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Professor: Chang-Ning Huang
Student: Chao-Hsiang Yeh
Reporting date: 2015 / 12/ 23
Outline
• Introduction
• Materials
• Experimental
• Results and discussion
• Conclusions
Introduction
• Nowadays, carbon nanotubes (CNTs) as particulate filler in
epoxy resin are widely used with remarkable improvements
in mechanical, electrical, optical and thermal properties.
• Nevertheless, there are huge challenges for researchers to
impart the intrinsic properties of CNT due to the difficulty of
dispersing CNT in the epoxy matrix.
• This CNT–Al2O3 hybrid filler was reported to improve
composite properties since Al2O3 particles work as a method
of transport for the CNTs to disperse into the epoxy matrix.
Introduction
• In this paper, CNT–Al2O3 hybrid was synthesised using nickel
vas the catalyst to grow CNT homogenously on Al2O3 particles.
• The study aimed to investigate the dispersion of CNT–Al2O3
hybrid in epoxy resin and to compare with the conventional
physical mixing technique in producing CNT–Al2O3 hybrid
epoxy composite system.
Materials
• Ni(NO3)2 ‧6H2O
• Al powder
[1]
[2]
• NaOH
• Al2O3 powder
[3]
• Multi-wall carbon nanotube (MWCNT)
• Diglycidyl Ether of Bisphenol A (DGEBA)
[4]
[5]
• Trimethylhexamethylenediamine (TMD)
[6]
Experimental
 Production of CNT–Al2O3 hybrid powder
• The CNT–Al2O3 hybrid compound was synthesised using the chemical
vapor deposition (CVD) method.
aluminium (Al) powder
Ni(NO3)2‧6H2O
in 1 L of distilled water
NaOH solution was gradually
added to the previous mixture
binary colloid (Ni(OH)2/Al)
Experimental
The colloid was aged at room temperature for 24 h and washed using distilled
water and then filtered.
dried at 110℃ for 2 h
The colloid was calcined at 900℃ to oxidize NiOH and Al(OH) to produce a
NiO–Al2O3 complex.
Finally, the reduction of NiO–Al2O3 complex was accomplished under
hydrogen atmosphere of 400℃ for 2 h.
Experimental
• To grow CNT on alumina
methane gas and nitrogen gas with a ratio of 1:7 at 800℃ for 30 min
Experimental
• The CNT–Al2O3 was also prepared by using a physical mixing method.
MWCNT was mixed with Al2O3 using a ball milling machine for
48 h at 20 rpm.
The ratio of CNT : Al2O3 used was 12:100.
Experimental
 Preparation of CNT–Al2O3 epoxy nanocomposites
The HYB and MIX were first dispersed in epoxy resin DGEBA using a sonicator
machine.
at the frequency of 25 kHz for 30 min
The temperature of the mixture was maintained in the range of 60–70℃.
Next, the curing agent TMD with mass ratio of 6:10 to the epoxy resin was
added to the mixture.
The mixture was placed in a vacuum of 76 cm Hg pressure for 30 min to remove
any trapped air.
Experimental
Finally, epoxy composites were poured into a silicon mold and cured at 120℃
for 1 h.
Results and discussion
A wire-like structure formed on
the alumina particle was believed
to be CNT.
The agglomeration of CNT was
due to the strong van der Waals’
force.
Fig. 2. SEM images of HYB with
magnification of (a) 3000X, (b)
10000X, (c) 30000X and (d) 50000X
and MIX with magnification of (e)
3000X, (f) 10000X, (g) 30000X and (h)
50000X.
Results and discussion
The diameter of the tube was 20
nm.
The size of CNT was dependent
on the size of the Ni catalyst.
Fig. 3. HRTEM image of
MWCNT of HYB.
Results and discussion
Fig. 4. Schematic diagram of CNT growth on alumina particle via tip growth
mechanism.
Results and discussion
Fig. 5. EDX spectrum of HYB.
Results and discussion
Fig. 6. XRD patterns of (a) HYB and (b) MIX.
Results and discussion
Fig. 7. Raman spectrum of HYB and MIX.
Results and discussion
Results and discussion
Fig. 8. Flexural stress–strain curves of neat epoxy and the epoxy composites
with 1%, 3%, and 5% weight percentage of HYB and MIX.
Results and discussion
Fig. 10. Flexural strength of neat epoxy and the epoxy composites with 1%, 3%
and 5% weight percentage of HYB and MIX.
Results and discussion
Fig. 11. Flexural modulus of neat epoxy and the epoxy composites
with 1%, 3% and 5% weight percentage of HYB and MIX.
Results and discussion
Fig. 12. SEM images of fracture surfaces of Epoxy/HYB with
magnification of (a) 1000X, (b) 5000X, (c) 10000X and (d) 30000X.
Results and discussion
Fig. 13. SEM images of fracture surfaces of Epoxy/MIX with
magnification of (a) 1000X, (b) 3000X, (c) 10000X and (d) 30000X.
Results and discussion
Fig. 14. HRTEM micrographs of Epoxy/HYB.
Results and discussion
Fig. 15. HRTEM micrographs of Epoxy/MIX.
Results and discussion
Fig. 16. Frequency dependent dielectric constant of neat epoxy and
epoxy filled with HYB and MIX at various different filler loadings.
Conclusions
• The CNT–Al2O3 hybrid filler synthesised using CVD was
adopted to improve the dispersion of CNT in the epoxy matrix.
• The Epoxy/HYB composites showed higher flexural strength
and flexural modulus than Epoxy/MIX.
• Epoxy/HYB and Epoxy/MIX also showed improvements in
the dielectric constant with enhancement of about 20% and
18% compared to the neat epoxy composite.
References
[1] http://www.chemicalbook.com/ProductChemicalPropertiesCB3115275.htm
[2] http://baike.baidu.com/view/136834.htm
[3] http://baike.baidu.com/view/157830.htm
[4] http://digi.163.com/11/0426/11/72IHU62600162OUT.html
[5] http://www.sigmaaldrich.com/catalog/product/sigma/d3415?lang=en&region=TW
[6] http://www.sigmaaldrich.com/catalog/product/aldrich/722650?lang=en&region=TW