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Hybrid Composites Combining Short Deformable Fibers and Particulate Fillers in Polymeric Matrix
Smrčková, Markéta ; Pavelka,, Vladimír (referee) ; Poláček, Petr (advisor)
In this work, the effect of adding short deformable polyvinylalcohol fibers into dimethacrylate resins on mechanical properties of composite materials was investigated. Furthermore, micro- or nano-fillers were added into the matrix. The effect of filler/short fibers combination on mechanical properties of so-called hybrid composites was studied. Composites were characterized by differential compensation photocalorimetry (DPC), termogravimetric (TGA) and dynamic mechanical (DMA) analysis. The fracture surfaces were examined using scanning electron (SEM) and confocal laser (CLSM) microscopy. Elastic modulus and strength, the critical value of stress intensity factor and strain energy release rate and the viscoelastic properties of composite materials were measured. The mechanical properties of composite materials are affected not only by the type of filler/reinforcement, but also by properties of the matrix. These properties also depend on the way of network formation during photo-initiated polymerization. For this reason, heat of polymerization, degree of conversion and the maximum polymerization rate of mixture of dimethacrylate monomers were determined.
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Optimization and characterization of dimethacrylate-based resin
Baradzina, Lizaveta ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This diploma thesis was focused on the optimization and characterization of resins based on dimethacrylate monomers. The polymerization process was also monitored depending on the type and molar ratio of monomers used, on the content of barium glass filler and the presence of glass fibers. Changes in the viscoelastic properties of materials during polymerization were also investigated. The following methods were used to characterize the prepared dimethacrylate resins and composite materials based on them: viscosimetry, differential scanning photocalorimetry (DPC), photoreology, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The dynamic viscosity of the prepared dimethacrylate matrices was determined by viscometry. Based on the results of DPC analysis of the tested resins, the dependences of heat flow on time, conversion on time and polymerization rate on conversion were created. With photoreology, the course of curing, the onset of the gelation point and changes in the viscoelastic properties of the systems were monitored. The viscoelastic properties of the cured composite materials were then determined by DMA in the three-point arrangement. TGA was performed to accurately determine the composition of the tested samples
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Photopolymerization study of composites
Baradzina, Lizaveta ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This bachelor thesis investigated the influence of ceramic nanofibers and particle filler on the curing kinetics of composite materials with dimethacrylate matrix. Changes in viscoelastic properties of materials during polymerization were also monitored. Within this work, four types of materials were prepared: particle composite, fiber composite, hybrid composite and pure matrix. Composite systems of different compositions were characterized by photorheology, differential photocalorimetry (DPC), and dynamic-mechanical analysis (DMA). The effect of light intensity and irradiation time on changes in the rheological properties of materials that occur during photopolymerization were investigated using photorheology. Based on the results of DPC analysis of the tested samples the dependencies of conversion on time and polymerization rate on conversion were created. The viscoelastic properties of the cured composites were determined by DMA analysis in a three-point arrangement.
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Optimization and characterization of dimethacrylate-based resin
Baradzina, Lizaveta ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This diploma thesis was focused on the optimization and characterization of resins based on dimethacrylate monomers. The polymerization process was also monitored depending on the type and molar ratio of monomers used, on the content of barium glass filler and the presence of glass fibers. Changes in the viscoelastic properties of materials during polymerization were also investigated. The following methods were used to characterize the prepared dimethacrylate resins and composite materials based on them: viscosimetry, differential scanning photocalorimetry (DPC), photoreology, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The dynamic viscosity of the prepared dimethacrylate matrices was determined by viscometry. Based on the results of DPC analysis of the tested resins, the dependences of heat flow on time, conversion on time and polymerization rate on conversion were created. With photoreology, the course of curing, the onset of the gelation point and changes in the viscoelastic properties of the systems were monitored. The viscoelastic properties of the cured composite materials were then determined by DMA in the three-point arrangement. TGA was performed to accurately determine the composition of the tested samples
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Photopolymerization study of composites
Baradzina, Lizaveta ; Petruš, Josef (referee) ; Poláček, Petr (advisor)
This bachelor thesis investigated the influence of ceramic nanofibers and particle filler on the curing kinetics of composite materials with dimethacrylate matrix. Changes in viscoelastic properties of materials during polymerization were also monitored. Within this work, four types of materials were prepared: particle composite, fiber composite, hybrid composite and pure matrix. Composite systems of different compositions were characterized by photorheology, differential photocalorimetry (DPC), and dynamic-mechanical analysis (DMA). The effect of light intensity and irradiation time on changes in the rheological properties of materials that occur during photopolymerization were investigated using photorheology. Based on the results of DPC analysis of the tested samples the dependencies of conversion on time and polymerization rate on conversion were created. The viscoelastic properties of the cured composites were determined by DMA analysis in a three-point arrangement.
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Hybrid Composites Combining Short Deformable Fibers and Particulate Fillers in Polymeric Matrix
Smrčková, Markéta ; Pavelka,, Vladimír (referee) ; Poláček, Petr (advisor)
In this work, the effect of adding short deformable polyvinylalcohol fibers into dimethacrylate resins on mechanical properties of composite materials was investigated. Furthermore, micro- or nano-fillers were added into the matrix. The effect of filler/short fibers combination on mechanical properties of so-called hybrid composites was studied. Composites were characterized by differential compensation photocalorimetry (DPC), termogravimetric (TGA) and dynamic mechanical (DMA) analysis. The fracture surfaces were examined using scanning electron (SEM) and confocal laser (CLSM) microscopy. Elastic modulus and strength, the critical value of stress intensity factor and strain energy release rate and the viscoelastic properties of composite materials were measured. The mechanical properties of composite materials are affected not only by the type of filler/reinforcement, but also by properties of the matrix. These properties also depend on the way of network formation during photo-initiated polymerization. For this reason, heat of polymerization, degree of conversion and the maximum polymerization rate of mixture of dimethacrylate monomers were determined.
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