For several decades, polymer science has sought to rationalize the mechanical and thermodynamic properties of polymer networks largely within the framework of statistical thermodynamics. Much of this effort has been directed toward the rubbery rather than the glassy state. It is generally assumed that networks possess an av erage composition to which average properties may be assigned; from such a continuum view, a powerful analysis of such properties as modulus, swelling, birefringence and thermoelasticity has emerged. In the years following the rise of polymer characterization (the late 40's and early 50's), many scientists began to study ap parent relations between the properties of linear polymer molecules and the networks obtainable therefrom. This search was also stimu lated by the wide range of applications of polymer networks in com mercial elastomers, thermosets and coatings. Frequently, these data were confidently matched with curves obtained from statisti cally describable models of networks of ghost chains, uniformly distributed in space. More recently, it has become apparent that polymer chains in networks are not as ideal as assumed in the formulation of statis tical models, and there has been a shift in emphasis towards the less than ideal, perturbed and possibly inhomogeneous networks which are more frequently encountered in practice. The continuum approach, however, had to be developed before inhomogeneous systems could be described; the present volume, therefore, contains both views."

These volumes, 3 and 4, of Fracture Mechanics of Ceramics con stitute the proceedings of an international symposium on the frac ture mechanics of ceramics held at the Pennsylvania State Univer sity, University Park, PA on July 27, 28, and 29, 1977. Volumes 1 and 2 were published previously as the proceedings of a sympo sium of the same name held July 11, 12, and 13, 1973, also at Penn State. All four volumes published to date concentrate on the fracture aspects of the mechanical behavior of brittle ceramics in terms of the characteristics of cracks. The program chairmen gratefully acknowledge the financial as sistance for the symposium provided by the Office of Naval Re search, the Energy Research and Development Administration, and the Army Research Office. Without their support the quality and mag nitude of this conference simply would not have been possible. Numerous individuals contributed to the success of the con ference, but unfortunately they cannot all be listed here. However the program chairmen would especially like to recognize the contri butions of Penn State Conference Coordinator, Mr. Ronald Avillion, whose expertise in planning and organization was indispensable; Dr. Fred R. Matson for his interesting after dinner speech; and Drs. A. M. Diness, J. C. Hurt, and D. W. Readey for their en couragement and valuable suggestions regarding the program. Finally, we wish to also thank our joint secretaries for the patience and help in bringing these proceedings to press."

Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.

Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.

Volume A of Handbook of Polymer Nanocomposites deals with Layered Silicates. In some 20 chapters the preparation, architecture, characterisation, properties and application of polymer nanocomposites are discussed by experts in their respective fields

Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.

These volumes, 3 and 4, of Fracture Mechanics of Ceramics con stitute the proceedings of an international symposium on the frac ture mechanics of ceramics held at the Pennsylvania State Univer sity, University Park, PA on July 27, 28, and 29, 1977. Volumes 1 and 2 were published previously as the proceedings of a sympo sium of the same name held July 11, 12, and 13, 1973, also at Penn State. All four volumes published to date concentrate on the fracture aspects of the mechanical behavior of brittle'ceramics in terms of the characteristics of cracks. The program chairmen gratefully acknowledge the financial as sistance for the symposium provided by the Office of Naval Re search, the Energy Research and Development Administration, and the Army Research Office. Without their support the quality and mag nitude of this conference simply would not have been possible. Numerous individuals contributedto the success of the con ference, but unfortunately they cannot all be listed here. However the program chairmen would especially like to recognize the contri butions of Penn State Conference Coordinator, Mr. Ronald Avillion, whose expertise in planning and organization was indispensable; Dr. Fred R. Matson for his interesting after dinner speech; and Drs. A. M. Diness, J. C. Hurt, and D. W. Readey for their en couragement and valuable suggestions regarding the program. Finally, we wish to also thank our joint secretaries for the patience and help in bringing these proceedings to press."

