トリステアリン-トリオレイン二成分系のレオロジー的性質 : 分散形のレオロジー, その他

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Pure glyceryl tristearate was prepared as solid fat particles by complete hydrogenation of olive oil, and pure glyceryl trioleate was prepared as liquid oil by solvent fractional of olive oil. The rheological properties of mixtures of these two components were investigated in comparison with their microstructure revealed by X-ray diffraction. The flow curves of various mixtures were measured by a Weissenberg rheogoniometer and the temperature dependence of viscoelasticity was studied by an forced oscillation apparatus. Two kinds of specimen were prepared. One is a suspension body, that is, simple mixture of triolein and tristearin which is uniformly mixed by stirring it with a glass rod at room temperature, and the other is a molten body, that is, the mixture of tristearin and triolein which is molten at 90℃ and recrystallized at 0℃. In each mixture the fraction of tristearin is from 5 to 45% by weight. All the flow curves for mixtures of 5 to 25% tristearin were typically non-Newtonian. From the relation between the apparent viscosity η and the rate of shear γ^・, the shear rate dependence of viscosity -(d logη/d logγ^・) was calculated at a high rate of shear 20sec.^<-1> and at a low rate of shear 1sec.^<-1>. From the relation between the fraction of tristearin and -(d logη/d logγ^・), it was observed that the shear rate dependence of viscosity was much larger for the suspension body and at a lower rate of shear. These results suggest that a firm texture is developed in the specimen after the melting of suspension due to the formation of network structure of crystallites of tristearin. The temperature dependence of dynamic elastic modulus E and loss factor tan σ has been measured for mixtures of 25 to 45% tristearin. It has been found that the mixtures of 25 to 40% tristearin show entropy elasticity, that is, the elastic modulus increases with the rise of temperature and that on the other hand, a 45% tristearin mixture shows energy elasticity, that is the elastic modulus decreases with the rise of temperature . It is reasonably assumed that a network structure having crosslinked molecular chains such as exists in rubber in the present mixtures. A number of small crystallites of tristearin would produce the crosslinking points, The molecular weight between crosslinks was tentatively calculated from the elastic modulus at room temperature using Kuhn's theoretical equation for rubber elasticity and found to be in the same order with the molecular weight of tristearin and triolein.
社団法人日本材料学会の論文
1964-05-15

トリステアリン-トリオレイン二成分系のレオロジー的性質 : 分散形のレオロジー, その他

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