Ultrasonic Study of Association in Fatty Acids

概要

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Association factors (x) for twelve fatty acids have been evaluated by using the method suggested by Jacobson from a knowledge of the deviations from the equation relating the adiabatic compressibility (β_<ad>) with the intermolecular free length (L_f) given by L_f^2=K^2β_<ad>, where K is a temperature dependent constant. The fatty acids show large deviations from Lagemann's empirical rule M^<1/2>(dc/dT)=39.0, where M is the molecular weight and dc/dT is the temperature coefficient of the ultrasonic velocity. When association is taken into account, however, the product (xM)^<1/2>dc/dT gives a constant value of 43.50. The constant 'a' in Rao's formula R=a(T_c/M)^<1/6>V_c, where R is Rao's constant, M is molecular weight and T_c, V_c are critical constants, also shows deviations from the value of 2.68 for normal liquids, but if xM is substituted in place of M in the formula, the constant a for fatty acids comes out to be the same as that of normal liquids.
社団法人日本物理学会の論文
1974-09-15