlíkových vlákien viedol k značnému zvýšeniu modulu pružnosti. Ukázalo sa, že po istej hodnote objemového zlomku dochádza k poklesu pevností kompozitov v dôsledku zvyšujúceho sa počtu defektov. Prídavok PBO vlákien preukázal len nepatrný vystužujúci efekt. Viskoelastické vlastností kompozitov boli skúmané pomocou dynamicko mechanickej analýzy (DMA). Termogravimetrická analýza (TGA), konfokálna laserová rastrovacia mikroskopia (CLSM) a rastrovacia elektrónová mikroskopia (SEM) boli využité k štúdiu štruktúry kompozitov.
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Polymer nanocomposites with PMMA matrix
Kostková, Jana ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
This bachelor thesis deals with s study of mechanical and viscoelastic properties of nanocomposites with PMMA matrix filled with different types of surface-modified silica, which differed by the specific surface area, surface treatment and particle size. Nanocomposites were prepared by dissolving, where nanofillers were injected into the dissolved matrix. Nanocomposite samples were tested in tensil and viscoelastic properties were determined till the softening point by dynamic-mechanical analysis (DMA). All types of nanofillers had almost no effect on tensile modulus of nanocomposites at room temperature (it was not reduced) one type of silica at a content 2 %, which was also confirmed by the DMA. The temperature DMA measurements showed that samples containing 2 % of silica were generally thermally more stable compared with nanocomposites containing 1 % of silica. Storage modulus of nanocomposites, except two ones, were similar or lower such pure PMMA to temperature 66 C, then the trend reversed. Loss modulus of all samples was one order of magnitude lower then the elastic modulus.
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