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Electromagnetic Simulation Using The Fdtd Method

Functionalization of Single Walled Carbon Nanotubes B y Lei Zhang Single walled carbon nanotubes (SWNTs) exhibit unique mechanical and physical properties and immediately after their discovery they were regarded as novel materials for future technologies. SWNTs are widely thought o f as one o f the basic building blocks to nanotechnology. However, they are very hard to disperse and dissolve in either water or organic solvent. The insolubility o f nanotubes makes it very difficult to make composites o f nanotubes with other materials. This limits nanotubes from the application for future technology. A feasible functionalization o f nanotubes, i.e., the attachment o f “chemical functional groups” provides a strategy for overcoming these barriers and has thus attracted synthetic chemists and materials scientists to contribute their efforts to making breakthrough. Functionalization can improve solubility and processibility, and will be able to link the unique properties o f nanotubes to those o f other types o f materials. Through the chemical functional groups, nanotube may show improved solubility and compatibility with solvents, polymers, nanoparticles and other nanotubes. A functionalized SWNT may have mechanical or electrical properties that are different from those o f the pristine SWNT, and thus may be used for fine-tuning the chemistry and physical properties o f SWNTs. Fluorination o f side walls o f the SWNTs has been performed by using the technology developed for the fluorination o f graphite, and then subsequent nucleophilic substitutions have been explored. It has been ascertained that in fluorination at the optimal temperature, C:F ratios o f up to 2:1 can be achieved without disruption o f the tubular structure. The fluorinated SWNTs proved to be much more soluble than pristine SWNTs in alcohols, N,N-dimethylformamide and some other selected organic solvents. This improved solubility and the high fluorine addition allow much more efficient solution-phase chemistry on the fluorinated SWNTs. R e p ro d u c e d with p erm iss ion of th e copyright ow ner. F u r the r reproduction prohibited without perm iss ion . The goals o f this work were to examine novel type o f reactions that one can do with fluorinated SWNTs and study the basic aspects o f functionalization o f SWNTs, i.e. the mechanism o f functionalization, the structure o f fluorinated SWNTs, and the distribution o f functional groups in the functionalized SWNTs. In this thesis, an extensive NMR study o f fluorinated SWNTs has been explored (Chapter 1) and this study gives us a deeper insight to the structure o f fluorinated SWNTs and the mechanism o f fluorination. A series o f “hydroxyl nanotube” have been simply prepared by two types o f one-step methods (Chapter 2). Amino-acid functionalized nanotubes with high water solubility and sensitive pH value dependence have been achieved, and the influence o f different chain length o f amino acid on the water solubility was detailed (Chapter 3). The nanotube-nanoparticle heterostructures have been prepared and used to investigate the distribution o f functional groups along the axis o f nanotubes (Chapter 4). Finally, a novel type o f reaction, Diels-Alder cycloaddition to fluorinated nanotubes was successfully performed under a mild reaction conditions (Chapter 5). R e p ro d u c e d with p erm iss ion of th e copyright ow ner. F u r the r reproduction prohibited without perm iss ion .

Functionalization of single walled carbon nanotubes

The combination of awareness of harmful industrial processes and environmental issues and depleting petroleum-based resources has spurred much research in developing materials from renewable sources. Epoxy resins are common pre-polymers used in a variety of industries, such as adhesives, coatings, insulations, and high performance composites. To transform epoxy resins into crosslinked networks with desirable thermal and mechanical properties, the resins must be cured with a curing agent. This review encompasses recent developments using bio-based epoxy resins and bio-based epoxy curing agents. Resins and curing agents synthesized from modified plant oils, sugars, polyphenols, terpenes, rosin, natural rubber, and lignin are highlighted and their thermal and mechanical properties reviewed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44103.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/app.44103

Recent advances in bio‐based epoxy resins and bio‐based epoxy curing agents

Effectiveness of vegetable oil based nanofluids as potential cutting fluids in turning AISI 1040 steel

Natural fibers from agricultural wastes are finding their importance in the polymer industry due to the many advantages such as their light weight, low cost and being environmentally friendly. Rice husk (RH) is a natural sheath that forms around rice grains during their growth. As a type of natural fiber obtained from agroindustrial waste, RH can be used as filler in composites materials in various polymer matrices. This review paper is aimed at highlighting previous works of RH filled polymer composites to provide information for applications and further research in this area. Based on the information gathered, application of RH filled composites as alternative materials in building and construction is highly plausible with both light weight and low cost being their main driving forces. However, further investigations on physical and chemical treatment to further improve the interfacial adhesion with polymeric matrix are needed as fiber-polymer interaction is crucial in determining the final composite properties. Better understanding on how the used polymer blends as the matrix and secondary fillers may affect the properties would provide interesting areas to be explored.

