scholarly journals Impact of Apparatus Orientation and Gravity in Electrospinning—A Review of Empirical Evidence

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2448
Author(s):  
Sinduja Suresh ◽  
Alexander Becker ◽  
Birgit Glasmacher
Keyword(s):  
Gravitational Force ◽  
Review Paper ◽  
Electrostatic Force ◽  
Fibre Diameter ◽  
Diameter Distribution ◽  
Jet Trajectory ◽  
Diameter Fibre ◽  
Primary Difference ◽  
Spinning Process ◽  
The Impact

Electrospinning is a versatile fibre fabrication method with applications from textile to tissue engineering. Despite the appearance that the influencing parameters of electrospinning are fully understood, the effect of setup orientation has not been thoroughly investigated. With current burgeoning interest in modified and specialised electrospinning apparatus, it is timely to review the impact of this seldom-considered parameter. Apparatus configuration plays a major role in the morphology of the final product. The primary difference between spinning setups is the degree to which the electrical force and gravitational force contribute. Since gravity is much lower in magnitude when compared with the electrostatic force, it is thought to have no significant effect on the spinning process. But the shape of the Taylor cone, jet trajectory, fibre diameter, fibre diameter distribution, and overall spinning efficiency are all influenced by it. In this review paper, we discuss all these developments and more. Furthermore, because many research groups build their own electrospinning apparatus, it would be prudent to consider this aspect as particular orientations are more suitable for certain applications.

scholarly journals Impact of Solid Content in the Electrospinning Solution on the Physical and Chemical Properties of Polyacrylonitrile (PAN) Nanofibrous Mats

Tekstilec ◽  
2020 ◽  
Vol 63 (3) ◽  
pp. 225-232
Author(s):  
Timo Grothe ◽  
◽  
Jan Lukas Storck ◽  
Marius Dotter ◽  
Andrea Ehrmann ◽  
...  
Keyword(s):  
Unit Area ◽  
Fibre Diameter ◽  
Chemical Properties ◽  
Solid Content ◽  
Diameter Distribution ◽  
Carbon Nanofibres ◽  
Physical And Chemical ◽  
The Impact ◽  
Fibre Morphology ◽  
And Chemical Properties

Polyacrylonitrile (PAN) belongs to the group of polymers that are often used for electrospinning, as it can be applied as a pre-cursor for carbon nanofibres and is spinnable from the low-toxic solvent dimethyl sulfoxide (DMSO). While the influence of different spinning parameters on fibre morphology and mass per unit area was investigated in a previous study, here we report on the impact of the spinning solution, using DMSO as a solvent and wire-based (needleless) electrospinning. Our results show that a broad range of solid contents can be applied, providing the opportunity to tailor the fibre diameter distribution or to optimize the areal weight of the nanofibrous mat by changing this parameter, while the chemical composition of the fibres remains identical.

scholarly journals Selection of Eucalyptus camaldulensis Families for Sustainable Pulpwood Production by Means of Anatomical Characteristics

Forests ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 31
Author(s):  
Ikumi Nezu ◽  
Futoshi Ishiguri ◽  
Haruna Aiso ◽  
Sapit Diloksumpun ◽  
Jyunichi Ohshima ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Fibre Diameter ◽  
Eucalyptus Camaldulensis ◽  
Principal Component ◽  
Wood Properties ◽  
Component Analysis ◽  
Pulp And Paper ◽  
Anatomical Characteristics ◽  
Diameter Fibre ◽  
Sib Families

Sustainable pulpwood production from fast-growing tree plantations is needed for pulp and paper industries. To increase the pulpwood production efficiency, the anatomical characteristics and derived-wood properties of 75 trees from 15 half-sib families of Eucalyptus camaldulensis Dehnh. planted in Thailand were investigated, and then the family was classified by suitability of wood as raw material for pulp and paper products using principal component analysis and clustering. The mean values of vessel diameter, vessel frequency, fibre diameter, fibre lumen diameter, and fibre wall thickness at 2 cm from the cambium were 128 µm, 16 no./mm2, 11.1 µm, 7.1 µm, and 1.88 µm, respectively. In addition, the Runkel ratio, Luce’s shape factor, flexibility coefficient, slenderness ratio, solids factor, and wall coverage ratio (i.e., derived-wood properties) were 0.53, 0.42, 0.64, 85.3, 68 × 103 µm3, and 0.34, respectively. Significant differences in fibre diameter, fibre lumen diameter, and Runkel ratio were found among families. Although significant differences among families were not found for other anatomical characteristics and derived-wood properties, the p-values obtained by an analysis of variance test ranged from 0.050 to 0.088. Based on the results of a principal component analysis and cluster analysis, 15 families were classified into four clusters with different expected pulp and paper characteristics. The suitability of wood from E. camaldulensis half-sib families for pulp and paper can be evaluated by principal component analysis using anatomical characteristics and physical properties as variables. Based on the results, desirable pulp and paper quality may be obtained through the selection of families from this species.

