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Theoretical rheology
BOOK REVIEWS Advances in Liquid Crystals, Volume 1. Edited by GLENN H. BROWN, Academi: Press, New York, 1975. 32O. $31.50. This volume fulfills the wish expressed by the editor, Glenn H. Brown, " t h a t the serial publication will become indispensable for those who are working ill the field of liquid crystals or are planning to enter the field." The five chapters in Volume 1 cover both lyotropic and thermotropic liquid crystals. This valuable volume brings together major contributions by principal senior investigators from four different countries. The chapter by Per Ekwall summarizes a good portion of his life's work. This intricate field of lyotropic liquid crystals is revealed even in the outline for the chapter, which cites the elaborate alphabetical and subscript schemes necessary to define the multitudinous phases which have been observed. Rather than a survey report, this chapter represents a specific detailed documentation for the optical observations for a myriad of liquid crystal phase diagrams involving quite common compounds. A major ramification of such studies is in the biological applications which do not receive attention. The contribution of I. Chistyakov provides incisive information on the structure of thermotropic liquid crystals. He properly introduces his chapter by the citation of the classic review article by Brown and Shaw which, at least in the United States, initiated the modern era of liquid crystal research. A. Skoulios has interpreted an important class of polymers in terms of liquid crystals, although such graft and block copolymers are not normally considered on this continent within the framework of liquid crystals. This chapter describes the fundamental and practical aspects of polymer compatibility and segregation in liquid crystal terminology. George Smith gives a marvelous historical documentation and a valuable perspective on liquid crystals vis-g-vis plastic crystals. This chapter also discusses phase diagrams for liquid crystals with the exclusion of this reviewer's early and extensive publications. This chapter provides many valuable generalizations such as a tabulation of polymorphism of thermotropic liquid crystals. He gives simple, yet descriptive, definitions such as: "The basic difference between a liquid crystal and a plastic crystal on a molecular scale is largely one of geometry. Whereas LC molecules are
largely long and rigid, PC molecules are usually compact and globular." And "Most plastic crystals studied so far are organic molecular crystals. However, inert gases, certain metal hexafluorides, metals and other inorganic compounds can also form plastic crystalline phases." Finally, Dr. Kleman focuses his presentation on defects within liquid crystals. This first volume indicates the diverse nature of liquid crystalline systems which can extend from inorganic plastic crystals, to multiphase aqueous colloids, to commerdal block eopolymers, and to solutions of rod-like biopolymers. ROGER S. PORTER Materials Research Laboratory Polymer Science Engineering University of Massachusetts Amherst, Massachusetts 01002 Received December 4, 1975
Theoretical Rheology J. F. Huz~o~, J. R.A. PEARSON, AND K. WALTERS,Eds. Appfied Science Publishers Ltd., Ripple Road, Barking, Essex, England, 1975. xvi + 377 + pages, 73 illustrations. £12.00. This book is a conference proceeding comprising 24 papers offered at a 1974 meeting in Cambridge, England. The authors were selected from a group whose approach is known in rheological circles as continuum mechanics, and as a result there is little direct bearing on the real problems confronted by industrial rheologists, despite the claim of the editors to have linked theory with reality. They have tried, admirably, but a gap persists. This gap does not necessarily lead to condemnation of the book any more significantly than of the general state of theology these days. The authors are well regarded in their specialities and therefore the presumed lack of adequate refereeing is less likely to be a cause for concern. But contention is the rule rather than the exception in continuum mechanics where much of the development rides on the assumption made by the authors, with the result that the skill of the editors in organizing the papers into sections and having them pass muster must not be overlooked. Collection of comments from the audience in a well-executed report of the discussions following each lecture is a welcome and helpful innovation.
