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Book Thermal Transport in Polymers  Polymer Nanocomposites and Semiconductors Using Molecular Dynamics Simulation and First Principles Study

Download or read book Thermal Transport in Polymers Polymer Nanocomposites and Semiconductors Using Molecular Dynamics Simulation and First Principles Study written by Rajmohan Muthaiah and published by . This book was released on 2021 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book First Principles based Molecular Modeling of Thermal Transport in Silicon based Nanomaterials

Download or read book First Principles based Molecular Modeling of Thermal Transport in Silicon based Nanomaterials written by Yongjin Lee and published by . This book was released on 2014 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: In today's nanotechnology, a critical issue is to gain the ability to control the structure and function of matter with a deeper understanding of the quantitative and qualitative relationship among their synthesis conditions, structures, and properties. Experiments may provide information regarding the behavior of nanomaterials, but their interpretations are often controversial due largely to the difficulty of direct measurement. Hereupon, with the amazing advance in computer technology since the late 20th century, computational modeling in science and engineering is increasingly important particularly in the fields of nanoscience and nanotechnology while it can provide researchers with significant insights into atomic-level interactions in various materials systems and underlying fundamental theories. The ability of engineering thermal conductivity of materials on the nanoscale has become extremely important in various applications including electronics and energy storage/conversion technologies. Due to technical difficulties in experimentally measuring the thermal conductivity of disordered and complex nanostructures, there has been much interest in use of theoretical and computational methods to investigate thermal transport properties nanostructured materials. One computational method that can perform an accurate analysis for the thermal conductivity of new or complex systems is molecular dynamics (MD), due to its capability of predicting the behaviors of atoms in large systems. In this work, we have developed a comprehensive MD-based computational platform capable of predicting and explaining thermal transport in disordered and complex nanostructured materials. The unique features include construction of realistic nanostructures, determination of reliable force fields, and direct simulation of large systems, which are allowed by coupling various state-of-the-art computational methods including quantum mechanics, molecular mechanics, statistical theories, and massively parallel computing. The computational scheme was applied to describe thermal transport in various silicon and carbon-based disordered and nanostructures. First, the effects of defects including vacancy clusters, substitutional dopants, and dopant-defect complexes on the thermal conductivity of bulk crystalline silicon were investigated. Next, we analyzed the factors affecting heat transport in silicon-germanium and ternary silicon-germanium-tin alloys. Lastly, we performed the analysis of heat transport in silicon-based nanostructures such as nanowires and polycrystalline structures.

Book Synthesis and Characterization of High Thermal Conductive Polymers and Fabrication of Polymer Based Thermal Strap

Download or read book Synthesis and Characterization of High Thermal Conductive Polymers and Fabrication of Polymer Based Thermal Strap written by Buxuan Li and published by . This book was released on 2021 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers have infiltrated almost every aspect of modern technology. Without polymer products, the society would look very different. As one of the most important and common engineering materials, traditional polymers are both electrically and thermally insulating, due to its organic nature and amorphous structures. In the late 20th century, electrically conductive polymers has been discovered. Thermally conductive polymers, however, were not demonstrated until the recent decades. Polymers are shown to have great potential in thermal conduction, even divergent thermal conductivity in theory. This counterintuitive finding is attributed to its one-dimensional periodic structure, where repeating monomers are connected by strong covalent bonds. Researchers have learned that special dynamics exist in non-linear one-dimensional chains since the Fermi-Pasta-Ulam-Tsingou report, where the evolution of state space was found to be non-ergodic, enabling an infinite long lifetime of excitations. As a result, such 1D nonlinear system favors scatter-free phonon transport. Molecular dynamics simulation shows a single polyethylene (PE) chain could have divergent thermal conductivity. Calculations from first principle also confirm the thermal conductivity is approximately 160 W/mK for bulk PE and 1400 W/mK for a single PE chain, with a three phonon process taken into consideration. In experiments, researchers measured enhanced thermal conductivity in stretched PE in the 1970s. In the last decades, researchers have made progress by demonstrating PE nanofibers with a thermal conductivity of over 100 W/mK. Recently, 2D PE films were fabricated and measured to have metal-like thermal conductivity of over 60 W/mK. With all these progresses, in this thesis, we aimed to develop scalable polyethylene films with high thermal conductivity and investigating temperature-dependent thermal transport properties. A differential steady state method was used to measure the thermal conductivity of the synthesized PE films. A thermal annealing of PE films was performed along with the temperature dependence test where a transition temperature was identified. Below the transition temperature, thermal annealing increased the thermal conductivity at room temperature. Above the transition temperature, thermal annealing irreversibly decreased the thermal conductivity. Our PE films featured reasonable thermal conductivity of 20~60 W/mK depending on draw ratio and much lower density comparing to metals such as copper and aluminum. A potential application of such films is a light-weight thermal strap, which is important for space technologies. We designed a strategy to overcome the issue that such films have a poor cross-plane thermal conductivity. We proved the idea based on both simulation and experiments. In simulations, we derived a steady state solution of a full-size physical device with conduction and radiation included. In experiments, we conducted a unit test on laboratory scale samples and argued its ability of scaling up by showing that multilayer PE films performed as expected.