Electrostatic-assisted centrifugal spinning for continuous collection of submicron fibers

2016 ◽  
Vol 87 (19) ◽  
pp. 2349-2357 ◽  
Author(s):  
Huanhuan Chen ◽  
XiangLong Li ◽  
Nan Li ◽  
Bin Yang
Keyword(s):  
Fiber Diameter ◽  
Electrostatic Force ◽  
Fiber Formation ◽  
Mechanism Analysis ◽  
Strongly Correlated ◽  
Fiber Morphology ◽  
Jet Trajectory ◽  
Centrifugal Spinning ◽  
Nozzle Size ◽  
Key Factor

Non-uniformity of the fiber diameter and difficulty in continuous web collection have limited the development and further application of centrifugal spinning (CS). Here, we present a feasible method for fibers' continuous collection and morphology optimization by utilizing vertical electrostatic-assisted centrifugal spinning (E-CS). The effects of spinning parameters, such as applied voltage, nozzle size, and rotational speed on fiber morphology have been evaluated systematically. We find that vertical voltage is strongly correlated with the formation of bead defects, and nozzle size is the most important parameter on fiber size, and the fiber diameter generally decreased with increasing rotation speed. Through the mechanism analysis and jet trajectory observation, we think that the Rayleigh–Taylor instability is the key factor in determining fiber formation in CS. When a vertical electrostatic force is applied to CS, the above instability phenomenon can be effectively controlled resulting more uniform fibers with thinner diameters and fewer beads.

Input and Design Optimization Under Uncertainty to Minimize the Impact Velocity of an Electrostatically Actuated MEMS Switch

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
M. S. Allen ◽  
J. E. Massad ◽  
R. V. Field ◽  
C. W. Dyck
Keyword(s):  
Impact Velocity ◽  
Deterministic Model ◽  
Electrostatic Force ◽  
Optimization Under Uncertainty ◽  
Model Parameters ◽  
Rf Switch ◽  
Voltage Waveform ◽  
Rigid Barrier ◽  
Mechanical Impact ◽  
The Impact

The dynamic response of a radio-frequency (RF) microelectromechanical system to a time-varying electrostatic force is optimized to enhance robustness to variations in material properties and geometry. The device functions as an electrical switch, where an applied voltage is used to close a circuit. The objective is to minimize the severity of the mechanical impact that occurs each time the switch closes because severe impacts have been found to significantly decrease the life of these switches. Previous works have demonstrated that a classical vibro-impact model, a single-degree-of-freedom oscillator subject to mechanical impact with a single rigid barrier, captures the relevant physics adequately. Certain model parameters are described as random variables to represent the significant unit-to-unit variability observed during fabrication and testing of a collection of nominally identical switches; these models for unit-to-unit variability are calibrated to available experimental data. Our objective is to design the shape and duration of the voltage waveform so that impact kinetic energy at switch closure is minimized for the collection of nominally identical switches, subject to design constraints. A voltage waveform designed using a deterministic model for the RF switch is found to perform poorly on the ensemble. An alternative waveform is generated using the proposed optimization procedure with a probabilistic model and is found to decrease the maximum impact velocity by a factor of 2 relative to the waveform designed deterministically. The methodology is also applied to evaluate a design change that reduces the impact velocity further and to predict the effect of fabrication process improvements.

Investigating systematic review for multi-disciplinary research in the built environment

2018 ◽  
Vol 8 (1) ◽  
pp. 78-90
Author(s):  
Subhadarsini Parida ◽  
Kerry Brown
Keyword(s):  
Systematic Review ◽  
Built Environment ◽  
Review Paper ◽  
Health Management ◽  
Green Building ◽  
Well Being ◽  
Evidence Base ◽  
Content Type ◽  
Powerful Means ◽  
The Impact

Purpose The purpose of this paper is to examine the extent to which a systematic review approach is transferable from medicine to multi-disciplinary studies in the built environment research. Design/methodology/approach Primarily a review paper, it focuses on specific steps in the systematic review to clarify and elaborate the elements for adapting an evidence base in the built environment studies particular to the impact of green building on employees’ health, well-being and productivity. Findings While research represents a potentially powerful means of reducing the gap between research and practice by applying tried and tested methods, the methodological rigour is debatable when a traditional systematic review approach is applied in the built environment studies involving multi-disciplinary research. Research limitations/implications The foundational contribution of this paper lies in providing methodological guidance and an alternative framework to advance the longstanding efforts in the built environment to bridge the practitioner and academic divide. Originality/value A systematic review approach in the built environment is rare. The method is unique in multi-disciplinary studies especially in green building studies. This paper adopts the systematic review protocols in this cross-disciplinary study involving health, management and built environment expertise.

Manufacturing and Evaluation of Porous PLA Nano/Micro Fibres

2016 ◽  
Vol 368 ◽  
pp. 146-149
Author(s):  
Eva Macajová
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Image Analysis ◽  
Polymer Solution ◽  
Process Parameters ◽  
Fibre Diameter ◽  
Solution Composition ◽  
Structure And Morphology ◽  
Spinning Process ◽  
Scanning Electron

This study is mainly focused on the study of pore size and shape, fibre diameter and also on the optimization of polymer solution composition and electrospinning parameters with respect to the final structure and morphology of PLA nano/microfibrous layers. The nano/microfibres were produced by electrospinning from the needle. Except the spinning process parameters, the morphology of nanofibrous layers can be also affected by the composition of the polymer solution and by the used solvents. Variations in technological process allows us to design the shape and form of nanofibrous structures upon request. The morphology of nano/microfibres was observed by scanning electron microscopy (SEM). Following image analysis and calculation enables the assessment of porosity contribution to the increase in micro/nanofibre surface area.

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