Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 7, p. 1784-1785. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thèse (M.Sc.)--Université Laval, 2003. / Bibliogr.: f. 83-96. Publié aussi en version électronique.

Thesis (M.A.)--Humboldt State University, 2006. / Includes bibliographical references (leaves 74-86). Also available via Humboldt Digital Scholar.

Th. doct.-ing.--Grenoble 1, 1981. N°: 124.

Th.--Sci. phys.--Lille 1, 1978. N°: 426.

Th. 3e cycle--Chim. struct.--Besançon, 1978. N°: 286.

Five models, ranging from a full molecular polar/polarizable model with C₃v symmetry, to the primitive model of ions in a dielectric continuum, have been used to study the properties of ammonia both as a pure liquid and as a solvent. Ammonia is modelled as a multipolar polaxizable hard sphere and ions as charged hard spheres. Using these models, in conduction with the Reference Hypernetted-chain integral equation theory, ammonia has been studied as a pure liquid, as a solvent near charged and uncharged surfaces, and in electrolyte solutions of finite concentration. The formalism of Kirkwood and Buff was used to obtain thermodynamic quantities of ionic solutions from calculated distribution functions. Structural, thermodynamic and. dielectric properties were calculated for pure ammonia and were compared with experiments where possible. Values for the dielectric constant and the configurational energy were found to compare favorably with experiment. Ammonia formed a relatively dense, highly structured layer within two solvent diameters of an uncharged surface. This structure was analyzed in terms of angular probability distributions of the molecular dipole vector and the NH-bond direction, and was found to be similar to that of frozen ammonia. The extreme asymmetry of solvation of unlike charges in ammonia was also investigated. Small cations were found to be more favorably solvated than small anions, but as the ion size was increased, the situation reversed. Estimates of the number of ion pairs in liquid ammonia and their effects on the behavior of mean molar activity coefficients were examined. Large differences between experimental activity coefficients and the Debye-Hückel hmiting law could not be explained by the usual ideas of ion pairing. It was found that the integral equation theories appear to have no solution between ionic concentrations of about 2 x 10⁻⁴M and 2 x 10⁻²M for either molecular or continuum models. Using rigorous stability criteria, this behavior was shown to be consistent with the onset of a phase change. It is proposed that such phase separation phenomena might explain the unusual behavior of the experimental activity coefficients. / Science, Faculty of / Chemistry, Department of / Graduate

Cette étude propose un procédé d’ignifugation par traitement en masse du PLA basé sur l’incorporation d’un retardateur de flamme phosphoré (APP) et de composés issus des ressources renouvelables agissant comme source de carbone dans le système intumescent. L’évaluation des propriétés RF des différents matériaux selon divers tests normalisés a permis de mettre en évidence que la formulation PLA/APP/amidon présentait les meilleures performances en termes de tenue au feu. Il se développe en surface du matériau une structure intumescente qui protège l’échantillon de l’action d’une flamme ou d’une source de chaleur et permet de limiter les transferts de gaz et de matière. Afin de tenter d’expliquer le comportement au feu de la formulation optimale, les caractéristiques physiques telles que la viscosité et la conductivité thermique du système ont été évaluées. De plus, pour mettre en évidence les éventuelles interactions chimiques, la dégradation thermique des additifs et des formulations a été étudiée. L’amélioration des propriétés feu est également due à la formation d‘espèces polyaromatiques principalement liées par des ponts phosphohydrocarbonés. Par ailleurs, plusieurs solutions ont été apportées afin d’améliorer la compatibilité entre le PLA et l’amidon et ainsi augmenter les propriétés mécaniques de la formulation intumescente / The aim of this study is to evaluate the efficiency of different intumescent formulations to flame retard polylactic acid (PLA) by the incorporation of a phosphorous flame retardant compound (APP) and products coming from renewable resources. PLA/APP/starch composite shows the best fire retardant properties. Upon heating, the material forms a foamed cellular charred layer which protects the underlying material from the action of heat flux and flame and slows down heat and mass transfer between the gas and the condensed phase. The efficiency of intumescent structure can be explained by the viscosity of the formulation. Moreover, the explanation of the improvement of the fire properties is because of chemical reactions between the components of the formulation leading to thermally stable species like phosphocarbonaceous compound. Several solutions have been studied to improve mechanical properties of intumescent formulation.

No description available.

For some years the crops of two of the plots on one of the fields of the experiment station farm had been very poor. These two plots had been received ammonium sulfate as a source of nitrogen for a long period of years and it seemed evident that the poor yield might be due to the continued use of this salt. In order to determine whether or not this was the case, the following investigations were undertaken.