Book Thermal Transport for Applications in Micro Nanomachining

Download or read book Thermal Transport for Applications in Micro Nanomachining written by Basil T. Wong and published by Springer Science & Business Media. This book was released on 2008-07-19 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beginning with an overview of nanomachining, this monograph introduces the relevant concepts from solid-state physics, thermodynamics, and lattice structures. It then covers modeling of thermal transport at the nanoscale and details simulations of different processes relevant to nanomachining. The final chapter summarizes the important points and discusses directions for future work to improve the modeling of nanomachining.

Book Thermal Transport Properties in Polymers and Hybrid Materials

Download or read book Thermal Transport Properties in Polymers and Hybrid Materials written by Hao Ma and published by . This book was released on 2020 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding thermal transport processes can guide the rational design of devices and systems for thermal energy conversion and management. Despite the significant progress in thermal transport of inorganic crystals, thermal transport in complicated materials, such as polymers and hybrid materials, remains largely unexplored. This thesis first presents our discovery of the large thermal rectification effects in the novel tapered bottlebrush polymers using nonequilibrium molecular dynamic simulations. In sharp contrast to all other reported asymmetric nanostructures, we observed that the heat current from the wide end to the narrow end in tapered bottlebrush polymers is smaller than that in the opposite direction. It was demonstrated that a more disordered to less disordered structural transition within tapered bottlebrush polymers is essential for generating non-linearity in heat conduction for thermal rectification. Moreover, the thermal rectification factor increases with device length, reaching as high as ~70% with a device length of 28.5nm. This large thermal rectification with strong length dependence uncovers an unprecedented phenomenon - diffusive thermal transport in the forward direction and ballistic thermal transport in the backward direction. This thesis then focuses on thermal transport properties in hybrid materials: graphene-C60 heterostructures and hybrid organic-inorganic (CH3NH3)3Bi2I9 crystals. Graphene-C60 heterostructures assembled by van der Waals interactions between graphene and C60 have shown exciting potential for multifunctional devices. Understanding thermal transport in graphene-C60 heterostructures is the key to guiding the design of vdW heterostructures with desired thermal transport properties. Our equilibrium molecular dynamics simulations found that the in-plane thermal conductivity of the graphene-C60 heterostructure is as high as about 234 W/(mK) at room temperature, exceeding those of most pure metals. On the other hand, vdW interactions enhance the interfacial thermal conductance between graphene and C60 by strengthening out-of-plane phonon couplings between graphene and C60 and increasing in-plane and out-of-plane phonon couplings of the graphene layer. Our study demonstrates that the interfacial thermal conductance of graphene-C60 heterostructure is comparable to that of graphene-hexagonal boron-nitride (hBN) heterostructure. Hybrid perovskite analogues, such as methylammonium bismuth iodide (CH3NH3)3Bi2I9, have emerged as candidate photovoltaic and thermoelectric materials due to their low toxicity and high stability. Thermal transport and phonon properties of (CH3NH3)3Bi2I9 were studied neither experimentally nor theoretically, which hinders the optimal selection and design of stable, non-toxic hybrid perovskite material for photovoltaic and thermoelectric applications. We mapped out the phonon dispersion of (CH3NH3)3Bi2I9 single crystals at 300 K using inelastic x-ray scattering. The frequencies of acoustic phonons are among the lowest of crystals. Nanoindentation measurements verified that these crystals are very compliant and considerably soft. The frequency overlap between acoustic and optical phonons results in strong acoustic-optical scattering. All these features lead to an ultralow thermal conductivity.

