Peixuan Wu

Effect of coupling agents on the dielectric properties and energy storage of Ba0.5Sr0.5TiO3/P(VDF-CTFE) nanocomposites

Dielectric materials with high electric energy density and low dielectric loss are critical for electric applications in modern electronic and electrical power systems. To obtain desirable dielectric properties and energy storage, nanocomposites using Ba0.5Sr0.5TiO3 (BST) as the filler and poly(vinylidene fluoride-chlorotrifluoroethylene) as the matrix material are prepared with a uniform microstructure by using a newly developed process that combines the bridge-linked action of a coupling agent, solution casting, and a hot-pressing method. When a proper amount of coupling agent is used to modify the surface of the nanoparticles, the composite exhibits a higher dielectric constant and a more uniform microstructure. A dielectric constant of 95, dielectric loss of 0.25, and energy density of 2.7 J/cm3 is obtained in the nanocomposite with 30 vol.% of BST and 15 wt.% of coupling agent. The results suggest that the energy storage ability of the composites could be improved by the surface modification of the f...

Controllable deposition distance of aligned pattern via dual-nozzle near-field electrospinning

For large area micro/nano pattern printing, multi-nozzle electrohydrodynamic (EHD) printing setup is an efficient method to boost productivity in near-field electrospinning (NFES) process. And controlling EHD multi-jet accurate deposition under the interaction of nozzles and other parameters are crucial concerns during the process. The influence and sensitivity of various parameters such as the needle length, needle spacing, electrode-to-collector distance, voltage etc. on the direct-write patterning performance was investigated by orthogonal experiments with dual-nozzle NFES setup, and then the deposition distance estimated based on a novel model was compared with measurement results and proven. More controllable deposition distance and much denser of aligned naofiber can be achieved by rotating the dual-nozzle setup. This study can be greatly contributed to estimate the deposition distance and helpful to guide the multi-nozzle NFES process to accurate direct-write pattern in manufacturing process in future.

Research on multinozzle near-field electrospinning patterned deposition

Multinozzle electrospinning systems are designed to increase productivity, while near-field electrospinning (NFES) systems are designed to deposit solid nanofibers in a direct, continuous, and controllable manner. In this paper, several multinozzle NFES setups are tested. The experiment reveals that the deposition distance becomes larger when working distance and needle spacing increase, and the influence of voltage is relatively weaker. The deposition of double nozzle NFES has been studied with Coulombs law and theoretical derivation has been verified by the experimental conclusion. The experiment result and theoretical derivation are helpful to get different distance of direct-written fibers by adjusting working distance or needle spacing to change distance of fibers largely and adjusting voltage to change distance slowly. Through these efforts, it is convenient to adjust the distance of straight fibers in multinozzle system.

Fabrication and evaluation of controllable deposition distance for aligned pattern by multi-nozzle near-field electrospinning

To mass-volume fabricate micro- and nano-scales aligned pattern, multi-nozzle near-field electrospinning (NFES) direct-writing technology is well proposed as a high-efficiency method in electrohydrodynamic (EHD) printing process. However, the interference effect among adjacent nozzles and coupling effect of various parameters have restricted to investigate deposition characteristic of multi-nozzle NFES and control EHD multi-jet deposition accuracy. In order to improve the accuracy of EHD multi-jet deposition with high-efficiency printing process, the experimental result compared with theoretical method were discussed. In this work, the influence of multi-nozzle geometry distribution and electrospinning parameters on deposition characteristic was studied with multi-nozzle NFES setup, and nozzles were in linear array. The deposition distance and homogeneity of aligned nanofibers were measured and explained with coefficient of dispersion on electric field among nozzles by simulation. Moreover, deposition distance of multi-nozzle NFES process was evaluated by modified theoretical derivation based on our previous studies. The modified theoretical derivation showed a good agreement with experiment results, and indicated that multi-nozzle NFES could accurately and efficiently direct-write aligned array pattern in future.To mass-volume fabricate micro- and nano-scales aligned pattern, multi-nozzle near-field electrospinning (NFES) direct-writing technology is well proposed as a high-efficiency method in electrohydrodynamic (EHD) printing process. However, the interference effect among adjacent nozzles and coupling effect of various parameters have restricted to investigate deposition characteristic of multi-nozzle NFES and control EHD multi-jet deposition accuracy. In order to improve the accuracy of EHD multi-jet deposition with high-efficiency printing process, the experimental result compared with theoretical method were discussed. In this work, the influence of multi-nozzle geometry distribution and electrospinning parameters on deposition characteristic was studied with multi-nozzle NFES setup, and nozzles were in linear array. The deposition distance and homogeneity of aligned nanofibers were measured and explained with coefficient of dispersion on electric field among nozzles by simulation. Moreover, deposition dis...

