Assignment of the Glass Transition


Book Description




Conformational Motion and Disorder in Low and High Molecular Mass Crystals


Book Description

The broad field of conformational motion disorder in crystals is described with particular attention to the separation from the well known mesophases of liquid crystals and plastic crystals. Structure, thermodynamics and motion of a larger number of small and large molecules are discussed. Of special interest are the borderlines between smectic and high viscosity liquid crystals and condis crystals and between plastic crystals and condis crystals as complicated by pseudorotation, jumping between symmetry-related states and hindered rotation. This paper illustrates the wide distribution of conformational disorder in nature. Condis crystals and glasses (Conformational Disorder) can be found in small and large molecule systems made of organic, inorganic and biological compounds. The condis state was newly discovered only four years ago. In this article over 100 examples are discussed as example of the condis state. In many cases the condis state was suggested for the first time. Motion in the Condensed State, Condis Crystals and their Relation to Plastic Crystals, Condis Crystals of Flexible Macromolecules, Condis Crystals and their Relation to Liquid Crystals, Condis Crystals of Stiff Macromolecules.







Glassy, Amorphous and Nano-Crystalline Materials


Book Description

Provides a summary of non-equilibrium glassy and amorphous structures and their macro- and microscopic thermal properties. The book contains a carefully selected works of fourteen internationally recognized scientists involving the advances of the physics and chemistry of the glassy and amorphous states.




Crystallization of Polymers


Book Description

Since the discovery that polymer single crystals are composed of chain folded macromolecules in 1957, the crystallization of polymers has attracted considerable interest and still provides fascinating and fruitful areas of research. Only a few books have been fully devoted to the crystallization of polymers in the past. This book contains the proceedings of the NATO ARW devoted to the `Crystallization of Polymers' which took place in September 1992 at the University of Mons-Hainaut (Belgium). In view of the variety of papers devoted to the crystallization of polymers, this book will be used in the next few years as a reference book for scientists concerned in the field of polymer physical chemistry. Crystallization of Polymers is mainly devoted to the experimental and theoretical study of the crystallization of synthetic polymers. As a kinetic study of the growth of polymer crystals should always be preceded by a morphological or a structural investigation, the structure, the morphology of polymer crystals and more particularly the lamellar and supralamellar organizations, as well as the nature of the crystal amorphous interface are reviewed and discussed.




Phase Transitions in Polymers: The Role of Metastable States


Book Description

A classical metastable state possesses a local free energy minimum at infinite sizes, but not a global one. This concept is phase size independent. We have studied a number of experimental results and proposed a new concept that there exists a wide range of metastable states in polymers on different length scales where their metastability is critically determined by the phase size and dimensionality. Metastable states are also observed in phase transformations that are kinetically impeded on the pathway to thermodynamic equilibrium. This was illustrated in structural and morphological investigations of crystallization and mesophase transitions, liquid-liquid phase separation, vitrification and gel formation, as well as combinations of these transformation processes. The phase behaviours in polymers are thus dominated by interlinks of metastable states on different length scales. This concept successfully explains many experimental observations and provides a new way to connect different aspects of polymer physics.* Written by a leading scholar and industry expert* Presents new and cutting edge material encouraging innovation and future research* Connects hot topics and leading research in one concise volume




Thermal Analysis of Polymeric Materials


Book Description

Thermal analysis is an old technique. It has been neglected to some degree because developments of convenient methods of measurement have been slow and teaching of the understanding of the basics of thermal analysis is often wanting. Flexible, linear macromolecules, also not as accurately simply called polymers, make up the final, third, class of molecules which only was identified in 1920. Polymers have neverbeenfullyintegratedintothedisciplinesofscienceandengineering. Thisbook is designed to teach thermal analysis and the understanding of all materials, flexible macromolecules, as well as those of the small molecules and rigid macromolecules. The macroscopic tool of inquiry is thermal analysis, and the results are linked to microscopic molecular structure and motion. Measurements of heat and mass are the two roots of quantitative science. The macroscopic heat is connected to the microscopic atomic motion, while the macroscopic mass is linked to the microscopic atomic structure. The macroscopic unitsofmeasurementofheatandmassarethejouleandthegram,chosentobeeasily discernable by the human senses. The microscopic units of motion and structure are 12 10 the picosecond (10 seconds) and the ångstrom (10 meters), chosen to fit the atomic scales. One notes a factor of 10,000 between the two atomic units when expressed in “human” units, second and gram—with one gram being equal to one cubic centimeter when considering water. Perhaps this is the reason for the much better understanding and greater interest in the structure of materials, being closer to human experience when compared to molecular motion.




NMR Methods for Characterization of Synthetic and Natural Polymers


Book Description

Since the introduction of FT-NMR spectroscopy around five decades ago, NMR has achieved significant advances in hardware and methodologies, accompanied with the enhancement of spectral resolution and signal sensitivity. Rapid developments in the polymers field mean that accurate and quantitative characterization of polymer structures and dynamics is the keystone for precisely regulating and controlling the physical and chemical properties of the polymer. This book specifically focuses on NMR investigation of complex polymers for the polymer community as well as NMR spectroscopists, and will push the development of both fields. It covers the latest advances, for example high field DNP and ultrafast MAS methodologies, and show how these novel NMR methods characterize various synthetic and natural polymers.




Reviews in Computational Chemistry


Book Description

THIS VOLUME, WHICH IS DESIGNED FOR STAND-ALONE USE IN TEACHING AND RESEARCH, FOCUSES ON QUANTUM CHEMISTRY, AN AREA OF SCIENCE THAT MANY CONSIDER TO BE THE CENTRAL CORE OF COMPUTATIONAL CHEMISTRY. TUTORIALS AND REVIEWS COVER * HOW TO OBTAIN SIMPLE CHEMICAL INSIGHT AND CONCEPTS FROM DENSITY FUNCTIONAL THEORY CALCULATIONS, * HOW TO MODEL PHOTOCHEMICAL REACTIONS AND EXCITED STATES, AND * HOW TO COMPUTE ENTHALPIES OF FORMATION OF MOLECULES. * A FOURTH CHAPTER TRACES CANADIAN RESEARCH IN THE EVOLUTION OF COMPUTATIONAL CHEMISTRY. * ALSO INCLUDED WITH THIS VOLUME IS A SPECIAL TRIBUTE TO QCPE. FROM REVIEWS OF THE SERIES "Reviews in Computational Chemistry proves itself an invaluable resource to the computational chemist. This series has a place in every computational chemist's library."-JOURNAL OF THE AMERICAN CHEMICAL SOCIETY




Amorphous Food and Pharmaceutical Systems


Book Description

During the past decade, the importance of amorphous water-soluble substances has been increasingly recognised within the food and pharmaceutical industries. In response, Amorphous Food and Pharmaceutical Systems brings together current leading experts to contribute to this unique cross-disciplinary account of the subject. Coverage includes: water-compatible amorphous solids (physical, chemical behaviour), low water content systems (water as plasticizer); applications in food and pharmaceutical sciences and industries (processing and stability) along with state-of-the-art technology in food and pharmaceutical systems. This timely publication will be welcomed by academic and industrial researchers and professionals in the pharmaceuticals, food, materials and polymer sciences.