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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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Activation admixtures in concrete
Eger, Lukáš ; Hela, Vlastimil (referee) ; Hela, Rudolf (advisor)
The aim of my bachelor´s work is the summarization and focus on admixure concrete,and the active and inert admixure, which have some positive characteristies for fresh and hardened concrete. Theoretically, I tried to study the increase of their joining potential while this characteristic can be used by either chemici or mechnical way, their combination as well. I also Works on evaluetion of physically mechanical influence for fresh and hardened concrete that can up to 60 days old while the cement was partly substituted by admixure of different character.
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Badminton rackets
Kuriál, Jakub ; Doležal, Pavel (referee) ; Molliková, Eva (advisor)
The fundamental topic of this thesis is the analysis of materials used in the production of sports equipment for badminton. The thesis describes the evolution of materials used in the context of the historical development of the game system. The thesis explains the game principles and the requirements for the technical characteristics of the gaming equipment. The thesis deals primarily with material properties of individual parts of the badminton racket (frame, string bed, wrap) but it also mentions the demands on the ball or the playing surface. In the final section of the thesis the expected development in the sports industry using the acquired knowledge is described. The most likely direction seems to be the area of nanotechnology. The importance of this work lies in the complete discussion of a topic in the field of material sciences which has not been composed yet.
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Durability of Polyehtylene Ribbons from Netwrap
Huljak, Pavel ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
This diploma thesis deals with the measurement of mechanical properties and accelerated aging of monoaxially stretched polyethylene strips coming from three types of polymeric mesh, which serves to pack hay on baling machines. The strength of the strips is evaluated from two points of view. The first one is static tensile strength measured before and after accelerated aging at 23 °C and 40 °C, the second one determines the strength as the weight that causes the strip failure on a simple machine at 23, 40, 60 and 80 ° C. The results show that the smallest static strength has the least stabilized strip, which, on the other hand, revealed the highest strength in a dynamic loading. The change of supermolecular structure was evaluated by calorimetric measurements. The data shown only very little change of inner structure due to the average response of the whole crystalline phase comprising relatively wide distribution of crystallites. It is more than probable that supermolecular structure had been changed but the method is not sensitive to see the change of orientation of lamellae and macromolecular chains in them.
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Optimizing the composition of micro concrete admixtures.
Juříková, Denisa ; Křížová, Klára (referee) ; Hela, Rudolf (advisor)
The aim of this paper is to summarize knowledges related to the use of fine-grained admixtures in cement composites. By utilizing of these admixtures it is possible to achieve extreme properties, especially high strenght and durability of concrete. These properties can be achieved by optimizing the density of the binder and filler in range of 0 to 0,25 mm. Therefore, large part of thesis is focused on admixtures and its effect on concrete. The experimental part of the thesis deals with optimization od selected admixtures in combination with cement to achieve the minimum of the voids and their compressive strenght were determined at 1, 3, 7, 28 and 60 days.
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Effect of type and dose of scattered reinforcement on selected properties of concrete.
Láníková, Lucie ; Schmid, Pavel (referee) ; Láník, Jaromír (advisor)
The Master’s thesis is focused on the research influence the dose and type of scattered reinforcement in a reference concrete on physical and mechanical properties of the resulting composite. The investigated properties of composite belongs compressive strength, tensile strength in the flexural and tensile strength in the transverse, static modulus of elasticity in compressive strength, dynamic modulus of elasticity determined using NDT tests. The reference concrete mixture is certified as structural concrete of the class, which is commonly used on construction sites.
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The evaluation of psysical ability of secondary school children among chosen Prague schools
Bláhová, Petra ; Panská, Šárka (advisor) ; Bunc, Václav (referee)
The work focuses on the evaluation of physical fitness of students, who are 12 and 13 years old. The main aim is to assess the physical fitness of students at general high school and primary school with sports classes. As a part of the thesis, standardized testing will be conducted using the UNIFITTEST (6-60) battery, and two modified tests with their own evaluation tables will be created. The results of the tests will be compared with standardized or modified tables and evaluated according to point standards. The survey will gather data regarding extracurricular physical activity, according to which a trained individual is identified. These individuals will be defined as those who train for at least 3 hours, twice a week. The survey will also collect basic anthropometric data for measuring BMI. All of these aspects were put into context and the results proved, that primary school sports classes achieved better results than general high school children in most tests. By comparing the statistical data, it was proven that although the results are different, the differences are inappreciable at the level of statistical significance. KEYWORDS Ability, motorical skills tests, flexibility, strenght, speed, endurance, pubescence
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