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Orientadores: Luis Alexandre Maffei Sartini Paulillo, Mario Fernandes de Goes, Van P. Thompson / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-05T23:14:53Z (GMT). No. of bitstreams: 1 Souza_GraceMendoncaDiasde_D.pdf: 4922491 bytes, checksum: 26ef96d5e0d142ac1640c476b8484024 (MD5) Previous issue date: 2006 / Resumo: A dificuldade em se obter valores de união elevados e duradouros entre cimento resinoso e cerâmicas de alto conteúdo cristalino tem limitado o emprego destes materiais. Desta maneira, o objetivo deste estudo foi avaliar a resistência de união entre dois cimentos resinosos e uma cerâmica à base de dióxido de zircônio após diferentes tratamentos superficiais da cerâmica. Trinta e seis amostras semi-circulares em cerâmica e compósito foram polidas até a granulação 600µm. Antes da cimentação as amostras de cerâmica (n=3) foram tratadas com duas soluções básicas: hidróxido de sódio (Na) ou hidróxido de tetrabutilamônio (Ta); e um primer para metal (Ap), e o primer foi associado ou não às soluções. Amostras sem tratamento foram utilizadas como controle. A cimentação foi realizada empregando-se dois cimentos contendo monômeros fosfato ¿ RelyX Unicem (RU) e Panavia 21 (Pa) ¿ sob aplicação de carga de 600g. Depois de 24 horas, as amostras foram seccionadas em dois eixos a fim de se obter 40 palitos por amostra aproximadamente, com uma interface adesiva de cerca de 0,8mm2, que foram armazenados em água destilada, a 37ºC, e testadas em dois tempos: após 72 horas (TI) ou após 60 dias+termociclagem (5-55oC/5000 ciclos) (TF). O teste de resistência de união foi realizado à velocidade de 1mm/min em máquina universal de ensaios. Os valores em Megapascal foram submetidos à Análise de Variância (ANOVA) e ao Teste de Variação Múltipla de Tukey (p>0,05). Os resultados apresentados foram: TI ¿ ApRU-28,53a, NaApRU-23,31ab, NaApPa-22,15ab, TaApPa-19,98b, TaPa-19,98b, NaPa-19,96b, ApPa-19,92b, TaRU-18,16b, TaApRU-17,53b, Pa-17,16bc, RU-10,79c, NaRU-10,49c; TF ¿ ApRU-31,69A, NaApPa-19,17B, NaApRU-17,91BC, TaApPa-16,00BCD, TaPa-7,76CDE, ApPa-6,94CDE, NaPa-5,61DE, TaApRU-3,94E, TaRU-3,61E, RU-2,85E, Pa-1,88E, NaRU-0,27E. Através dos resultados obtidos, foi possível concluir que o maior valor de resistência de união no tempo inicial foi apresentado pela associação primer para metal e RelyX Unicem, mantendo médias com valores semelhantes após o envelhecimento. Para o cimento Panavia, não houve diferença estatística entre todos os tipos de tratamento no tempo inicial. Após o envelhecimento, a associação de primer para metal e solução básica resultou nos maiores valores de resistência de união para o cimento Panavia / Abstract: The difficulty to obtain high and durable bond strength values between high crystalline content ceramics and resin luting system has reduced the employment of those materials. The purpose of this study was to evaluate the bond strength between two luting systems and zirconium dioxide ceramic after different ceramic¿s surface treatment. Thirty-six half-circled shaped composite and zirconia samples were roughened up to 600 grit carbide silicon paper. Before the luting steps, samples (n=3) were treated either with basic solutions: sodium hydroxide (Na) or tetrabutylammonium hydroxide (Ta); or with a metal primer (Ap) and the primer was also combined with the basic solutions. Samples with no treatment were considered as control. The cementation was done employing two phosphate monomer containing systems - RelyX Unicem (RU) and Panavia 21 (Pa) ¿ under 600g loading. After 24 hours, samples were cut in two axis in order to obtain 40 beams per sample approximately, with an adhesive interface about 0.8mm2, and were placed in deionized water at 37ºC, being tested in two different times: 72 hours (TI) or after 60 days+thermocycling (5-55oC/5000 cycles) (TF). Bond strength test was conducted at 1mm/min crosshead speed in an universal testing machine. The values in MPa were analyzed through Analysis of Variance (ANOVA) and LSMeans Test (p>0.05). The results presented were: TI ¿ ApRU-28.53a, NaApRU-23.31ab, NaApPa-22.15ab, TaApPa-19.98b, TaPa-19.98b, NaPa-19.96b, ApPa-19.92b, TaRU-18.16b, TaApRU-17.53b, Pa-17.16bc, RU-10.79c, NaRU-10.49c; TF ¿ ApRU-31.69A, NaApPa-19.17B, NaApRU-17.91BC, TaApPa-16.00BCD, TaPa-7.76CDE, ApPa-6.94CDE, NaPa-5.61DE, TaApRU-3.94E, TaRU-3.61E, RU-2.85E, Pa-1.88E, NaRU-0.27E. Based on the results obtained, it was possible to conclude that the combination primer and RelyX Unicem presented the highest values, which were maintained after aging. For Panavia system, there was not significant statistical difference among all the treatments employed at the initial time. After aging, the association metal primer and basic solution produced the highest bond strength values for Panavia system / Doutorado / Dentística / Doutor em Clínica Odontológica

