Thickness shear mode (TSM) sensors, also known as quartz crystal micro-balances (QCM) are a class of acoustic wave sensors that have been used for gas phase sensing. In this thesis this device is used to measure vapor-liquid equilibrium data for copolymers of poly(styrene-butadiene) at 294K. Copolymers of poly(styrene-butadiene) with varying percentages of styrene (85%, 45% and 21 %) were studied with benzene, n-hexane, dichloroethane and chloroform as solvents. Literature data for pure polystyrene/benzene and polystyrene/chloroform and polybutadiene/benzene were obtained to complement the measured data. Obtained experimental data were fit with a modified Flory-Huggins model and compared with the predictions of three models (UNIFAC-FV, Entropic-FV, and GK-FV). Flory-Huggins model gave a good quantitative fit for the solvent activities in the copolymer solutions.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1939. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf [15]).

Orientador: Pedro Luiz Onofrio Volpe / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-10T12:07:02Z (GMT). No. of bitstreams: 1 Magalhaes_JucelioGobi_M.pdf: 1140868 bytes, checksum: d62e85eff178ff4099f0d70cd3421f98 (MD5) Previous issue date: 2007 / Resumo: Este trabalho consiste em um estudo experimental do volume molar em excesso 'V POT. E' m de soluções líquidas binárias de clorofórmio + n-butilamina ou + s-butilamina; ou + dietilamina; ou + trietilamina a 288,15, 293,15, 298,15 e 303,15 K em função da composição e à pressão atmosférica, com o objetivo de estudar os possíveis efeitos físicos, químicos e estruturais nestes sistemas. Os dados experimentais foram ajustados a um polinômio do tipo Redlich-Kister e os resultados foram utilizados no cálculo de outras grandezas termodinâmicas, tais como, volume parcial molar, volume parcial molar em excesso, volume molar aparente, e volume molar aparente total. O 'V POT. E' m foi determinado indiretamente pela técnica de densitometria de oscilação mecãnica. Para os quatro sistemas estudados, e em todas as temperaturas os dados de 'V POT. E' m são negativos e tornam-se mais negativos com o aumento da temperatura. Os pontos de mínimo nos gráficos de 'V POT. E' m versus fração por mol de clorofórmio situam-se entre 0,35 e 0,50, dependendo do sistema. Os volumes parciais molares à diluição infinita do clorofórmio e das aminas são negativos em todas as temperaturas estudadas, e tornam-se mais negativos com o aumento da temperatura. Os resultados sugerem um pronunciado efeito estrutural (volume molar e volume livre) no valor de 'V POT. E' m , assim como a indicação da existência de fortes interações entre clorofórmio e aminas, mais evidentes no sistema contendo trietilamina / Abstract: This work consists on a experimental study of excess molar volume 'V POT. E' m of binary liquid solutions of chloroform + n-butylamine, or + s-butylamine, or + diethylamine, or + triethylamine at 288,15, 293,15, 298,15, 303,15 K as a function of composition and at atmospheric pressure, with the objective to study the possibles physical, chemical and structural effects in these systems. The experimental data were adjusted to a Redlich-Kister type equation, and the results were used to determine other thermodynamic functions, as, partial molar volume, excess partial molar volume, apparent molar volume and total apparent molar volume. The 'V POT. E' m was determined indirectly through mechanical oscilation densitometry technique. For the four systems studied, at all temperatures the data of 'V POT. E' m are negative and become more negative with the increasing of the temperature. The points of minimum on the plots of 'V POT. E' m versus molar fraction of chloroform are in between 0,35 and 0,50, depending of the system. The partial molar volumes at infinite dilution of chloroform and of the amines are negative on every studied temperatures, and become more negative with the increasing of the temperature. The results suggest a pronounced structural effect (molar and free volume) on the value of 'V POT. E' m , as well as an indication of the existence of strong interactions between chloroform and amine, wich is more evident in the system containing triethyamine / Mestrado / Físico-Química / Mestre em Química

Diploma thesis deals with the grafting of vinyltrimethoxysilane (VTMOS) onto poly(3–hydroxybutyrate)PHB. Subsequent characterization of the amount of grafted VTMOS and changes in the thermal properties associated with the rate of crystallization. The theoretical part deals with mechanism and the influences of grafting. In the experimental part VTMOS was grafted onto PHB without subjecting VTMOS to hydrolysis and subsequent crosslinking. By differential scanning calorimetry (DSC) and Avrami equation, the effect of grafted silane group on pure was studied. The MVR was used to compare the rheological properties of initial PHB, grafted PHB and crosslinked PHB by siloxane linkages.

In this work, we use pulsed-field gradient (PFG) NMR to probe molecular diffusion of liquids inside mesoporous structures and assess the influence of surface modifications, namely, deposition of palladium (Pd) nanoparticles over alumina (Al2O3) surfaces and passivation of titania (TiO2) surfaces with alkyl chains, on the diffusion pattern.

Philosophiae Doctor - PhD / The ideal conditions for the use of hydrazinium sulphate as a reducing agent to determine phosphorus in dental plaque were investigated. When this method was compared to the tin (II) chloride (Kuttner and Cohen, 1927) and ascorbic acid method (Chen, loribara and Warner, 1956),which is generally in use for the measurement of phosphorus in plaque, it was found to have certain advantages. Different ashing techniques were compared, as well as the influence of different acids on wet ashing. The hydrazinium sulphate method could determine as little as 1,8 ~g phosphorus per 50 ml and is recommended for the routine analysis of phosphorus in dental plaque samples with wet ashing. Today phosphorus can be determined, among other methods gravimetrically, titrimetically and spectroscopically (Williams, 1979). Through spectroscopic methods phosphate might be analysed spectrophotometrically by 3 main methods, as molybdophosphoric acid, its reducing product molybdenum blue and the yellow vanadomolybdophosphoric complex (Stuart and Duff, 1980). In addition indirect methods derived from molybdophosphoric acid might also be used (Williams, 1979). When phosphorus is spectrophotometrically determined during the reduction of a phosphomolybdate complex by means of different reducing agents (Kuttner and Cohen, 1927; Chen et aI, 1956; Fiske and Subbarow, 1925 and 1929, Taylor and Miller, 1914; Martin and Doty, 1949; Eibl and Lands, 1969; Vogel, 1961; Boltz and Mellong, 1947; Lazarus and Chou, 1972; Laws and Webley, 1959; Burton and Riley, 1955; Dickman and Bray, 1940), it is necessary to establish the optimum conditions under which the reducing agent, hydrazinium sulphate, can be used. In spite of this, many details about exact experimental procedures are not known (Taylor and Miller, 1914; Vogel, 1961; Boltz and Mellon, 1947). The present investigation is an attempt to establish the ideal conditions for the use of hydrazinium sulphate as a reducing agent during the formation of molybdenum blue (Schirmer et al, 1942) and the effectiveness of the method for the determination of phosphorus in dental plaque by different ashing techniques. The hydrazine method is also compared to that of Chen et al (1956) which is generally in use for plaque phosphate determinations by many authors (Ashley, 1975; Ashley and Wilson, 1976; Kleinberg et al, 1971; Zuniga et al, 1973), as well as to the sometimes used (Dawes and Jenkins, 1962) tin (II) chloride method of Kuttner and Cohen (1927). For the review of many other accepted methods, see Lindberg and Ernster (1956), and Williams (1979). The results are compared to the modified ascorbic acid method (Chen et al, 1956) as well as to the tin (II) chloride method (Kuttner and Cohen, 1927).

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