The fluorine atom, by virtue of its electronegativity, size, and bond strength with carbon, can be used to create compounds with remarkable properties. Small molecules containing fluorine have many positive impacts on everyday life of which blood substitutes, pharmaceuticals, and surface modifiers are only a few examples. Fluoropolymers, too, while traditionally associated with extreme hi- performance applications have found their way into our homes, our clothing, and even our language. A recent American president was often likened to the tribology of PTFE. Since the serendipitous discovery of Teflon at the Dupont Jackson Laboratory in 1938, fluoropolymers have grown steadily in technological and marketplace importance. New synthetic fluorine chemistry, new processes, and new apprec- tion of the mechanisms by which fluorine imparts exceptional properties all contribute to accelerating growth in fluoropolymers. There are many stories of harrowing close calls in the fluorine chemistry lab, especially from the early years, and synthetic challenges at times remain daunting. But, fortunately, modern techniques and facilities have enabled significant strides toward taming both the hazards and synthetic uncertainties. In contrast to past environmental problems associated with fluorocarbon refrigerants, the exceptional properties of fluorine in polymers have great environmental value. Some fluoropolymers are enabling green technologies such as hydrogen fuel cells for automobiles and oxygen-selective membranes for cleaner diesel combustion.

Lead-based paint has become a national issue and will continue to be a hi- priority focus ofnational, state, and local agencies until there is no lead-based paint in the United States. Lead-based paint has become a tremendous health hazard for people and animals. Lead-based paint has been in widespread use throughout Europe and the United States. Lead has been known to be a health hazard since the time ofPliny the Elder (A. D. 23-79), but it was deemed that the advantages of lead in paint outweighed the health hazards. There has been a change in outlook, and in 1973 the U. S. Congress banned all lead paint from residential structures. A voluminous number of law suits have been initiated since, and continue to be litigated with the purpose of determining the parties responsible for the lead poisoning of children and others and to exact the indemnities. Lead-based paint is still authorized for use on bridges and nonresidential structures, and thousands of city, state, military, and federal government housing projects still contain lead-based paint. This paint must be removed if these dwellings are to be safe living quarters, especially for children. Aba- ment techniques continue to be evaluated; some have been used successfully. Lead-based paint abatement will continue into the next century, and it is hoped that this comprehensive volume will serve as a guide for those seriously interested in this important subject.

To the biochemist, water is, of course, the only solvent worthy of consideration, because natural macromolecules exhibit their remarkable conformational properties only in aqueous media. Probably because of these remarkable properties, biochemists do not tend to regard proteins, nucleotides and polysaccharides as polymers in the way that real polymer scientists regard methyl methacrylate and polyethylene. The laws of polymer statistics hardly apply to native biopolymers. Between these two powerful camps, lies the No-man's land of water soluble synthetic polymers: here, we must also include natural polymers which have been chemically modified. The scientific literature of these compounds is characterized by a large number of patents, which is usually a sign of little basic understanding, of 'know-how' rather than of 'know-why'. Many of the physical properties of such aqueous solutions are intriguing: the polymer may be completely miscible with water, and yet water is a 'poor' solvent, in terms of polymer parlance. ~kiny of the polymers form thermorever sible gels on heating or cooling. The phenomena of exothermic mixing and salting-in are common features of such systems: neither can be fully explained by the available theories. Finally, the eccentric behaviour of polyelectrolytes is well documented. Despite the lack of a sound physico-chemical foundation there is a general awareness of the importance of water soluble vinyl, acrylic, polyether, starch and cellulose derivatives, as witnessed again by ~he vast patent literature.

In this reference, the author thoroughly reviews the current state of condensed phosphate chemistry. A unique feature of this volume is an examination of the recent developments in X-ray structural techniques, reporting on fundamental results obtained through their use. Enhanced by comprehensive tables reporting crystal data, chapters identify and characterize more than 2,000 compounds. Additional features include a concise survey of the historical development of condensed phosphate chemistry; the presently accepted classification system; a review of each family of condensed phosphates and much more.

Water-soluble polymers have been attracting increasing atten tion because of their utility in industrial applications of great current concern. Perhaps preeminent among these is their ability to flocculate suspended solids, e.g., wastes in municipal sew age-treatment plants or pulp in papermaking. other important appli cations are to aid in so-called secondary recovery of petroleum, to reduce turbulent friction of water, and as components of water-based finishes developed in response to environmental con straints. Some water-soluble polymers have shown interesting bio logic activity, which is being investigated further. This book is based on papers presented at a symposium held by the American Chemical Society, Division of Organic Coatings and Plastics Chemistry, in New York City on 30-31 August 1972. The large attendance and the favorable response of the audience con firmed not only our view of the importance of the field but also the need to bring these topics together. The chapters in this book are generally enlarged and more detailed, with more complete bibliographies, than the papers presented at the Symposium. They include not only the important applications described above, but also descriptions of new syntheses and characterization methods."

