Polymer(polar/nonpolar)/metal composites(PMC)were prepared under different process conditions.In polar PMC,dipolar relaxation plays a predominant role below percolation threshold(f_(c))and anomalous low frequency disp...Polymer(polar/nonpolar)/metal composites(PMC)were prepared under different process conditions.In polar PMC,dipolar relaxation plays a predominant role below percolation threshold(f_(c))and anomalous low frequency dispersion(ALFD)becomes dominant above f_(c)while ALFD is the only likely possibility for nonpolar PMC above f_(c).The magnitude of relaxation exponents"m","p"and"n",evaluated from the experimental results using Jonscher's universal dielectric response(JUDR)laws,falls within the universal limit[0,1]with additional feature of strong dependence on volume fraction of conductor(f_(c)on).The decrease in the relaxation exponent"m"with an increase of f_(c)on is directly linked with decrease in the number of dipoles of the polymer in the composite and is accompanied by a distribution of relaxation time due to increased heterogeneity of the system.The magnitude of the relaxation exponent"n"decreases at f_(c),due to the prevalence of Maxwell–Wagner–Sillar polarization contributed by uncorrelated electrons.展开更多
文摘Polymer(polar/nonpolar)/metal composites(PMC)were prepared under different process conditions.In polar PMC,dipolar relaxation plays a predominant role below percolation threshold(f_(c))and anomalous low frequency dispersion(ALFD)becomes dominant above f_(c)while ALFD is the only likely possibility for nonpolar PMC above f_(c).The magnitude of relaxation exponents"m","p"and"n",evaluated from the experimental results using Jonscher's universal dielectric response(JUDR)laws,falls within the universal limit[0,1]with additional feature of strong dependence on volume fraction of conductor(f_(c)on).The decrease in the relaxation exponent"m"with an increase of f_(c)on is directly linked with decrease in the number of dipoles of the polymer in the composite and is accompanied by a distribution of relaxation time due to increased heterogeneity of the system.The magnitude of the relaxation exponent"n"decreases at f_(c),due to the prevalence of Maxwell–Wagner–Sillar polarization contributed by uncorrelated electrons.
