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Inorganic nanotubes reinforced polyvinylidene fluoride composites as low-cost electromagnetic interference shielding materials.

Eswaraiah V, Sankaranarayanan V, Ramaprabhu S - Nanoscale Res Lett (2011)

Bottom Line: Homogeneous distribution of f-MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy.The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs) to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m).EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region.

View Article: PubMed Central - HTML - PubMed

Affiliation: Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials, Technology Centre (NFMTC), Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India. ramp@iitm.ac.in.

ABSTRACT
Novel polymer nanocomposites comprising of MnO2 nanotubes (MNTs), functionalized multiwalled carbon nanotubes (f-MWCNTs), and polyvinylidene fluoride (PVDF) were synthesized. Homogeneous distribution of f-MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy. Electrical conductivity measurements were performed on these polymer composites using four probe technique. The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs) to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m). Electromagnetic interference shielding effectiveness (EMI SE) was measured with vector network analyzer using waveguide sample holder in X-band frequency range. EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region.

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Field emission scanning electron microscope images. (a) PVDF, (b) f-MWCNTs, (c) MNTs, (d) 1 wt.% MNTs-PVDF, (e) 2 wt.% MNTs-PVDF, and (f) high-resolution image of 2 wt.% f-MWCNTs-PVDF.
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Figure 5: Field emission scanning electron microscope images. (a) PVDF, (b) f-MWCNTs, (c) MNTs, (d) 1 wt.% MNTs-PVDF, (e) 2 wt.% MNTs-PVDF, and (f) high-resolution image of 2 wt.% f-MWCNTs-PVDF.

Mentions: Morphology is an important factor which affects the EMI SE of the composites. Figure 5a, b, c, d, e, f shows the FESEM images of polymer, nanofillers and nanofiller reinforced polymer composites. The corresponding images are (a) pure PVDF, (b) f-MWCNTs, (c) pure MNTs, (d) 1 wt.% MNTs-PVDF composite, (e) 2 wt.% MNTs-PVDF composite, and (f) high resolution image of 2 wt.% MNTs-PVDF composite. As shown in the Figure 5b andc, MWCNTs are 30 to 40 nm in diameter and approximately 10 μm in length and MNTs are 50 to 70 nm in diameter and in micron length. It can be observed that MWCNTs are entangled with each other because of Van der Waals interactions, whereas manganese dioxide nanotubes were straight and rigid and PVDF shows smooth surface as shown in the Figure 5a. f-MWCNTs and MNTs were homogeneously distributed and embedded in the PVDF matrix as shown in Figure 6a, b, c, d, e, f due to ultrasonication and shear mixing of the solutions at high rpm in the formation of composite films. Figure 6d, e, f indicates that the space between filler aggregates in carbon nanotube-PVDF composites is much smaller than that of MNTs-PVDF composites. Figure 6e shows the FESEM image of 5 wt.% MNTs filled PVDF composite along with 1 wt.% MWCNTs. It is observed that a very good microstructure has been formed, and f-MWCNTs were uniformly dispersed and embedded between the MNTs throughout the PVDF matrix. This good network can increase the number of inter nanostructure connections, and hence provide better EMI SE. Further, to confirm the homogeneity of the composites, we have performed X-ray elemental mapping over the sample surface to visualize the atomic elements of manganese, oxygen, carbon, and fluorine. Figure 7 shows the EDX spectra of PVDF-based MNTs and f-MWCNTs composite. It confirms the presence of manganese and oxygen from MnO2, carbon from f-MWCNTs, and fluorine from the PVDF polymer. Figure 8 shows the elemental mapping of the 5 wt.% MNTs-1 wt.% f-MWCNTs-PVDF composite. As can be seen from the figures, all the elements were distributed homogeneously in the polymer matrix.


Inorganic nanotubes reinforced polyvinylidene fluoride composites as low-cost electromagnetic interference shielding materials.

