Browsing by Author "Hájková, Pavlína"
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- ItemDBD Plasma Influence on the Adhesion of Paints on Polymeric Substrates(SLOVENSKO KEMIJSKO DRUSTVO, HAJDRIHOVA 19, LJUBLJANA 1000, SLOVENIA, 2020) Matoušek, Jindřich; Hájková, Pavlína; Perner, JakubThe, polyethylene (PE), polypropylene (PP) and polycarbonate (PC) flat substrates were treated by the DBD plasma in air for 1 s, 2 s and 3 s. The adhesion of two types of paints (water based and solvent based) was studied by the pull-off test. The other methods were utilized to gain the information about the surface of the samples. The measurement of contact angle of water and Arcotest (commercial test using set of fluids with defined surface tension) and the XPS technique were used to obtain the chemical composition of the sample surface. The pull-off test confirmed increased adhesion of both types of paints, which is related to oxygen content confirmed by XPS. The aged (60 days) samples keep their enhanced properties although some return to initial state was observed.
- ItemFotokatalytické účinky TiO2 vrstev připravovaných plazmochemickou depozicí z plynné fáze (PECVD)(Technická Univerzita v Liberci, 2007) Hájková, Pavlína; Špatenka, Petr
- ItemFotokatalytické vlastnosti plazmově připravovaných tenkých vrstev TiO2(Technická Univerzita v Liberci, 2012) Koutecký, Jan; Hájková, PavlínaThe aim of this thesis is to create a photocatalytic TiO2 layers by low pressure plasma-chemical vapor deposition (PECVD). Deposited layers were treated by heat and examine the effect of temperature on activity decomposition of organic matter Acid Orange 7. Further, do research on the influence of heat treatment on surface morphology change of deposited TiO 2 layers. Bachelor thesis is divided into three basic parts - the theoretical part, used experimental methods and apparatus, experimental results and conclusion
- ItemHodnocení tloušťky vrstvy a morfologie v závislosti na času depozice(Technická Univerzita v Liberci, 2010) Pfeifer, Jan; Hájková, PavlínaThe aim of the baccalaurean thesis was the research the deposition of thin layers by the plasma enhanced-chemical vapour deposition (PECVD) method and the measurement of their morphology. Layers were deposed by PECVD method with the changes of the deposition parameters, with the emphasis on the deposition times. The morphology of the surface and the thickness of those deposing layers were ascertained. At the end the conclusions concerning the coherence between the deposing parameters and the characteristics of the layers were made.
- ItemMechanical properties of geopolymer foam at high temperature(2020-01) Le, Van Su; Szczypinski, Michal M.; Hájková, Pavlína; Kovačič, Vladimír; Bakalova, Totka; Voleský, Lukáš; Hiep, Le Chi; Louda, PetrIn this work, geopolymer foam composites containing waste basalt fibre (10, 30, and 50%wt) were exposed to elevated temperatures of 200, 400, 600, 800 and 1000 degrees C. With an increase in high temperature, the geopolymer foams material exhibits a decrease in compressive strength and bending strength. When heated above 600 degrees C, geopolymer foams materials exhibit a significant reduction in mechanical properties. It shows clearly with the naked eye that surface cracks in case of samples containing 10% of basalt filler. However, when increasing fillers with basalt fibres up to 30% and 50%, the cracking of the sample surface is no longer visible to the naked eye. Especially when the temperature increases, the mechanical properties also increase without decreasing in the sample of 50% by weighing to the binder. The results show that reinforcing the geopolymer foams with basalt ground fibre improves the mechanical properties at high temperatures.
- ItemModifikace plniv kompozitních materiálů pomocí atmosférického plazmatu(Technická Univerzita v Liberci, 2012) Kovář, Marek; Hájková, PavlínaIn this thesis there was studied the influence of cold atmospheric barrier discharge on the textile fabrics. As the samples for the experiment were used glass, basalt and carbon fabrics. The aim of this thesis was to induce chemical reactions on the surface of selected fabrics using DBD plasma and research of increase wettability according to various lengths of modification and influence of aging period on the modified fabric. Damage on the surface of fibers was examined using SEM electron microscope. Chemical composition and character of the samples was verified using XRF and XRD analysis.