Book Nanoscale Thermal and Thermoelectric Energy Transport in Crystalline and Disordered Materials

Download or read book Nanoscale Thermal and Thermoelectric Energy Transport in Crystalline and Disordered Materials written by Jiawei Zhou and published by . This book was released on 2019 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Energy transport provides the fundamental basis for operation of devices from transistors to solar cells. Despite past theories that successfully illustrate the principles behind the energy transport based on solid state physics, the microscopic details of the energy transport are not always clear due to the lack of tool to quantify the contribution from different degrees of freedom. Recent progress in first principles computations and development in optical characterization has offered us new ways to understand the energy transport at the nanoscale in a quantitative way. In this thesis, by leveraging these techniques, we aim to providing a detailed understanding of thermal and thermoelectric energy transport in crystalline and disordered materials, especially about how the energy transport depends on atomistic level details such as chemical bondings. Specifically, we will discuss three examples. 1) Electron transport in semiconductors: how electrons propagate as they interact with lattice and impurities. 2) Interaction between charge and heat: how the free carriers have an impact on the heat dissipation in semiconductors 3) Heat conduction in polymers: how the heat transfer in an amorphous system depends on its molecular structures. In the case of electron transport, we developed and applied first principles simulation to show that a large electron mobility can benefit from symmetry-protected non-bonding orbitals. Such orbitals result in weak electron-lattice coupling that explains the unusually large power factors in half-Heusler materials - a good thermoelectric material system. By devising an optical experiment to probe the ultrafast thermal decay, we quantified the effect of electron-phonon interaction on the thermal transport. Our results show that the thermal conductivity can be significantly affected by the free carriers. Lastly, we built a theoretical model to understand the heat conduction in amorphous polymers, and used this knowledge to design materials that are heat-conducting yet soft. These understandings will potentially facilitate discovery of new material systems with beneficial charge and heat transport characteristic.

Book Nano scale Heat Transfer in Nanostructures

Download or read book Nano scale Heat Transfer in Nanostructures written by Jihong Al-Ghalith and published by Springer. This book was released on 2018-03-06 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book introduces modern atomistic techniques for predicting heat transfer in nanostructures, and discusses the applications of these techniques on three modern topics. The study of heat transport in screw-dislocated nanowires with low thermal conductivity in their bulk form represents the knowledge base needed for engineering thermal transport in advanced thermoelectric and electronic materials, and suggests a new route to lower thermal conductivity that could promote thermoelectricity. The study of high-temperature coating composite materials facilitates the understanding of the role played by composition and structural characterization, which is difficult to approach via experiments. And the understanding of the impact of deformations, such as bending and collapsing on thermal transport along carbon nanotubes, is important as carbon nanotubes, due to their exceptional thermal and mechanical properties, are excellent material candidates in a variety of applications, including thermal interface materials, thermal switches and composite materials.

Book Nanoscale Energy Transport

Download or read book Nanoscale Energy Transport written by LIAO and published by IOP Publishing Limited. This book was released on 2020-03-20 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book brings together leading names in the field of nanoscale energy transport to provide a comprehensive and insightful review of this developing topic. The text covers new developments in the scientific basis and the practical relevance of nanoscale energy transport, highlighting the emerging effects at the nanoscale that qualitatively differ from those at the macroscopic scale. Throughout the book, microscopic energy carriers are discussed, including photons, electrons and magnons. State-of-the-art computational and experimental nanoscale energy transport methods are reviewed, and a broad range of materials system topics are considered, from interfaces and molecular junctions to nanostructured bulk materials. Nanoscale Energy Transport is a valuable reference for researchers in physics, materials, mechanical and electrical engineering, and it provides an excellent resource for graduate students.

Book Molecular Dynamics Simulation Study of a Polymer Droplet Transport Over an Array of Spherical Nanoparticles

Download or read book Molecular Dynamics Simulation Study of a Polymer Droplet Transport Over an Array of Spherical Nanoparticles written by Anish Thomas and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study uses molecular dynamics simulations to evaluate the dynamic behavior of a partially wetting polymer droplet driven over a nanostructured interface. We consider the bead-spring model to represent a polymeric liquid that partially wets a rough surface composed of a periodic array of spherical particles. Results show that at sufficiently small values of external force, the droplet remains pinned at the particle's surface, whereas above the threshold its motion consists of alternating periods of pinning and rapid displacements between neighboring particles. The latter process involves large periodic variation of the advancing and receding contact angles due to the attachment and detachment of the contact line. Finally, upon increasing the external force, the droplet's center of mass is steadily displaced, while at the same time the oscillation amplitude of the receding contact angle as well as the maximum contact angle hysteresis remain relatively unchanged.

