Moscow, U.S.S.R., 1977, 438 pp. Rub. 3.16.Chapter 1 (nearly a quarter of the book) deals with the basic notions of rheology to which the stress tensors and deformation tensors belong, and in which elastic solids, viscous liquids, and viscoelastic materials are considered. The treatment is mathematical and general, so that the main concern is with rheology rather than with polymers. In Chapter 2, equally long, on viscosity in shear flow, experimental data are used to illustrate the validity of the equations derived (such as the temperature superposition rule), but the theory still predominates. Fully eight sections in this chapter have headings such as A's theory, B's theory, etc.The next 90 pages are taken up by relaxation (viscoelastic) properties of flowing polymer systems. Here also many mechanical models of these systems are clearly and critically discussed. Chapter 5 is shorter and devoted to the normal shear stresses (the Weissenberg effect), including the flow birefringence. The next chapter is on high elasticity of liquid polymers; and the last is on uniaxial extension of polymers.The book certainly can be recommended to anyone working in one of the above mentioned areas of science (and can read Russian). A peculiarity of the text is that, although so many ideas and experimental data are covered, literature references are distinctly scarce. We find, e.g., on p. 176, eleven empirical equations relating the effective viscosity to the shear rate or the shear stress, but no authors are quoted. J. J. Bikerman 15810 Van Aken Blvd. Shaker Heights, Ohio

The dynamic shear modulus and the flow rate through capillaries under constant pressure and under constant velocity of the piston, have been measured for polybutadienes and polyisoprenes of narrow molecular weight distribution with molecular weights ranging, respectively, from 3.8 × 104 to 5.8 × 105 and from 1.06 × 105 to 6.02 × 105. The phenomena of the discontinuous increase of volume flow rate and self‐oscillatory flow regime at critical rates of deformation have been considered in detail. It is proposed that these phenomena are due to the induced transition of the polymer from the fluid to the high‐elastic state at higher deformation rates. As a result, an inference has been made that polybutadienes and polyisoprenes with a narrow molecular weight distribution in the high‐elastic state, behave in certain respects as crosslinked polymers incapable of displaying fluidity. The quantitative relationships among the viscoelastic characteristics measured under dynamic regimes, the parameters determining the critical flow regimes, and the molecular weights of polybutadienes and polyisoprenes have been worked out.

SynopsisA stud) has been made of the viscous properties of poly(paru-benzamide) (PBA) solutions in dmethyl acetamide, which undergo a transition from an isotopic to an anisotropic (liquid-crystal) state at a definite concentration C*. The polymer solutions behave in many respects (as regards the concentration and temperature dependence of viscosity, etc.) like solutions of low molecular weight compounds forming a liquidcrystal phase, although the transitions are less pronounced in the polymer solutions owing to their polydispersity. It is shown that the viscometric method, being extremely sensitive to C*, is convenient for determining phase diagrams of anisotropic polymer solutions. The values of C* as related to the molecular weight of PBA have been determined, and a general criterion for transition from isotropic to anisotropic solutions established; the latter has the form ( C M ) * = 1.3 X lo6 at 20°C. This criterion is in line with the condition for the formation of the liquid-crystal structure in a dispersion of rodlike particles as proposed by Flory.Generalized concentration dependences of viscosity have been plotted by reducing concentration to C* and viscosity, to the maximum viscosity a t the phase transition point. In investigating the flow properties of PBA solutions we revealed the existence of a yield point in the range of low shear stresses, and an intersection of the flow curves of solutions of different concentration at high shear stresses, which excludes a generalized representation of the flow curves in reduced ordinary-type coordinates.

A new macrokinetic equation of the autocatalytic type is proposed to describe the polymer crystallization process. The derived equation is compared with the known Avrami equation. It is shown to be consistent with the results of isothermal experiments.

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