the toxic effects resulting from acrylic monomer exposure can pose as occupational risk factors for those involved in the manufacture, distribution, and use of the monomer and as potential risk factors for those accidentally exposed. This study is a toxicological assessment of the in vivo (intact animal) and in vitro (isolated human cell culture) responses to acute methyl (α)-chloroacrylate (MCA) exposure.

Blue-Phase liquid crystal display possesses potential to become next generation display technology because of its submillisecond response time, alignment-layer-free process and wide view angle. Intrinsically, BP only operates across a narrow temperature range due to the influence of intrinsic structural defects. Recently, the temperature range of BP has been successfully extended beyond 60K through the polymer-stabilized effect. Unfortunately, the structure of the polymer networks poses a number of problems, for instance, hysteresis effect, which degrades the accuracy of grayscale control, and residual birefringence, which decreases the contrast ratio of LCDs. This paper investigates the voltage-induced hysteresis and residual birefringence in the polymer-stabilized blue phase I and II, under various phase separation conditions and material ratio. Based on experiment result, the polymer network morphology, distribution and pure BP temperature can result in a variety of PSBP electro-optical properties. Hysteresis and residual transmittance free PSBP display could be achieved by choosing appropriated phase separation condition and material ratio. Key word¡Gblue phase¡Bmonomer¡Bhysteresis¡Bresidual transmittance

In previous studies, I learned the curing of the electro-optical effects in polymer stabilize blue phase liquid crystal under different temperature, such as the hysteresis effect, residual transmittance, drive voltage. So find out before curing blue phase temperature range is very important. Since previous studies have used methods is polarizing microscope and measuring reflectance spectra. In order to the blue phase be used in the display. If we use of Bragg reflectors in the visible blue phase liquid crystal. Resulting in the dark state is not good, the contrast reduction, so we must use the blue phase liquid crystal reflectance spectra in the non-visible light. But this liquid crystal cannot use the previously described methods to define the blue phase liquid crystal temperature range. In our experiment, we use different ways to recognized liquid crystal. We have used polarizing microscope, DSC, Kossel diagram and measuring reflectance spectra. We cannot see blue phase by polarizing microscope and Kossel diagram because the blue phase liquid crystal reflectance spectra in the non-visible light. The liquid crystal material absorbs the UV light. Our DSC resolution is not enough to found the blue phase temperature range. When we recognized liquid crystal, we found the light run through the liquid crystal box. In different phase have different lateral scattering intensity. When we cooling temperature can found the lateral scattering intensity is weak in isotropic. When we phase enter the blue phase II, the lateral scattering intensity rise slowly. When the blue phase II into the blue phase I, we can see first decreased and then increased curve. Last when into the cholesterol phase, the lateral scattering intensity rises quickly. We observe this property can discriminate the blue phase temperature range. When we found the blue phase temperature range, we analyze the hysteresis and drive voltage in different curing temperature. We found this material property. When we curing in high temperature. The drive voltage has decrease, but the hysteresis has increase. When curing in low temperature. The drive voltage has increase, but the hysteresis has decrease. Last we use SEM analyze the polymer structure. But we lost the slight polymer structure when we wash the liquid crystal. So we cannot analyze the slight polymer structure.

<p> Polymerization of bulk styrene initiated thermally as well as with di-tertiary-butyl peroxide was studied in isothermal batch reactors. Thermal polymerization was carried out at 100, 140, 170 and 200°C while polymerization with di-tertiary butyl peroxide was at 100 and 140°C. A kinetic model was derived therefrom accounting for initiation reactions from a first order decomposition of catalyst and a second order reaction between two monomer molecules to form two monoradicals, propagation, chain transfer to monomer and termination by combination only. Gel effect was allowed by the variation of rate constants with conversion. Both the thermal initiation rate constant and the first order decomposition rate constant of di-tertiary butyl peroxide were found to agree with literature values with the present values slightly higher. The initial rate constants for propagation, chain transfer to monomer, and termination were extrapolated to the range, 100-200°C using literature data. This kinetic model was used in the simulation of polymer reactor systems studying the effect of recycle and operating conditions on the molecular weight distribution and rate of production of polymer products.</p> <p> The main body of this thesis reports the polymerization study and the development of the kinetic model. The details of the kinetic equations and methods of solution, experimental techniques involved, and the simulation of polymer reactor systems are reported in the Appendices.</p> / Thesis / Doctor of Philosophy (PhD)