Development Of Novel Hybrid Silica Aerogels With A Reticulated Structure Using New Generation Of Marcromolecular Precursors
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Development Of Novel Hybrid Silica Aerogels With A Reticulated Structure Using New Generation Of Marcromolecular Precursors
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Author : Sasan Rezaei
language : en
Publisher:
Release Date : 2020
Development Of Novel Hybrid Silica Aerogels With A Reticulated Structure Using New Generation Of Marcromolecular Precursors written by Sasan Rezaei and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Aerogels (e.g. silica aerogel) have created a prospective market for oil-absorption, insulation and aerospace applications. However, their intrinsic fragility and poor mechanical properties have been a stumbling block to their wider applications. These drawbacks originate from their inherent particulate structure and weak interparticle interactions. For several decades, researchers have been trying to enhance the aerogels' mechanical properties by improving the particle-to-particle connections. However, the cost was increased processing time, increased density, and increased total thermal conductivity. Therefore, this Ph.D. research aims to find an industrially viable and fast manufacturing technology to produce ultra-light weight and mechanically robust and resilient aerogel while preserving the unique features of the aerogels such as the good thermal insulation properties and high surface area. This dissertation fundamentally addressed the difficulties associated with the improvement of the particle-to-particle connection in the conventional aerogels by inventing a novel non-particulate and reticulate structure, free from the troublesome particles. This new technology relied on the development of a new generation of polymeric silica precursor and a meticulous control of thermodynamics at gelation step. Polymeric precursors with different chemistries and molecular weights were synthesized in the preparatory stage and then through spinodal decomposition, non-particulate and reticulate aerogels were afforded. Thermodynamics variables, molecular weight of the polymeric precursor, solvent, temperature, and the amount of the nonsolvent were systematically studied and correlated to structural parameters and consequently to the final properties. It was found that there is a critical point where a particulate structure transfers to a non-particulate one. The findings have also demonstrated how to tailor the structural factors such as the void fraction, the average pore sizes to optimize the final properties. This study provided an in-depth understanding of processing-structure-property relationship and a novel technology to molecularly engineer the structure and properties of hybrid silica aerogels. Various aerogels' building blocks assemblies, polymeric precursors, and thermodynamics variables have been investigated to identify the optimal structure and processing methodology to obtain highly robust and super-insulative aerogels.
Aerogels I
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Author : Inamuddin
language : en
Publisher: Materials Research Forum LLC
Release Date : 2020-11-15
Aerogels I written by Inamuddin and has been published by Materials Research Forum LLC this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-11-15 with Technology & Engineering categories.
This book focuses on aerogels and their applications in such areas as energy storage, thermal storage, catalysis, water splitting and environmental remediation. The materials covered include nanocellulose-, porous-, silica-, hybrid silica-, carbon-, graphene- and magnetic aerogels. Ways of modulating the pore structure of aerogels are presented, as well as surface modifications and the application of coatings. Future perspectives focus on functional foods, thickeners, stabilizers, and scaffolding in tissue repair. Keywords: Aerogels, Nanocellulose Aerogels, Non-Silicate Aerogels, Organic Aerogels, Composite Hybrid Aerogels, Carbon-based and Graphene-based Aerogels, Biogels, Hybrid Silica-based Aerogels, Energy Storage, Thermal Storage, Catalysis, Water Splitting, Environmental Remediation, Absorbents, Gas Filters, Packaging Materials, Electrical Devices, Thermal Insulations, Fire Retardants, Pharmaceutical and Biomedical Applications, Functional Foods, Thickeners, Stabilizers, Scaffolding in Tissue Repair.
Properties And Structures Of Sulfonated Syndiotactic Polystyrene Aerogel And Syndiotactic Polystyrene Silica Hybrid Aerogel
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Author : Huan Zhang (Polymer engineer)
language : en
Publisher:
Release Date : 2014
Properties And Structures Of Sulfonated Syndiotactic Polystyrene Aerogel And Syndiotactic Polystyrene Silica Hybrid Aerogel written by Huan Zhang (Polymer engineer) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Aerogels categories.
