Download or read book Molecular Modeling of Polymer Crystallization and the Effect of Nucleating Agents written by Alexander Jules Bourque and published by . This book was released on 2017 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstructure in a semicrystalline polymer material ultimately determines its material properties. Despite the abundance of research into the semicrystalline microstructure and its evolution during crystallization, a clear description of its development remains elusive. The advent of advanced computing and algorithms, however, have promoted molecular modeling of polymer crystallization, providing a new perspective on the development of the microstructure. This thesis revisits and challenges many aspects of microstructural development in macromolecular materials by applying new modeling techniques and recent technologies. Through atomistic simulations of n-alkane crystallization, this thesis presents new molecular evidence of surface nucleation processes that contribute to the propagation of the crystal growth front in a macromolecular system. Crystallization in polymeric systems has long been theorized to proceed by "secondary nucleation." In this work, molecular dynamics (MD) simulations were engineered to probe this surface nucleation process by systematically inducing crystal growth for a system of macromolecules. In a novel application of mean first passage time analysis, the critical surface nucleus sizes, waiting times, and surface nucleation rates were extracted from atomically-detailed molecular trajectories using a layer-by-layer approach. Insight from MD simulations was used to build a new kinetic model to describe the structure and rate of advancement of the growth front during crystallization. In the model, solidification occurs through the mechanisms of surface nucleation and lateral spreading of the solid phase within layers in the vicinity of the growth front. Transformation within each layer is described by an equation similar to the two-dimensional variant of the Johnson-Mehl-Avrami equation. The kinetic model is computationally efficient and predictive of important macroscopic observables. Finally, this thesis presents the first computational screening of nucleating agents for macromolecular crystallization. Screens were conducted for two families of crystal materials: tetrahedrally coordinated materials isomorphic to diamond and silicon, and 2D, hexagonally coordinated materials isomorphic to graphene. The induction time for heterogeneous nucleation was shown to depend strongly on crystallographic registry between the nucleating agent and the critical nucleus, but the severity of this registry requirement weakened with increasing strength of attraction to the surface of the nucleating agent. In an unprecedented find, the substrate rigidity significantly influenced heterogeneous nucleation. The molecular organization of nalkane chains at the nucleating surface was also investigated to build a fundamental understanding of the mechanisms for heterogeneous nucleation and spreading.
Download or read book Handbook of Polymer Crystallization written by Ewa Piorkowska and published by John Wiley & Sons. This book was released on 2013-07-01 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymeric crystals are more complex in nature than other materials' crystal structures due to significant structural disorder present. The only comprehensive reference on polymer crystallization, Handbook of Polymer Crystallization provides readers with a broad, in-depth guide on the subject, covering the numerous problems encountered during crystallization as well as solutions to resolve those problems to achieve the desired result. Edited by leading authorities in the field, topics explored include neat polymers, heterogeneous systems, polymer blends, polymer composites orientation induced crystallization, crystallization in nanocomposites, and crystallization in complex thermal processing conditions.
Download or read book Polymer Crystallization written by Jyotishkumar Parameswaranpillai and published by John Wiley & Sons. This book was released on 2023-07-03 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: Control the development of polymer crystals with this groundbreaking introduction Polymer crystallization is a crucial component of polymer development that impacts processing, applications, presentation, and more. Intervention in the polymer crystallization process, in the form of nanofilters, compatibilizers, and more, has the potential to improve optical and chemical properties, improve degrees of crystallinity, and increase hardness of polymer composites. The myriad applications of crystalline polymers make this one of the most exciting and fast-growing fields in polymer research. Polymer Crystallization provides a comprehensive introduction to this field and its most important recent developments. It characterizes and analysis an expansive range of crystalline polymers and discusses possible mechanisms for influencing their crystallization processes to impact a variety of outcomes and applications. These applications include industries from food packaging to automotive parts to medical and aerospace materials. Polymer Crystallization readers will also find: Detailed treatment of polymer morphology, rheology, modeling, and more Thorough introduction to the fundamentals of polymer crystallization Discussion of environmental safety issues and avenues for future research Polymer Crystallization is a useful reference for materials scientists, polymer scientists, biomedical scientists, and advanced undergraduate and graduate students in these and related fields.
Download or read book Nucleating Agents written by Stuart Fairgrieve and published by iSmithers Rapra Publishing. This book was released on 2007-11 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: A very important factor in obtaining optimised physical properties from a semi-crystalline polymer is the size of the crystalline structures present in the material, and this crucially depends on the initiation process of crystallisation of the polymer from the melt - nucleation. This review provides information on the development of materials and methods for influencing the nucleation of polymer crystallisation in commercial processing by means of addition of low levels of adjuvants specifically selected for this purpose.
