Assessment of Dispersion Evolution of Carbon Nanotubes in Shear-Mixed Epoxy Suspensions by Interfacial Polarization Measurement PDF Download
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Author: Ganiu Babatunde Olowojoba
Publisher: Fraunhofer Verlag
ISBN: 9783839605844
Category :
Languages : en
Pages : 128
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Book Description
Owing to their remarkable properties, carbon nanotubes (CNTs) hold a huge potential as fillers in the production of multifunctional composites for many applications. However, their tendency to agglomerate as well as their chemically inert surface makes the task of dispersion very challenging. In spite of the immense effort aimed at understanding CNT dispersions and its implication for the properties of nanocomposites and suspensions, very little progress has thus far been made in terms of correlating the microstructural morphology of nanocomposites to their properties. By measuring the extend of interfacial polarization in CNT/epoxy suspensions subjected to oscillatory shear flow in a rheometer, a novel measurement strategy for assessing the dispersion evolution of CNTs, during shear mixing in an epoxy resin with a three-roll mill, has been developed in this study. This allowed the influence of applied shear intensity, compatibility between CNT and matrix, initial CNT agglomerate morphology, as well as matrix viscosity on CNT dispersion quality during shear mixing to be investigated.
Author: Ganiu Babatunde Olowojoba
Publisher: Fraunhofer Verlag
ISBN: 9783839605844
Category :
Languages : en
Pages : 128
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Book Description
Owing to their remarkable properties, carbon nanotubes (CNTs) hold a huge potential as fillers in the production of multifunctional composites for many applications. However, their tendency to agglomerate as well as their chemically inert surface makes the task of dispersion very challenging. In spite of the immense effort aimed at understanding CNT dispersions and its implication for the properties of nanocomposites and suspensions, very little progress has thus far been made in terms of correlating the microstructural morphology of nanocomposites to their properties. By measuring the extend of interfacial polarization in CNT/epoxy suspensions subjected to oscillatory shear flow in a rheometer, a novel measurement strategy for assessing the dispersion evolution of CNTs, during shear mixing in an epoxy resin with a three-roll mill, has been developed in this study. This allowed the influence of applied shear intensity, compatibility between CNT and matrix, initial CNT agglomerate morphology, as well as matrix viscosity on CNT dispersion quality during shear mixing to be investigated.
Author: Oxana Vasilievna Kharissova
Publisher: Springer
ISBN: 3319629506
Category : Technology & Engineering
Languages : en
Pages : 258
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Book Description
This book describes a series of contemporary techniques and their combinations used for CNTs solubilization, from physical to chemical and biological, applying inorganic and organic compounds, as well as some metal complexes. In some cases, successive steps can be applied, for instance the use of low and high-weight surfactants, or mineral acid treatment for creation of –OH and –COOH groups and their further interaction with organic molecules. Each discussed method leads to an improvement of CNT solubility, frequently a considerable one. The formed dispersions can be stable for long periods of time, from several weeks to some months, and they sometimes even remain stable after centrifugation. Several special studies have been carried out in the areas of influence of solvent and light on CNTs dispersibility, combinations and abilities of surfactants, CNT cytotoxicity, etc. Applications of solubilized CNTs are discussed in this book as well.
Author: Jyotishkumar Parameswaranpillai
Publisher: John Wiley & Sons
ISBN: 3527824065
Category : Technology & Engineering
Languages : en
Pages : 448
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Book Description
Discover a one-stop resource for in-depth knowledge on epoxy composites from leading voices in the field Used in a wide variety of materials engineering applications, epoxy composites are highly relevant to the work of engineers and scientists in many fields. Recent developments have allowed for significant advancements in their preparation, processing and characterization that are highly relevant to the aerospace and automobile industry, among others. In Epoxy Composites: Fabrication, Characterization and Applications, a distinguished team of authors and editors deliver a comprehensive and straightforward summary of the most recent developments in the area of epoxy composites. The book emphasizes their preparation, characterization and applications, providing a complete understanding of the correlation of rheology, cure reaction, morphology, and thermo-mechanical properties with filler dispersion. Readers will learn about a variety of topics on the cutting-edge of epoxy composite fabrication and characterization, including smart epoxy composites, theoretical modeling, recycling and environmental issues, safety issues, and future prospects for these highly practical materials. Readers will also benefit from the inclusion of: A thorough introduction to epoxy composites, their synthesis and manufacturing, and micro- and nano-scale structure formation in epoxy and clay nanocomposites An exploration of long fiber reinforced epoxy composites and eco-friendly epoxy-based composites Practical discussions of the processing of epoxy composites based on carbon nanomaterials and the thermal stability and flame retardancy of epoxy composites An analysis of the spectroscopy and X-ray scattering studies of epoxy composites Perfect for materials scientists, polymer chemists, and mechanical engineers, Epoxy Composites: Fabrication, Characterization and Applications will also earn a place in the libraries of engineering scientists working in industry and process engineers seeking a comprehensive and exhaustive resource on epoxy composites.