Uniform electric field enabled multi-needles electrospinning head based on trapezoid arrangement

The electrospinning electric field is the main factor responsible for the jet stretching force. Previous studies showed that nonhomogeneous electric field would affect the jets formed during the multi-needles electrospinning. Therefore, a multitude of methods were explored to optimize the electric field in multi-needles electrospinning, such as adjusting the supplied voltage on each needle, varying the space of the needles and spatial distribution of the needles. In this paper, three categories of needles distribution were explored for a homogeneous electric field and the design of a higher needles density of electrospinning head. The theoretical and experimental results showed that the homogeneous electric field formed with the trapezoidal head at 15mm distance while the others’ head required over 30mm. Hence, the trapezoidal arrangement is a better multi-needles distribution for electrospinning head, and has much more significance for high yield of electrospinning nanofibers.The electrospinning electric field is the main factor responsible for the jet stretching force. Previous studies showed that nonhomogeneous electric field would affect the jets formed during the multi-needles electrospinning. Therefore, a multitude of methods were explored to optimize the electric field in multi-needles electrospinning, such as adjusting the supplied voltage on each needle, varying the space of the needles and spatial distribution of the needles. In this paper, three categories of needles distribution were explored for a homogeneous electric field and the design of a higher needles density of electrospinning head. The theoretical and experimental results showed that the homogeneous electric field formed with the trapezoidal head at 15mm distance while the others’ head required over 30mm. Hence, the trapezoidal arrangement is a better multi-needles distribution for electrospinning head, and has much more significance for high yield of electrospinning nanofibers.

Fabrication of three-dimensional micro-nanofiber structures by a novel solution blow spinning device

The fabrication of three-dimensional scaffolds has attracted more attention in tissue engineering. The purpose of this study is to explore a new method for the fabrication of three-dimensional micro-nanofiber structures by combining solution blow spinning and rotating collector. In this study, we successfully fabricated fibers with a minimum diameter of 200 nm and a three-dimensional structure with a maximum porosity of 89.9%. At the same time, the influence of various parameters such as the solvent volatility, the shape of the collector, the feed rate of the solution and the applied gas pressure were studied. It is found that solvent volatility has large effect on the formation of the three-dimensional shape of the structure. The shape of the collector affects the porosity and fiber distribution of the three-dimensional structure. The fiber diameter and fiber uniformity can be controlled by adjusting the solution feed rate and the applied gas pressure. It is feasible to fabricate high-quality three-dimen...

The direction and stability control system for near-field electrospinning direct-writing technology

Due to the great promise and potential of the near-field electrospinning direct-writing technology, it had played a great role on the field using micro structure like flexible electronic devices, advanced optics, adsorption, filtration material, drug delivery and biomedical. But the printing process is very complex to represent. And the descriptive hydrodynamic equation was not established yet. Furthermore the determination of the process parameters depends by experiences mostly. It is difficult to guarantee the stability of the jet printing process. This article explores the conventional systems of the near-field electrospinning direct-writing technology, especially for the instability of the whip in the printing process. The direction and stability control system is designed for near-field electrospinning direct-writing technology in improving the printing process of the stability and reliability in the production.