Physical properties of high pressure phase of oleic acid

Rafał Kościesza

Abstract

This thesis entitled “Physical Properties of High Pressure Phase of Oleic Acid” is divided into seven chapters. The first, introductory chapter, presents the aims of the thesis. The second section contains basic information on oleic acid, especially its physical and chemical properties in room temperature and atmospheric pressure conditions. Further the basic functional aspects of fatty acids and their more complex compounds are briefly described. The next section refers to pressure, its definition, generation and methods of measurement. Chapter four presents part of the results of the experimental work which constitutes basis of the thesis. The results presented in this chapter concern dielectric properties of oleic acid where the mean square dipole moment has been calculated. The resultant weak dipole moment may be induced by segmental movements of carbon atoms in acid chains. The movements partially cancel compensation of the moment, where the compensation is a result of anti-parallel alignment of dimmerised molecules. Additionally the dipole moment of monomers is also a component the resultant moment. The moment grew with pressure rise and it was induced by increase in number of elementary dipoles per volume unit. There was noticed no significant influence of phase change on the resultant dipole moment of the investigated sample as it was observed in the case of glycerides. In the fourth chapter analysis based on Fr¨ohlich’s theory of dielectrics is preceded by a short theoretical description. The fifth chapter presents the phase change observed in the sample with details of the phase change phenomena, and the thermodynamic and kinetic aspects of fats crystallization. Furthermore the chapter briefs the properties of oleic acid crystals at atmospheric pressure. Results of the experimental part concern the creation of the high pressure phase of oleic acid, which depends on thermodynamic conditions of the acid crystal growth. The thesis gives some major characteristics of the high pressure phase with their dependence on P-T conditions. Apart from that, so–called molecular collapse, that is a sudden drop in volume during pressure building, is analyzed. The final part of the chapter presents numeric calculations of thermodynamic parameters obtained from the equation of state surface and their dependence on pressure. The sixth section presents rheological properties of oleic acid in high pressure conditions. Two methods were adopted to research these properties, the first being a falling sinker type device and the other - an oscillatory method - depending on surface acoustic waves (SAW). Viscosity measured with the falling sinker revealed its rise with pressure rise and its fall with increasing temperature. In the range of pressure in which viscosity was measured it appeared to be well described by Barus formula where the upper limit of the range depends on temperature. The SAW method measurements were performed at room temperature. Relative viscosity vs pressure profile obtained with the method and with the falling sinker type device proved similar. The SAW method allowed to investigate rheological properties of acid in the P-VT region after the phase change where the sinker remained motionless. The seventh chapter is a summary.
Diploma typeDoctor of Philosophy
Author Rafał Kościesza (FP / HPRD)
Rafał Kościesza,,
- High Pressure Research Division
Title in EnglishPhysical properties of high pressure phase of oleic acid
Languagepl polski
Certifying UnitFaculty of Physics (FP)
Disciplinephysics / (physical sciences domain) / (physical sciences)
Defense Date21-10-2010
Supervisor Ryszard Siegoczyński (FP / HPRD)
Ryszard Siegoczyński,,
- High Pressure Research Division

Internal reviewers Bronisław Pura (FP / SRD)
Bronisław Pura,,
- Structural Research Division
External reviewers Bogdan Woźniak
Bogdan Woźniak,,
-
Pages144
Keywords in Englishxxx
Abstract in EnglishThis thesis entitled “Physical Properties of High Pressure Phase of Oleic Acid” is divided into seven chapters. The first, introductory chapter, presents the aims of the thesis. The second section contains basic information on oleic acid, especially its physical and chemical properties in room temperature and atmospheric pressure conditions. Further the basic functional aspects of fatty acids and their more complex compounds are briefly described. The next section refers to pressure, its definition, generation and methods of measurement. Chapter four presents part of the results of the experimental work which constitutes basis of the thesis. The results presented in this chapter concern dielectric properties of oleic acid where the mean square dipole moment has been calculated. The resultant weak dipole moment may be induced by segmental movements of carbon atoms in acid chains. The movements partially cancel compensation of the moment, where the compensation is a result of anti-parallel alignment of dimmerised molecules. Additionally the dipole moment of monomers is also a component the resultant moment. The moment grew with pressure rise and it was induced by increase in number of elementary dipoles per volume unit. There was noticed no significant influence of phase change on the resultant dipole moment of the investigated sample as it was observed in the case of glycerides. In the fourth chapter analysis based on Fr¨ohlich’s theory of dielectrics is preceded by a short theoretical description. The fifth chapter presents the phase change observed in the sample with details of the phase change phenomena, and the thermodynamic and kinetic aspects of fats crystallization. Furthermore the chapter briefs the properties of oleic acid crystals at atmospheric pressure. Results of the experimental part concern the creation of the high pressure phase of oleic acid, which depends on thermodynamic conditions of the acid crystal growth. The thesis gives some major characteristics of the high pressure phase with their dependence on P-T conditions. Apart from that, so–called molecular collapse, that is a sudden drop in volume during pressure building, is analyzed. The final part of the chapter presents numeric calculations of thermodynamic parameters obtained from the equation of state surface and their dependence on pressure. The sixth section presents rheological properties of oleic acid in high pressure conditions. Two methods were adopted to research these properties, the first being a falling sinker type device and the other - an oscillatory method - depending on surface acoustic waves (SAW). Viscosity measured with the falling sinker revealed its rise with pressure rise and its fall with increasing temperature. In the range of pressure in which viscosity was measured it appeared to be well described by Barus formula where the upper limit of the range depends on temperature. The SAW method measurements were performed at room temperature. Relative viscosity vs pressure profile obtained with the method and with the falling sinker type device proved similar. The SAW method allowed to investigate rheological properties of acid in the P-VT region after the phase change where the sinker remained motionless. The seventh chapter is a summary.
Thesis file
Kosciesza.pdf 9.1 MB

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