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Single fibres of pyro-electrospinned PVDF-HFP/MWCNT unveal high electrical conductivity
摘要： Formation of single fibres of polymer nanocomposite PVDF-HFP containing MWCNT by Pyro-EHD electrospinning is reported for the first time. Pyro-EHD gives the chance to drawing fibres directly from a viscous polymeric solution containing MWCNT, with respect to classical electrospinning in which highly viscous materials have strong limitation due to the clogging effect. This method allows achieving an electrical conductivity of the fibres considerably higher with respect to the bulk state. The improvement of the electrical conductivity is of one order of magnitude and the electrical percolation threshold is reduced from 2.5 to 0.3 wt%. We also show that the MWCNT are highly oriented in the longitudinal direction of the fibres, producing the improvement in the electrical properties of the composite.
关键词： carbon nanotubes,electrical percolation,PVDF-HFP
更新于2025-09-10 09:29:36
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Performance of PVDF/TiO<SUB align="right">2 nano-composite film in the application of energy harvester
摘要： The compression mode and shear mode for energy harvesting experimental platform was estabished. The energy collection efficiency of PVDF/TiO2 nano-composite film in the two mode and nonlinear piezoelectric effect were analysed. Experimental results show that the energy collection efficiency of the shear mode was higher than the compressed mode. The Piezoelectric constant and piezoelectric coupling coefficient have nonlinear changes under large stress. In this paper, the experimental data establish a relationship electromechanical coupling coefficients and parameters of composite thin film piezoelectric stress.
关键词： nano-composite film,PVDF,TiO2,energy harvester
更新于2025-09-10 09:29:36
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Poly(vinylidene fluoride)/Plasma-Treated BaTiO3 Nanocomposites with Enhanced Electroactive Phase
摘要： Functional C=O and C-O groups are successfully fixated onto the surface of a high dielectric constant material barium titanate (BaTiO3) via non-thermal plasma. The strong dipole interaction exists between these functional groups and CH2 or CF2 groups of poly(vinylidene fluoride) (PVDF), resulting in the enhancement of the electroactive γ-phase of PVDF/BaTiO3 nanocomposites on one hand; on the other hand the dispersion of BaTiO3 is enhanced in the PVDF matrix, where the smaller spherulite size and better hydrophilic property are observed in the PVDF/plasma-treated BaTiO3 nanocomposite, comparing with the untreated ones. Therefore, the PVDF/plasma-treated BaTiO3 nanoparticles exhibited higher dielectric constant and lower dielectric loss than the PVDF/BaTiO3 nanoparticles.
关键词： plasma-treated barium titanate nanocomposites,dielectric constant,electroactive γ-phase,dielectric loss,poly(vinylidene fluoride) (PVDF)
更新于2025-09-09 09:28:46
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A Guided Wave Sensor Enabling Simultaneous Wavenumber-Frequency Analysis for Both Lamb and Shear-Horizontal Waves
摘要： Guided waves in plate-like structures have been widely investigated for structural health monitoring. Lamb waves and shear horizontal (SH) waves, two commonly used types of waves in plates, provide different benefits for the detection of various types of defects and material degradation. However, there are few sensors that can detect both Lamb and SH waves and also resolve their modal content, namely the wavenumber-frequency spectrum. A sensor that can detect both waves is desirable to take full advantage of both types of waves in order to improve sensitivity to different discontinuity geometries. We demonstrate that polyvinylidene difluoride (PVDF) film provides the basis for a multi-element array sensor that detects both Lamb and SH waves and also measures their modal content, i.e., the wavenumber-frequency spectrum.
关键词： shear horizontal waves,Lamb waves,PVDF sensor,wavenumber-frequency analysis
更新于2025-09-09 09:28:46
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Performance analysis of fiber reinforced piezoelectric lead zirconate titanate/poly(vinylidene fluoride) composites
摘要： In this paper, the PZT/PVDF composites were prepared by hot-pressing method. The effects of different PZT volume fractions on dielectric, piezoelectric, mechanical and microstructure properties of the composites were investigated. The ratio range of the composites constituent components was determined to enhance mechanical properties. Carbon fiber was used as reinforcing material to enhance the mechanical properties of PZT/PVDF composites. The results showed that PZT/PVDF composites doping with properly carbon fiber had a good compactness, and the relative dielectric constant (εr), the piezoelectric strain constant (d33) and the polarisability were all increased. Finally, the optimal proportion of PZT/PVDF was 50%/50% and carbon fiber content was 0.25%, the d33 of composite increased 14.2%, bending strength increased 7.2% and tensile strength increased 11.5%.
关键词： Tensile Strength,PZT/PVDF,Carbon Fiber,Electrical Properties,Bending Strength
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) - Cancun, Mexico (2018.10.21-2018.10.24)] 2018 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) - Piezoelectric Nanofibers for Integration in Multifunctional Materials
摘要： This paper deals with realization of multifunctional composite materials, having piezoelectric effect. First of all polymeric mats of electrospun piezoelectric nanofibers were realized with different geometries. Such effect has been maximized by designing properly the electrospinning apparatus in order to enhance the electric field in the interelectrodic space which polarize the dipolar moments. The mats are then integrated in a silicon rubber matrix and measurements of the electromechanical response of the composite materials thus manufactured are performed. A good integration of nanofibers inside the host material is evidenced by electron microscopy images, allowing delaminations, which could occur using piezoelectric films, to be avoided. A large electrical response to both impact and vibration stimuli has been finally demonstrated.
