RELAXATIONAL PROPERTIES OF SHEAR AND BULK ELASTIC-MODULI OF VISCOUS-LIQUIDS

Complex shear moduli G = G1 + iG2 and elastic bulk moduli K = K1 + iK2 have been calculated for glycerol and various alcohols, using the rec tangular form of the viscoelastic relaxation time distribution functio n used in the theory of magnetic disaccommodation. The relaxational bu lk moduli K(r) have been estimated from the temperature dependence of the velocity of ultrasonic waves and the hole theory of liquids. Real and imaginary parts of K and G have been studied as functions of the f requency of the applied stresses, the mean relaxation time and the lim iting values tau1 and tau2 of relaxation time distribution. It has bee n shown that values of G1 and G2 calculated in this work are in good a greement with those obtained from the Barlow, Erginsav and Lamb model of viscoelastic liquids, if the value of the ratio tau2/tau1 is taken as about 1000. The coefficient Q = K1/K2 used by Qaisar to characteriz e elastic energy dissipation in viscoelastic materials has been calcul ated using the rectangular relaxation time distribution function. The value of square-root K0/K(infinity) determines the maximum of Q, where K0 and K(infinity) are the limiting bulk moduli at low and high frequ encies. In the case of alcohols, values of K0/K(infinity) decrease wit h increasing molecular mass of the chemical compound.