scholarly journals A review on nanofiber fabrication with the effect of high-speed centrifugal force field

2019 ◽  
Vol 14 ◽  
pp. 155892501986751 ◽  
Author(s):  
Zhi-Ming Zhang ◽  
Yao-Shuai Duan ◽  
Qiao Xu ◽  
Biao Zhang
Keyword(s):  
Surface Tension ◽  
Force Field ◽  
Centrifugal Force ◽  
Formation Process ◽  
Rotational Speed ◽  
High Speed ◽  
Solution Concentration ◽  
Solution Viscosity ◽  
Centrifugal Spinning ◽  
Solution Parameters

Among the traditional methods for nanofiber fabrication, their inherent defects limit their application in industry. This work presents a simple and novel spinning technology to fabricate nanofiber, which uses a high-speed rotary spinneret called high-speed centrifugal spinning. Unlike electrospinning, the electric field is not required, and it could fabricate nanofiber in bulk from melt or solution materials. This work introduces the mechanism principle and development of high-speed centrifugal spinning. Besides, the high-speed centrifugal spinning is compared with the traditional spinning methods. The jet movement and nanofiber formation process under the action of centrifugal force are explained in detail. The effects of equipment parameters and spinning solution parameters on final nanofiber morphology are presented. These parameters are controllable, they include rotational speed of spinneret, length and diameter of nozzle, spinning solution concentration, spinning solution viscosity and surface tension, and collection distance.

scholarly journals Needleless Electrospinning of PA6 Fibers: The Effect of Solution Concentration and Electrospinning Voltage on Fiber Diameter

2020 ◽  
Vol 66 (7-8) ◽  
pp. 421-430
Author(s):  
Alexandra Aulova ◽  
Marko Bek ◽  
Leonid Kossovich ◽  
Igor Emri
Keyword(s):  
Electrical Conductivity ◽  
Surface Tension ◽  
Fiber Diameter ◽  
Polymer Concentration ◽  
Solution Concentration ◽  
Fine Tuning ◽  
Solution Viscosity ◽  
Diameter Distribution ◽  
Needleless Electrospinning ◽  
Pore Size Distributions

Needleless electrospinning is the process of forming thin material fibers from the open surface of its solution or melt in a strong electrostatic field. Electrospun non-woven materials are used in various applications that require specific fiber diameters and pore size distributions. Fiber diameter depends on the properties of the polymer solution and manufacturing conditions. A needleless electrospinning process using the Nanospider setup was investigated using the commonly used polyamide 6 (PA6) solution in a mixture of acetic and formic acids. Polymer solutions with different polymer concentrations were characterized by viscosity, surface tension and electrical conductivity. An increase in polymer content in the solution resulted in the exponential increase of the solution viscosity, polynomial increase of electrical conductivity and had almost no effect on surface tension. The effect of the polymer concentration in the solution, as well as electrospinning voltage on fiber diameter and diameter distribution, was investigated using scanning electron microscopy images. The average fiber diameter linearly increases with the increased polymer concentration and also demonstrates an increase with increased electrospinning voltage, although less pronounced. Therefore, a change in the PA6 solution concentration should be used for the robust adjustment of fiber diameter, while changes in electrospinning voltage are more appropriate for fine tuning the fiber diameter during the process of needleless electrospinning.

Modal Comparison of Crankshaft under Multi-Speed

2014 ◽  
Vol 533 ◽  
pp. 48-51
Author(s):  
Ran Ran Wang ◽  
Xian Bin Teng ◽  
Yan Ming Xu ◽  
Tao Ge
Keyword(s):  
Centrifugal Force ◽  
Vibration Frequency ◽  
Rotational Speed ◽  
High Speed ◽  
Vibration Mode ◽  
Large Deviation ◽  
Frequency Change ◽  
Low Speed ◽  
The Impact

Considering the effect of centrifugal force generated by the rotation to the crankshaft frequency and vibration mode, the frequency and vibration mode of multi-speed cases are calculated. The results showed that the impact of the centrifugal force on the crankshaft vibration increases with the increase of rotational speed, especially in the high speed region, this phenomenon is more obvious. From low speed to high speed, the vibration frequency has a large deviation, which shows that in this case, it is necessary to consider the frequency change caused by pre-stress.