This study focuses on hybrid aerogels of syndiotactic polystyrene (sPS) and silica where silica concentration is varied and silica condensation conditions are varied to produce various mesoporous materials. In addition, the study investigates hybrid materials obtained by coating sulfonated syndiotactic polystyrene on a cellulose filter paper. In first part of this study, syndiotactic polystyrene is modified by sulfonation to enable further chemical modifications. Specifically, sulfonated syndiotactic polystyrene (ssPS) is coated on macroporous cellulose filter paper using a dip coating process, ssPS is turned into gel by thermoreversible gelation, and finally aniline is polymerized on ssPS strands to obtain a hybrid aerogel with electrical conductivity. The aerogels are recoved by removing the solvents under supercritical conditions. The ssPS aerogels are coated on cellulose filter materials to derive two benefits: first, to capitalize on the large surface area of ssPS aerogels and second, to exploit the mechanical strength of the cellulose filter. In second part of this study, silane precursor is absorbed inside the macropores of sPS gels and silica gels are grown under both a two-step reaction and a one-step reaction. Type A silica aerogel is synthesized by acid-base catalyzed sol-gel method, while type B silica aerogel is prepared only by acid catalyzed sol-gel process. Type A silica gels exhibit pearl-necklace structure, while type B silica gels are composed of strand-like silica particles. In the process, the mesoporous hydrophilic silica particles are combined with macro- and microporous hydrophobic sPS in single articles. This unique combination of organic and inorganic materials and their associated surface area and surface energy offer a number of attractive properties. The sPS/silica hybrid aerogels are fabricated from different concentrations of sPS in solution and from different weight ratio of sPS to silica. The sPS/silica hybrid aerogels exhibit predominant pores located in the mesopore range (2~50 nm), and at higher silica content, silica particles undergo more aggregation as evident from larger fractions mesopore size (~15 nm). In contrast to native sPS aerogel, the compressive modulus of hybrid aerogel is increased up to 100%. In addition, the hybrid aerogels present specific surface area as high as 693 m2/g, high porosity, fast absorption and high absorption capacity of crude oil. Type A hybrid aerogels are composed of both fiber-like strands of sPS and pearl-necklace particles of silica. At low weight ratio of sPS to silica, the silica forms aggregates on sPS backbones as conformal coating. At higher weight ratio of sPS to silica, the silica particles not only coated on the polymer backbones, but also filled the macropores of sPS. Type B hybrid aerogels present fiber-like interpenetrating networks formed by sPS strands of 50-100 nm and silica strand of 200 nm.
Fundamental Studies On Polymer And Organic Inorganic Hybrid Nanoparticles Reinforced Silica Aerogels
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Author : Yannan Duan
language : en
Publisher:
Release Date : 2012
Fundamental Studies On Polymer And Organic Inorganic Hybrid Nanoparticles Reinforced Silica Aerogels written by Yannan Duan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Aerogels categories.