Author: Ramesh Kumar Nayak
Publisher: CRC Press
ISBN: 1000045730
Category : Technology & Engineering
Languages : en
Pages : 237
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Book Description
Hydrothermal Behavior of Fiber- and Nanomaterial-Reinforced Polymer Composites provides critical information regarding the in-service environmental damage and degradation studies of nano/fiber reinforced polymer (FRP) composites focusing on hydrothermal degradation. Covering hydrothermal properties of a wide range of polymer composites, the book is aimed at graduate students, researchers, and professionals in material engineering, composite materials, nanomaterials, and related fields.
Author: Chandrasekar Muthukumar
Publisher: CRC Press
ISBN: 1000898172
Category : Technology & Engineering
Languages : en
Pages : 347
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Book Description
Epoxy-Based Biocomposites highlights the influence of fibre type, nanofillers, and ageing conditions on the performance of epoxy-based biocomposites subjected to various loading conditions. This book serves as a useful reference for researchers, graduate students, and engineers in the field of polymer composites. In addition to investigating the behaviour of hybrid biocomposites and biocomposites reinforced with various nanofillers, this book discusses the response of epoxy-based biocomposites exposed to moisture absorption, accelerated weathering, and hygrothermal ageing. This book also considers the static and dynamic properties, such as creep, fatigue, and free vibration properties.
Author: Vasan Churchill Srinivasan Chandrasekaran
Publisher:
ISBN: 9781124608815
Category : Carbon
Languages : en
Pages :
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Book Description
The motivation of this thesis is to investigate the role of multi-walled carbon nanotube (MWCNT) in enhancing the interlaminar shear strength (ILSS) of hybrid composites. The objective of this thesis is to understand the relationships between processing history, material variability, matrix properties, glass fiber/matrix interface properties and their correlations with interlaminar shear strength of hybrid composites. The interlaminar shear strength (ILSS) of hybrid composites made from glass fiber and multi-walled carbon nanotube (MWCNT) modified epoxy is compared with that for unmodified epoxy/glass fiber composites (control). By combining the techniques of high speed mechanical stirring and ultrasonic agitation, 0.5% MWCNT by weight were dispersed in epoxy to prepare a suspension. Composites were manufactured by both injection double vacuum-assisted resin transfer molding (IDVARTM) and the flow flooding chamber (FFC) methods. Compression shear tests (CST) were conducted on the manufactured samples to determine the ILSS. The effect of processing history and batch-to-batch variability of materials--glass fiber preform, resin and carbon nanotubes--on the ILSS of samples made by both techniques was investigated. Statistical comparison of the measured ILSS values for hybrid composites with the control specimens clearly show that hybrid composites made by the FFC process resulted in significant ILSS enhancement relative to the control and the IDVARTM specimens. After it was established that the FFC process improved the ILSS, the effect of functionalizing the nanotubes was explored. Multi walled carbon nanotubes (MWCNT) were oxidized by acid treatment and heated with triethylene tetra amine (TETA) to obtain amino functionalized MWCNTs (f-MWCNT). Hybrid composites with f-MWCNTs were manufactured using FFC technique and control samples were fabricated using the same E-Glass fiber mat and unmodified epoxy resin subjected to the same processing history. CST results show 41% increase in ILSS for hybrid composites containing p-MWCNTs and a 61% increase for samples containing f-MWCNTs relative to the control samples without MWCNT. Tests of the epoxy preparations were conducted to investigate if the increase in ILSS is due to an increase in the shear strength of epoxy containing nanotubes or to strengthening of the interface between the glass fiber and the epoxy containing nanotubes. Small punch test and miniature shear punch tests were conducted to characterize the young's modulus, yield shear strength and ultimate shear strength of the neat epoxy and MWCNT epoxy composites and micro droplet tests were conducted to characterize the interfacial shear strength, the strength of the fiber-matrix interface for both modified and unmodified matrix. The results indicate that the ILSS increase was due to the stronger interface bond due to the addition of nanotubes rather than any enhancement in the epoxy shear properties.