Until comparatively recently, trace analysis techniques were in general directed toward the determination of impurities in bulk materials. Methods were developed for very high relative sensitivity, and the values determined were average values. Sampling procedures were devised which eliminated the so-called sampling error. However, in the last decade or so, a number of developments have shown that, for many purposes, the distribution of defects within a material can confer important new properties on the material. Perhaps the most striking example of this is given by semiconductors; a whole new industry has emerged in barely twenty years based entirely on the controlled distribu tion of defects within what a few years before would have been regarded as a pure, homogeneous crystal. Other examples exist in biochemistry, metallurgy, polyiners and, of course, catalysis. In addition to this of the importance of distribution, there has also been a recognition growing awareness that physical defects are as important as chemical defects. (We are, of course, using the word defect to imply some dis continuity in the material, and not in any derogatory sense. ) This broadening of the field of interest led the Materials Advisory Board( I} to recommend a new definition for the discipline, "Materials Character ization," to encompass this wider concept of the determination of the structure and composition of materials. In characterizing a material, perhaps the most important special area of interest is the surface.

Morphology-Property Relationship in Rubber-Based Nanocomposites: Some Recent Developments, by A. K. Bhowmick, M. Bhattacharya, S. Mitra, K. Dinesh Kumar, P. K. Maji, A. Choudhury, J. J. George and G. C. Basak; * Rubber-Clay Nanocomposites: Some Recent Results, by Amit Das, De-Yi Wang, Klaus Werner Stoeckelhuber, Rene Jurk, Juliane Fritzsche, Manfred Kluppel and Gert Heinrich; * Surface Modification of Fillers and Curatives by Plasma Polymerization for Enhanced Performance of Single Rubbers and Dissimilar Rubber/Rubber Blends, by J. W. M. Noordermeer, R. N. Datta, W. K. Dierkes, R. Guo, T. Mathew, A. G. Talma, M. Tiwari and W. van Ooij; * Recent Developments on Thermoplastic Elastomers by Dynamic Vulcanization, by R. Rajesh Babu and Kinsuk Naskar; * PTFE-Based Rubber Composites for Tribological Applications, by M. S. Khan and G. Heinrich

Shunsuke Hirotsu "Coexistence of Phases and the Nature of First-Order Transition in Poly-N-isopropylacrylamide Gels," Masayuki Tokita "Friction between Polymer Networks of Gels and Solvent," Masahiro Irie "Stimuli-Responsive Poly(N-isopropyl- acrylamide), Photo- and Chemicals-Induced Phases Transitions Edward Cussler, Karen Wang, John Burban"Hydrogels as Separation Agents," Stevin Gehrke "Synthesis, Equilibrium Swelling, Kinetics Permeability and Applications of Environmentally Responsive Gels," Pedro Verdugo "Polymer Gel Phase Transition in Condensation- Decondensation of Secretory Products," Etsuo Kokufuta "Novel Applications for Stimulus-Sensitive Polymer Gels in the Preparation of Functional Immobilized Biocatalysts," Teruo Okano "Molecular Design of Temperature-Responsive Polymers as Intelligent Materials," Atsushi Suzuki "Phase Transition in Gels of Sub-Millimeter Size Induced by Interaction with Stimuli," Makoto Suzuki, O. Hirasa "An Approach to Artificial Muscle by Polymer Gels due to Micro-Phase Separation."

