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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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Thermal Stability/Degradation of High Viscosity Dental Resins
Bystřický, Zdeněk ; Trautmann, Radoslav (referee) ; Poláček, Petr (advisor)
This diploma thesis deals with the influence of long term thermal load on the stability of high-viscous resins used for dental composites matrix. The process of polymerization was also investigated in connection with type and ratio of monomer units, mass content of the initiator system and the presence of nanosilica filler. Prepared resins were characterized by differential compensation photocalorimetry (DPC) and dynamic mechanical analysis (DMA). The dependence of the heat flow on time was measured by DPC. Based on the experimental data, the dependence of conversion on time and the dependence of polymerization rate on conversion were determined. Viscoelastic properties of the cured resins were determined by DMA. Experimentally measured data implies that by the influence of elevated temperature both the degree of conversion and the polymerization rate decreased. With a higher content of the initiator system incorporated in resin the decrease was more significant. Therefore, we can conclude that when the resin was exposed to the elevated temperature one of the components of the initiator system was inactivated. For the photopolymerized resins presence of two glass transition temperatures is typical due to the inhomogenous morphology of the cured resin. There are two types of domains with varying relative composition. However, after the degradation only one glass transition temperature was detected. That was caused by reducing the resin viscosity due to the increased temperature. Higher mobility of the initiator system molecules and monomers itself resulted in more homogenous structure of the cured resin. In case of elevated temperature exposed resins more significant decrease of the elastic modulus was observed. The curing process is considerably influenced by the type and ratio of the monomer units and by the presence of filler.
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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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Thermal Stability/Degradation of High Viscosity Dental Resins
Bystřický, Zdeněk ; Trautmann, Radoslav (referee) ; Poláček, Petr (advisor)
This diploma thesis deals with the influence of long term thermal load on the stability of high-viscous resins used for dental composites matrix. The process of polymerization was also investigated in connection with type and ratio of monomer units, mass content of the initiator system and the presence of nanosilica filler. Prepared resins were characterized by differential compensation photocalorimetry (DPC) and dynamic mechanical analysis (DMA). The dependence of the heat flow on time was measured by DPC. Based on the experimental data, the dependence of conversion on time and the dependence of polymerization rate on conversion were determined. Viscoelastic properties of the cured resins were determined by DMA. Experimentally measured data implies that by the influence of elevated temperature both the degree of conversion and the polymerization rate decreased. With a higher content of the initiator system incorporated in resin the decrease was more significant. Therefore, we can conclude that when the resin was exposed to the elevated temperature one of the components of the initiator system was inactivated. For the photopolymerized resins presence of two glass transition temperatures is typical due to the inhomogenous morphology of the cured resin. There are two types of domains with varying relative composition. However, after the degradation only one glass transition temperature was detected. That was caused by reducing the resin viscosity due to the increased temperature. Higher mobility of the initiator system molecules and monomers itself resulted in more homogenous structure of the cured resin. In case of elevated temperature exposed resins more significant decrease of the elastic modulus was observed. The curing process is considerably influenced by the type and ratio of the monomer units and by the presence of filler.
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