Eswaraiah V, Sankaranarayanan V, Ramaprabhu S - Nanoscale Res Lett (2011)

Field emission scanning electron microscope images. (a) PVDF, (b) f-MWCNTs, (c) MNTs, (d) 1 wt.% MNTs-PVDF, (e) 2 wt.% MNTs-PVDF, and (f) high-resolution image of 2 wt.% f-MWCNTs-PVDF.
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Figure 5: Field emission scanning electron microscope images. (a) PVDF, (b) f-MWCNTs, (c) MNTs, (d) 1 wt.% MNTs-PVDF, (e) 2 wt.% MNTs-PVDF, and (f) high-resolution image of 2 wt.% f-MWCNTs-PVDF.
Mentions: Morphology is an important factor which affects the EMI SE of the composites. Figure 5a, b, c, d, e, f shows the FESEM images of polymer, nanofillers and nanofiller reinforced polymer composites. The corresponding images are (a) pure PVDF, (b) f-MWCNTs, (c) pure MNTs, (d) 1 wt.% MNTs-PVDF composite, (e) 2 wt.% MNTs-PVDF composite, and (f) high resolution image of 2 wt.% MNTs-PVDF composite. As shown in the Figure 5b andc, MWCNTs are 30 to 40 nm in diameter and approximately 10 μm in length and MNTs are 50 to 70 nm in diameter and in micron length. It can be observed that MWCNTs are entangled with each other because of Van der Waals interactions, whereas manganese dioxide nanotubes were straight and rigid and PVDF shows smooth surface as shown in the Figure 5a. f-MWCNTs and MNTs were homogeneously distributed and embedded in the PVDF matrix as shown in Figure 6a, b, c, d, e, f due to ultrasonication and shear mixing of the solutions at high rpm in the formation of composite films. Figure 6d, e, f indicates that the space between filler aggregates in carbon nanotube-PVDF composites is much smaller than that of MNTs-PVDF composites. Figure 6e shows the FESEM image of 5 wt.% MNTs filled PVDF composite along with 1 wt.% MWCNTs. It is observed that a very good microstructure has been formed, and f-MWCNTs were uniformly dispersed and embedded between the MNTs throughout the PVDF matrix. This good network can increase the number of inter nanostructure connections, and hence provide better EMI SE. Further, to confirm the homogeneity of the composites, we have performed X-ray elemental mapping over the sample surface to visualize the atomic elements of manganese, oxygen, carbon, and fluorine. Figure 7 shows the EDX spectra of PVDF-based MNTs and f-MWCNTs composite. It confirms the presence of manganese and oxygen from MnO2, carbon from f-MWCNTs, and fluorine from the PVDF polymer. Figure 8 shows the elemental mapping of the 5 wt.% MNTs-1 wt.% f-MWCNTs-PVDF composite. As can be seen from the figures, all the elements were distributed homogeneously in the polymer matrix.

Bottom Line: Homogeneous distribution of f-MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy.The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs) to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m).EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region.

View Article: PubMed Central - HTML - PubMed

Affiliation: Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials, Technology Centre (NFMTC), Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India. ramp@iitm.ac.in.

ABSTRACT
Novel polymer nanocomposites comprising of MnO2 nanotubes (MNTs), functionalized multiwalled carbon nanotubes (f-MWCNTs), and polyvinylidene fluoride (PVDF) were synthesized. Homogeneous distribution of f-MWCNTs and MNTs in PVDF matrix were confirmed by field emission scanning electron microscopy. Electrical conductivity measurements were performed on these polymer composites using four probe technique. The addition of 2 wt.% of MNTs (2 wt.%, f-MWCNTs) to PVDF matrix results in an increase in the electrical conductivity from 10-16S/m to 4.5 × 10-5S/m (3.2 × 10-1S/m). Electromagnetic interference shielding effectiveness (EMI SE) was measured with vector network analyzer using waveguide sample holder in X-band frequency range. EMI SE of approximately 20 dB has been obtained with the addition of 5 wt.% MNTs-1 wt.% f-MWCNTs to PVDF in comparison with EMI SE of approximately 18 dB for 7 wt.% of f-MWCNTs indicating the potential use of the present MNT/f-MWCNT/PVDF composite as low-cost EMI shielding materials in X-band region.

No MeSH data available.


Related in: MedlinePlus