- ItemPLASMA TREATMENT & SURFACE MODIFICATION(CZECH SOC INDUSTRIAL CHEMISTRY, NOVOTNEHO LAVKA 5, PRAGUE, 116 68, CZECH REPUBLIC, 2020-03-25) Hájková, PavlínaThis works deals with the plasma surface treatment of various materials. The treatment was carried out using cold atmospheric plasma (volume DBD). The treatment was units of seconds long and the working conditions were as follows: frequency 3 kHz, discharge voltage 20 kV, electrode distance 5 mm. The treated materials were either powder materials (grass seeds, polyethylene powder), either bulk materials (polycarbonate sheets) or porous materials (polypropylene nonwoven fabrics, polycaprolactone microfibers and polyurethane nanofibers). The treatment resulted in significant changes of all of the tested materials.
- ItemTHERMAL CONDUCTIVITY OF REINFORCED GEOPOLYMER FOAMS(UNIV CHEMISTRY & TECHNOLOGY, PRAGUE, TECHNICKA 5, PRAGUE 6, DEJVICE 166 28, CZECH REPUBLIC, 2019) Le, Van Su; Hájková, Pavlína; Kovačič, Vladimír; Bakalova, Totka; Voleský, Lukáš; Le, Chi Hiep; Seifert, Kevin Ceccon; Peres, Amanda Pereira; Louda, PetrReinforced geopolymer foams were studied in this work as potential building materials. It has been widely assumed that for a given thermal conductivity. [W center dot m(-1)center dot K-1], geopolymer foams can have a lighter density than other materials. The study sought to test this assumption by comparing the thermal conductivity between geopolymer foams. The thermal conductivity. was measured using an ISOMET 2014 device. In all the experiments, the geopolymer foams were obtained by adding aluminium powder and several combinations: silica fume and fine sand reinforced by short basalt fibres. Curing was carried out at room temperature and then in a furnace at 70 degrees C. After the curing process, the properties of the samples were tested at 7 and 28 days. The results show that the thermal conductivity, porosity, compressive strength, flexural strength and density for all of the tests ranged in the following values: 0.13 - 0.359 W center dot m(-1)center dot K-1; 41.8 - 62.5 %; 1.94 - 9 MPa; 0.96 - 2.93 MPa; 546 - 1028 kg center dot m(-3), respectively. It was proven that the filler in the geopolymer foams has a significant influence on the mechanical and physical properties of the tested samples.
- ItemVlastnosti tenkých uhlíkových vrstev připravovaných metodou PECVD(Technická Univerzita v Liberci, 2015) Koutecký, Jan; Hájková, PavlínaCílem této diplomové práce bylo seznámit se a vypracovat podrobnou rešerši dle zadání, dále pak pomocí metody plazmové depozice z plynné fáze (PECVD), vytvořit sérii DLC (Diamond like carbon) vrstev s různou tloušťkou na substrátu z lékařské oceli AISI 316 L. Tyto vrstvy byly následovně podrobeny testu vyluhovatelnosti, při kterém bylo zkoumáno, zda vrstvy působí jako bariéra pro prvky ze substrátu (především pro alergenní Ni). Dále byla zkoumána morfologie a integrita deponovaných vrstev pomocí AFM,SEM a adheze vrstev. Pomocí kalotestu byly zjištěny tloušťky vrstev. U vrstev bylo zjištěno chemické složení povrchu pomocí EDS analýzy. Diplomová práce je členěna na základní části - úvod, teoretickou část, použité experimentální metody a přístroje, výsledky experimentů, diskuzi a závěr.
- ItemWater Absorption Properties of Geopolymer Foam after Being Impregnated with Hydrophobic Agents(MDPI, 2019) Hájková, Pavlína; Louda, Petr; Voleský, Lukáš; Le Chi, Hiep; Le Van, SuGeopolymer foam is classified as a lightweight material with high porous in its matrix which has great offer for applications requiring fire-resistant, thermal, and acoustic properties. However, the high sensitivity to humid environments can be a major barrier of geopolymer foam that limits the variety of applications of this material. Based on this drawback, two types of hydrophobic agent (Lukosil M130 and Lukofob ELX) were used as an impregnator to treat the surface of geopolymer foam samples. This paper presented the results of water absorption properties of the untreated and treated geopolymer foam composites. The obtained properties were flexural strength, compressive strength, density, total water absorption, the rate of water absorption, and water absorption coefficient. The results showed that the samples after being impregnated with hydrophobic agents improved significantly their waterproof property especially using Lukosil M130. Moreover, the samples treated with Lukosil M130 had positive impact on their mechanical strength.