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IFM's Gayathri Devi Rajmohan has won the People's Prize in Deakin's Three Minute Thesis competition for 2013.
Meet the team at Deakin making it happen.
Dr Xiujuan Jane Dai
+61 3 522 72427
We have developed a stirring plasma technology to address the challenges of achieving uniform treatment with a high density of functional groups and easy handling. We have also developed a novel plasma method that combines advantages of both continuous wave (CW) plasma and pulsed plasma for surface functionalization of nanomaterials, especially nanotubes, where we have:
Uniform treatment of multiwalled carbon nanotubes by plasma treatment has been investigated using a custom-built stirring plasma system. A thin plasma polymer with high levels of amine groups has been deposited on MWCNTs using a combination of continuous wave and pulsed plasma polymerization of heptylamine in the stirring plasma system. Scanning electron microscopy showed that the plasma polymerization improved the dispersion and interfacial bonding of the MWCNTs with an epoxy resin at loadings of 0.1, 0.3 and 0.5 wt%. The flexural and thermal mechanical properties of plasma polymerized MWCNT / epoxy nanocomposites were also significantly improved while untreated MWCNT / epoxy nanocomposites showed an opposite trend. The epoxy with 0.5 wt% plasma polymerized MWCNTs had the greatest increase in flexural properties, with the flexural modulus, flexural strength and toughness increasing by about 22%, 17% and 70%, respectively.
The N₂ / H₂ CW + P method has been applied to a thin film of multiwalled carbon nanotubes, a nanostructured and relatively inert material. Contact angle measurements, using different probe liquids, plus model calculations of surface energy agree well with the spectroscopy and electron microscope results, i.e. the polar part shows significant changes while the non-polar part was unchanged. These results indicate that the wettability changes in the thin film of carbon nanotubes by the plasma treatment are due to the changes in surface chemistry. This confirms the effectiveness and practicality of the improved plasma method that should greatly help the use of nanotubes in applications from biomaterials to nanocomposites.
Higher levels of primary amines on the surface of multiwalled carbon nanotubes (MWCNTs) achieved by the N₂ / H₂ CW + P plasma improved their dispersion and interfacial bonding with an epoxy resin. The properties of MWCNT reinforced Bisphenol F epoxy resin were significantly improved using just 0.1wt% of these nanotubes. The incorporation of only 0.1wt% of functionalized MWCNTs leads to marked increases in both nano- and macro-mechanical properties compared to neat epoxy. Nanoindentation tests showed that the hardness and elastic modulus increased by 40% and 19%, respectively, using the functionalized nanotubes. Macro-mechanical properties from thermo-mechanical and flexural analysis were also enhanced.
A combined continuous wave plus pulsed plasma (CW + P) effectively functionalized multi-walled carbon nanotubes. The combined mode allowed the highest reported levels of primary amines and the replacement of ammonia with N₂ plus H₂ (15%). It also gave better results for plasma polymerization using the less toxic heptylamine. The resultant epoxy composites were harder (smaller indentations) even at 0.1 wt% loading.
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