Research Article Influence of Salts on Electrospinning of ...F : Surface tension of polymer...

Research ArticleInfluence of Salts on Electrospinning of Aqueous andNonaqueous Polymer Solutions

Fatma Yalcinkaya Baturalp Yalcinkaya and Oldrich Jirsak

Department of Nonwovens and Nanofibrous Materials Faculty of Textile Engineering Technical University of LiberecStudentska 14022 46117 Liberec Czech Republic

Correspondence should be addressed to Fatma Yalcinkaya yenertexhotmailcom

Received 7 October 2014 Revised 21 December 2014 Accepted 8 January 2015

Academic Editor Yuqin Wan

Copyright copy 2015 Fatma Yalcinkaya et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A roller electrospinning system was used to produce nanofibres by using different solution systems Although the process ofelectrospinning has been known for over half a century knowledge about spinning behaviour is still lacking In this work weinvestigated the effects of salt for two solution systems on spinning performance fibre diameter and web structure Polyurethane(PU) and polyethylene oxide (PEO) were used as polymer and tetraethylammonium bromide and lithium chloride were usedas salt Both polymer and salt concentrations had a noteworthy influence on the spinning performance morphology anddiameter of the nanofibres Results indicated that adding salt increased the spinnability of PU Salt created complex bondingwith dimethylformamide solvent and PU polymer Salt added to PEO solution decreased the spinning performance of fibres whilecreating thin nanofibres as explained by the leaky dielectric model

1 Introduction

Polymer nanofibres have attracted increasing attention inprevious decades because of their high surface to mass ratiosmall pore size and special characteristics attractive inadvanced applications They have potential application intissue engineering scaffolds filters wound dressings drugdelivery materials biomimetic materials electronics andcomposite reinforcement among others [1ndash6]

Techniques to produce nanofibres have been developedfor many years Electrospinning is one of the versatile meth-ods to produce nanofibres Various worldwide researchershave started to develop alternativemethods to produce nano-fibres to improve production rates and quality The mostcommon methods are melt-blown phase separation self-assembly template synthesis bicomponent centrifugal anddrawing methods among others [7ndash13]

An effective electrospinningmethod was recently investi-gated by Jirsak et al [14]The principle of thismethod is basedon free surface spinning This method involves an electroderotating roller that is immersed in a solution bathThe role ofthe roller is to feed the solution to the surface of the roller to

continue spinning Fibres formbetween the roller surface andthe collector By changing the spinning parameters havinghundreds of Taylor cones on the surface of the roller at thesame time is possibleTherefore a highly dense nanoweb canbe achieved by using this method In general the diameterof fibres changes from 50 nm to 800 nm depending on thesolution properties and spinning parameters

This paper aims to evaluate the influence of salt on thespinning performance of both aqueous and nonaqueous solu-tion systems by using the roller electrospinning system Todate many researchers have studied the salt effect on nanofi-bremorphology but only a few have focused on spinning per-formance For instance Cengiz and Jirsak [15] examined theeffect of salt on polyurethane nanofibre and spinning perfor-mance They found that adding salt increases the number ofTaylor cones on the roller surface thus increasing spinningperformance By contrast Dao and Jirsak showed that addingsalt to polyvinyl alcohol (PVA) solution decreases the numberof jets and spinning performance [16]

To the best of our knowledge no study has been made toexplain the opposite effect of salt on spinning performancewith different solution systems To achieve this aim we used

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2015 Article ID 134251 12 pageshttpdxdoiorg1011552015134251

2 Journal of Nanomaterials

761 055

Take-upcylinder

Rotating cylinder

Air

Input ofconditioned air

High voltagesupplier

Nanoweb

Nanofiber

Output ofair

Collectorelectrode Supporting material

Roller

Air

Incondi

Figure 1 Diagram of the roller electrospinning system

polyurethane (PU) and polyethylene oxide (PEO) polymerswith various concentrations of tetraethylammonium bro-mide (TEAB) and lithium chloride (LiCl) salts We chose PUin this work for two reasons First the PU used in this studyis pure and industrially produced Second much informationon this polymer is available from previous studies includinginformation on optimum spinning conditions