F.J. Balta-Calleja, A. Gonzalez Arche, T.A. Ezquerra, C. Santa Cruz, F. Batallan, B. Frick, G.A. Arche, E. Lopez Cabarcos, Structure and Properties of Ferroelectric Copolymers of Poly (vinylidene) Fluoride H.G. Kilian, T. Pieper Packing of Chain Segments: A Method for Describing X-Ray Patterns of Crystalline, Liquid Crystalline and Non-Crystalline Polymers K. Miyasaka PVA-Iodine Complexes: Formation, Structure and Properties

In 1975, a symposium was held in Midland, Michigan, co-sponsored by the Dow Chemical Company and the then Midland Macromolecular Institute in honor of Raymond F. Boyer on the occasion of his 65th birthday and retirement from Dow. The topic of that first Boyer symposium dealt with an area of interest to Boyer, namely, polymer transitions and relaxations. One decade later, after ten years of additional fruitful scientific endeavor at MMI, Ray Boyer was again honored with a symposium, this time celebrating his 75th birthday and 10th anniversary at the Michigan Molecular Institute. The topic of the second Boyer symposium in 1985 was somewhat more focused, this time concentrating on the subject of order (or structure) in the amorphous state of polymers and the attendant polymer transitions that are observed. This volume contains the full manuscripts of the contributors to the 17th MMI International Symposium, held in Midland, Michigan on August 18-21, 1985. Eleven one-hour plenary lectures and ten 20-minute contributed papers were presented during the Symposium. An open forum panel discussion was also scheduled; the edited transcript of that session is included at the end of this volume. One of our tasks in organizing this Symposium was to attempt to gather together a number of speakers who would be able to define what, if any, physical structure might be present in anwrplwus polymers and what the nature of this order might be.

One of the most significant challenges facing mankind in the twenty-first century is the development of a sustainable global economy. Within the scientific community, this calls for the development of processes and technologies that will allow the sustainable production of materials from renewable natural resources. Plant material, in particular lignin, is one such resource. During the annual production of about 100 million metric tons of chemical wood pulps worldwide, approximately 45 and 2 million metric tons/year of kraft lignin and lignosulfonates, respectively, are also generated. Although lignosulfonates have found many applications outside the pulp and paper industry, the majority of kraft lignin is being used internally as a low-grade fuel for the kraft pulping operation. A surplus of kraft lignin will become available as kraft mills increase their pulp production without expanding the capacity of their recovery boilers that utilize lignin as a fuel. There is a tremendous opportunity and an enormous economic incentive to find better uses of kraft lignin, lignosulfonates and other industriallignins. The pulp and paper industry not only produces an enormous amount of lignins as by products of chemical wood pulps, but it also utilizes about 10 million metric tons of lignin per year as a component of mechanical wood pulps and papers. Mechanical wood pulps, produced in a yield of 90-98% with the retention of lignin, are mainly used to make low-quality, non-permanent papers such as newsprint and telephone directories because of the light-induced photooxidation of lignin and the yellowing of the papers.

Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.

Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.

These volumes constitute the Proceedings of a Symposium ort the Fracture Mechanics of Cerarnics, held at the Pennsylvania State University, University Park, Pennsylvania, July 11, 12, and 13, 1973. The theme of the symposium focussed on the mechanical behavior of brittle cerarnics in terms of the characteristics of cracks. The 52 contributed papers by 87 authors, present an overview of the cur rent understanding of the theory and application of fracture mechan ics to brittle cerarnics. The prograrn chairmen gratefully acknowledge the financial assistance for the Symposium provided by the Office of Naval Re search, the College of Earth and Mineral Sciences of the Pennsyl vania State University, the Materials Research Center of Lehigh University, Bethlehem, Pennsylvana and Westinghouse Research Laboratories, Pittsburgh, Pennsylvania. Special appreciation is extended to the expert organization provided by the J. Orvis Keller Conference Center of the Pennsyl vania State Conference Center of the Pennsylvania State University. In particular, Mrs. Patricia Ewing should be acknowledged for the excellent prograrn organization and planning. Dean Harold J. O'Brien, who was featured as the after-dinner speaker and who presented a most stimulating talk on the cornrnunication between people, also contrib uted to the success of the meeting. Finally, we also wish to thank our joint secretaries for the patience and help in bringing these Proceedings to press. University Park R. C. Bradt Bethlehem D. P. H. Hasseiman Pittsburgh, Pennsylvania F. F. Lange July, 1973 v CONTENTS OF VOLUME 2 Contents of Volume 1 . . . . . . . . . . . . . . . . . . .