Author: Abdulkadir Sanli
Publisher:
ISBN: 9783961000470
Category :
Languages : en
Pages : 0
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Book Description
Author: Jian Zhao
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Dispersion and morphology of carbon nanotubes as well as enhancement for rubber reinforcement are studied. Several approaches including surfactant aids, functionalization and plasma treatment are used to assist dispersion. Several characterization methods are used to assess both the degree of dispersion and the level of reinforcement. Small angle light scattering is carried out as a primary tool to assess structure and dispersion of nanotubes treated through these approaches Stress-strain measurement and dynamic mechanical analysis are performed on elastomeric composites to study polymer reinforcement. These results are divided into five sections. The first section focuses on dispersion of untreated and acid-treated multi-walled carbon nanofibers (MWNF) suspended in water. Light scattering data provide the first insights into the mechanism by which surface treatment promotes dispersion. Both acid-treated and untreated nanofibers exhibit hierarchical morphology consisting of small-scale aggregates (bundles) that agglomerate to form fractal clusters that eventually precipitate. Although the morphology of the aggregates and agglomerates is nearly independent of surface treatment, their time evolution is quite different. Acid oxidation has little effect on bundle morphology. Rather acid treatment inhibits agglomeration of the bundles. The second section focuses on dispersion of the solubilized nanofibers. Light scattering data indicate that PEG-functionalized sample is dispersed at small rod-like bundle (side-by-side aggregate) level. Solubilization is achieved not by disrupting small-scale size-by-side bundles, but mainly by completely inhibiting large-scale agglomeration. The third section focuses on dispersion of plasma-treated carbon nanofibers. Comparison of untreated and plasma-treated nanofibers indicates that plasma treatment facilitates dispersion of nanofibers. The fourth section focuses on dispersion and structure of single-walled carbon nanotubes (SWNTs) and multi-walled nanofibers (MWNFs) suspended with surfactants. Disordered fractal network of "ropes" is observed for SWNTs whereas the MWNFs show rod-like character on large length scales. Sonication can produce either better dispersion or aggregation depending on the surfactants. The fifth section focuses on rubber reinforcement by MWNFs. The nanofiber-polyurethane composites show large Payne and Mullins effects. By adding various concentrations of nanofibers, both Young's modulus and the load at high strain increased. A carbon-black filled analogue shows much less enhancement.
Author: Krishna Chaitanya Etika
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Nanoparticles (such as, carbon nanotubes, carbon black, clay etc.) have one or more dimensions of the order of 100 nm or less. Owing to very high van der Waals force of attraction, these nanoparticles exist in a highly aggregated state. It is often required to break these aggregates to truly experience the "nanosize" effect for any required end use. There are several strategies proposed for dispersing/exfoliating nanoparticles but limited progress has been made towards controlling their dispersion state. The ability to tailor nanoparticle dispersion state in liquid and solid media can ultimately provide a powerful method for tailoring the properties of solution processed nanoparticle-filled polymer composites. This dissertation reports the use of a variety of stimuli-responsive polymers to control the dispersion state of single-walled carbon nanotubes. Stimuli-responsive polymers exhibit conformational transitions as a function of applied stimulus (like pH, temp, chemical etc.). These variations in conformations of the polymer can be used tailor nanotube dispersion state in water and solid composites. The use of pH and temperature responsive polymers to stabilize/disperse single walled carbon nanotubes (SWNTs) in water is presented. Non-covalent functionalization of SWNTs using pH and temperature responsive polymer show tailored dispersion state as a function of pH and temperature, respectively. Carbon nanotube microstructure in these aqueous suspensions was characterized using several techniques (cryo-TEM, viscosity measurements, uv-vis spectroscopy, zeta potential measurements and settling behavior). Furthermore, nanotube dispersion state in aqueous suspensions is preserved to a large extent in the composites formed by drying these suspensions as evidenced by SEM images and electrical conductivity measurements. Based on the results obtained a mechanism is proposed to explain the tailored dispersion of SWNTs as a functions of applied external stimulus (i.e., pH, temperature). Such stimuli-controlled dispersion of carbon nanotubes could have a variety of applications in nanoelectronics, sensing, and drug and gene delivery systems. Furthermore, this dissertation also contains a published study focused on controlling the dispersion state of carbon black (CB) in epoxy composites using clay.
Author: Barry Halstead
Publisher:
ISBN:
Category : Carbon
Languages : en
Pages : 341
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Book Description
This study investigates the interfacial shear strength between aligned carbon nanotubes and epoxy resin. Optimisation of this interfacial region influences the mechanical behaviour of the composite material. The interfacial improvement has considerable industrial applications in the aerospace and manufacturing industries. Interest has focused on the various physical properties of nanotubes functionalised in different ways. The surface chemistry of nanotubes was modified by plasma treatment and monitored using x-ray photoelectron spectroscopy. Mechanical testing with a custom designed adhesiometer suggested a possible improvement in interfacial shear strength. Additionally, an extended shear-lag model of the interfacial region has been used to show strong correlation with experimental findings. Electron and optical microscopy was used to determine the failure mechanisms between the carbon nanotube and epoxy resin.
