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URN etd-0830110-002838 Statistics This thesis had been viewed 4451 times. Download 692 times. Author Chih-Min Hsieh Author's Email Address email@example.com Department Materials Engineering Year 2009 Semester 2 Degree Master Type of Document Master's Thesis Language Chinese&English Page Count 79 Title Effects of Surfactant Contents and Acid Treatment on EMI Shielding Effectiveness of EVA/CNT-PPy Composites Keyword surfactant polypyrrole composite composite polypyrrole surfactant Abstract In this investigation, in various content of cetyltrimethylammonium chloride (CTAC) ─ferric chloride (FeCl3), the composited conductive carbon nanotubes (CNT) -PolyPyrrole (PPy) was synthesized by chemical oxidative polymerization from pyrrole monomers polymerized in the CTAC-ferric chloride (FeCl3) covering the surface of CNT.. The composited conductive CNT-PPy was compounded with the polymeric substrate; ethylene-vinyl acetate (EVA) into the composites achieved the electromagnetic interference shielding effectiveness (EMI SE) by CNT-PPy dispersing in the substrate to form conductive networks. In the systemization process of CNT–PPy, the influence of CNT and CTAC contents was analyzed by Raman and SEM to observe variations of structure, and covering conditions of PPy on the surface of CNT. The effect of acid treatment of CNT was using 4-point-probes and EDS to research the variations of resistance and compositions. The conductive CNTAT-PPy that CNT after acid treatment synthesized with PPy was analyzed as CNT-PPy by Raman and SEM; furthermore, the differences of structure between CNT-PPy and CNTAT-PPy were compared by using FE-SEM.
In results of investigation, the contents of CNT would affect the attaching of PPy but the large amount of CNT just increased EMI SE in 2~3 dB. Therefore, this investigation used CTAC to improve the dispersing of PPy in CNT. When the CNT-PPy contained a large amount of CNT would result a self-aggregated phenomenon and formed not uniform conductive filler without CTAC. The EMI SE of composites could not achieve 5 dB. However, the EMI SE of the composites could raise to 10~15dB when the CNT content was 2g, and added 0.01mole CTAC in the synthesizing process of CNT-PPy. Besides, this investigation found the acid treatment of CNT would increase the conductivity and surface areas of CNT and made PPy easily attached on the surface of CNT. If added CTAC in CNTAT-PPy, and the EMI SE of CNTAT-PPy composites were substantially improved. In the same CNT content (2g), the EMI SE of composites obviously raised to 27~30dB when CNTAT-PPy adding 0.015mole CTAC.
Advisor Committee CHI-Yuan Huang - advisor
Files Date of Defense 2010-07-12 Date of Submission 2010-09-01