Filled Poly Vinylidene Fluoride Research Articles

Electrical and EMI shielding studies of ferrite/MWCNTs/PVDF composites

AbstractIn this work, CFO/MWCNTs/PVDF and BFO/MWCNTs/PVDF composites are prepared and the comparative analysis of electrical properties and electromagnetic interference (EMI) shielding performance of both type of composites are investigated. The dielectric and conductivity characteristics are observed with varying ferrite concentration, frequency, and temperature. Ferroelectric properties are also obtained at 6 kV/cm field and EMI shielding behavior is observed in 8–12 GHz frequency range. Results exhibited that the studied properties of the composite enhances with increasing ferrite concentration that attributed to increased amount of magnetic nanoparticles. Cobalt ferrite (CFO) filled polyvinylidene fluoride (PVDF) composite is showing better properties as compared to barium ferrite (BFO) filled PVDF composites. The mechanism involve for this behavior is discussed herein.

Electromagnetic wave shielding and mechanical properties of vapor-grown carbon nanofiber/polyvinylidene fluoride composite fibers

The demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new conductive composite fibers. This study focuses on the development of Vapor-grown carbon nanofibers (VGCNFs) filled Polyvinylidene Fluoride (PVDF) composite fibers. Polyvinylidene fluoride (PVDF) reinforced with (1, 3, 5, and 8 wt.%) carbon nanofibers were produced as a masterbatch. The production of PVDF and PVDF/CNF composite fibers have been done successfully by using melt spinning processing technique. Conductive woven fabrics were produced with composite fibers on handloom machines to measure electromagnetic interference (EMI) shielding efficiency. Tensile strength of fibers increased with increase in CNF loading up to 3%. The tensile strength displayed a decrease of 5% and 8% CNF loading. Electromagnetic shielding effectiveness (EMSE) of woven fabrics with composite fibers were tested by using the coaxial transmission line method for planar materials standard that is based on ASTM D 4935-10. The electromagnetic shielding effectiveness of woven fabric which is consist of conductive composite fibers were increased with increasing CNFs loading and amount of fabric layers. It can be seen that the woven fabrics displayed between 2–10 dB and 2–4 dB EMSE values in the 15–600 MHz and 600–3000 MHz-frequency range, respectively. Nevertheless, it was observed that conductive filler content, dispersion, and network formation within the composite fibers were highly influent on the electromagnetic shielding effectiveness performance of the structures.

2D Ti3C2Tx MXene/polyvinylidene fluoride (PVDF) nanocomposites for attenuation of electromagnetic radiation with excellent heat dissipation

The present study deals with novel, and cost-effective preparation of 2D MXene (Ti3C2Tx) filled polyvinylidene fluoride (PVDF) polymer nanocomposite for the attenuation of electromagnetic interference (EMI). The obtained nanocomposite showed remarkable shielding effectiveness (SE) of 48.47 ± 3.5 dB for 22.55 vol% filler contents at a thickness of 2 mm. Formation of conducting network along with the assembly of micro capacitor network preserved for its high EMI shielding performance. The absorption dominated EMI shielding mechanism explained by the strong resonance, and interfacial polarization favors the loss of incident EM energy confirmed from dielectric measurements. Besides, the enhanced thermal conductivity of MXene-PVDF nanocomposites about 0.767 ± 0.034 Wm−1K−1 at 22.55 vol% filler content depicts that a large amount of incident EM wave attenuated majorly by dielectric components which would be dissipated as heat quickly. The fabricated MXene-PVDF nanocomposites could be a potential candidate for EMI shielding materials and promising multifaceted electronic utilization.

