Epoxy nanocomposites containing magnetite-carbon nanofibers aligned using a weak magnetic field

Abstract

a b s t r a c tNovel magnetite-carbon nanofiber hybrids (denoted by "Fe 3 O 4 @CNFs") have been developed by coating carbon nanofibers (CNFs) with magnetite nanoparticles in order to align CNFs in epoxy using a relatively weak magnetic field. Experimental results have shown that a weak magnetic field (~50 mT) can align these newly-developed nanofiber hybrids to form a chain-like structure in the epoxy resin. Upon curing, the epoxy nanocomposites containing the aligned Fe 3 O 4 @CNFs show (i) greatly improved electrical conductivity in the alignment direction and (ii) significantly higher fracture toughness when the Fe 3 O 4 @CNFs are aligned normal to the crack surface, compared to the nanocomposites containing randomly-oriented Fe 3 O 4 @CNFs. The mechanisms underpinning the significant improvements in the fracture toughness have been identified, including interfacial debonding, pull-out, crack bridging and rupture of the Fe 3 O 4 @CNFs, and plastic void growth in the polymer matrix.

A novel route for tethering graphene with iron oxide and its magnetic field alignment in polymer nanocomposites

“…The liquid epoxy resin ('105') and hardener ('206') were supplied by WEST SYSTEM ® . The composite substrates were manufactured from T700 carbon-fibre/epoxy prepreg ('VTM 264') supplied by Applied Composites Group, and the details can be found in our previous work [22,23,25].…”

“…Nevertheless, due to the low magnetic susceptibility of carbon nanomaterials, a relatively high magnetic field is usually required which greatly limits its practical applications. However, we [25] have shown that the attachment of Fe 3 O 4 nanoparticles can greatly enhance the magnetic susceptibility of CNFs, allowing the Fe 3 O 4 /CNFs to be aligned in the epoxy before it cures, using a weak magnetic field (i.e. 0.05 T).…”

“…The supernatant liquid, obtained as described above, was used as the starting material to synthesize Fe 3 O 4 /PVP-GNPs nanohybrids by a facile co-precipitation method under a nitrogen atmosphere using a 1:2 mol ratio of Fe 2+ and Fe 3+ [25,27] …”

“…0.05 T). The resulting epoxy polymer nanocomposites were found to possess a greatly improved fracture toughness [25]. However, the alignment of graphene in polymers using a magnetic field has not been extensively investigated.…”

Synthesis of Carbon Nanofibers with Maghemite via a Modified Sol-Gel Technique

“…Nevertheless, no researches have been reported about the implementation of the same technique using CNFs, which could result in better synthesis results due to the CNF's morphology, in addition to the low cost of the nanohybrid material. CNFs have been functionalized with magnetite (Fe 3 O 4 ) by a coprecipitation method in order to align them in an epoxy matrix, resulting in a higher electrical conductivity along the direction of the alignment [26]. Maghemite, -Fe 2 O 3 , is a member of the same iron oxide family as magnetite (Fe 3 O 4 ) and the main difference between these two oxides is the presence of only ferric (Fe 3+ ) ions in the maghemite allotropic form, while both ferrous (Fe 2+ ) and Fe 3+ ions are found in magnetite.…”