This study investigates the tunability of the electrical and dielectric properties of polyvinylidene fluoride (PVDF) through the incorporation of multi-walled carbon nanotubes (MWCNTs). Structural analysis confirmed β-phase formation and good MWCNT dispersion up to 6 wt%, beyond which agglomeration occurred. Broadband dielectric spectroscopy was employed to characterize (PVDF)1−x(MWCNTs)x films (0.00 ≤ x ≤ 0.09) across a frequency range of 0.1 Hz to 20 MHz and a temperature range of 30 °C to 120 °C. For example, the dielectric constant (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\varepsilon^{\prime}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>ε</mi> <mo>′</mo> </msup> </math></EquationSource> </InlineEquation>) measured at 10 Hz and 30 °C increases from 2.08 for pure PVDF to 3.11 at x = 0.03 (⁓ 49% improvement), while the <InlineEquation ID="IEq2"> <EquationSource Format="TEX">${\sigma}_{ac}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mrow> <mi mathvariant="italic">ac</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> at 10 Hz and 120 °C increases from 6.95 × 10⁻10 S/cm for pure PVDF to 1.26 × 10⁻8 S/cm at x = 0.09. A preliminary observation is a possible transition in the conduction mechanism from electronic (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">$s$</EquationSource> <EquationSource Format="MATHML"><math> <mi>s</mi> </math></EquationSource> </InlineEquation> > 0.5) to hole-dominated (<InlineEquation ID="IEq4"> <EquationSource Format="TEX">$s$</EquationSource> <EquationSource Format="MATHML"><math> <mi>s</mi> </math></EquationSource> </InlineEquation> < 0.5) at 120 °C. The activation energy for conduction (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">${E}_{a}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation>) at 0.1 Hz is 1.16, 1.46, 1.20, and 1.43 eV, while for α-relaxation (<InlineEquation ID="IEq6"> <EquationSource Format="TEX">${E}_{a,relax}$</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>E</mi> <mrow> <mi>a</mi> <mo>,</mo> <mi>r</mi> <mi>e</mi> <mi>l</mi> <mi>a</mi> <mi>x</mi> </mrow> </msub> </math></EquationSource> </InlineEquation>) it is 1.06, 1.21, 1.44, and 1.36 eV for x = 0.00, 0.03, 0.06, and 0.09, respectively. Impedance analysis reveals that increasing temperature (60–120 °C) or MWCNT concentration reduces grain and grain boundary resistance. The F-factor improves by 60% and 100% at 20 MHz for x = 0.09 compared to pure PVDF at 30 °C and 120 °C, respectively. The optimal MWCNT loading is x = 0.03 for maximum dielectric constant and x = 0.06 for minimum activation energy. The enhanced electrical properties position MWCNT-incorporated PVDF films as promising candidates for telecommunications, solar cells, and supercapacitors.

Temperature, frequency, and composition dependence of electrical and dielectric properties in PVDF/MWCNT

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发表日期：

2026年7月16日

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Noha Younis,
Naglaa AbdelAll,
Alaa M. Abd-Elnaiem,
A. Sedky,
Ghada A. Khouqeer,
Taha A. Hanafy,
M. Rashad

摘要

This study investigates the tunability of the electrical and dielectric properties of polyvinylidene fluoride (PVDF) through the incorporation of multi-walled carbon nanotubes (MWCNTs). Structural analysis confirmed β-phase formation and good MWCNT dispersion up to 6 wt%, beyond which agglomeration occurred. Broadband dielectric spectroscopy was employed to characterize (PVDF)_1−x(MWCNTs)_x films (0.00 ≤ x ≤ 0.09) across a frequency range of 0.1 Hz to 20 MHz and a temperature range of 30 °C to 120 °C. For example, the dielectric constant ( $\varepsilon^{\prime}$ $ε^{'}$ ) measured at 10 Hz and 30 °C increases from 2.08 for pure PVDF to 3.11 at x = 0.03 (⁓ 49% improvement), while the ${\sigma}_{ac}$ $σ_{ac}$ at 10 Hz and 120 °C increases from 6.95 × 10⁻¹⁰ S/cm for pure PVDF to 1.26 × 10⁻⁸ S/cm at x = 0.09. A preliminary observation is a possible transition in the conduction mechanism from electronic ( $s$ $s$ > 0.5) to hole-dominated ( $s$ $s$ < 0.5) at 120 °C. The activation energy for conduction ( ${E}_{a}$ $E_{a}$ ) at 0.1 Hz is 1.16, 1.46, 1.20, and 1.43 eV, while for α-relaxation ( ${E}_{a,relax}$ $E_{a, r e l a x}$ ) it is 1.06, 1.21, 1.44, and 1.36 eV for x = 0.00, 0.03, 0.06, and 0.09, respectively. Impedance analysis reveals that increasing temperature (60–120 °C) or MWCNT concentration reduces grain and grain boundary resistance. The F-factor improves by 60% and 100% at 20 MHz for x = 0.09 compared to pure PVDF at 30 °C and 120 °C, respectively. The optimal MWCNT loading is x = 0.03 for maximum dielectric constant and x = 0.06 for minimum activation energy. The enhanced electrical properties position MWCNT-incorporated PVDF films as promising candidates for telecommunications, solar cells, and supercapacitors.