Download or read book Progress in Understanding of Polymer Crystallization written by Günter Reiter and published by Springer Science & Business Media. This book was released on 2007-02-05 with total page 521 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the context of polymer crystallization there are several still open and often controversially debated questions. The present volume addresses issues such as novel general views and concepts. It presents new ideas in a connected and accessible way. The intention is thus not only to provide a summary of the present state-of-the-art to all active works but to provide an entry point to newcomer and graduate students entering the field.
Download or read book Flow Induced Crystallization of Polymers written by Gaetano Guerra and published by Wiley-VCH. This book was released on 2002-12-20 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: In polymer processing, the molecular orientation induced by flow has a significant effect on the crystallization kinetics and final morphology of the polymer produced. The impact on processing operations and object properties is extremely important and recently scientific and technological researchers have begun to quanitify these effects. The international conference 'Flow-Induced Crystallization of Polymers', held in October 2001 in Salerno, Italy, was timely and well attended. An interdisciplinary approach was taken and presentations were made on topics ranging from real-time measurement, through modelling, to final morphology and properties of polymers. Invited and other selected contributions from the conference are collected here, in this volume of Macromolecular Symposia
Download or read book Polymer Crystallization written by Günter Reiter and published by Springer Science & Business Media. This book was released on 2003-05-06 with total page 403 pages. Available in PDF, EPUB and Kindle. Book excerpt: The classical view on polymer crystallization basically focused on the expla- tion of a few macroscopically observable parameters like the thickness of the resulting lamellar structure and the corresponding growth rates. However, the emerging paradigm for the description of chain crystals is too simple and cannot account for the complex non-equilibrium processes responsible for structure f- mation on various levels, ranging from the nanometer up to the millimeter scale. This complexity detected by several novel experimental results led to a renewed interest in this ”old” topic of polymer crystallization. These new ?ndings c- cern the early stages of the crystallization process, crystal formation in con?ned geometries like ultra-thin ?lms and the competition between (micro)phase s- aration and crystallization in copolymers and blends. In particular, high spatial resolution techniques such as atomic force microscopy provided deeper insight into the molecular organization of crystallizable polymers. Computer simu- tions based on microscopic processes were used to improve our understanding of how polymer crystals are nucleated and how they grow. New ideas emerged about possible multistage pathways which are followed during the formation of polymer lamellae. The importance and the consequences of the non-equilibrium character of polymer crystals got signi?cantly more attention. Links and ana- gies to growth phenomena and pattern formation in general are being developed. However, these ideas are still subject of intensive and controversial discussions.
Download or read book Molecular Dynamics Modeling of Orientation induced Nucleation in Short Alkanes written by Predrag Dragutin Đurdjević and published by . This book was released on 2013 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The enhancement of the primary flow-induced nucleation rate in short chain alkanes (C20 and C150) has been examined for different levels of orientation by atomistic molecular dynamics simulations. The nucleation rate has been found to change drastically by varying average molecular orientation and temperature. For example, it is possible to accelerate nucleation kinetics by three orders of magnitude at the same temperature, but varying the average level of orientation (P2 (cos [Theta])) . The size of the critical nucleus has been found to increase with the level of undercooling Tm - T decrease, consistent with the classical nucleation theory. Our atomnistic molecular dynamics simulation model is even tractable at the small levels of undercooling, thus clearly demonstrating the effects of orientation (melt anisotropy) on nucleation kinetics when thermal nucleation is expected to be negligible. Furthermore, we calculate the influence of melt anisotropy on the growth rate. As expected, the growth rate is also altered by melt anisotropy. Furthermore, the growth rate maximum always occurs at the temperature above the nucleation kinetics maximum.
Download or read book Polymer Crystallization II written by Finizia Auriemma and published by Springer. This book was released on 2016-12-21 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Advances in Polymer Science presents critical reviews of the present and future trends in polymer and biopolymer science. It covers all areas of research in polymer and biopolymer science including chemistry, physical chemistry, physics, material science. The thematic volumes are addressed to scientists, whether at universities or in industry, who wish to keep abreast of the important advances in the covered topics. 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. Review articles for the individual volumes are invited by the volume editors. Single contributions can be specially commissioned. Readership: Polymer scientists, or scientists in related fields interested in polymer and biopolymer science, at universities or in industry, graduate students
Download or read book Crystallization of Polymers written by Marcel Dosière and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book SPE ANTEC 1996 Proceedings Print version 3 volumes written by Spe and published by CRC Press. This book was released on 1996-05-02 with total page 1400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Crystallization of Polymers Volume 2 Kinetics and Mechanisms written by Leo Mandelkern and published by Cambridge University Press. This book was released on 2004-09-30 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Crystallization of Polymers, 2nd Edition, Leo Mandelkern provides a self-contained, comprehensive, and up-to-date treatment of polymer crystallization. Volume 2 of this edition provides an authoritative account of the kinetics and mechanisms of polymer crystallization, building from the equilibrium concepts presented in volume 1. As crystalline polymers rarely, if ever, achieve their equilibrium state, this books serves as a bridge between equilibrium concepts and the state that is finally achieved. With a comprehensive treatment of the surrounding theories and experimental results from simple to complex polymer systems, this book will be an invaluable reference work for all chemists, physicists and materials scientists working in the area of polymer crystallization.
