Investigating the Impact of Polymer/Nanoparticles Interaction on the Impedance Properties

In this study, interaction between polymer and nanoparticles effect on impedance properties was studied. The nanocomposites of Polypropylene (PP), Poly (Propylene- grafted maleic anhydride) (PP-g-MA), and Poly (Ethylene- Vinyl Acetate) (EVA) with different surface energies, containing Multiwalled Carbon Nanotubes (MWCNTs) were prepared by melt mixing. Thermodynamic affinity between MWCNTs and polymers were estimated by thermodynamic equations. According to that, PP, PP-g-MA, EVA interfacial tensions with MWCNTS were estimated as ۱۳.۰۷, ۸.۱, and ۲.۱, respectively. Optical micrographs showed that the dispersion of MWCNTs in PP, PP-g-MA, and EVA polymers is influenced by the interfacial tension between the polymer and MWCNTs. Poor dispersion was observed for PP, attributed to weak interaction and high crystallinity. The percolation threshold of PP and PP-g-MA was lower than that of EVA due to weak interactions between MWCNTs and PP and the formation of an interconnected structure between the nanoparticles, as well as the high crystallinity of PP leading to a phase segregation structure in the polymer. According to impedance measurements, PP exhibited the highest critical frequency (fc) due to its interconnected structure resulting from phase-segregated structure and weak interactions with MWCNTs. The existence of more conductive pathways in PP compared to EVA was validated by peak shifting to high frequencies and decline in peak height. EVA exhibited the best electromagnetic interference shielding capability among PP, PP-g-MA, and EVA samples, as indicated by the higher loss tangent of impedance.

Keywords:

Interfacial tension , MWCNTs , Impedance , EMI shielding , Percolation threshold.