Polymer-derived SiCN ceramics as fillers for polymer composites with high dielectric constants

High-dielectric-constant (high-e) ceramic/polymer composites are an important class of advanced functional materials due to their applications in energy storage fields, such as embedded capacitors. Here, we synthesized novel polymer-derived silicon carbonitride (SiCN)-filled polyvinylidene fluoride (PVDF) composites by the tape-casting method. For comparison, commercial BaTiO3-filled PVDF composites were synthesized following the same process. The SiCN/PVDF composites showed much higher e than the BaTiO3/PVDF composites over a broad frequency range (10−1–106 Hz). Furthermore, the SiCN/PVDF composites showed ultrahigh e at low frequencies. The e of the 40 vol% SiCN/PVDF composite was as high as 2600 at 10−1 Hz. Although the dielectric breakdown strengths of the SiCN/PVDF composites were slightly lower than those of the BT/PVDF composites, the calculated maximum energy storage density of the 40 vol% SiCN/PVDF composites (17.5 J cm−3) was much higher than that of 40 vol% BT/PVDF (0.773 J cm−3) at 10−1 Hz. This is the first report on the use of polymer-derived ceramics as a component of ceramic/polymer composites. The results indicate that the polymer-derived SiCN ceramics can serve as promising ceramic fillers for high-e composites and that the obtained SiCN-filled composites have promising applications in energy storage fields.

Improving the electroactive phase, thermal and dielectric properties of PVDF/graphene oxide composites by using methyl methacrylate-co-glycidyl methacrylate copolymers as compatibilizer

In this work, graphene oxide sheets (GO) filled polyvinylidene fluoride (PVDF) nanodielectric composites with methyl methacrylate-co-glycidyl methacrylate copolymer (MG) as compatibilizer were fabricated by solution blend process. MG improved the dispersion of GO and enhanced the interface strength between GO and PVDF matrix. The strong dipolar interaction between MG on the surface of GO and PVDF resulted in the crystal transformation of PVDF from α-phase to β/γ-phase and nearly 81% β/γ-phase PVDF formed for PVDF/MG@GO7.0 composite. The thermal stability, mechanical property, melting and crystallization behaviors of PVDF/MG@GO composites were improved obviously due to the enhanced interface strength between GO and PVDF matrix with the aid of MG. MG copolymers not only contributed to the uniform dispersion of GO in PVDF, but also prevented the direct connection of GO and effectively inhibited the occurrence of leakage current in composites. Therefore, the dielectric properties of PVDF/MG@GO composites were also enhanced significantly with the addition of MG compared with the PVDF/GO composites, which supported the fact that the dielectric properties of resulted composites could be tailored by using MG copolymer as compatibilizer.

Laser induced periodic surface structures on nano metal oxide filled polyvinylidene fluoride nanocomposites

The ability of polarized pulsed laser in surface modification of substrate surfaces without thermally destroying them is a well-established concept of scientific procedure. In this work, we report the laser induced surface structures that are created on the semi crystalline polyvinylidene fluoride (PVDF) polymer and its composites containing transition metal oxides-zinc oxide of 100 nm and iron oxide of 30 nm diameter. The PVDF nanocomposites are fabricated by solution casting method and films of 0.2 mm thickness are used for laser treatment. The periodic structures formed are demonstrated by atomic force microscopy and profilometry investigations. Influence of laser pulses on the material properties is also addressed by means of Fourier transform infrared spectroscopy, contact angle measurements and thermogravimetric/differential scanning calorimetric studies.

Towards suppressing loss tangent: Effect of polydopamine coating layers on dielectric properties of core–shell barium titanate filled polyvinylidene fluoride composites

Barium titanate (BT) particles coated with different thickness of polydopamine (PDA) layers were incorporated into polyvinylidene fluoride (PVDF) to investigate influence of PDA coating layers on dielectric properties of composites. It is found that PDA coating layers not only effectively improved the interfacial interaction between BT particles and matrix but also significantly affected dielectric properties. PVDF composites loaded with modified BT exhibits superior dielectric properties in comparison with unmodified BT. Interfacial polarization is substantially suppressed because the catechol groups of PDA are able to constrain the mobility of nomadic charge carriers and ionizable hydroxyl groups on surface of BT particles. As a result, dependency of dielectric constant on frequency attenuates and tan δ is lowered to below 0.050 (1 kHz). The effect of suppression on tan δ tends to be more prominent as the thickness of PDA coating layer increases. The tan δ derived from ionic relaxation polarization is also constrained due to the chelation of PDA catechol groups with migrated cations. The as-prepared composites possess high dielectric constant and ultralow tan δ, making them promising for the industrial application as embedded capacitors.