401 Copyright ~ 1976 by Academic Press, Inc. All rights of reproduction in any form reserved.
Journal of Colloid and Interface Science. Vol. 56, No. 2, August 1976
402
BOOK REVIEWS
A section on converging flow, comprising five papers, bears on problems of extrusion and spinning. Thermomechanics papers numbering five were either too general to be tested by experiment or too restricted to be of theoretical interest, and much time was devoted to the challenge of defining entropy. Five papers (a coincidence) on composites may some day apply to problems encountered in pigmented systems, soils, drawn filaments, biorheology, and perhaps high-speed coating. The concluding seven papers on rheometry come closest to utility; they cover elongation flow, normal stresses in shear flow, system resonance in oscillatory rheometry (a breakthrough), single relaxa-
fion time models, and kinematic anomalifies in nonNewtonian fluids. The typography is excellent and great care was taken to minimize errors, which would be devastating in a volume containing as many equations as this one. The book is recommended for the serious practicing rheologist in academic and industrial research but not for the practitioner who is not well grounded in the science. RAYMOND R. i~YERS Kent State University Kent, Ohio 44242 Received December 9, 1975
Journal of Colloid and Interface Science, Vol. 56, No. 2, August 1976
largely long and rigid, PC molecules are usually compact and globular." And "Most plastic crystals studied so far are organic molecular crystals. However, inert gases, certain metal hexafluorides, metals and other inorganic compounds can also form plastic crystalline phases." Finally, Dr. Kleman focuses his presentation on defects within liquid crystals. This first volume indicates the diverse nature of liquid crystalline systems which can extend from inorganic plastic crystals, to multiphase aqueous colloids, to commerdal block eopolymers, and to solutions of rod-like biopolymers. ROGER S. PORTER Materials Research Laboratory Polymer Science Engineering University of Massachusetts Amherst, Massachusetts 01002 Received December 4, 1975
Theoretical Rheology J. F. Huz~o~, J. R.A. PEARSON, AND K. WALTERS,Eds. Appfied Science Publishers Ltd., Ripple Road, Barking, Essex, England, 1975. xvi + 377 + pages, 73 illustrations. £12.00. This book is a conference proceeding comprising 24 papers offered at a 1974 meeting in Cambridge, England. The authors were selected from a group whose approach is known in rheological circles as continuum mechanics, and as a result there is little direct bearing on the real problems confronted by industrial rheologists, despite the claim of the editors to have linked theory with reality. They have tried, admirably, but a gap persists. This gap does not necessarily lead to condemnation of the book any more significantly than of the general state of theology these days. The authors are well regarded in their specialities and therefore the presumed lack of adequate refereeing is less likely to be a cause for concern. But contention is the rule rather than the exception in continuum mechanics where much of the development rides on the assumption made by the authors, with the result that the skill of the editors in organizing the papers into sections and having them pass muster must not be overlooked. Collection of comments from the audience in a well-executed report of the discussions following each lecture is a welcome and helpful innovation.
401 Copyright ~ 1976 by Academic Press, Inc. All rights of reproduction in any form reserved.
Journal of Colloid and Interface Science. Vol. 56, No. 2, August 1976
402
BOOK REVIEWS
A section on converging flow, comprising five papers, bears on problems of extrusion and spinning. Thermomechanics papers numbering five were either too general to be tested by experiment or too restricted to be of theoretical interest, and much time was devoted to the challenge of defining entropy. Five papers (a coincidence) on composites may some day apply to problems encountered in pigmented systems, soils, drawn filaments, biorheology, and perhaps high-speed coating. The concluding seven papers on rheometry come closest to utility; they cover elongation flow, normal stresses in shear flow, system resonance in oscillatory rheometry (a breakthrough), single relaxa-
fion time models, and kinematic anomalifies in nonNewtonian fluids. The typography is excellent and great care was taken to minimize errors, which would be devastating in a volume containing as many equations as this one. The book is recommended for the serious practicing rheologist in academic and industrial research but not for the practitioner who is not well grounded in the science. RAYMOND R. i~YERS Kent State University Kent, Ohio 44242 Received December 9, 1975
Journal of Colloid and Interface Science, Vol. 56, No. 2, August 1976