In the current work PEO was used with both TEAB andLiCl salts In case of PEO adding salt decreases its spinningperformance similar to PVA solutions Moreover PEO isproduced in better purity than PVA One of the aims ofthis study is to determine the different spinning behavioursof both water-soluble and -insoluble polymers Using PVAwhich ismostly used in electrospinning is possible AlthoughPVA has been studied by many researchers PEO was chosenin this work for its more stable quality and better purityThe possible salt-polymer salt-solvent and solvent-polymerrelations are explained in the following section

2 Experimental

21 Materials Polyurethane Larithane LS 1086 (Novo-tex Italy) which is an aliphatic elastomer composed of2000 gmol linear polycarbonate diol and isophorone diiso-cyanate and extended by isophorone diamine was chosen asthe second polymer

Most PUs are block polymers prepared with a diiso-cyanate which is a short diol such as 14-butanediol or 16-hexanediol a diamine (the chain extender) and a diol with amolecular weight of 500 to 4000 based on a polyetherpolyester or polycarbonate Preparation is usually performedin two steps the reaction of the longer polyol with isocyanate

in the first stage and that with the chain extender in thesecond stage [17] PU has excellent damping properties goodmechanical and physical properties even at low temperatureshigh combustion resistance and low thermal conductivity[18] DMF (Fluka Switzerland) was used as the solvent

Water-soluble PEOwithmolecularweight of 400 kDawaspurchased from Scientific Polymers Inc USA Distilledwater was used as the solvent PEO is a water-soluble andnon-ionic polymer PEOs are also commonly studied in elec-trospinning They are available in a large range of molecularweights PEOs can be applied in areas such as textile appli-cations cosmetics antifoaming agents and food industryamong others PEOs are produced by the polymerization ofethylene oxide and they have a structural polyether unit ofndashCH2ndashCH2ndashOndash They are a good candidate for an electro-

spinning system because of their high spinnability and watersolubility

Tetraethylammonium bromide was purchased fromFluka (Switzerland) and LiCl from Lach-Ner sro (CzechRepublic) Based on previous works 6 PEO and 175 PUwere chosen as the constant polymer concentrations Variousamounts of salt were used according to themolar ratio of saltThe nomenclature of solutions is tabulated as shown inNomenclature and Symbols of Solutions according to saltcontent We used a small amount of LiCl salt content for thePEO solution because the fibre diameter increases withincreased amount of salt

22 Methods

221 Spinning Conditions The solutions were spun usinga spinning device as shown in Figure 1 All the measured

Journal of Nanomaterials 3

Table 1 Spinning conditions of PEO solutions in the roller electrospinning system

Sample Voltage(kV)

Distance(mm)

Roller speed(rpm)

RH()

Temperature(∘C)

Roller length(mm)

Roller diameter(mm)

6 PEO + salt series 42 150 1 285 plusmn 2 23 plusmn 1 145 20

Table 2 Spinning conditions of PU solutions in the roller electrospinning system

Sample Voltage(kV)

Distance(mm)

Roller speed(rpm)

RH()

Temperature(∘C)

Roller length(mm)

Roller diameter(mm)

175 PU + salt series 62 130 15 245 plusmn 2 16 plusmn 1 145 20

results in the figure have an error bar at 95 confidence inter-vals The spinning conditions of PEO and PU are shown inTables 1 and 2

(i) Measurement of surface tension measurement wascarried out using a KRUSS tensiometer at 25∘C andLabDesk software by using plate method

(ii) Measurement of viscosity the zero-shear viscositiesof solutions were measured by Haake RotoVisco1 at23∘C

(iii) Measurement of conductivity the conductivities ofpolymer solutions were measured at 23∘C by aRadelkis OK-1021 conductivity meter

(iv) Measurement of jets and spinning area a Sony FullHD NEX-VG10E Handycam E 18ndash200mm lens cam-era was used in the experiments By using camera thenumber of jets was recorded Spinning area and num-ber of jets were determined by taking an image fromthe camera and using NIS-Elements software 10images per second were taken A number of jets werecounted by using images

