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Unformatted text preview: le compounds at the 6 -31G*, 6-31+G** and 6-311++G** basis set levels.Predicted vibrational frequencies have been assigned and compared with experimental FT-IR spectra and they are supported each other. PHY-P5 RHEOLOGICAL PROPERTIES OF ESSENTIAL OIL EMULSION Saw, M. M. and Misni, M. Chemistry Department, Faculty Science, University of Malaya, 50603 Kuala Lumpur, Malaysia E-mail: email@example.com Essential oils are oils that carry a distinctive characteristic aroma from parts of a plant where it is been extracted. Essential oils have widely been known for its aromatherapy and therap eutic effect on human. A high concentration of Thyme essential oil in emulsion has been formulated using Olive oil as carrier oil and stabilized by glycolipids surfactants such as sucrose stearate, sucrose palmitate and sucrose myristate. Triton X-100 was added into the emulsion system to aid the formation of oil in water emulsion system as it has a higher interaction and compatibility with Thyme oil that mostly consist of phenolic compounds with short hydrocarbon chain. Cetearate -20 was used to increase the viscosity of the emulsion system. The physical properties of the emulsions are evaluated by stability test conducted at 45 °C, zeta potential and mean droplet size by means of visual observation using ZetaSizer and polarising microscope respectively. Oscillatory and viscometry studies were carried out on the emulsion samples at temperature of 30 °C. Flow curve obtained shows that the emulsions always exhibit shear thinning behaviour and obeys power law. Viscosity, critical strain and elastic modulus magni tude decrease with the decrease lipid chain length of the glycolipid surfactant and increase concentration of Cetearate-20. Decrease in viscosity is mainly due to decrease in emulsion droplet size, while decreased in droplet integrity affects the critical strain and elastic modulus. The emulsions maintain its viscoelasticity even at low viscosity. Frequency sweep data show that elastic modulus (G’) dominant over viscous modulus (G”) responded through the measured frequency (ω) domain implies that the emulsions exhibit solid like behavio...
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- Spring '11