Preface

Encyclopedia of polymer blends will include scientific publications in various areas of blends. Polymer blends are mixtures of two or more polymers and/or copolymers. Polymer blending is used to develop new materials with synergistic properties that are not achievable with individual components without having to synthesize and scale up new macromolecules. Along with a classical description of polymer blends, articles in the encyclopedia will describe recently proposed theories and concepts that may not be accepted yet but reflect future development. Each article provides current points of view on the subject matter. These up-to-date reviews are very helpful for understanding the present status of science and technology related to polymer blends.

The encyclopedia will be the source of existing knowledge related to polymer blends and will consist of five volumes. Volume 1 describes the fundamentals including the basic principles of polymer blending, thermodynamics, miscible, immiscible, and compatible blends, kinetics, and composition and temperature dependence of phase separation. Volume 2 provides the principles, equipment, and machinery for polymer blend processing. Volume 3 deals with the structure of blended materials that governs their properties. Volume 4 describes various properties of polymer blends. Volume 5 discusses the blended materials and their industrial, automotive, aerospace, and other high technology applications. Individual articles in the encyclopedia describe the topics with historical perspective, the state-of-the-art science and technology and its future.

This encyclopedia is intended for use by academicians, scientists, engineers, researchers, and graduate students working on polymers and their blends.

Volume 3 is devoted to the structure of blended materials that governs their properties and consists of seven chapters. These chapters cover glass transition phenomena, crystallization and melting behavior, structure-property relationship, morphology and structure of polymer blends, and blends containing various nanofillers. Existing theoretical approaches to describe morphology and structure of blends are extensively discussed. The importance of flow, rheology of components, and rheological aspects of blends is emphasized. These aspects are detailed below and build on each other.

Chapter 1 addresses a number of topics, including general phenomenology, theories, and metrology of the glass transition of polymer blends. The theoretical foundations and practical examples from the analysis of experimental data for miscible systems including binary polymer blends, oligomer/polymer mixtures, and copolymers are critically reviewed. The applicability ranges of important theoretical, semi-empirical, or purely phenomenological mixing rules used for describing the compositional dependence of the glass transition are explored. Examples demonstrating the physical meaning of model parameters are given. A number of case studies involving hydrogen-bonding binary polymer blends and ternary polymer systems are presented. The chapter ends by summarizing general rules that relate the results of glass-transition studies with structural characterizations and miscibility evaluations of polymer blends.

Chapter 2 deals with crystallization and melting behavior of crystalline/amorphous and crystalline/crystalline polymer blends that are strongly influenced by the miscibility and morphology of the polymers. The interspherulitic and intraspherulitic segregations are considered in the case of crystalline/amorphous polymer blends. The crystallization and morphology of crystalline/crystalline polymer blends related to differences in the melting points of each of component, thermodynamic, and kinetic factors during crystallization are discussed. The influence of the composition, rheological characteristics, the interfacial tension, and processing conditions on the superstructures of immiscible polymer blends is presented. Immiscible blends with a crystallizable matrix and an amorphous dispersed phase, and blends with an amorphous matrix and a crystallizable dispersed phase are discussed. The effect of the addition of a copolymer as a compatibilizer that decreases or increases the tendency for crystallization of polymer blends is considered. Reactive compatibilization of polymer blends and its influence on crystallization and morphology are discussed. In addition, the effect of the fillers on the crystallization of immiscible polymer blends is presented.

Chapter 3 is devoted to the morphology and structure of crystalline/crystalline polymer blends with strong emphasis to the recent progress in this field. It focuses mainly on the influence of crystallization on the microphase separation and the effect of phase separation on the crystallization of the blending components. Special attention is given to the various possible crystalline morphologies and phase structures formed in different crystalline/crystalline polymer blends under controlled crystallization conditions. The mechanism of the formation of specific morphologies, such as interpenetrating spherulites, is discussed with elaborately selected model systems. Also, examples of specific polymer blends are presented along with their morphology and structure.

Chapter 4 describes the physics and chemistry of rubber-plastic blends and their structure-property relationship. A greater attention is paid to understanding the interface and the role of the physical process in enabling and extending the interfacial effects of rubber-plastic blends. Various models for the rubber toughening of plastics are described. Numerous techniques that are for the characterization of rubber-plastic blends are provided. Many industrially important examples of many rubber-plastic blends are given along with their structure and morphology.

Chapter 5 deals with the current state of knowledge on the structure and morphology of rubber-rubber blends. Characterization techniques suitable for the study of these blends are introduced. The effect of material parameters and processing conditions on the structure and morphology of rubber-rubber blends is discussed along with the issues related to the filler distribution and curative migration in blends. Various blends containing different pairs of rubbers are presented. When dealing with specific rubber-rubber blends, the characteristics of each rubber component in the blends, such as the crystallization behavior, curing state, and preference of filler distribution is considered, since all these factors influence the blend morphology and structure.

Chapter 6 deals with the miscibility, phase morphology, and properties of ternary polymer blends. A number of interesting cases of miscibility and immiscibility in ternary blends are examined. It is stressed that a simple summation of the contributions of binary interactions to the free energy of mixing in ternary polymer blends is a simplification. The review is devoted to the prediction and formation of phase morphologies in immiscible binary and ternary polymer blends. The theory of spreading coefficients is analyzed in detail and the formation of all the possible morphological types is discussed. Particularly, phase morphologies with separated, fully encapsulated, and partially capsulated dispersed phases are described. Effects of blend composition, kinetic factors as well as the interaction of droplets upon mixing cycle are discussed in detail. An attempt is made to provide the understanding of the principles of the blend formation influencing the mechanical properties of ternary blends. Several cases of property-composition relationships for ternary composition are revised. A hypothesis is offered claiming that the experimental values of the properties of the ternary blends are much closer to those calculated by the additivity properties of the corresponding binary blends.

Chapter 7 deals with the morphology and structure of polymer blends containing various nanofillers. This subject area is increasingly growing due to the interest in polymer nanocomposite indicating that small addition of nanoparticles can dramatically change various properties of a polymer matrix including electrical and thermal conductivity, dielectric and magnetic permeability, gas barrier properties, and mechanical performances. A combination of polymer blending and nanoscale filler reinforcement has received a special attention due to the fact that the addition of nanofillers into multiphase polymer blends is proved to be an efficient strategy to develop a new family of polymer nanocomposites with a great tailoring potential for producing products with a combination of prescribed properties. Among various nanofillers considered in this chapter are silica nanoparticles (hydrophilic and hydrophobic), layered silicate, surface modified nanosilicates (nanoclays), single and multiwalled carbon nanotubes, and graphene along with their surface modification.

There are many people who contributed to the completion of this volume. I wish to express my profound appreciation to the contributors of the various chapters for being patient with my requests for revisions and corrections. I would also like to thank Dr. David Simmons for providing excellent review. I am thankful to Wiley-VCH Publishers for undertaking this project and for their patience, understanding, and cooperation with the authors at all stages of preparation. Finally, the support and patience of my family and the families of all the chapter authors contributed to the completion of this volume.