Role of polymer matrix in large enhancement of dielectric constant in polymer-metal composites

Abstract

Dielectric behavior of polymer (polar/nonpolar)-metal nanocomposites (PMCs) prepared under identical processing conditions have been compared. A high effective dielectric constant (ɛeff>2500) with a moderate loss and a lower ɛeff (74) with low loss was observed, respectively, for polar and nonpolar PMC at their respective percolation thresholds (fc). The results have been explained with the help of percolation theory and dipolar polarization. Similar value of fc observed in both the PMC is attributed to the same order of conductivity of polymer matrices. The dipolar polarization present in the polymer plays a major role in the enhancement of ɛeff.

Evidence of a third kind of Johnscher’s like universal dielectric response

“…5 PVDF/nc-Ni composite samples were prepared with varying volume fractions of nickel (f con ) through cold pressing and the details of sample preparation and characterizations can be found from the earlier published literatures. [4][5][6][7][8][9] The detailed method of image processing of the optical micrographs of the samples with different f con done through MATLAB software is described as follows. The image processing is done for seeking the percolation channels formed in the host polymer PVDF due to varying f con introduced into the PMC.…”

“…20 Hence with the expectation of getting this unique type of dielectric relaxation behavior, a variety of series of PVDF/Ni composites with varying size and type of filler and varying process conditions (hot molding and cold pressing) were investigated. [4][5][6][7][8][9] Although a variety of series of PVDF/ Ni composites have been investigated, 4-9 the expected dielectric relaxation behavior was observed in the cold pressed PVDF/nanocrystalline nickel (nc-Ni) composites, which opens an interesting and novel dielectric response associated with the novel physical phenomena, which may make the material suitable for their possible electrical and electronics engineering applications.…”

“…are undergoing extensive investigations through various experimental methods. [1][2][3][4][5][6][7][8][9] Out of these methods (hot molding, cold pressing, etc. ), recent results have confirmed the importance and usefulness of the cold pressing method in case of FPD as compared to the traditional hot molding process, since cold pressing method develops better polymer dielectrics by retaining the spherulites as well as the flexibility of PVDF.…”

“…[1][2][3] Out of these polymer dielectrics, ferroelectric polymer dielectrics (FPD) have proven themselves as the emerging materials of future for electrostatic energy storage and dielectric applications, due to their higher dielectric constant, lower loss tangent and higher dielectric field strength. [1][2][3][4][5][6][7][8][9] In development of these FPD, the hit and trial combination method comprising of varieties of ferroelectric polymers (polyvinylidene fluoride (PVDF), PVDF trifluoroethylene (PVDF TrFE), etc. and varieties of fillers (metal, carbon nano tube, carbon black, graphene, etc.)…”

“…Interestingly, I also do believe that there must be a different dielectric system, completely different from the traditional fundamental systems as discussed above, which must be neither a dipolar nor a charge carrier-dominated system or must be an equally dipolar/charge carrier-dominated system and that must be at the exact boundary of the insulator to metal transition (IMT) of the polymer/metal composites (PMC). It has been found that PVDF/Ni composites have proven themselves as very good materials for energy storage [3][4][5][6][7][8][9] and electromagnetic interference shielding applications. 20 Hence with the expectation of getting this unique type of dielectric relaxation behavior, a variety of series of PVDF/Ni composites with varying size and type of filler and varying process conditions (hot molding and cold pressing) were investigated.…”