Book Thermal Conduction in Polymer Based Materials by Engineering Intermolecular Interactions

Download or read book Thermal Conduction in Polymer Based Materials by Engineering Intermolecular Interactions written by Nitin Mehra and published by . This book was released on 2019 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Though lots of work is available in thermally conductive filler-polymer composite, clear understanding of the heat conduction mechanism in neat polymers or polymer blends is a subject of great investigation especially for the promotion and development of new thermal management technologies. This dissertation focuses on two important aspects. First, probing fundamental factors governing thermal conduction in polymers that is to understand the fundamentals factors governing the heat transport in polymer based material especially by engineering molecular level interactions in polymer chains. Second, to develop metallic/ceramic filler free thermal conductive - electrically insulative polymer based material for thermal management applications. One of the major objective of thesis is to open new avenues for thermal management using filler-free technologies for high thermal conductive and electrically insulating polymer based material for electronic packaging and advanced engineering application. Impact of intermolecular interaction in governing thermal conduction in polymers and how the quality of "thermal connections" through intermolecular interactions like hydrogen bonding can effectively drive heat propagation in polymer is shown first through a polymer hydrogen bonded with water. By engineering intermolecular interaction through hydrogen bonding in polymer chains, a significant enhancement in thermal conductivity was achieved and corresponding decrement was observed by breaking those interactions through heat. Thermal conductivity of free standing PVA films with different molecular weights and its interaction with water molecules was investigated. Further, effect of the absorption of vapor molecules of ethanol, methanol and ethylene diamine on polymer film's thermal conductivity was studied. Penetration of water molecule in films was found to drastically alter inter-molecular interaction contributing to remarkable 200% increment in thermal conductivity. Neat PVA films with lower molecular weight had higher thermal conductivity due to less dense and hindered polymer chains and ease of interaction to form continuous thermal network. After demonstrating that small molecule such as water through hydrogen bonding can significantly impact the thermal conduction, we prepared polymer blend of PEG-PVA. Thermal conduction pathways were introduced in a blend film of long chain polymer Poly (vinyl alcohol) (PVA) and short chain Poly (ethylene glycol) (PEG). Thermal conductivity enhancement of around 1.6 times of neat polymer was achieved. The critical factor responsible for thermal conduction in these films was found to be homogeneous distribution of "thermal bridges" formed by hydrogen bonding between PVA and short PEG chain. Reduction in thermal conductivity was observed when PVA blend film with longer PEG chain, which is mainly due to poor thermal bridges distribution and chain agglomeration. This work presents a fascinating yet promising non-conventional method to make thermally conductive polymer based material without using traditional fillers for thermal management applications.Size of the "thermal bridges" can have significant impact on the overall thermal conductivity of the polymer system. To further elucidate this factor, polymer blend with different molecular weight of PEG - DEG, TEG, HEG. Short chains of diethylene glycol (DEG) were incorporated into base polymer matrix of polyvinyl alcohol (PVA) which lead to remarkable thermal conductivity enhancement of 260% and 175 % than DEG and neat PVA respectively. Phonon transport was driven by the "thermal bridges" designed through intermolecular hydrogen bonding between PVA and DEG. A further impact of the length of "thermal bridges" and its functional groups (hydroxyl, carboxyl, carbonyl) at terminal position were investigated. It was found that shorter organic molecules are more efficient in driving thermal conduction owing to less inter-chain resistance. Interestingly, these materials were found to have inverse thermal conductivity-crystallinity relationship which is usually an opposite trend to the present belief.The type of intermolecular interactions formed by the terminal groups of the thermal bridging molecule can affect the phonon transport across polymer chains. We demonstrated how by employing organic molecule with hybrid terminal groups resulted in enhanced thermal conductivity than the bulk polymer. The highest thermal conductivity of 0.55 W/m·K was achieved when organic molecule with hybrid terminal groups was incorporated in base polymer. Engineering intermolecular interaction helps to create continuous thermal network which facilitates phonon transport. The hybrid thermal bridges created with the base polymer act as synergistic center which further boost phonon transport. Interestingly, such thermal conductivity enhancement with hybrid terminal groups was found both in amorphous and crystalline organic molecules. Further, such molecules were incorporated in polymer chains with different backbone structure. PVA with different degree of hydrolysis was selected. Due to the presence of a bulkier acetyl group in PVA with lower degree of hydrolysis thermal conduction was hindered and vice-versa.At last, multiple hydrogen bonded pathways were created for effective phonon transport via supramolecular chemistry. Melamine-Cyanurate (MC), a multiple hydrogen bonded supramolecular filler was employed for this purpose. It has remarkable potential to develop self-assembled 2-D layered sheet structure at the same time strengthening thermal interfaces. This resulted in composite thermal conductivity of 1.65 times the thermal conductivity of neat PVA at 50 wt % loading. Such composite is prepared by non-conventional mixing by in-situ co-precipitation of filler resulting in homogenous distribution.

