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Functionalization of carbon nanotubes and carbon nanofibers used in epoxy/amine matrices that avoid partitioning of the monomers at the fiber interface
Author(s) -
Auad Maria L.,
Mosiewicki Mirna A.,
Uzunpinar Cihan,
Williams Roberto J.J.
Publication year - 2010
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.21509
Subject(s) - materials science , diglycidyl ether , carbon nanotube , epoxy , surface modification , nanocomposite , dynamic mechanical analysis , carbon nanofiber , monomer , composite material , polymerization , chemical engineering , glass transition , polymer , polymer chemistry , bisphenol a , engineering
Single‐wall carbon nanotubes (SWCNT), multiwall carbon nanotubes (MWCNT), and carbon nanofibers (CNF) were oxidized with a conventional H 2 SO 4 /HNO 3 treatment, and the resulting COOH groups were esterified with phenyl glycidyl ether (PGE). Pristine, oxidized and esterified SWCNT, MWCNT, and CNF (1 wt%) were dispersed in diglycidyl ether of bisphenol A/polyether triamine, and cured to produce epoxy nanocomposite. The quality of the dispersion varied with surface modification in the order: COOH > unmodified > PGE, as assessed for SWCNT/epoxy composites using radial breathing modes in Raman spectra and scanning electron microscopy. Local bundling of PGE‐modified nanofillers was explained by a polymerization‐induced phase‐separation process. Dynamic mechanical analysis showed the presence of two relaxation peaks in nanocomposites prepared with unmodified and COOH‐modified SWCNT, MWCNT, and CNF, assigned to a partitioning of monomers at the carbon interface. This produced a significant decrease of the glass transition temperature. However, the esterification with PGE led to a single relaxation peak close to the one of the neat epoxy, for the three types of nanofillers without any penalty in the glassy and rubbery elastic moduli. The effect was explained by matrix exclusion from phase‐separated domains. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers