ABSTRACT
High density polyethylene (HDPE) and polypropylene (PP) based nanocomposites were fabricated using a constant 20 wt. % of carbon black (CB) as the base and different wt.% (0.25 to 1) of multiwalled carbon nanotubes (MWNT). The conductivity and the electromagnetic interference shielding effectiveness (EMI SE) and nano size free volume cavities of conducting HDPE/PP nanocomposites and their interrelation is explored. We found that the resistivity decreases by ~13 orders of magnitude and EMI SE shows a maximum of -30 dB in the three nanocomposites as the loading of MWNT increases. We obtained higher value of EMI SE in PP based nanocomposite compared to HDPE based ones. X-ray diffraction (XRD) results indicated that HDPE is highly crystalline while PP is highly amorphous. Filler loading reveals changes in crystalline and amorphous contents in the nanocomposites. Differential scanning calorimetry (DSC) results support the findings of the XRD data. Free volume data derived from positron annihilation lifetime spectroscopy (PALS) exhibits a linear relation with EMI SE values of the three composite. Better EMI SE is achieved for PP composite without the use of functionalized MWNT with PAni.