Download or read book Polymer Crystallization written by Jerold M. Schultz and published by . This book was released on 2001 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Table of contents
Download or read book Modeling and Simulation of Crystallization Processes in Polymer Melt Flows written by Stefan Descher and published by BoD – Books on Demand. This book was released on 2020-01-01 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describing crystallization processes in polymer melt flows involves many effects. Objective of this work is to capture a selection in a simulation environment, for a certain material, starting from executing experiments on. This means aspects of experimental investigations, modeling and special numerical methods used to create a simulation environment will be highlighted. Because this involves many fields, works covering all aspects are rare1. It is intended to contribute such a work by the publication of this thesis.
Download or read book Polymer Crystallization written by Jyotishkumar Parameswaranpillai and published by John Wiley & Sons. This book was released on 2023-06-28 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer Crystallization Control the development of polymer crystals with this groundbreaking introduction Polymer crystallization is a crucial component of polymer development that impacts processing, applications, presentation, and more. Intervention in the polymer crystallization process, in the form of nanofilters, compatibilizers, and more, has the potential to improve optical and chemical properties, improve degrees of crystallinity, and increase the hardness of polymer composites. The myriad applications of crystalline polymers make this one of the most exciting and fast-growing fields in polymer research. Polymer Crystallization provides a comprehensive introduction to this field and its most important recent developments. It characterizes and analysis an expansive range of crystalline polymers and discusses possible mechanisms for influencing their crystallization processes to impact a variety of outcomes and applications. These applications include industries from food packaging to automotive parts to medical and aerospace materials. Polymer Crystallization readers will also find: Detailed treatment of polymer morphology, rheology, modeling, and more Thorough introduction to the fundamentals of polymer crystallization Discussion of environmental safety issues and avenues for future research Polymer Crystallization is a useful reference for materials scientists, polymer scientists, biomedical scientists, and advanced undergraduate and graduate students in these and related fields.
Download or read book Handbook of Polymer Crystallization written by Ewa Piorkowska and published by John Wiley & Sons. This book was released on 2013-05-30 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymeric crystals are more complex in nature than other materials' crystal structures due to significant structural disorder present. The only comprehensive reference on polymer crystallization, Handbook of Polymer Crystallization provides readers with a broad, in-depth guide on the subject, covering the numerous problems encountered during crystallization as well as solutions to resolve those problems to achieve the desired result. Edited by leading authorities in the field, topics explored include neat polymers, heterogeneous systems, polymer blends, polymer composites orientation induced crystallization, crystallization in nanocomposites, and crystallization in complex thermal processing conditions.
Download or read book Molecular Simulation of Nucleation from Flowing Polymer Melts written by David Andrew Nicholson (Ph. D.) and published by . This book was released on 2020 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: During processing, flow drastically accelerates the kinetics of polymer crystallization, altering the morphology and properties of the resulting material The earliest stage of flow-induced crystallization, known as flow-enhanced nucleation (FEN), is challenging to study experimentally due to the small spatiotemporal scale over which it occurs Non-equilibrium molecular dynamics (NEMD) simulation, which operates at short time and length scales, has proven to be a useful tool for investigating this stage Using NEMD, FEN was studied in n-eicosane (C20), n-pentacontahectane (C150) and their blends Analysis of these simulations provided insight into the underlying mechanism and constitutive relationships that govern FEN A method was developed to extract kinetic rates and critical parameters from direct simulations of nucleation events It is based on the first-passage time statistics of a stochastic process obeying the classical nucleation theory (CNT) and utilized a novel approximation for the first-passage time distribution. Using this method, FEN in C20 was determined to occur through both a reduction in the barrier to nucleation and enhanced diffusion Mechanistically, the barrier reduction is consistent with CNT with an extra driving force due to flow-induced stretching and orientation. In FEN simulations of C150, intense fluctuations gave rise to domains with high local alignment on the Kuhn length-scale Upon quenching, the nucleation of small crystallites occurred preferentially within these domains. This behavior is at odds with CNT and indicates a more complex mechanism at play The C150 simulations were further utilized to draw correlations between the nucleation rate and the response of the melt to the applied flow field. Based on the fidelity of the observed correlations, empirical models reported in the literature were evaluated for their consistency with the NEMD data, and new models are proposed for data that do not comport with existing ones In bimodal blends of C20 and C150, nucleation kinetics were found to depend on the degree to which both the long and short chains are deformed This result conflicts with experimental evidence that the nucleation rate in a polydisperse melt is determined only by the high molecular weight component.