(v) Measurement of spinning performance and perfor-mance per jet 10 times 10 cm2 nanofibre webs were pre-pared and measured on a balance The calculationswere made according to (1)-(2)

(vi) Measurement of fibre diameter and diameter distri-bution images of the microstructure of the nanofibremembrane were taken by scanning electron micro-scope (SEM Feico) NIS-Elements software was usedto determine the fibre diameter and diameter distri-bution

(vii) Measurement of nonfibrous area using SEM imagesand NIS-Elements software nonfibrous areas werecalculated

222 Calculation of Spinning Performance Spinning perfor-mance (SP) can be determined from the mass of nanofibresproduced in a 1m long roller spinning electrode in 1minSpinning performance is calculated froman areaweight of theproduced nanofibre layer as follows

SP =119866 lowast V lowast 119871

119891

119871119903

gminm (1)

where 119866 is the area weight of the nanofibre membrane perarea in gm2 V is the velocity of running of the collected fabricin mmin 119871

119891is the width of the nanofibre membrane on the

collected fabric in m 119871119903is the length of the spinning roller in

mSpinning performance per one Taylor cone (SPC) can be

calculated from the known values of spinning performanceand an average total number of Taylor cones in the spinningelectrode Nc using (2) SPC is an amount of polymer solutiontransported through one Taylor cone (or a jet)

SPC =SP lowast 119871

119903lowast 60

Nc gh (2)

SPC is one of the parameters to be measured in the exper-iments to determine whether spinning performance is real-ized through SPC or Nc

3 Results and Discussions

31 Polymer Solution Properties The basic properties ofpolymer solutions are given in Figures 2 3 and 9

Surface tension of the solutions corresponds to that of theused solvents and is not significantly dependent on the con-tent of salts Thus surface tension is not an influencing inde-pendent parameter such as spinning performance and fibrediameter in the experiments

Viscosity of the solutions as a function of share rateshows considerably different characteristics of both poly-mers Effective viscosity of PEO strongly depends on sharerate and that of PU shows only moderate dependenceThere-fore themacromolecules of PEO 400 kDa show a high degreeof mechanical entanglement and a highly macromolecularcharacteristicThe strength of PEO jets as a necessary require-ment for spinnability is satisfactorily high at a relativelylow polymer concentration and corresponding viscosityHowever spinnability of PU requires a high polymer concen-tration and corresponding viscosity Viscosity of PU solutionsincreases with salt content this is not the case in PEOsolutions

The addition of LiCl to PU solution increases its viscosityErokhina et al explained that this increase in viscosity couldbe due to the same coordination of lithium cation bonds inthe solution with DMF molecules They concluded that thepartial recoordination of the lithium cation from the DMFcarbonyl groups to the PU carbonyl groups in the ternarysystem probably caused the unfolding of macromolecular


PU

TEABLiCl

00010

15

20

25

30

35

40

45

Surfa

ce te

nsio

n (m

Nm

)

002 004 006Molar concentration of salt (molL)

008

(a)

PEO

TEABLiCl

000

50

45

60

55

65

Surfa

ce te

nsio

n (m

Nm

)


008 010 012 014

(b)

Figure 2 Surface tension of polymer solutions

100000

04

08

12

16

2000 3000

PUPUL1PUL2PUL3

PUT1PUT2PUT3

4000Shear rate (1s)

Visc

osity

(Pamiddot

s)

1000 2000 3000 4000Shear rate (1s)

PEOPEOL1PEOL2PEOL3

PEOT1PEOT2PEOT3

00

02

04

06

08

Visc

osity

(Pamiddot

s)

Figure 3 Viscosity of polymer solutions

coils in PU with the formation of intermolecular crosslinks[20]

PU and LiCl salts have secondary bonds similar to the H-bridges between PU and LiCl ions (Figure 4) Intermolecularinteractions are positively influenced by polar groups Besidethis LiCl makes the functional groups of PU more polar

