Photonic crystals in biology - NanoTR-VI

Poster Session, Thursday, June 17Theme F686 - N1123MWCNT-Al 2 O 3 Hybrids Dispersed in Epoxy CompositesSeda Aksel 1 , Özge Malay 1 , Dominik Eder 2 , Yusuf Z. Menceloğlu 1, *1 Sabanci University, Materials Science and Engineering Program, İstanbul,34956, Turke.2 University of Cambridge, Department of Materials Science and Metallurgy, Cambridge, UKAbstract— This work aims to investigate dispersion state and thermo-mechanical properties of aluminium oxide (Al 2 O 3 ) coated multi- walledcabon nanotubes (MWCNTs) in epoxy matrix. MWCNT-inorganic hybrids were introduced as an efficient filler to reduce entangledagglomerates in epoxy resin with improved thermal and mechanical characteristics.Carbon nanotube (CNT)-inorganic hybrids are a new class ofmaterials that carbon nanotubes are coaxially coated withinorganic components. These materials show superior optical,mechanical, electrical and thermal properties with respect to thephysical nature of inorganic component [1].Previous studies which focus on addition of inorganicnanoparticles into carbon nanotube/epoxy nanocomposite alsoproved that inorganic nanoparticles diminish the agglomerationof carbon nanotubes in polymeric matrix [2]. This workprimarily concentrates on coating of carbon nanotubes withaluminium oxide (Al 2 O 3 ) in order to improve dispersion ofcarbon nanotubes in epoxy matrix and to characterize CNT-Al 2 O 3 /epoxy nanocomposites prior to its use for specificapplications with respect to enhanced thermal, mechanical andelectrical properties.Multi-walled carbon nanotubes (MWCNTs) which wereprepared by chemical vapor deposition (CVD) method, wereused in this study. The average diameter of the nanotubes is 70nm and the length range is 100-200 μm. MWCNTs were coatedwith inorganic components via sol-gel process. Benzyl alcoholwas used to functionalize hydrophobic surface of MWCNTs viathe π-π interaction between the aromatic MWCNT surface andbenzyl ring of benzyl alcohol [1,3].MWCNTs, benzyl alcohol functionalized MWCNTs andAl 2 O 3 –MWCNT hybrids were used as filler and eachnanocomposite film contains 0.05 wt% filler. The polymermatrix used for the composites was an epoxy based system withamine hardener.Solid State13 C-NMR spectroscopy of functionalizedMWCNTs clearly shows the presence of -CH 2 group bonded tohydroxyl group (-OH) on the surface of MWCNTs by the peakat 62 ppm. Al 2 O 3 coating on MWCNTs hybrid was confirmed byXRD and SEM/EDX analyses as shown in Figure 1 (a,b). Inaddition to graphite peaks at 2θ values of 26 and 44 in the XRDplot of MWCNTs, alumina peak was observed at 39 for Al 2 O 3 -MWCNT hybrid. Weight percentage of aluminium and oxygenin the sample detected by EDX analysis also confirmed thatsample was derived from the Al 2 O 3 molecules in Figure 2 (a,b).Optical microscope images in Figure 3 (a,b,c,d), which showdispersion state of MWCNTs in uncured epoxy resin, demostratethat degree of filler dispersion increases along with functionalizedMWCNTs and hybrids.Figure 3. MWCNT dispersion in uncured epoxy matrix (a) 0.05 wt%MWCNTs (b) 0.05 wt% functionalized MWCNTs (c) 0.05 wt%MWCNT-Al 2 O 3 hybrids (d) 0.05 wt% MWCNT, 0.2 wt% Al 2 O 3 hybrids.MWCNT-Al 2 O 3 hybrids could be homogeneously dispersed inepoxy resin due to the less attractive forces between carbonnanotubes. SEM (Scanning Electron Microscopy) images inFigure 4 (a,b,c) show that functionalization of MWCNTs anduniform coating by Al 2 O 3 decrease the degree of agglomeration.Since the free surface area of carbon nanotubes reduces, weakelectrostatic forces provided via inorganic coating decreases theentanglement degree.(a) (b) (c)Figure 4. SEM image of (a) MWCNTs (b) BA-functionalized MWCNTs(c) MWCNT-Al 2 O 3 hybrids.Addition of MWCNTs decreases the glass transition temperature(Tg) due to lower cross-linking degree of the epoxy matrix.Addition of benzyl alcohol and coating MWCNTs by Al 2 O 3reduces the decrease of Tg with respect to increase in dispersionstate of the filler. On the other hand, 3-point bending analysisreveals that both flexural strength and flexural modulus of thenanocomposites increases via functionalization of the MWCNTs.In summary, MWCNTs were uniformly coated with an inorganiccomponent, Al 2 O 3 . New filler type was developed to attain novelAl 2 O 3 -MWCNT/epoxy nanocomposite materials.*Corresponding author: yusufm@sabanciuniv.eduFigure 1.a. XRD Plotof the MWCNTsFigure 1.b. XRD Plot of theAl 2 O 3 -MWCNT HybridsFigure 2.a. EDX Spectrum Figure 2.b. EDX Spectrum ofof the MWCNTs the Al 2 O 3 -MWCNT Hybrids[1] Eder, D., Windle, A. H., 2008. Carbon-Inorganic Hybrid Materials:The Carbon-Nanotube/TiO 2 Interface, Advance Materials 20: 1787-1793.[2] Sumfleth, J., Prado, L.A, Sriyai, M., Schulte, 2008. K., Titania-dopedmulti-walled carbon nanotubes epoxy composites: Enhanceddispersion and synergistic effects in multiphase nanocomposites, Polymer49: 5105-5112.[3] Eder, D., Windle, A. H., 2008. Morphology control of CNT-TiO 2hybrid materials and rutile nanotubes, Journal of Materials Chemistry18: 2036-2043.6th Nanoscience and Nanotechnology Conference, zmir, 2010 730