The theory of waves travelling on the core in a swirling liquid

1951 ◽  
Vol 205 (1083) ◽  
pp. 530-540 ◽  
Keyword(s):  
Surface Tension ◽  
Cross Section ◽  
Centrifugal Force ◽  
High Speed ◽  
Critical Length ◽  
The Core ◽  
Angular Velocities ◽  
The Waves ◽  
Minimum Velocity ◽  
Group Velocities

An examination is made of waves moving under centrifugal force and surface tension along the oore in a swirling liquid. The waves may be of varicose form in which the cross-section of the core remains circular, or they may be helical, giving the core the shape of a multithreaded screw. The relation is obtained between the lengths of the waves and their axial and angular velocities; at a critical length the waves possess a minimum velocity. The group velocities are determined, and are shown to be negative under certain conditions. It is found that waves can exist which move so slowly that they should be readily visible although the core may be revolving at high speed.

scholarly journals The movement and forces of spinning solution in the nozzle during high-speed centrifugal spinning

2019 ◽  
Vol 14 ◽  
pp. 155892501982820 ◽  
Author(s):  
Yaoshuai Duan ◽  
Zhiming Zhang ◽  
Binbin Lu ◽  
Boya Chen ◽  
Zilong Lai
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Large Scale ◽  
Production Efficiency ◽  
Critical Value ◽  
Parametric Model ◽  
Rotating Speed ◽  
Centrifugal Spinning ◽  
Novel Method

High-speed centrifugal spinning is a novel method to fabricate nanofiber. It has the potential to fabricate nanofiber on a large scale because its production efficiency is much greater than traditional methods. Nozzle is an important part of high-speed centrifugal spinning equipment because its length, shape, and diameter all will affect the morphology and quality of nanofiber. It is useful to study the movement and forces of spinning solution in the nozzle. In this article, the principle and equipment structure of high-speed centrifugal spinning are briefly introduced at first. Then the movement and forces of spinning solution are analyzed by establishing parametric model at nozzle. It can be found that the spinning solution is ejected from nozzle when the rotating speed reaches a critical value. The critical rotating speed is inversely proportional to the radius of nozzle and directly proportional to the viscosity of spinning solution. There are several nozzle structures proposed and compared for nozzle optimization. Finally, the effects of nozzle parameters, concentration of spinning solution, and rotational speed on the morphology of nanofiber are verified by high-speed centrifugal spinning experiments. It lays the foundation for optimizing spinning equipment.

Balancing of Tool/Toolholder Assembly for High-Speed Machining

2004 ◽  
Vol 471-472 ◽  
pp. 542-546
Author(s):  
Song Zhang ◽  
Xing Ai ◽  
Wei Xiao Tang ◽  
J.G. Liu
Keyword(s):  
Centrifugal Force ◽  
Rotational Speed ◽  
High Speed ◽  
Manufacturing Industry ◽  
High Speed Machining ◽  
High Rotational Speed ◽  
Good Balance ◽  
Machining Quality ◽  
System Maintenance

High-speed machining has become mainstream in machining manufacturing industry. In industries such as moldmaking and aerospace, it has become the norm rather the exception. The centrifugal force increases as the square of the speed. At rotational spindle speeds of 6,000 r/min and higher however, centrifugal force from unbalance becomes a damaging factor and it reduces the life of the spindle and the tool, as well as diminishes the quality of the finished product. Under high rotational speed, good balance becomes issue. High-speed machining experimental results shown that a well-balanced tool/toolholder assembly could obviously improve machining quality, extend tool life and shorten downtime for spindle system maintenance etc.

scholarly journals Assembly of Oriented Ultrafine Polymer Fibers by Centrifugal Electrospinning

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Shu-Liang Liu ◽  
Yun-Ze Long ◽  
Zhi-Hua Zhang ◽  
Hong-Di Zhang ◽  
Bin Sun ◽  
...  
Keyword(s):  
Image Analysis ◽  
Rotational Speed ◽  
Solution Concentration ◽  
Polymer Fibers ◽  
Optimum Conditions ◽  
Analysis Techniques ◽  
Aligned Arrays ◽  
Centrifugal Spinning ◽  
Experimental Parameters ◽  
Image Analysis Techniques

Uniaxially aligned and cross-aligned arrays of ultrafine polymer fibers have been fabricated by a novel and effective centrifugal electrospinning setup with rotating polymer solution jets. Comparing with conventional electrospinning (10–30 kV) and centrifugal spinning (4,000–12,000 rpm), this technique only requires a lower working voltage (2.8–6.0 kV), a slower rotational speed (360–540 rpm), and a shorter spinning distance (2.0–4.0 cm). In addition, the influences of experimental parameters such as working voltage, rotational speed, collecting distance, and solution concentration on the alignment of the as-spun fibers are investigated using image analysis techniques. It is found that the working voltage and rotational speed mainly influence the perpendicular and linear velocities of the fibers, respectively. The polymer fibers tend to show higher alignment degree when these two velocities are very close. Optimum conditions (working voltage 3.0 kV, rotational speed 420 rpm, collecting distance 2.5 cm, and solution concentration 18 wt%) to maximize alignment degree (~97%) of polystyrene fibers are also obtained.

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