Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2009. / Includes bibliographical references. Also available online.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 237-250). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Lehigh University, 2003. / Includes bibliographical references and vita.

This PhD dissertation addresses a number of issues pertaining to the use and application of surface treatments using asphalt emulsions. The work conducted as part of this research study shows in detail the problems associated with the state-of-practice and how these issues can be addressed using a scientific and rational approach as opposed to the experience-based approach which is prevailing currently. The first objective of this research study focuses on developing a methodology to determine the total amount of evaporative water loss of an emulsion before the aggregates are placed. An algorithm is presented that can be used by field inspectors and practitioners for the optimal timing of chip placement. The second objective focuses on another key aspect associated with the constructability of surface treatments, i.e., the optimal time to open a new surface treatment to traffic. Laboratory tests were conducted on the emulsion and aggregates to measure the rate of moisture loss and the evolution of the rheological properties as function of time. This was related to the field measured evaporation rates to determine the minimum stiffness required for optimal performance of the chip seal towards adequate resistance to raveling. The final objective of this dissertation focuses on developing a theoretical understanding of the current flowing through a circuit when an emulsion separates into its constituent phases when placed in an electric field. The measured current depends on a set of material properties that include the emulsion’s viscosity, surface potential, and dielectric of the medium and the strength of the electric field. A theoretical formulation was developed that relates the current flowing through the circuit with the mobility of the charged particles and the bulk charge density. The proposed theory was further utilized in developing a test procedure to quantify the breaking characteristics of asphalt emulsions. Results demonstrated that the parameters obtained from these tests were repeatable and different for different types of asphalt emulsions. It was also noticed that for a given type of emulsion the test method is sensitive to factors such as water content and partial breaking due to mechanical agitation. / text

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Crude mannoproteins (MP) from several different industrial yeast sources were obtained by heating (3 h at 121$ sp circ$C) cells suspended in citrate buffer (pH 7.0) followed by ultrafiltration and washing. Crude mannoproteins and their ammonium sulfate fractions exhibited varying degrees of emulsifying activities, i.e., ease and extent of emulsification. Not all of the oil and water emulsions were stable for three weeks, whereas all of the oil and vinegar emulsions remained stable for up to three months. Addition of NaCl increased both emulsifying activity and emulsion stability. Emulsions with an acidic pH were the most stable. With pH emulsion stability was greatly reduced and more work was required to establish an emulsion. Heating and cooling, and freezing and thawing caused vary degrees and rapidity of emulsion breakdown. Addition of NaCl maintained the emulsion stability when subjected to these various treatments. Deglycosylation of MP with trifluoromethane sulfonic acid and anisole did not significantly reduce the emulsifying activity of the MP. These preparations still contained ca. 3% carbohydrate and consisted of two distinct entities of mw ca. 36 and 41 kDa as observed by gradient SDS-PAGE.

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