The objective of this research was to reinforce silica aerogels using functional organic-inorganic hybrid nanoparticles, silane end-capped polyurethane oligomer and chain extended polymer, and self-crosslinkable multi-functional polyurethane-urea such that aerogel articles with negligible changes in density and porosity could be produced. The reinforcing entities used in the study were expected to reinforce the aerogel structures by (a) bridging the neighboring secondary particles at the neck region, (b) by forming conformal coatings on several secondary particles, or (c) by forming coating layers on all secondary particles. The baseline aerogels were synthesized from tetraethoxy silane (TEOS) or a mixture of TEOS and aminopropyltriethoxy silane (APTES). The aerogels were prepared using two- step sol-gel process followed by supercritical drying in liquid carbon dioxide. Polyhedral oligomeric silsesquioxanes (POSS) with different organic side groups and Si-OH or epoxide functionalities were used. Four types of POSS with silanol groups but with different side groups, tri-POSS, cyclo-POSS, i-butyl POSS, and tetra-POSS, were utilized to modify the silica aerogels before the gelation step. Silanol groups from POSS nanoparticles participated in condensation reactions with other silanes, while epoxy-POSS grafted on to the aerogel structures via the reactions with amine groups of APTES after the formation of gel network. The gels were also surface modified with dimethoxy-methyl (3,3,3-trifluoropropyl) silane to render them super-hydrophobic and to compare the performance of such surface modification with those of POSS molecules containing hydrocarbon side groups. The morphology, and mechanical and surface properties of the resultant aerogels were investigated respectively using scanning electron microscopy (SEM), Instron tensile tester, contact angle goniometry, and BET surface area and porosity analyzer. Solid state 13C and 29Si NMR spectra were used to investigate the chemical reactions between the silane monomers and POSS molecules. Small angle X-ray scattering (SAXS) was used to investigate the change of fractal dimension. It was observed that small amounts of POSS significantly enhanced the hydrophobicity and the compressive strength and modulus of the resultant aerogels, with small changes of density. It was found that silanol POSS reacted with other silanols and became part of aerogel structures. Silica aerogels with polymeric reinforcement such as pre-modified polyurethanes and prepolymers, with functionality greater than or equal to 2, were produced by one-step sol-gel process. The morphology and mechanical and surface properties of the resultant aerogels were investigated respectively using scanning electron microscopy (SEM), Instron tensile tester, contact angle measurement and BET surface area and porosity analyzer. The chemical structures of aerogels were studied by solid state 13C NMR and 29Si NMR. The fractal dimension was studied by SAXS. It was found that the addition of pre-modified polymer alleviated the issues of brittleness and moisture adsorption by either coating the surface of secondary particles or forming reinforced domains at the neck regions between the secondary particles. Of all the reinforcement methods used, aerogels reinforced with POSS nanoparticles yielded the best results in that compressive modulus showed an improvement by a factor of six compared to TEOS-based aerogels with less than 10 % change in density.
Hybrid Carbon Modified Polymer Based Silica Aerogels With Low Thermal Conductivity And Improved Mechanical Properties
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Author : Solmaz Karamikamkar
language : en
Publisher:
Release Date : 2020
Hybrid Carbon Modified Polymer Based Silica Aerogels With Low Thermal Conductivity And Improved Mechanical Properties written by Solmaz Karamikamkar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
Recently, graphene nanoplatelets (GnPs) have attracted a great deal of attention as a multifunctional reinforcing nanofiller in polymer composites, which is due to their unique two-dimensional layer structure with honeycomb characteristics, their excellent mechanical properties and their isotropic reinforcement capability in more than one direction. Here, the effect of the spinodal decomposition process in creating a nonparticulate morphology in the GnPs' orientation and dispersion is investigated. It is also studied how the gelation reaction can participate in the inclusion of GnPs in the aerogel backbone during the sol-gel process to strengthen the body of the gel. Meanwhile, the process of GnP exfoliation and restacking elimination during sol-gel transition is comprehensively studied. The present thesis also analyzes the gelation kinetics and thermodynamics in the presence of GnP and graphene oxide (GO) using in-situ rheology, light scattering (DLS), small-angle X-ray scattering (SAXS) and pore-structure-analyzer. The data collected during the gel network formation obtained with and without GnP or GO are analyzed in which to fully study the kinetics of structure evolution during the gelation. It is confirmed that the use of spinodal decomposition to create a nonparticulate gel network helps to offset the required long aging step during the sol-gel process, which is inevitable to strengthen the particle-to-particle neck using conventional methods such as nucleation and growth. It is also verified that this gelation technique enables the system to take advantage of GnP's full potential through correct exfoliation and elimination of restacking and re-agglomeration. The carbon-modified polymeric silica-based aerogels were first modified to enhance their mechanical properties by the addition of flexible nanofibers and stiff nanosheets into the structurer. The composites assembled homogeneously into the carbon-modified polymeric silica-based aerogel structure to create a uniform network of the solid struts along with the backbone. With such a network, the mechanical properties of the aerogels increased dramatically while preserving/advancing their unique features such as high surface area and thermal stability. The new aerogels could operate a high temperature with a high surface area. Furthermore, such material could resist moisture, which makes this material ideal to be used in high temperatures and humid environments.
