Studies on Interaction between Castor Oil and Dissolved Water by Hot Wire Method

Kyo TAKAOKA*, Koichi KOBAYASHI, Masashi TAKAHASHI and Mototaka SONE†

Department of Energy Science and Engineering, Faculty of Engineering, Musashi Insutitute ofTechnology; 1-28-1 Tamazutumi, Setagaya-ku, Tokyo 158-8557 Japan
† Department of Electrical and EIectronics Engineering, Faculty of Engineering, Musashi Instituteof Technology; 1-28-1 Tamazutsumi, Setagaya-ku, Tokyo 158-8557 Japan

The effect of added water on structual change in castor oil was studied by a hot wire method. The change in kinematic-viscosity coefficients for anhydrous and hydrous castor oil were measured to evaluate the interaction between water and castor oil molecules.
The kinematic-viscosity coefficient gradually increases with increasing the water content and reaches the maximum value at 4075 ppm of water. However, with the further increase in water, the kinematic-visocosity coefficient sharply decreases due to the destruction in the liquid structure of castor oil. Eventually, the maximum value is attained at the solubility limit of water in oil.
The ratio of the number of hydroxy groups of glycerol triricinoleate in the castor oil to the amount of water molecule is 5/mol H2O at the maximum kinematic-viscosity coefficient, where the liquid structure is developed due to the intermolecular crosslinking of water.
However, the crosslinking of water disappears at the solubility limit of water and a water cluster is formed. In this case, water acts as a kind of a plasticizer and decreases the kinematic-viscosity coefficient.
The liquid sturucture is gradually destroyed at each water content with the rise in temperature from 10 to 50 °C and it almost disappears at 60 °CD


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