Rice Husk Filled Polymer Composites

This paper discusses the processing of a hybrid of TPNR-MWNTs-OMMT nanocomposites with different percentages of filler to determine the optimum mechanical properties of the hybrid nanocomposites. Three types of hybrid nanocomposites with various MWNTs-OMMT compositions (1%wt MWNTs+3%wt OMMT), (2%wt MWNTs+2%wt OMMT) and (3%wt MWNTs+1%wt OMMT) were prepared. The OMMT layers were found to be separated further with higher nanotubes content as exhibited by X-ray diffraction. The result of tensile test showed that tensile strength and Young's modulus increase in the presence of nanotubes and maximum value were obtained for the nanocomposites with highest nanotubes (3%wt) which increased about 33% and 36%, respectively compared with pure TPNR matrix. On other hand, the elongation at break considerably decreased with increasing the percentage of MWNTs. TEM micrographs revealed aspect ratio and fillers orientation in the TPNR matrix also promoted strongly to interfacial adhesion between fillers and the matrix which contributed significantly to the improvement of the mechanical properties

Mechanical properties of TPNR-MWNTs-OMMT hybrid nanocomposites

Multi walled carbon nanotubes (MWCNT) hold the increasing interest in many different fields. To employ MWCNT as an effective reinforcement in order to enhance the thermal conductivity of polylactic acid (PLA) modified with liquid natural rubber (LNR), proper dispersion and appropriate interfacial adhesion between MWCNT and PLA/LNR have to be guaranteed. This paper used ultrasonic technique as the method to help to improve the dispersion of MWCNT in PLA/LNR matrix. The result shown that the sample with 3.5 wt.% of MWCNT provided higher thermal conductivity which is believe to be the optimum loading due to better dispersion of MWCNT in PLA/LNR matrix. The 4 wt.% of MWCNT shows decreasing of thermal conductivity due to the presence of agglomeration of MWCNT. The results confirmed by Scanning Electron Microscopy (SEM) micrograph. Fourier Transform Infrared (FTIR) spectra shown that there were no chemical changes happen.

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Kesan penambahan nanotiub karbon berbilang dinding ke atas kekonduksian terma polilaktik asid nanokomposit

This study investigates the effect of ultrasonic treatment on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites reinforced with multi‐walled nanotubes. The TPNR nanocomposites were prepared using melt blending method from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, respectively, with 1% of Multi‐wall nanotubes. The nanocomposite was prepared using the indirect technique (IDT) with the optimum processing parameters at 180° C with 80 rpm mixing speed and 11 minutes processing time. The results have showed that the good dispersion on nanotubes was achieved by ultrasonic treatment. The optimization of ultrasonic time indicated that the maximum tensile and impact properties occurred with 1 h ultrasonic treatment. The Young’s modulus, tensile strength, elongation at break and impact strength have increased by almost 11%, 21%, 43% and 50%, respectively. The results from our study indicate that nanotubes have as excellent reinforcement filler in TPNR matrix.

Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

In this study, nanoclay and multi-wall carbon nanotubes have been used as a dual filler in an epoxy matrix. In the design of the experiment (DOE) the Taguchi Method was selected to study the effect of the factors involved in this study. The effect of the clay/MWNT ratio, types of solvent, clay cation, composition of LENR, cure time and cure temperature on tensile properties of the epoxy nanocomposites were investigated. The confirmation experiment obtained from Taguchi analysis, achieved 57% improvement in tensile strength. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the presence of intercalated and aggregated structures. Due to the lower crosslink density of the system, a decrease in decomposition temperature and glass transition temperature was observed in the optimum sample.

Optimization of Tensile Properties of Epoxy/Nanoclay/MWNT Nanocomposites by Taguchi Method

In this work, thin films of solid polymer electrolyte made of pure poly (ethylene oxide) doped with cesium iodide (CsI) were prepared using casting method. The films contain different (CsI) concentrations: 0 %, 1 %, 4 %, 8 %, 12 %, and 16 % by weight. The optical properties such as the absorption coefficient, energy gap, refractive index, extinction coefficient, and dielectric constants have been determined in the wavelength range (300 – 800) nm. The results obtained showed that the optical constants change with increase of cesium iodide concentration. The absorption spectra of thin films at different CsI concentrations showed changes in the wavelength range. The optical dispersion parameters have been analyzed by the single oscillator model. The value of Eo and Ed were found and the other parameters have been determined by Wemple-DiDomenico method.

Mou'ad A. Tarawneh

Papers

Mechanical properties of TPNR-MWNTs-OMMT hybrid nanocomposites

Kesan penambahan nanotiub karbon berbilang dinding ke atas kekonduksian terma polilaktik asid nanokomposit

Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

Optimization of Tensile Properties of Epoxy/Nanoclay/MWNT Nanocomposites by Taguchi Method

Optical Characterization of Thin Films Poly (Ethylene Oxide) Doped with Cesium Iodide