The interactions between dimethylformamide (DMF)and TEAB [19] or between PU and salts [15 21] are shown inFigures 5 and 6

C C

HH

+ Li+

Li+

+ ClminusN N

O

O O

ClminusPolyurethane Dissociated LiCl

|O|

Figure 4 Chemical interaction between PU and LiCl


Fry studied the interactions between polar organic sol-vents and salts [19] The electrostatic interaction between thedipolar solvent and the individual ions of the salt is greaterthan the attraction of the ions of the salt for each otherin the lattice Salts dissolve in polar solvents and this phe-nomenon is called as general solvation Fry [19] found thataside from general solvation small or highly charged metalcations such as Li+ or Mg+2 in water or other electron pairdonor solvents could also attract a shell of tightly bound sol-vent moleculesThis phenomenon known as inner-sphere orspecific solvation provides added stability to the positivecharge in the cation through its interaction with the negativeend of the solvent dipoles General solvation mainly dependson the dielectric constant (120576) of the solvent regardless of itschemical structure Conversely specific solvation depends onthe chemical structures of both solute and solvent Fryconducted a computational study demonstrating that smallertetraalkylammonium ions (Me

4N+ and Et

4N+) are sur-

rounded by a strong solvation shell in the strong donor DMFsolventThe four solventmolecules are distributed symmetri-cally around the tetrahedral cation and no remaining space issterically allotted for a fifth solvent molecule The tetrahedralarrangement of solvent molecules is the same as the structureof Et4N+(H

2O)4 as established by molecular dynamics and

is similar to that of the Li(THF)4

+ion as established by X-raycrystallography [19]

Rastogi [22] studied the ion-dipole interaction energy ofalkalimetal cations (eg Li+) anions (eg Clminus) and symmet-rical tetraalkylammonium ions in DMF and other solventsHe showed that the ion-dipole interaction energy decreasesin increasing order of Li+ gt Clminus gt Et

4N+ in DMF solvent

Moreover the ion-dipole interaction energy of ions is gener-ally higher than the dipolar interaction energy of solvents thatcause secondary solvation in large ions (Clminus Brminus) and long-range polarization in small ions (Li+)

In the case of PEO-water solutions the addition ofsalt only affects conductivity and permittivity Viscosity ofsolutions does not change when salt is added Salt andpolymer macromolecules do not seem to have a significantinteraction

The values of solution conductivities of LiCl and TEABsalts in the same molar concentration in DMF are illustratedin Figure 7 Dash lines indicate the connection points

The conductivity of LiCl and TEAB in the same molarconcentration in water is illustrated in Figure 8 Dotted linesindicate the connection points

The conductivity of the solutions of both TEAB andLiCl in water and DMF is generally high and all the valuesare surprisingly close to each other TEAB shows the sameconductivity in water as LiCl does despite its evidently largerionsThe values of conductivity inDMF are surprisingly closeto those in water thus indicating the high degree of dissocia-tion of salt in DMF Conversely the conductivities of polymersolutions containing salt differ from each other to someextent PEO solutions show higher conductivity than PUsolutions because of their lower viscosity and correspondinggreater movability of ions in a direct electric field PUsolutions containing LiCl are more conductive than those

with TEAB because their ions are more movable in highlyviscous liquid

According to Karmakar and Ghosh in PEO-lithium salt-based solid polymer the macromolecule coils around Li+ions and the O-atom in PEO chain provide a coordinationsite for Li+ ions through the Lewis acid-base interaction Li+ions jump from one coordination site to another within theamorphous phase Moreover the chain mobility of the poly-mer host which plays an important role in ion transportmakes the ion transport mechanism in polymer electrolytescomplex [23]

Collins et al [24] showed that in the absence of an electricfield charged structures capable of supporting current couldbe produced by the general equilibrium as follows

Neutral molecule1198961

999448999471

1198962

ion pair119896119889

999448999471

119896119891

free ions (3)

The neutral molecule and the ion pair are not capable of sup-porting current and the rate constants 119896