Effect of CaCu3Ti4O12 powders prepared by the different synthetic methods on dielectric properties of CaCu3Ti4O12/polyvinylidene fluoride composites

CaCu3Ti4O12 (CCTO) particles were prepared separately by the sol–gel method (sg) and solid-state method (ss). CCTO-sg particles were more uniform, narrower distribution size and smaller (effective diameter of 290 nm) than that of CCTO-ss particles with the value of 480 nm for CCTO-ss particles. The CCTO-sg particles exhibited a small particle size and in turn improved chemical activity and lower crystallization temperature, which give rise to the enhanced dielectric properties. CCTO-sg and CCTO-ss filled polyvinylidene fluoride (CCTO/PVDF) were molded by solution mixing process and hot-pressing. The enhanced dielectric constant, good frequency and temperature stability of CCTO/PVDF composites were significant with increasing the volume fraction of CCTO particles. Compared to two kinds of composites, the CCTO-sg/PVDF composites exhibited better dielectric properties than CCTO-ss/PVDF composites. The dielectric constant of 50 vol% CCTO-sg/PVDF composites reached the maximum value of 62.3, which was 8 times and 2 times larger than that of pure PVDF and 50 vol%CCTO-ss/PVDF composites, respectively. The temperature coefficient \(\left( {\frac{{C_{T} - C_{25^\circ C} }}{{C_{25^\circ C} }} \times 100\;\% } \right)\) of CCTO-sg/PVDF composites was −3 to 10 % from −10 to 150 °C at 10 kHz, which was lower than that of CCTO-ss/PVDF composites. Meanwhile, the dielectric constant of CCTO/PVDF obtained by Maxwell–Garnett model and Yamada model were in close agreement with the experimental data, respectively.

Critical interparticle distance for the remarkably enhanced dielectric constant of BaTiO3-Ag hybrids filled polyvinylidene fluoride composites

Discrete nano Ag-deposited BaTiO3 (BT-Ag) hybrids with varied Ag content were synthesized, and the hybrids filled polyvinylidene fluoride (PVDF) composites were prepared. The effect of Ag content on the dielectric properties of the composites were analyzed based on the diffused electrical double layer theory. Results showed that with a higher Ag content in BT-Ag hybrids, the dielectric constant of BT-Ag/PVDF composites increases fast with the filler loading, while the dielectric loss and conductivity showed a suppressed and moderate increase. The dielectric constant of BT-0.61Ag/PVDF (61 wt. % of Ag in BT-Ag hybrid) composites reached 613, with the dielectric loss of 0.29 at 1 kHz. It was deduced that remarkably enhanced dielectric constant appeared when the interparticle distance decreased to a critical value of about 20 nm.

High dielectric permittivity in semiconducting Pr0.6Ca0.4MnO3 filled polyvinylidene fluoride nanocomposites with low percolation threshold

Semiconducting Pr0.6Ca0.4MnO3 nanoparticles with width of ∼50nm and length ∼80–150nm were prepared by sol-gel method. The dielectric behavior of Pr0.6Ca0.4MnO3, polyvinylidene fluoride composites was investigated by varying the Pr0.6Ca0.4MnO3 volume fraction and frequency. The percolation threshold of the composites was found to be 0.1 and an enhanced effective dielectric permittivity of ∼700 with low dielectric loss of ∼0.3 at 103Hz near the percolation threshold was observed. The low percolation threshold was attributed to the nanosize and nonspherical shape of the filler particles, and the enhanced dielectric properties have been explained by using boundary layer capacitance effect and percolation theory.