Processing and characterization of carbon nanotube based conductive polymer composites

Download
index.pdf
2010
Yeşil, Sertan
Show full item record
366
views
192
downloads
The aim of this study was to improve the mechanical and electrical properties of conductive polymer composites. For this purpose, different studies were performed in this dissertation. In order to investigate the effects of the carbon nanotube (CNT) surface treatment on the morphology, electrical and mechanical properties of the composites, poly(ethylene terephthalate) (PET) based conductive polymer composites were prepared by using as-received, purified and modified carbon nanotubes in a twin screw extruder. During the purification of carbon nanotubes, surface properties of carbon nanotubes were altered by purifying them with nitric acid (HNO3), sulfuric acid (H2SO4), ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2) mixtures. Electron Spectroscopy for Chemical Analysis (ESCA) results indicated the removal of metallic catalyst residues from the structure of carbon nanotubes and increase in the oxygen content of carbon nanotube surface as a result of purification procedure. Surface structure of the purified carbon nanotubes was also modified by treatment with sodium dodecyl sulfate (SDS), poly(ethylene glycol) (PEG) and diglycidyl ether of Bisphenol A (DGEBA). Fourier Transformed Infrared Spectroscopy (FTIR) spectra of the carbon nanotube samples indicated the existence of functional groups on the surfaces of carbon nanotubes after modification. All composites prepared with purified and modified carbon nanotubes had higher electrical resistivities, tensile and impact strength values than those of the composite based on as-received carbon nanotubes, due to the functional groups formed on the surfaces of carbon nanotubes during surface treatment. In order to investigate the effects of alternative composite preparation methods on the electrical and mechanical properties of the composites, in-situ microfiber reinforced conductive polymer composites consisting of high density polyethylene (HDPE), poly(ethylene terephthalate) and carbon nanotubes were prepared in a twin screw extruder followed by hot stretching of PET/CNT phase in HDPE matrix. Composites were produced by using as-received, purified and PEG treated carbon nanotubes. SEM micrographs of the hot stretched composites pointed out the existence of in-situ PET/CNT microfibers dispersed in HDPE matrix up to 1 wt. % carbon nanotube loadings. Electrical conductivity values of the microfibrillar composites were higher than that of the composites prepared without microfiber reinforcement due to the presence of continuous PET/CNT microfibers with high electrical conductivity in the structure. To investigate the potential application of conductive polymer composites, the effects of surfactant usage and carbon nanotube surface modification; on the damage sensing capability of the epoxy/carbon nanotube/glass fiber composite panels during mechanical loadings were studied. Surface modification of the carbon nanotubes was performed by using hexamethylene diamine (HMDA). 4-octylphenol polyethoxylate (nonionic) (Triton X-100) and cetyl pyridinium chloride (cationic) (CPC) were used as surfactants during composite preparation. Electrical resistivity measurements which were performed during the impact, tensile and fatigue tests of the composite panels showed the changes in damage sensing capabilities of the composites. Surface treatment of carbon nanotubes and the use of surfactants decreased the carbon nanotube particle size and improved the dispersion in the composites which increased the damage sensitivity of the panels.
Chemical engineering., Electrical conductivity., Mmicrofiber reinforced composites., Mechanical properties.
http://etd.lib.metu.edu.tr/upload/3/12611984/index.pdf
https://hdl.handle.net/11511/19586
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Preparation and characterization of conductive polymer composites, and their assessment for electromagnetic interference shielding materials and capacitors
Köysüren, Özcan; Bayram, Göknur; Department of Chemical Engineering (2008)
The aim of this study was to improve electrical properties of conductive polymer composites. For this purpose, various studies were performed using different materials in this dissertation. In order to investigate the effect of alternative composite preparation methods on electrical conductivity, nylon 6/carbon black systems were prepared by both in-situ polymerization and melt-compounding techniques. When compared with melt compounding, in-situ polymerization method provided enhancement in electrical condu...
Processing and characterization of carbon fiber reinforced silicon carbide (c/c-sic) matrix composites
Tülbez, Simge; Dericioğlu, Arcan Fehmi; Esen, Ziya; Department of Metallurgical and Materials Engineering (2015)
The current study was undertaken to investigate the production and characterization of Carbon Fiber Reinforced Silicon Carbide (C/C-SiC) Matrix Composites. Liquid silicon infiltration (LSI) method was utilized to produce the C/C-SiC composites. Processing of these composites via LSI process composed of three main stages. CFRP production, pyrolysis and liquid silicon infiltration. Each production stage has an important effect on the efficiency of the LSI process, therefore present study investigates the effe...
Preparation and characterization of recycled polypropylene based nanocomposites
Cengiz, Filiz; Yılmazer, Ülkü; Department of Chemical Engineering (2008)
The aim of this study was to improve the mechanical properties of a recycled grade polypropylene. Polymer blends and nanocomposites were prepared by melt compounding method in a twin screw extruder. Cloisite® 15A, Cloisite® 25A and Cloisite® 30B were used as organoclays, and ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) and maleic anhydride grafted polypropylene (PP-MAH) were used as compatibilizers. The effects of additive concentrations, types of organoclays and compatibilizers, processing con...
Processing and assessment of aluminum ceramic fiber reinforced aluminum metal matrix composite parts for automotive and defense applications
Türkyılmaz, Gökhan; Kalkanlı, Ali; Department of Metallurgical and Materials Engineering (2009)
The aim of this study was to produce partially reinforced aluminum metal matrix composite components by insertion casting technique and to determine the effects of silicon content, fiber vol% and infiltration temperature on the mechanical properties of inserts, which were the local reinforcement parts of the components. Silicon content of alloys was selected as 7 wt% and 10 wt%. The reinforcement material, i.e. Saffil fiber preforms, had three different fiber vol% of 20, 25 and 30 vol% respectively. The inf...
Production and characterization of boron nitride nanotubes
Özmen, Didem; Sezgi, Naime Aslı; Department of Chemical Engineering (2008)
The further developments in nanotechnology in last few years provide usage of nanoscale particles for many applications in various areas such as electronics, pharmaceutical, and biomedical due to their strengthened mechanical, thermal and electrical properties. Boron nitride nanotubes are a good example of nanoparticles. In this study, boron nitride nanotubes were successfully synthesized from the reaction of ammonia gas with mixture of boron and iron oxide. Physical and structural properties of the synthes...
Citation Formats
S. Yeşil, “Processing and characterization of carbon nanotube based conductive polymer composites,” Ph.D. - Doctoral Program, Middle East Technical University, 2010.
METU IIS - Integrated Information Service open@metu.edu.tr