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Surface modification of glass fibers for polymer composites
Knob, Antonín ; Marek,, Aleš (referee) ; Burša, Jiří (referee) ; Čech, Vladimír (advisor)
The doctoral thesis is aimed at preparation of glass fiber reinforced polymer composites with controlled interphase formed by plasma-polymerized tetravinylsilane and tetravinylsilane/oxygen thin films. The thin polymer films of specific physico-chemical properties and thickness were deposited to improve interfacial adhesion of glass fiber/polyester composites. The fiber surface modification was performed by using plasma enhanced chemical vapor deposition in low-temperature RF plasma operating in an various effective power range and different treatment time. Test results were examined in relation to the interlayer thickness and different treatment conditions. The prepared interlayers were analyzed to evaluate physico-chemical composition and properties (XPS, RBS, ERDA, FTIR and spectroscopic elipsometry). Selected mechanical properties were evaluated by AFM. Mechanical response of plasma interlayers was evaluated by short beam shear test and direct method of testing the interfacial shear strength using microindentation. The interphase shear failure was controlled by the shear strength at the interlayer/fiber interface as follows from experimental and model data.
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Surface modification of glass fibers using plasma nanotechnology
Sedlák, Filip ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
Diploma thesis is aimed at deposition of thin films on glass fibers using plasma-enhanced chemical vapor deposition from tetravinylsilane as a monomer. Such surface modified glass fibers were used as reinforcements for fabrication of polymer composites with unsaturated polyester resin as a matrix. Chemical and optical properties of prepared thin films were characterized using infared spectroscopy and spectroscopic ellipsometry. An influence of deposited thin films on the shear strength of composite material was observed using short-beam shear test.
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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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Shear strength of the fiber-reinforced polymer composite
Jurko, Michal ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
The diploma thesis deals with the study of Inter-Laminar Shear Strength (ILSS) of polymer composites, based on unsaturated polyester resin with unidirectionally oriented basalt or glass fibers. The basis of the experimental part is the preparation of composite samples with different types of surface treatment of a fibers (a reinforcement) as well as the surface treatment itself. The untreated, the commercially treated fibers and the plasmatreated fibers used as reinforcement in the polymer composites were analysed by a short beam shear test and their ILSS was determined. The effect of various deposition conditions during Plasma-Enhanced Chemical Vapour Deposition (PECVD) on the value of ILSS of the composite with originally unsized glass or basalt fibers was studied. The impact of aging on the interlaminar shear strength of the composites was investigated for commercially treated glass fibers. The Scanning Electron Microscopy (SEM) is also used in the thesis together with the Energy Dispersive Spectroscopy (EDS). Based on all the results a proposal was made to correct and improve the deposition conditions and thus improve the interphase to achieve the required shear properties of polymer composites.
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Plasmachemical processing of fibrous reinforcements for polymer composites
Knob, Antonín ; Lapčík, Ĺubomír (referee) ; Čech, Vladimír (advisor)
The diploma thesis is aimed at coating of glass fibers using tetravinylsilane as a monomer by Plasma-Enhanced Chemical Vapor Deposition (PECVD). The surface modified fibers were used as reinforcements for unsaturated polyester resin to form composites of controlled interphase. Chemical and mechanical properties of thin films were controled by the effective power. Determination of fiber-matrix adhesion and an influence of polymer-interface on mechanical properties of composites were characterized by Scanning Electron Microscopy (SEM) and microindentation technique using Interfacial Testing System (ITS) enabling to measure the interfacial shear strength.
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Polymer composites with controlled interphase
Zvonek, Milan ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
Cieľom diplomovej práce je príprava polymerných kompozitov vyztužených sklenenými vláknami s riadenou medzifázou za použitia metódy plazmochemickej depozície z plynnej fáze a monomeru tetravinylsilanu. Teoretická časť je zameraná na literárnu rešerš o plazme, plazmovej polymerácií, tenkých vrstvách a kompozitoch. Experimentálna časť popisuje použité materiály a aparaturu použitú na povrchovú modifikáciu sklenených vlákien a prípravu vláknom vyztužených kompozitov. Povrchová úprava sklenených vlákien prebiehala za rôznych depozičných podmienok. Chemické a mechanické analýzy vytvorenej medzivrstvy prebiehali za použitia FTIR spektrometrie a vrypového testu. Vliv povrchovej úpravy bol zistený pomocou získanej interlaminárnej šmykovej sily použítím testu krátkych trámečkov.
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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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Shear strength of the fiber-reinforced polymer composite
Jurko, Michal ; Knob, Antonín (referee) ; Čech, Vladimír (advisor)
The diploma thesis deals with the study of Inter-Laminar Shear Strength (ILSS) of polymer composites, based on unsaturated polyester resin with unidirectionally oriented basalt or glass fibers. The basis of the experimental part is the preparation of composite samples with different types of surface treatment of a fibers (a reinforcement) as well as the surface treatment itself. The untreated, the commercially treated fibers and the plasmatreated fibers used as reinforcement in the polymer composites were analysed by a short beam shear test and their ILSS was determined. The effect of various deposition conditions during Plasma-Enhanced Chemical Vapour Deposition (PECVD) on the value of ILSS of the composite with originally unsized glass or basalt fibers was studied. The impact of aging on the interlaminar shear strength of the composites was investigated for commercially treated glass fibers. The Scanning Electron Microscopy (SEM) is also used in the thesis together with the Energy Dispersive Spectroscopy (EDS). Based on all the results a proposal was made to correct and improve the deposition conditions and thus improve the interphase to achieve the required shear properties of polymer composites.
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