关键词： electrospinning,piezoelectrics,smart materials,Nanofibers,electric response,PVdF-TrFE
更新于2025-09-04 15:30:14
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Investigation on the electrospun PVDF/NP-ZnO nanofibers for application in environmental energy harvesting
摘要： PVDF is one of the most widely used dielectric polymers that has four phases. Among them, only its β phase shows piezoelectric property, which is accessible through an electrospinning synthesis method. In this research, a solution of dimethylformamide (DMF) and tetrahydrofuran (THF), with different ratios, and two different polymer concentrations, as well as various ZnO percentages, were used for synthesis of PVDF/NP-ZnO nano?bers composite. The samples that led to the formation of nano?bers were characterized. The results indicate that nano?bers were appropriately formed at lower concentrations of polymer and zinc oxide with equal ratio of the two solvents. To study the effects of synthesis conditions on the morphology and diameter of the nano?bers, the samples were synthesized at different intervals and at different injection rates. The results show that at lower intervals, the injection rate should be reduced to form more uniform nano?bers without nodes and sprays. Finally, ?exible piezoelectric nanogenerators were fabricated based on the best samples and were tested under vibrational mechanical forces. The results indicate a maximum output power of 32 nW/cm2. The greater output current and voltage were resulted by using more uniform and stretched nano?bers.
关键词： Nano?bers,Nanogenerator,PVDF,ZnO,Electrospinning
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Singapore, Singapore (2018.4.22-2018.4.26)] 2018 IEEE 13th Annual International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Enhancement in Energy Harvesting Performances of Piezoelectric Nanogenerator by Sandwiching Electrostatic rGO Layer Between PVDF-BTO Layers
摘要： Herein the fabrication and characterizations of self-poled, tri-layer piezoelectric nanogenerators (PENGs) have been investigated. The tri-layer structure was obtained by sandwiching surface modified n-type reduced graphene oxide (n-rGO) layer between poly(vinylidene fluoride)-barium titanate (PVDF-BTO) sheets. The highly charged n-rGO layer facilitates in improving the crystallinity of PVDF by attracting and aligning the dipoles from lower and upper PVDF-BTO sheets without any external electric field. The enhancement in electro-active beta (β) phase of PVDF was also confirmed through X-ray diffraction pattern. For the comparison analysis three different, single layer (PVDF-BTO), bi-layer (n-rGO/PVDF-BTO), and tri-layer (PVDF-BTO/n-rGO/PVDF-BTO) NGs were prepared. Among them, tri-layer NG reveals maximum open circuit voltage of 10 Vpk-pk. Furthermore, it exhibits short circuit current of 2.5 μApk-pk at an applied force of 2N. Finally, the mechanical stability of fabricated NG was also tested under several pressing and releasing cycles. It was estimated that our fabricated PENG can be a promising building block for powering flexible small electronics.
关键词： energy harvesting,n-rGO,PVDF-BTO,piezoelectric nanogenerators,flexible electronics
更新于2025-09-04 15:30:14
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Feasibility of PCB-Integrated Vibration Sensors for Condition Monitoring of Electronic Systems
摘要： The increasing complexity of electronics in systems used in safety critical applications, such as for example self-driving vehicles requires new methods to assure the hardware reliability of the electronic assemblies. Prognostics and Health Management (PHM) that uses a combination of data-driven and Physics-of-Failure models is a promising approach to avoid unexpected failures in the field. However, to enable PHM based partly on Physics-of-Failure models, sensor data that measures the relevant environment loads to which the electronics is subjected during its mission life are required. In this work, the feasibility to manufacture and use integrated sensors in the inner layers of a printed circuit board (PCB) as mission load indicators measuring impacts and vibrations has been investigated. A four-layered PCB was designed in which piezoelectric sensors based on polyvinylidenefluoride-co-trifluoroethylene (PVDF-TrFE) were printed on one of the laminate layers before the lamination process. Manufacturing of the PCB was followed by the assembly of components consisting of BGAs and QFN packages in a standard production reflow soldering process. Tests to ensure that the functionality of the sensor material was unaffected by the soldering process were performed. Results showed a yield of approximately 30 % of the sensors after the reflow soldering process. The yield was also dependent on sensor placement and possibly shape. Optimization of the sensor design and placement is expected to bring the yield to 50 % or better. The sensors responded as expected to impact tests. Delamination areas were present in the test PCBs, which requires further investigation. The delamination does not seem to be due to the presence of embedded sensors alone but rather the result of a combination of several factors. The conclusion of this work is that it is feasible to embed piezoelectric sensors in the layers of a PCB.
关键词： PVDF-TrFE,piezoelectric sensors,Prognostics and Health Management (PHM),condition monitoring,electronic systems,PCB-integrated vibration sensors
更新于2025-09-04 15:30:14