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Influence of glass fiber degradation on the mechanical response of a polymer composite
Součková, Lenka ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
The bachelor thesis studies the effect of fiber degradation with commercial sizing on the flexural properties of polymer composite based on unsaturated polyester resin reinforced with long unidirectionally oriented glass fibers. Fibres of age 23, 61, 67, 112 and 135 months were used to prepare a series of composite samples. The mechanical properties of a composite containing 40.5% % vol of fiber were determined using a three-point bending test defined by ASTM D790-17 standard. From the obtained data, the flexural strength, the flexural modulus and the flexural strain were evaluated. It has been found that the degradation of the fibers and their sizing leads to a reduction in flexural strength. This was due to the reduction of adhesion between the fibers and the matrix, thus also the quality of the interface, which caused insufficient stress transfer from the matrix to the fibre. The resulting difference in strength of composites with fibers aged 23 and 135 months was 0,19 GPa with respect to the origin value of 1,17 GPa. The obtained values were used to assess the correlation between the flexural strength of the composite and the shear strength. Pearson's correlation coefficient set at 0,71 corresponds to a strong correlation. The effect of fiber degradation on the flexural modulus has not been demonstrated.
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Plasma surface modification of glass fibers and its optimization
Širjovová, Veronika ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
Diploma thesis deals with glass fiber surface modification using plasma-enhanced chemical vapor deposition in order to prepare functional interface that enhances the properties of polymer composites. The effect of deposition conditions on shear strength was observed with respect to the chemical composition of the deposited film. Thin films were deposited on planar substrates and fibers using monomer tetravinylsilane in a mixture with oxygen at selected power of plasma discharge. Chemical composition of prepared material was analyzed by infrared spectroscopy. Planar substrate film adhesion was measured using the scratch test. The composite sample was prepared by embedding the surface modified fibers in unsaturated polyester resin, followed by the curing process. The cured composite sample underwent the short beam shear test.
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Fiber reinforcements for polymer composites
Knob, Antonín ; Grégr, Jan (referee) ; Čech, Vladimír (advisor)
The bachelor thesis is concerned with an influence of surface modification of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber-reinforced polymer composites. Polyester resin was used as a matrix, glass and carbon fibers were the reinforcements. The composite sample consisted of polymer matrix in a form of cylindrical body placed on a bundle of fibers. Untreated fibers and fibers with a commercial sizing were used for fabrication of composite samples. The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface.
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The Body as a Fragment
Dohnalová, Tea ; Sobotka, Jiří (referee) ; Gabriel, Michal (advisor)
In my Bachelor Thesis I focused on masks as an authentic imprint of human face. My intention was to verify the possibility of working with specific people in the broadest possible spectrum. My work has both artistic and psychological extent. I work with human identity and its forms within different social roles. This work is time consuming. I make plaster casts of faces of many dozen people. After removing, I get a form from which I cast the final form of masks. I work with a polyester resin that I mix with other materials. This gives me very different structures, colors and the appearance of masks. In this way I try to emphasize the differences of individual people. Every specimen is original, exceptional and inimitable.
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"Centrum" Department Store in Brno
Dvořáková, Zuzana ; Sznapková, Radka (referee) ; Vojtová, Lea (advisor)
The subject of the thesis is an architectural study of the reconstruction and extension of the "Centrum" department store in Brno. It is a dominant building designed by the famous czech architect Vladimir Karfík, which is located at the Urban Conservation Area Brno. Object wasn´t realized with the full extent of the original proposal, so in the project is planned a completion of it. The new solution respects the historical quality of Urban Conservation Area Brno with a concurrent view of the location on the lucrative land in the city center. The architectural concept is based on a return to the original idea of the architect and the addition of my own creative contribution within the extension of the new floors. Draft of the extension is intended so that the individual parts of an object communicate with each other, but they are easily recognizable as well. This idea was filled by both parts linked together visually by horizontal lines and ripple, which is used on balconies of the extension and behind the facade of the current building by shielding walls. However it is emphasized the contrast between an enclosed mass and a free-flowing space. The existing part of the building is used especialy as a leasable area of trade and services. On the upper floors there are areas of administration. Furthermore, there will be a restaurant and cafe with exhibition galleries and apartments are designed on the new added floors. The building is adapted to use by person with limited mobility. Newly added uses in the object will increase the attractiveness of the building and its surroundings.
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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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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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Application of functional fillers in composites: Effects of fillers content on the mechanical properties
Krhut, Jiří ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This work deals with the application of selected types of fillers and monitoring their addition to the specific properties of the resulting composite material. The theoretical part of this work includes a general description of composite materials, and selected types of matrices, followed by a brief description of the characteristics of particulate composites and the effect of fillers on selected material properties. In the experimental part, samples of polyester resin were prepared to contain the given content of filler based on aluminium hydroxide (Al(OH)3), expanded glass, hollow glass microspheres, and fillers based on nitrogen and phosphorus compounds. Subsequently, the influence of the used fillers on the rheological properties, flammability of the material, on mechanical and thermomechanical properties was monitored. Flame test methods, bending test methods and dynamic mechanical analysis (DMA) were used to evaluate the samples. Finally, the measurement was supplemented by an analysis of fracture surfaces using a scanning electron microscope (SEM). The addition of additives improved the fire resistance of the prepared materials. The mechanical and thermomechanical properties of the prepared materials differed significantly depending on the applied fillers and their content.
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Application of functional fillers in composites: Effects of fillers content on the mechanical properties
Krhut, Jiří ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This work deals with the application of selected types of fillers and monitoring their addition to the specific properties of the resulting composite material. The theoretical part of this work includes a general description of composite materials, and selected types of matrices, followed by a brief description of the characteristics of particulate composites and the effect of fillers on selected material properties. In the experimental part, samples of polyester resin were prepared to contain the given content of filler based on aluminium hydroxide (Al(OH)3), expanded glass, hollow glass microspheres, and fillers based on nitrogen and phosphorus compounds. Subsequently, the influence of the used fillers on the rheological properties, flammability of the material, on mechanical and thermomechanical properties was monitored. Flame test methods, bending test methods and dynamic mechanical analysis (DMA) were used to evaluate the samples. Finally, the measurement was supplemented by an analysis of fracture surfaces using a scanning electron microscope (SEM). The addition of additives improved the fire resistance of the prepared materials. The mechanical and thermomechanical properties of the prepared materials differed significantly depending on the applied fillers and their content.
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Lightweight composite materials for automotive applications
Sousedík, Jan ; Poláček, Petr (referee) ; Přikryl, Radek (advisor)
This bachelor thesis investigated the influence of lightening filler in the form of hollow glass microbeads on the mechanical properties of composite material. The method chosen for the preparation of composite material was pultrusion. Two types of composite material were prepared as part of the bachelor thesis, specifically epoxy-vinyl ester resin-based composites and unsaturated polyester resin-based composites. Special bulked glass fibres were used as reinforcement. The final composite material was subjected to a three-point flexural test where mechanical properties were monitored. In addition, control of the distribution and adhesion of the filler was performed by using light microscopy and scanning electron microscopy (SEM).
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