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Properties comparison of two products used for skating rink based on ehtylene-propylene-dien rubber
Kostková, Jana ; Kučera, František (referee) ; Bálková, Radka (advisor)
This master thesis deals with characterization of two black and white products based on ethylene-propylene-diene rubber (EPDM) used for skating rink. Products marked with A and are different in their diameter of circular tubes trough which cooling medium passes and also in the distance of these tubes. Both of materials were characterized in order to determine whether it is the EPDM and how are they different. The characterization methods were used: differential scanning calorimetry, thermogravimetric analysis, attenuated total reflectance Fourier transform infrared spectroscopy, tensile test, swelling test, thermooxidative test. The composition of both materials, including fillers and others additives is almost the same but difference is in structure of EPDM and probably also in interaction with fillers, what exhibits different mechanical properties, thermooxidative stability and thermal capacity. These differences which have been found are essential for long-term use properties of both materials.
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Influnce of chemical composition on mechanical properties of LLDPE stretch film
Vojáček, Jakub ; Tocháček, Jiří (referee) ; Poláček, Petr (advisor)
Thesis summarizes the problems of production and use of stretch film. The change of strength, ductility and relative relaxation effect in different times of drawing from role in three weeks was observed. Further, change of strength and ductility due to changes in the rate of deformation, exposure to accelerated aging in a UV chamber and changes in the loading direction were observed. Mechanical tests were realized on a tensile tester, relaxation tests on DMA and crystallinity changes were observed on the DSC. Relationship between chemical composition of stretch film and mechanical and thermomechanical properties were studied. It was found that chemical composition essential for stretch film properties. However, due to the impossibility to distinguish effects of chemical composition and process parameters was impossible to find clear relation describing this relationship.
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Physical ageing of polypropylene
Weiss, Jiří ; Kučera, Jaroslav (referee) ; Tocháček, Jiří (advisor)
Physical aging of commercially produced polypropylene homopolymers Mosten was studied. The work is focused on monitoring the changes in physical properties of polymer in the time period 90 days from the date of preparation of the test specimen. The aging of polymers was realized at storage temperatures of 23 and 80 °C. The changes in crystallinity, yield strength, modulus, elongation and impact strength using DSC method, tensile tests and impact tests according to Charpy were monitored. Molecular weight distribution was determined by means of GPC at each polymer. Relationships between the changes in physical properties and polymer molecular weight were sought.
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Analysis of mechanical properties of polymers and polymer compsites from video record of tensile test
Ščudlová, Jolana ; Nezbedová, Eva (referee) ; Žídek, Jan (advisor)
This thesis described mechanical tests with monitoring of camera. The aim of this work is to obtain additional information about material behavior during the test. The mechanical tests were monitored high-definition (HD) digital video-camera and camera with high resolution. The method was applied to the tensile test and Pennsylvania notch test (PENT test). The videorecordings were processed with the assistance image analysis method. The marks were placed on both of these specimens, mutual movement these marks were used to obtain following characteristics. It was Poisson’s ratio and true stress by tensile test. By PENT test it was rate growth crack. The investigated material was elastomeric polyurethane filled by biodegradable polyhydroxybutyrate for tensile test. Second material was polypropylene for PENT test. The camera is adding to the test gives extended information about the material and better interpretation results.
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The influence of surface modification of glass fibers on mechanical response of the GF/polyester composite
Janeček, Pavel ; Richtera, Lukáš (referee) ; Čech, Vladimír (advisor)
The diploma 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 bundle of glass fibers. The design of the sample was constructed with respect to results of Finite Element Analysis (FEA). The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface. Untreated glass fibers, fibers with commercial sizing, and fibers modified by deposition of plasma polymer film using Plasma-Enhanced Chemical Vapor Deposition (PECVD) at different deposition conditions were used for fabrication of composite samples. The fibers and composite samples were analyzed by Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM).
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Mechanical properties of fiber reinforced composites for automotive applications
Bayer, Adam ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
Bachelor’s thesis deals with studying mechanical features of fiber composites. As a matrix was chosen PMMA and as reinforcement was chosen glass fabric. Theoretical part sums up contemporary issues of polymer composites in automotive industry such as their production techniques and methods of impregnation. In experimental part were prepared samples by block polymerization of 30 % solution PMMA in monomer with initiator by 65° Celsius warmth oath, when was fabric directly unfolded in pre-polymer solution. On these samples were executed tensile tests by testing device Zwick and these samples were compared with results of theoreticaly calculated values.
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Optimalization of parts bonded by hot crimping
Liškář, Ladislav ; Řiháček, Jan (referee) ; Lidmila, Zdeněk (advisor)
The thesis describes the procedure for verifying the conceptual ideas of the company. Design and production of prototypes, testing and evaluation, quantifying savings. Two variants of crimped bond were chosen. For each was length of shaft changed to three and four crimped grooves. These prototypes were tested in two static and one dynamic tests. Recommendation for company is continue with other phases of development for shaft with four grooves.
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Influence of input material on technology and production of deep drawn product
Černá, Monika ; Peterková, Eva (referee) ; Šulák, Ivo (advisor)
This bachelor thesis was elaborated in cooperation with company ITW Pronovia, s.r.o within the scope of the bachelor degree and presents an assessment of the effect of material properties and manufacturing technology of a deep-drawn product. In this work the mechanical and technological tests were carried out on the supplied material HT179. This material is further processed into a cartridge for an airbag deployment. During production many defects occurred, especially after cutting out the holes of deep-drawn product. The company established these defects as material property. Therefore it is necessary to evaluate the characteristics of different material sets.
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Mechanical Properties of Plastics
Suchý, Marek ; Němec, Karel (referee) ; Molliková, Eva (advisor)
This bachelor thesis deals with the plastics in terms of their internal structures. Analyzes the impact of these characteristics on the resulting mechanical properties of materials. Furthermore, examining the external influences significantly on the polymer chain operates. Concludes two basic methods for the detection of mechanical properties - tensile test and 3-point bend tests.
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Structure and Properties of Selected Magnesium Cast Alloys
Svozil, Libor ; Pacal, Bohumil (referee) ; Podrábský, Tomáš (advisor)
Microstructure and mechanical properties of AZ91 magnesium alloy after die cast (casting under pressure) and squeeze casting were comparated. The compare of incident phases, their microhardness, gas bubbles in the alloy, hardness and other mechanical properties of alloy are included in this work. For compare has been used a light microscopy, tensile test, hardness and microhardness measurements, image analysis and scaning electron microscopy.
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