Natural Fibers Plastics And Composites
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Author : Frederick T. Wallenberger
language : en
Publisher: Springer Science & Business Media
Release Date : 2011-06-28
Natural Fibers Plastics And Composites written by Frederick T. Wallenberger and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-06-28 with Technology & Engineering categories.
Freezing Colloids Observations Principles Control And Use
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Author : Sylvain Deville
language : en
Publisher: Springer
Release Date : 2017-01-19
Freezing Colloids Observations Principles Control And Use written by Sylvain Deville and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-19 with Technology & Engineering categories.
This book presents a comprehensive overview of the freezing of colloidal suspensions and explores cutting-edge research in the field. It is the first book to deal with this phenomenon from a multidisciplinary perspective, and examines the various occurrences, their technological uses, the fundamental phenomena, and the different modeling approaches. Its chapters integrate input from fields as diverse as materials science, physics, biology, mathematics, geophysics, and food science, and therefore provide an excellent point of departure for anyone interested in the topic. The main content is supplemented by a wealth of figures and illustrations to elucidate the concepts presented, and includes a final chapter providing advice for those starting out in the field. As such, the book provides an invaluable resource for materials scientists, physicists, biologists, and mathematicians, and will also benefit food engineers, civil engineers, and materials processing professionals.
Introduction To Sol Gel Processing
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Author : Alain C. Pierre
language : en
Publisher: Springer Nature
Release Date : 2020-03-10
Introduction To Sol Gel Processing written by Alain C. Pierre and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-03-10 with Technology & Engineering categories.
This book presents a broad, general introduction to the processing of Sol-Gel technologies. This updated volume serves as a general handbook for researchers and students entering the field. This new edition provides updates in fields that have undergone rapid developments, such as Ceramics, Catalysis, Chromatropgraphy, biomaterials, glass science, and optics. It provides a simple, compact resource that can also be used in graduate-level materials science courses.
Handbook Of Nanoparticles
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Author : Mahmood Aliofkhazraei
language : en
Publisher: Springer
Release Date : 2015-08-07
Handbook Of Nanoparticles written by Mahmood Aliofkhazraei and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-08-07 with Technology & Engineering categories.
This Handbook covers all aspects of Nanoparticles, from their preparation to their practical application. The chapters present different ways to synthesize nanometer particles, as well as their functionalization and other surface treatments to allow them to a practical use. Several industrial applications of such nanometer particles are also covered in this Handbook. It is a complete reference for those working with Nanotechnology at the lab level, from students to professionals.
Polyimide For Electronic And Electrical Engineering Applications
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Author : Sombel Diaham
language : en
Publisher: BoD – Books on Demand
Release Date : 2021-05-05
Polyimide For Electronic And Electrical Engineering Applications written by Sombel Diaham and has been published by BoD – Books on Demand this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-05-05 with Technology & Engineering categories.
Polyimide is one of the most efficient polymers in many industries for its excellent thermal, electrical, mechanical, and chemical properties as well as its easy processability. In the electronic and electrical engineering industries, polyimide has widely been used for decades thanks to its very good dielectric and insulating properties at the high electric field and at high temperatures of around 200°C in long term-service. Moreover, polyimide appears essential for the development of new electronic devices where further considerations such as high power density, integration, higher temperature, thermal conduction management, energy storage, reliability, or flexibility are required in order to sustain the growing global electrical energy consumption. This book gathers interdisciplinary chapters on polyimide in various topics through state-of-the-art and original ongoing research.