1and 1198962are generally

not known and are not important to the treatment of theproblem of conduction in liquidsThis step that produces freeions from ion pairs is critical to understanding the devel-opment of conduction in liquids The rate constant 119896

119889is

related to the dissociation of the ion pair into the chargedions and the rate constant 119896

119891is related to the removal of

free ions through the recombination into ion pairsMoreoverwith the application of a voltage with a positive polarity tothe electrode that supports the solution the mechanism ofthe charge carrier generation is called field enhanced disso-ciation Negative charges are immobilized in the electrodeleavingmobile positive charges to respond to the electrostaticstresses imposed by the electric field The unconstrainedsurface of the fluid enables multiple spinning sites to developas shown in Figure 10 [24]

In the case of PEO in water solution the dissociation ofthe ion pair into the charged ions of the water moleculesunder electric field is expressed as follows

2H2Olarrrarr H

3O+ +OHminus (4)

This creates a high number of ions Negatively charged ionsare immobilized in the positively charged spinning electrodewhereas positive charges move towards the collector elec-trode Adding salt increases the conductivity of solution overthe value required for the leaky dielectric model and leads tothe decreased number of Taylor cones In the case of PUsolution the molecules of DMF solvent do not dissociateTherefore field enhanced dissociation is also not present

PEOs in water solution show extremely high spinningperformance because of their high polarity and hygroscop-icity The PEO chains are used as a hygroscopic part ofdetergents because of these properties Their high polarityespecially in water solutions is characterized by a high valueof the dielectric constant 120576 = 39 [25 26]

Other basic properties of the solutions were not mea-sured However a number of differences between the twosolutions may exist that may cause their different behavioursin the electrospinning process For instance the kind and


H3C

H3C

H3C

H3C

H3C H3C

CH3

CH3

CH3

CH3 CH3

CH3

Ominus

H3C

H3C Ominus

Ominus

H3C CH3

Ominus

Ominus

H3C CH3

Ominus

+ Li+

Ominus

CH3

CH3Ominus

N

N

N

N N

N NNN

C

C C

C C

C CC

Figure 5 Computed structure of the tetramethylammonium ion and lithium ion complexed to four NN-dimethylformamidemolecules [19]

NC C

O

C

O

O O + LiCl

Lithium chlorideH

N

HHPolyurethane

H

C

H

H

C C C C

OO

CNN

H H

HHHHH

H

C

H

H

O OC

H

H

C

H

H

Li+

Clminus

Figure 6 Chemical interaction between LiCl and PU

0000

1

3

4

5

TEABLiCl

Con

duct

ivity

(mS

cm)

002 004 006 008 010Molar concentration of salt in DMF (molL)

2

Figure 7 Conductivity of TEAB and LiCl solutions in DMF Dashlines indicate the connection of points

concentration of polar groups in polymers solvents andpolymer-solvent-salt systems are responsible for the inter-actions of the component solutions with the electric fieldThe characteristic and content of polar groups influence thedielectric constant of materials Water DMF and PEO showhigh values of permittivity (80 38 and 39 resp) [25 26]The permittivity of PU is low (5ndash7) which may be the reasonfor its poor spinnability Spinnability of PU considerablyincreases with the addition of salt [15] This increase may be

0000

4

6

8

10

TEABLiCl

Con

duct

ivity

(mS

cm)

002 004 006 008 010Molar concentration of salt in water (molL)

2

Figure 8 Dependence of water solution conductivity on the con-centrations of LiCl and TEAB Dash lines indicate the connectionpoints

caused by the interactions between DMF and TEAB [19] orbetween PU and salt

32 Number of Jets In electrospinning PU and PEO showimportant differences in their behaviour such as the numberof jets on the spinning roller as shown in Figure 11


TEABLiCl

000 002 004 006Molar concentration of salt (molL)

008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl

Figure 9 Conductivities of polymer solutions with salt content (dotted lines indicate the connection of points)

kVDC

+

++

+ ++

++

+

minusminusminusminusminusminusminusminusminus

Figure 10 Multiple fluid jets using the plane-plane electrodeconfiguration without capillaries