Book Organic Thermoelectric Materials

Download or read book Organic Thermoelectric Materials written by Zhiqun Lin and published by Royal Society of Chemistry. This book was released on 2019-10-18 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarises the significant progress made in organic thermoelectric materials, focusing on effective routes to minimize thermal conductivity and maximize power factor.

Book Molecular Dynamics Simulations of Thermal Transport in Silicon based Nanostructures

Download or read book Molecular Dynamics Simulations of Thermal Transport in Silicon based Nanostructures written by Rafael Frieling and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Thermal Transport in Nanoporous Materials for Energy Applications

Download or read book Thermal Transport in Nanoporous Materials for Energy Applications written by Jin Fang and published by . This book was released on 2012 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study investigates the complex relationship between nanostructures and microscale thermal transport in nanoporous thin films for energy applications. It experimentally and numerically demonstrates that the effective thermal conductivity of nanoporous materials can be tuned by controlling their nanoscale architectures including porosity, pore diameter, wall thickness, nanocrystal size, and crystallinity as well as surface passivation. This study reports measurements of the cross-plane thermal conductivity of nanoporous thin films with various architectures between 25 and 315 K. Physics-based models combining phonon transport theory and effective medium approximations were developed to interpret the experimental data. Ordered mesoporous titania and silicon thin films were prepared based on evaporation-induced self-assembly method. Pure silica zeolite films were produced by either in-situ growth or by spin coating a zeolite nanoparticle suspension followed by crystal growth upon heating. These synthesized thin films were systematically and fully characterized. They featured ordered nanopores with porosity, pore diameter, and film thickness ranging from 30% to 59%, 0.5 to 25 nm, and 120 to 370 nm, respectively. Their dense matrix was amorphous, polycrystalline, or consisted of an aggregate of nanocrystals. The thermal conductivity of all synthesized nanoporous films increased monotonically with temperature within the temperature range considered. At low temperatures, the nanoporous films behaved like amorphous or strongly disordered materials and their thermal conductivity was proportional to T^n with n varied between 1 and 2.3. At high temperatures, the thermal conductivity increased slowly with temperature or reached a plateau due to strong phonon Umklapp scattering and the saturation of phonon modes. The presence of pores in amorphous mesoporous thin films had a purely geometrical effect by reducing the cross-sectional area through which heat can diffuse. By contrast, in crystalline mesoporous thin films the presence of pores also increased phonon scattering. In addition, the film thickness generally did not affect the measured thermal conductivity. Indeed, phonon scattering by pores and by nanocrystal grain boundary dominated over boundary scattering and were identified as the dominant scattering mechanisms for nanoscale energy transport in the synthesized nanoporous films. This study further establishes that the effective thermal conductivity keff of crystalline nanoporous silicon was strongly affected not only by the porosity fv and the system's length Lz but also by the pore interfacial area concentration Ai. A modified effective medium approximation combining kinetic theory and the coherent potential approximation suggested that keff was proportional to (1-1.5fv) and inversely proportional to the sum (Ai/4+1/Lz). This scaling law was in excellent agreement with the thermal conductivity of nanoporous silicon predicted by molecular dynamics simulations for spherical pores as well as for cylindrical pores and vacancy defects. Finally, this study demonstrated, using equilibrium molecular dynamics simulations, that surface passivation added another parameter for reducing the thermal conductivity of nanostructured materials. To do so, there should be strong acoustic vibrational modes coupling between surface and passivation atoms. For example, oxygen passivation reduced the thermal conductivity of nanoporous crystalline silicon. In addition, the effect of passivation reduced with temperature because of increasing contribution of Umklapp scattering. These results could help establish new strategies to control the thermal conductivity of nanoporous materials for a wide range of applications including thermoelectric devices, supercapacitors, dye-sensitized solar cells, and hydrogen storage devices.

