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Adhesion Strength and Fracture Morphology between FRC Root Canal Post and Particulate Filled Composite Core
Kročová, Blanka ; Pavelka,, Vladimír (referee) ; Poláček, Petr (advisor)
This bachelor thesis examines the influence of composition and structure of the dental pin on its mechanical properties. It deals with the adhesion strength and fracture morphology of adhesive joints between composite, fiber stiffened root pin (FRC) and a core of particle composite. There is observed adhesive strength dependence on the diameter of the pin FRC, the fiber content of the pin and the use of the composite particle in which the pin is embedded. Shear, adhesive joint strength was measured using a universal testing instrument with specially-made jaws. Fracture morphology was analyzed by the scanning electron microscope (SEM). Obtained data shows that the shear strength of adhesive joints for the used materials is most affected by the quality of wetting the surface of the FRC. Effect on the results could be stress distribution in adhesive strength measurements because the used jaws were not in an ideal proportion for all diameters of the samples. In another part of thesis the samples of dental pins were tested in three point bending. For the study of fracture analysis, selected samples were tested by impact in bending and test was captured with high-speed camera. With the dental pin composed of more FRC posts with a smaller diameter at the same time there is not so extensive the quarry, as in the case of using the post with a large diameter. Character of a fracture in a compound dental pin is also influenced by the type of connecting material and quality of adhesion between the material and individual posts.
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Short Fibers Reinforced Particulate Filled Composites
Kročová, Blanka ; Pavelka, Vladimír (referee) ; Poláček, Petr (advisor)
This diploma thesis examines the effect of short fiber reinforcement in particle composite with a polymer matrix and the effect of its structure on the mechanical properties. It studies the refraction toughness depending on the addition of short polyvinylalcohol fibers (PVAL), nanosilica and pulverized polymethylacrylate (PMMA) to a dimethylacrylate matrix. Matrix strengthening was characterised with the help of differential compensation photocalorimetry. The inner structure of the composite and the morphology of fracture were studied using a scanning electron microscope. For the tested samples, the modules of elasticity and toughness were measured, the critical values of stress intensity factor and the energy release rate were determined. The findings suggest that the limit value of short fibers content is 4 vol. %. This content of fibers significantly increases the tenacity of the material but at the same time the uniform distribution of fibers and the ease of preparation of the material decrease. Within the possible applications, the manipulation of this material worsens as well. The fibers content of 2 ± 0.5 vol. % is an acceptable compromise between good treatability, uniform distribution of fibers and the required mechanical properties. During the study of the fracture surfaces of the material, different types of fibers disruption were witnessed (extraction from the matrix, plastic deformation, fibrillation on the surface of the fibers, fracture) depending on the type of used matrix and filling.
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Short Fibers Reinforced Particulate Filled Composites
Kročová, Blanka ; Pavelka, Vladimír (referee) ; Poláček, Petr (advisor)
This diploma thesis examines the effect of short fiber reinforcement in particle composite with a polymer matrix and the effect of its structure on the mechanical properties. It studies the refraction toughness depending on the addition of short polyvinylalcohol fibers (PVAL), nanosilica and pulverized polymethylacrylate (PMMA) to a dimethylacrylate matrix. Matrix strengthening was characterised with the help of differential compensation photocalorimetry. The inner structure of the composite and the morphology of fracture were studied using a scanning electron microscope. For the tested samples, the modules of elasticity and toughness were measured, the critical values of stress intensity factor and the energy release rate were determined. The findings suggest that the limit value of short fibers content is 4 vol. %. This content of fibers significantly increases the tenacity of the material but at the same time the uniform distribution of fibers and the ease of preparation of the material decrease. Within the possible applications, the manipulation of this material worsens as well. The fibers content of 2 ± 0.5 vol. % is an acceptable compromise between good treatability, uniform distribution of fibers and the required mechanical properties. During the study of the fracture surfaces of the material, different types of fibers disruption were witnessed (extraction from the matrix, plastic deformation, fibrillation on the surface of the fibers, fracture) depending on the type of used matrix and filling.
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Adhesion Strength and Fracture Morphology between FRC Root Canal Post and Particulate Filled Composite Core
Kročová, Blanka ; Pavelka,, Vladimír (referee) ; Poláček, Petr (advisor)
This bachelor thesis examines the influence of composition and structure of the dental pin on its mechanical properties. It deals with the adhesion strength and fracture morphology of adhesive joints between composite, fiber stiffened root pin (FRC) and a core of particle composite. There is observed adhesive strength dependence on the diameter of the pin FRC, the fiber content of the pin and the use of the composite particle in which the pin is embedded. Shear, adhesive joint strength was measured using a universal testing instrument with specially-made jaws. Fracture morphology was analyzed by the scanning electron microscope (SEM). Obtained data shows that the shear strength of adhesive joints for the used materials is most affected by the quality of wetting the surface of the FRC. Effect on the results could be stress distribution in adhesive strength measurements because the used jaws were not in an ideal proportion for all diameters of the samples. In another part of thesis the samples of dental pins were tested in three point bending. For the study of fracture analysis, selected samples were tested by impact in bending and test was captured with high-speed camera. With the dental pin composed of more FRC posts with a smaller diameter at the same time there is not so extensive the quarry, as in the case of using the post with a large diameter. Character of a fracture in a compound dental pin is also influenced by the type of connecting material and quality of adhesion between the material and individual posts.
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