First the number of jets is considerably larger in PU thanin PEO by adding salt Two attempts have been made toexplain this difference

(1) The theory of shielding effect of conducting lightningrods was considered [27] According to this theorythe electric field is screened out in conical spacewith atip at the end of the conductor and a top angle of about45∘ndash60∘ [28ndash34]

(2) Lukas et al [35ndash37] calculated the distance betweenjets by calculating the inter-jet distance called the crit-ical wavelength This parameter enables the estima-tion of the relative productivity of the electrospinningprocess

Second the number of PU cones increases with the saltcontent of the solution By contrast the number of PEO cones

decreaseswith the increase in salt concentrationThese effectsare difficult to explain as salt plays multiple roles

(1) Salt (TEAB more than LiCl) creates complex struc-tures (Figure 6)with PUwhich leads to changes in themacromolecule-macromolecule andmacromolecule-solvent interactions Consequently viscosity relatedentanglement number and stronger jets increaseThefollowing are the effects of salt on a PU solution

(i) Stronger jets result in longer average life of jets[20]

(ii) The jets are shorter because of higher content ofions and greater viscosity [38] and the numberof jets increases

These effects of salt do not occur in a PEO solution as salt doesnot create complex structures with PEO

(2) Salt increases the conductivity of polymer solutionsIncrease in conductivity changes the characteristic ofthe polymer solution from a semiconductor to a con-ductorTherefore the solution loses the characteristicof a leaky model which leads to the loss of abilityto create Taylor conesThe leaky dielectric model wasfirst proposed by Melcher and Taylor [39] Accordingto Bahattacharjee and Rutledge [40] ldquoa leaky dielec-tric differs from a perfect conductor or a dielectricmaterial in that free charges accumulate on thesurface of the material in the presence of an externalelectric field and modify the local field Under theseconditions two components of the electrical fielddevelop one tangential to the interface and anothernormal to it The presence of a tangential componenton the surface prevents the interface from being in anequilibrium condition and provokes it to deform Bycontrast the electrical stress in perfect dielectrics andconductors is always perpendicular to the interface


Content of salt (molL)002

50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

Content of salt (molL)000 004 008 012 016

Figure 11 Number of jets on a roller

Electromechanical coupling occurs at the fluid-fluidinterface alone forces resulting from charges in thebulk are negligibly small As the fluid acceleratesthe tangential component of the electrical stress islargely balanced by the viscous or viscoelasticresponse of the fluid Therefore both the constitutivebehaviour and the electrical properties of the fluiddetermine the condition of the process If changes inthe conductivity resulting from salt addition are largeenough to alter the behaviour of the fluid from that ofa leaky dielectric to that resembling a conductor thenthe tangential component of the electrical stress thataccelerates the fluid is likely to diminish and the flowprocess to be stopped Through this limit the elec-trical stress is balanced only by the alteration of theshape of the interface and surface tension onlyrdquo [40]

Apparently the effect of salt according to (2) works againstthat in (1) In the case of PU the effects described in (1)predominate those in (2) In the case of PEO only the effectsaccording to (2) apply

The differences between PU and PEO behaviours are alsobased on different polymer characteristics

(1) PEO 400 kDa has a molecular weight high enough tocreate strong jets even at a low concentration and cor-responding viscosity This is not the case in PU as PUneeds an increase in entanglement level using salt

(2) PEO contains strong polar groups to obtain stronginteractions with an electric field This conditionis expressed by a high value of dielectric constantAgain this is not the case in PU as PU needs anincrease in polarity by creating complexes with salt

33 Spinning Performance and Spinning Performance per OneCone Spinning performance and spinning performance perjet were measured and calculated for both solution systemsIn case of PU without salt spinning was not observed How-ever in the case of PEO without salt spinnability was highand only the polymer solution was transported to the surfaceof the collector without forming fibres A possible consequ-ence of this behaviour is the electrical conductivity variation

