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Acid modified multiwalled carbon nanotubes condition by reflux
Author(s)
Manrean, Rawijee
Pornteeranawapat, Natchanun
Neamyooyong, Saichon
Date Issued
September 25, 2019
Type
Article
Abstract
Nanomaterials, especially carbon nanotubes (CNTs), show excellent combinations of thermal, mechanical and electrical properties. However, as-produced CNTs are entangled and form agglomerates, due to their several micron lengths. Therefore, the dispersion efficiency of CNTs is limited. We decreased the length and improved dispersion with acid modified multiwall-CNTs (A-MWCNTs) formed by a reflux method. MWCNTs were modified with an acid mixture of sulfuric acid and nitric acid at the ratio of 3:1 by volume. The reflux temperature and time were varied between 80 to 120 °C and 10 to 30 min. FTIR found an increase in carboxylic acid groups on the surfaces with increasing reflux temperature and time. Therefore, A-MWCNTs showed good dispersion in polar solvents; i.e. water, DMF and DMAc. Furthermore, A-MWNCT lengths were shortened with increased reflux temperature and time. Carboxylic acid groups on A-MWCNT surfaces decreased the electrical conductivity by two orders of magnitude. However, epoxy resin in which the A-MWCNTs, modified at 120 °C and 30 min were encapsulated, showed better conductivity, since the shortest MWCNT lengths and the carboxylic groups on the A-MWCNT surfaces allowed good dispersion in epoxy resin.
Citation
Materials Research Express, 6(11), 2019