This thesis is concerned with the study by solid-state NMR of the polymers formed by acid anhydride/hydroxyl cross-linking systems. The polymers studied in this thesis are based on a copolymer containing either itaconic or maleic anhydride which cross-Jinks with a polyester tipped with triethanolamine. The mobility of the polyester chains in the cross-linked films is probed by solid-state NMR, and the kinetics of the cure between acid anhydride/hydroxyi systems is discussed. The degradation of the cross-Jinked films is studied by (^13)C solid-state NMR. The films are shown to undergo hydrolysis when subjected to their exposure environment. The theory behind transient nuclear Overhauser effects in the solid state is discussed, and comparisons are made between the theoretical simulations and the experimented data for the cross—linked films. Lastly, a solid-state heteronuclear NOESY experiment is presented for a (^13)C(_2)-enriched acid anhydride/hydroxyl cross-linked film.

No description available.

No description available.

O surgimento de um material na área de engenharia torna-se um marco para buscar novas aplicações gerando assim novas tecnologias. Neste estudo utilizou-se a vermiculita expandida e processada como novo material para sistemas uretânicos. A utilização de qualquer novo material, requer conhecimento prévio de seu desempenho em algumas situações técnicas; resultando com isso, desenvolvimentos de tecnologias para o emprego deste material nos segmentos adequados. Na busca para compreender o comportamento da vermiculita em sistemas uretânicos, esta vermiculita foi processada, a partir da sua forma bruta, até obter uma granulometria adequada para adição em meios uretânicos. A adição da vermiculita em vernizes uretânicos, foi no sentido de gerar conhecimentos sobre o comportamento deste material em sistemas formadores de filmes. Neste estudo, foi investigado o aparecimento de cor, o surgimento de tonalidades, a elevação de dureza de filmes uretânicos, a investigação de ação reacional em sistemas uretânicos de dois componentes e, foi também investigado o efeito de barreira em filmes uretânicos contendo vermiculita processada na sua composição. E, após avaliação dos resultados obtidos, comprovou-se que a vermiculita piroexpandida processada por moagem pode ser utilizada como matéria-prima de interesse em vernizes de composição uretânica. / The discovery of a material in the area of engineering is a milestone to seek new applications thus generating new technologies. In this study the expanded vermiculite was processed as a new material for urethane systems. To use any new material it is necessary to know its performance in some technical situations; to gets developments in technologies for the new use of this material in the appropriate segments. In the search to visualize the behavior of the vermiculite in urethane systems, this vermiculite was processed, from its crude form, until obtaining suitable granulometry for addition in urethane media. The addition of vermiculite to urethane varnishes was aimed at generating knowledge about the behavior of this material in film forming systems. In this study, the development ocolor, the appearance of shades, urethane film hardness increase, reactional action investigation in two component urethane systems were investigated and the barrier effect was also investigated in urethane films containing vermiculite processed in Its composition. After evaluation of the obtained results, it was verified that the vermiculite pyroexpandida processed by grinding can be used as raw material of interest in varnishes of urethane composition.

O surgimento de um material na área de engenharia torna-se um marco para buscar novas aplicações gerando assim novas tecnologias. Neste estudo utilizou-se a vermiculita expandida e processada como novo material para sistemas uretânicos. A utilização de qualquer novo material, requer conhecimento prévio de seu desempenho em algumas situações técnicas; resultando com isso, desenvolvimentos de tecnologias para o emprego deste material nos segmentos adequados. Na busca para compreender o comportamento da vermiculita em sistemas uretânicos, esta vermiculita foi processada, a partir da sua forma bruta, até obter uma granulometria adequada para adição em meios uretânicos. A adição da vermiculita em vernizes uretânicos, foi no sentido de gerar conhecimentos sobre o comportamento deste material em sistemas formadores de filmes. Neste estudo, foi investigado o aparecimento de cor, o surgimento de tonalidades, a elevação de dureza de filmes uretânicos, a investigação de ação reacional em sistemas uretânicos de dois componentes e, foi também investigado o efeito de barreira em filmes uretânicos contendo vermiculita processada na sua composição. E, após avaliação dos resultados obtidos, comprovou-se que a vermiculita piroexpandida processada por moagem pode ser utilizada como matéria-prima de interesse em vernizes de composição uretânica. / The discovery of a material in the area of engineering is a milestone to seek new applications thus generating new technologies. In this study the expanded vermiculite was processed as a new material for urethane systems. To use any new material it is necessary to know its performance in some technical situations; to gets developments in technologies for the new use of this material in the appropriate segments. In the search to visualize the behavior of the vermiculite in urethane systems, this vermiculite was processed, from its crude form, until obtaining suitable granulometry for addition in urethane media. The addition of vermiculite to urethane varnishes was aimed at generating knowledge about the behavior of this material in film forming systems. In this study, the development ocolor, the appearance of shades, urethane film hardness increase, reactional action investigation in two component urethane systems were investigated and the barrier effect was also investigated in urethane films containing vermiculite processed in Its composition. After evaluation of the obtained results, it was verified that the vermiculite pyroexpandida processed by grinding can be used as raw material of interest in varnishes of urethane composition.