PU polymer shows good spinnability when salt is addedto it Two kinds of salts (TEAB and LiCl) are used as additivesboth increase the conductivity and viscosity of solutionsCengiz and Jirsak [15] observed that TEAB increases theviscosity of PU solutions which means more extensiveinteractions among macromolecules A polymer networkbecomes more solid It leads to higher spinning performanceof solution [21]

PEO solution without salt is transported from the spin-ning electrode to the collector in the electrospinning devicebut no fibres are formed only the polymer solution movestowards the collector Hundreds of jets can be observedThe addition of salt to the solution decreases its spinningperformance and nanofibres are formed

In principle the spinning performance (Figure 12) showsthe same tendencies as the number of jets Nevertheless spin-ning performance per jet (Figure 13) is not an independentquantity The amount of polymer solution flowing throughone Taylor cone depends on the viscosity of solution thethickness of a solution layer and the drawing force of anelectric field which are dependent on the dielectric propertiesof the polymer or polymer solution

34 Fibre Diameter and Nonfibrous Area Quality of theproduced nanofibres and nanofibre layers was tested in the


Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20

Content of salt (molL)002 004 006 008

PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1


Figure 12 Spinning performance of PU and PEO nanofibres in various salt contents

PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)

004 006 008Content of salt (molL)

000000

003

006

009

012

004 012008

Figure 13 Spinning performance per jet of PU and PEO nanofibres in various salt contents

experiments in terms of fibre diameter (Figure 14) and nonfi-brous area (Figure 15) In the PU electrospinning the highestsalt content leads to an increase in viscosity and slightlychanges fibre diameters High salt content also leads to alow quality of PU nanofibre layers By contrast PEO nanofi-bre diameter and quality of nanofibre layers do not signifi-cantly depend on salt content above a certain limit

4 Conclusion

Themain results of the experiments are as follows

(i) Salt may influence the entanglement number andpolarity of macromolecules when creating complexbonds with them It also increases the conductivity of


Fibr

e dia

met

er (n

m)

0

100

200

300

400

Content of salt (molL)000 003

PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400

Content of salt (molL)000 004 012008

(b)

Figure 14 Fibre diameter versus salt content (a) PU with TEAB and LiCl salts (b) PEO with TEAB and LiCl salts

PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)

Figure 15 Nonfibrous area versus salt content (a) PU (b) PEO nanofibres

solutions that may cross the limit suggested in theleaky dielectric model

(ii) PEOat 400 kDawith its high polarity andhigh entan-glement number (strength of jets) shows high spin-ning performance This performance is reduced bythe increase in conductivity

(iii) In the case of PU salt creates complex bonds with thepolymer and increases the low polarity and entangle-ment number consequently increasing the spinning

performance Further addition of salt may lead toreduced spinning performanceHowever it cannot beproved because of the extreme increase in solutionviscosity

Future Works

The results of this work should be considered as initialfindings on defining the parameters of needleless electrospin-ning introducing new parameters and developing methods


to measure these new parameters for both aqueous andnonaqueous solution systems In the future the followingtopics should be focused on

(i) Not enough studies have been conducted on thepermittivity effect on electrospinning Theoreticalstudies should present a full explanation and completedescription of the electrospinning process involvingthe effects of permittivity on dependent parameterssuch as length of jet distance between jets current ona jet spinning performance fibre diameter lifetime ofjets and spinning area

(ii) Studies should be made on dependent and indepen-dent parameters for both solution systems

(iii) A full understanding of the relation between indepen-dent and dependent parameters should be presented

Nomenclature and Symbols of Solutions

PEO Solutions in Water Polymer Concentration 6wt

PEO- 0 concentration of saltsPEOT1- 0024molL TEABPEOT2- 0062molL TEABPEOT3- 0124molL TEABPEOL1- 0024molL LiClPEOL2- 0062molLPEOL3- 0124molL

PU Solutions in DMF Polymer Concentration 175 wt

PU- 0 concentration of saltsPUT1- 0022molL TEABPUT2- 0044molL TEABPUT3- 0071molL TEABPUL1- 0014molL LiClPUL2- 0028molL LiClPUL3- 0056molL LiCl

