The Development Of Carbon Nanotube/Carbon Nanofibre From Polyacrylonitrile Electrospun Nanofibre Precursor For Electronic Applications

• Main Author: Abdul Munajat, Nurain
• Format: Thesis
• Language: English; English
• Published: 2019
• Subjects: QD Chemistry
• Online Access: http://eprints.utem.edu.my/id/eprint/24660/; https://plh.utem.edu.my/cgi-bin/koha/opac-detail.pl?biblionumber=116915

Carbon nanofibre (CNF) have attracted much attention among researchers due to their excellent properties such as high mechanical strength, thermal and electrical conductivity. CNF have been proposed for various applications such as filtration, smart material, tissue engineering, fuel cell, capacitors and sensors. Recently, electrospinning technique followed by pyrolysis process of the precursor material has been proposed as a simple and economic alternative for fabricating CNF. In this study, the best parameters on fabrication process of CNF with and without the inclusion of multi-walled carbon nanotubes (MWCNT) fillers were determined and their properties were characterised. MWCNT was selected due to its superior electrical properties. Previously, considerable amount of effort have been made on studying the physical, chemical, and mechanical properties of electrospun CNF. However, there are limited studies dedicated to investigating the electrical properties of the CNF especially in terms of conductivity, complex permittivity (dielectric constant and loss factor)and loss tangent. Therefore, the scope of this research is to investigate the relationship of electrical properties with physical and chemical properties of the fibres. Polyacrylonitrile (PAN) precursor nanofibre were prepared using electrospinning technique. The best parameters for electrospinning were investigated by preparing the samples at electrospinning distances of 5 cm to 30 cm and applied voltage of 5 kV to 20 kV. Furthermore, the best pyrolysis process was determined by varying the carbonisation temperature of 800 ºC, 1000 ºC and 1200 ºC with heating rate of 3 ºC/min and 5 ºC/min in a nitrogen filled furnace. As the optimum parameters were achieved, nanofibre samples with and without MWCNT were prepared. The characterization of the electrospun CNF was carried out using scanning electron microscopy (SEM), transmission electron microscope (TEM), ImageJ software, Fourier transform infrared spectroscopy (FTIR), four-point probe methods and dielectric probe. Based on fibre diameter, morphology, and deposition amount; the optimum electrospinning distance was found to be between 10 cm to 20 cm with an applied voltage between 15 kV to 20 kV. The results also suggest that increase in carbonisation and heating rate during pyrolysis process would increase the rate of elimination of non-carbon elements. This is evidenced by flatter FTIR spectrum and higher electrical conductivity of the samples which were carbonised at 1200 ºC and heating rate of 5 ºC/min. The electrical conductivity of CNF was significantly increased with the inclusion of MWCNT. The highest electrical conductivity was showed by CNF with 0.1 wt% of CNT with value 155.90 S/cm. However, samples with higher amount of MWCNT (> 0.1 wt%) showed reduced electrical conductivity to 21.56 S/cm. This could be explained by the formation of broken fibre network and agglomeration of MWCNT as observed using SEM and TEM. Finally, complex permittivity values of pure CNF and MWCNT-filled CNF were highest with dielectric constant value of 338.38 and loss factor value 488.72 at 1 GHz frequency. The knowledge gained from this study would extend the use of electrospun nanofibre in electronic applications such as sensors and other nano-sensing applications.