Book Nanoscale Energy Transport and Conversion

Download or read book Nanoscale Energy Transport and Conversion written by Gang Chen and published by Oxford University Press. This book was released on 2005-03-03 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a graduate level textbook in nanoscale heat transfer and energy conversion that can also be used as a reference for researchers in the developing field of nanoengineering. It provides a comprehensive overview of microscale heat transfer, focusing on thermal energy storage and transport. Chen broadens the readership by incorporating results from related disciplines, from the point of view of thermal energy storage and transport, and presents related topics on the transport of electrons, phonons, photons, and molecules. This book is part of the MIT-Pappalardo Series in Mechanical Engineering.

Book Artificial Intelligence for Materials Science

Download or read book Artificial Intelligence for Materials Science written by Yuan Cheng and published by Springer Nature. This book was released on 2021-03-26 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: Machine learning methods have lowered the cost of exploring new structures of unknown compounds, and can be used to predict reasonable expectations and subsequently validated by experimental results. As new insights and several elaborative tools have been developed for materials science and engineering in recent years, it is an appropriate time to present a book covering recent progress in this field. Searchable and interactive databases can promote research on emerging materials. Recently, databases containing a large number of high-quality materials properties for new advanced materials discovery have been developed. These approaches are set to make a significant impact on human life and, with numerous commercial developments emerging, will become a major academic topic in the coming years. This authoritative and comprehensive book will be of interest to both existing researchers in this field as well as others in the materials science community who wish to take advantage of these powerful techniques. The book offers a global spread of authors, from USA, Canada, UK, Japan, France, Russia, China and Singapore, who are all world recognized experts in their separate areas. With content relevant to both academic and commercial points of view, and offering an accessible overview of recent progress and potential future directions, the book will interest graduate students, postgraduate researchers, and consultants and industrial engineers.

Book Transport Modeling of Simple Fluids and Nano colloids

Download or read book Transport Modeling of Simple Fluids and Nano colloids written by Jacob Eapen and published by . This book was released on 2006 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: (cont.) This thesis also addresses several theoretical concerns regarding the microscopic thermal transport in colloids by using non-equilibrium molecular dynamics simulations (NEMD). The time averaged microscopic heat flux which assumes spatial homogeneity is shown to be applicable to nano-colloidal systems. Further, it is demonstrated that the thermal conductivity from a NEMD simulation is statistically equivalent to that of an equilibrium linear response evaluation only under certain dynamic conditions at the cluster-fluid interface. The concept of interfacial dynamical similarity is developed to establish this equivalence. The proposed thermal conduction model is consistent with several experimental observations such as the anomalous enhancement at small volume fractions with very small nanoparticles (3-10nm), limiting behavior at higher volume fractions, and the lack of correlation of the enhancement to the intrinsic thermal conductivity of the nano-clusters. The model also suggests possible avenues for optimizing the colloids by developing nano-clusters that have functionalized surface layers to maximize the interactions with the fluid atoms. In the second part of this thesis, smooth field estimators based on statistical inference and smoothing kernels are developed to transfer molecular data to the continuum for hybrid and equation-free multiscale simulations. The field estimators are then employed to implement coarse projection, a multiscale integration scheme, for a shear driven flow in an enclosure. This thesis shows that the spatial continuity and smoothness of the microscopically generated coarse variables, geometrically similar initial conditions and the separation of timescales are essential for the correct coarse field evolution with coarse projection.

Book The Chemistry of Polymers

Download or read book The Chemistry of Polymers written by Margaret Morris and published by . This book was released on 2020-09-22 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: The scientific field that is concerned with the chemical synthesis, structure, and the physical and chemical properties of polymers and macromolecules is known as polymer chemistry. Its principles and methods are also applicable in a variety of sub-disciplines of chemistry such as organic chemistry, physical chemistry and analytical chemistry. On the basis of their origin, polymers are subdivided into biopolymers and synthetic polymers. The functional and structural materials that make most of the organic matter in organisms are biopolymers. Synthetic polymers are the structural materials that are manifested in synthetic fibers, paints, building materials, furniture, plastics, mechanical parts and adhesives. This book is a compilation of chapters that discuss the most vital concepts in the field of polymer chemistry. Some of the diverse topics covered herein address the varied branches that fall under this category. Those in search of information to further their knowledge will be greatly assisted by this book.