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Preparation of glass fiber/polyester composites
Horská, Pavlína ; Richtera, Lukáš (referee) ; Čech, Vladimír (advisor)
The bachelor thesis is aimed at an influence of surface modifications of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber reinforced composites. Glass fibers were used as reinforcements and polyester resin was the matrix. The sample of composite consisted of polymer matrix in a form of cylindrical body placed on a bundle of glass fibers. The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface. Untreated glass fibers and fibers with commercial sizing were used for fabrication of composite samples.
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Cement composite materials with polypropylene fibers
Preisner, Martin ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This thesis deals with summarizing the possible effects of the addition of polypropylene fibers, especially low temperature plasma treated on the properties of cement composites and concrete. They are given basic information and distribution of polypropylene fibers. It describes the finish polypropylene fiber low-temperature plasma. The experimental part focuses on the effect of dispersion of polypropylene fibers treated plasma in the cement matrix.
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Modification of protective lime coating systems for the porous limestone using lime nanomaterials: assessment of mechanical properties and ageing resistance
Navrátilová, Michaela ; Bayer, K. ; Ghaffari, E. ; Macounová, Dana ; Slížková, Zuzana ; Weber, J.
Within the area of care for sculptural and architectonic monuments of limestone in Austria there has been a historic continuity of use of protective lime coatings. In the regions of Upper and Lower Austria, Vienna and Burgenland mainly Leitha limestone (named after the Leitha Mountains) are dealt with. In Czech lands such approach was disrupted from 19th century by application of the “purist” idea of bare surface of stone. Nevertheless, this treatment of stone surface has been coming back into use for many various reasons in the past few decades. Requirements for preservation of pieces of art and handcraft made of limestone using lime coatings are most often applied in the regions of Vyso!ina, South Moravia and South Bohemia, which directly border on the Northern States of Austria. Owing to the resource locations of Leitha limestone in these regions, there is a higher representation of cultural heritage monuments made of this type of stone in the Czech Republic.
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Computational study of cellular assembly on hydrophobic/hydrophilic micro-patterns
Ukraintsev, Egor ; Brož, A. ; Kalbáčová, M.H. ; Kromka, Alexander ; Rezek, Bohuslav
We develop simple onedimensional stochastic model of cell behavior on chemically patterned surfaces that is based on three key parameters: speed of cell movement (motility) across substrate, probability of cell adhesion to substrate, and probability of cell division on substrate when adhered on substrate. Amount of adhered cells on hydrophobic and hydrophilic regions is calculated as function of time (number of cycles up to 2000). The model is correlated with in-vitro data obtained within 48 h in real time. We show that this simple stochastic model with the three parameters (where cell motility is the most important one) can describe with high accuracy the experimental data and thereby explain the observed preferential cell assembly on hydrophilic/hydrophobic micro-patterns (up to 200 um width).
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Application of acoustic emisssion for thin layer mechanical toughness evaluation
Boháč, Petr ; Tomáštík, Jan ; Koula, V. ; Dráb, M. ; Jastrabík, Lubomír
The thin films are used as a functional coating of components. The limiting factor of their application is the adhesion to substrate. The laboratory method to investigation of their adhesion and mechanical toughness is the scratch test. This method emulates a mechanism of the abrasive wear in a way. Evaluation of the test results is mainly performed by microscopic investigation of deformations and micro cracks in the scratch track. Irreversible deformations, which arise during scratch test generate an acoustic emission (AE). By simultaneous scanning and recording of the increasing depth of penetration with increasing load of the stylus in the nanotester and by this way generated AE (recorded by analyzer)one can obtain data files, which contain a course of the whole experiment including AE.
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Parameters Affecting Process of Particles Sedimentation: III
Kulaviak, Lukáš ; Růžička, Marek ; Drahoš, Jiří ; Hladil, Jindřich
The aim of our contribution is to study the effect of the particles properties on their settling behaviour in solid-liquid suspensions. Generally, the particles interact mutually in a complex way. They are also coupled with the motion of the liquid whose flow they generate. The resulting behaviour depends on many mechanical particle properties (roughness, shape, size, abrasive hardness, texture, fine particle presence) and electrochemical properties of the interface between the particles and water (surface tension, zeta-potential, electrostatic potential, etc.).
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Studium mechanických vlastností DLC tenkých vrstev deponovaných v jedno a dvoufrekvenčním kapacitním výboji
Buršíková, V. ; Stoica, A. ; Sobota, Jaroslav ; Grossman, Jan ; Fořt, Tomáš ; Klapetek, P. ; Buršík, Jiří ; Bláhová, O.
Nanostructured diamond-like carbon coatings were deposited on several different substrate materials (silicon, glass, polycarbonate and steel) in single (13.56 MHz) and dual capacitive r.f. discharges (LF=100-300kHz, HF =13.56 MHz). The objective of our study was to find the optimum combination of the high and low frequency (continuous or pulsed) excitation enabling to cover uneven substrate surfaces and significant lowering of the internal stress in films.
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