M.A. Florida State College for Women 1928 / Includes bibliographical references

Purpose: The purpose of this study was to asses fluoride varnish use by dental practitioners in Virginia. Methods: Using a cross sectional survey design, all dentists in Virginia who are members of the Virginia Dental Association (VDA) were sent an online survey about usage and knowledge of fluoride varnish. Results: The majority of the respondents were general dentists (79%) followed by pediatric dentists (12%). Fluoride varnish use increased with year of graduation from dental school. Dentists who thought fluoride varnish was more effective and less time consuming use it more than other topical fluorides. Dentists who thought their patients prefer fluoride varnish use it more than other topical fluorides.Conclusion: The majority of dentists are not aware of the advantages of fluoride varnish. However, those who are, choose to use it as opposed to foams and gels. Recent graduates, with more exposure to fluoride varnish, use it more frequently.

Organic solvents in varnish can easily cause volatile organic compounds (VOCs) and odorous problems in manufacturing plants of enamel insulated wire. In general, the related process exhaust gases are treated by catalytic incinerators. However, the slight odors in the incinerated exhausts may induce uncomfortable feels to the inhabitants in the vicinity of the plants. Main components of odors are reported to be xylenes and to a lesser extent ketones. This study intended to oxidize the odorous compounds by chemical scrubbing method with either sodium hypochlorite or ozone as an oxidant and hydrogen peroxide as a reducing agent for the elimination of residual chlorine or ozone emitted from the oxidation scrubber. An additional study was the oxidation of aqueous mixed xylenes by sodium hypochlorite. The first part of the study was the chemical oxidation of aqueous xylenes by sodium hypochlorite. Results indicated that more than 95 % of 20 mg/L xylenes could be converted to some oxygenated hydrocarbons with an initial effective chlorine concentration of 180 mg/L at pH 6.5 over a prolonged reaction time of over 120 min. With pH < 3 and a reaction time of 120 min, xylenes could be oxidized to benzene carboxylic acid that precipitated as organic crystalline solids to the reactor bottom. The second part was chemical scrubbing of the odorous gases emitted from the catalytic incinerator. Operation conditions were an effective chlorine concentration of 1,500 mg/L and pH 6.5 for the oxidative scrubbing liquor, and a hydrogen peroxide concentration of 700 mg/L and pH > 12 for the reductive one. Results indicated that on an average, around 59 % of the influent xylenes could be removed, and the scrubbed gas was nearly odorless. 65.0 - 98.5 % of the influent non-aromatic compounds could be removed with trace amounts of chlorinated compounds in the gas were detected. The third one was the treatment of the odorous gases by using ozone as an oxidant and followed by activated carbon adsorption. 18 - 34 mg/m3 of ozone was added to the test gas with initial xylene concentrations of 25 - 55 mg/m3. Results indicated that only around 35 % of the added xylene was removed with ozone contact times of 0.15 - 0.6 min. Although 99.9 % of the residual ozone and odors were removed by the activated carbon, a longer operation time should be tested to verify the performance. Trace amounts of ring cleavage precursors of 2.4-dimethylphenol and ring cleavage products were found in the ozonized gas.

Thesis (PH. D.)--Columbia University, 1926. / Vita. Also issued in print.

Thesis (PH. D.)--Columbia University, 1926. / Vita. eContent provider-neutral record in process. Description based on print version record.