Eswaraiah et al. Nanoscale Research Letters 2011, 6:137 http://www.nanoscalereslett.com/content/6/1/137 Page 8 of 11 Figure 8 X-ray elemental mapping of 5 wt.% MNT-1 wt.% f-MWCNTs-PVDF composite. Hence, it is clear that the major contribution to the EMI shielding comes from the addition of semiconducting MNTs to the PVDF matrix. This increment in EMI SE can be attributed to the formation of conductive and connective network in the PVDF matrix, which is in accordance with the high-resolution FESEM image of MNTs filled PVDF composite (Figure 5f). Since electri- cal conductivity of the MNTs is two orders less Table 1 Percentage of chemical resistance for different polymer composites Chemical Percentage of chemical resistance PVDF 5 wt.% MNT-f- MWCNT-PVDF 1 wt.% f-MWCNT- PVDF 5 wt.% MNT- PVDF Acetic acid glacial Oleic acid Sodium hydroxide solution Ammonia solution n-Hexane 2-Propanol Toluene Chloroform 98.9 100 97.6 98.7 97.8 98.9 97.0 100 97.9 100 96.0 98.4 100.0 100.0 98.1 97.9 98.2 98.5 98.8 95.7 98.7 98.3 97.0 100 98.0 100 97.2 96.8 100 97.3 97.2 96.8 compared to that of carbon nanotubes, there is a limit over the highest obtainable conductivity of the total composite. This limits the EMI SE to approximately 12 dB for 5 wt.% MNTs/PVDF composite. These results suggest that the MNTs/PVDF composites can be used for electrostatic discharge applications. In order to make it suitable for EMI shielding applications, a small amount of (1 wt.%) f-MWCNTs have been incorporated in MNT/PVDF matrix. With this, 1 wt.% f-MWCNTs in 5 wt.% MNTs/PVDF composite, we could achieve an EMI SE of 18 to 22 dB. For comparison, the EMI SE of 7 wt.% f-MWCNTs/PVDF composites alone in the same frequency region has been measured, and in this case, an EMI SE of 18 dB has been obtained as shown in Figure 10c. Table 2 shows the overall EMI SE of different composites and their electrical conductivities. It is clear that 5 wt.% MNTs-1 wt.% f-MWCNTs-PVDF composite can be a better and low-cost EMI shielding material. Shielding mechanism in MNTs/f-MWCNTs/PVDF composites It is well reported that reflection is the most prominent EMI shielding mechanism in CNT-polymer composites [34]. In the present case, EMI shielding in f-MWCNTs reinforced PVDF composites has been studied and from the measured scattering parameters reflectivity, trans- missivity, and absorptivity were derived using the