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors would like to thank the Ministry of EducationYouth and Sports of the Czech Republic Studentrsquos GrantCompetition TUL in Specific University Research in 2013(Project no 48004) and in 2014 (Project no 21041) for theirfinancial support

References

[1] T Lin H Wang and X Wang ldquoSelf-crimping bicomponentnanofibers electrospun from polyacrylonitrile and elastomeric

polyurethanerdquo Advanced Materials vol 17 no 22 pp 2699ndash2703 2005

[2] D H L Bail W Schneider K Khalighi and H SeboldtldquoTemporary wound covering with a silicon sheet for the softtissue defect following open fasciotomy Technical noterdquo Journalof Cardiovascular Surgery vol 39 no 5 pp 587ndash591 1998

[3] P Taepaiboon U Rungsardthong and P Supaphol ldquoDrug-loaded electrospun mats of poly(vinyl alcohol) fibres and theirrelease characteristics of four model drugsrdquo Nanotechnologyvol 17 no 9 pp 2317ndash2329 2006

[4] K Kosmider and J Scott ldquoPolymeric nanofibre exhibit anenhanced air filtration performancerdquo Filtration and Separationvol 39 no 6 pp 20ndash22 2002

[5] A C Patel S Li J-M Yuan and Y Wei ldquoIn situ encapsulationof horseradish peroxidase in electrospun porous silica fibers forpotential biosensor applicationsrdquo Nano Letters vol 6 no 5 pp1042ndash1046 2006

[6] X M Mo C Y Xu M Kotaki and S Ramakrishna ldquoElectro-spun P(LLA-CL) nanofiber a biomimetic extracellular matrixfor smooth muscle cell and endothelial cell proliferationrdquoBiomaterials vol 25 no 10 pp 1883ndash1890 2004

[7] P X Ma and R Y Zhang ldquoSynthetic nano-scale fibrousextracellular matrixrdquo Journal of Biomedical Materials Researchvol 46 no 1 pp 60ndash72 1999

[8] L Torobin and R C Findlow ldquoMethod and apparatus forproducing high efficiency fibrous media incorporating discon-tinuous sub-micron diameter fibers and web media formedtherebyrdquo Google Patents 2001

[9] T J Fabbricante A S Fabbricante and G F Ward ldquoMicro-denier nonwoven materials made using modular die unitsrdquoUS6114017 A 2000

[10] T Huang L R Marshall J E Armantrout et al ldquoProduction ofnanofibers by melt spinningrdquo Google Patents 2012

[11] T Huang ldquoCentrifugal solution spun nanofiber processrdquoGoogle Patents 2010

[12] R D Pike ldquoSuperfine microfiber nonwoven webrdquo GooglePatents 1999

[13] A S Nain J C Wong C Amon and M Sitti ldquoDrawing sus-pended polymer micro-nanofibers using glass micropipettesrdquoApplied Physics Letters vol 89 no 18 p 183105 2006

[14] O Jirsak F Sanetrnik D Lukas V Kotek L Martinova and JChaloupek ldquoMethod of nanofibres production from a polymersolution using electrostatic spinning and a device for carryingout the methodrdquo Google Patents 2009

[15] F Cengiz and O Jirsak ldquoThe effect of salt on the roller electro-spinning of polyurethane nanofibersrdquo Fibers and Polymers vol10 no 2 pp 177ndash184 2009

[16] T A Dao and O Jirsak The Role of Rheological Properties ofPolymer Solutions in Needleless Electrostatic Spinning 2010

[17] T H Meyer and J Keurentjes Handbook of Polymer ReactionEngineering Wiley-VCH Weinheim Germany 2005

[18] J E Mark Polymer Data Handbook Oxford University PressNew York NY USA 1999

[19] A J Fry ldquoTetraalkylammonium ions are surrounded by aninner solvation shell in strong electron pair donor solventsrdquoElectrochemistry Communications vol 11 no 2 pp 309ndash3122009

[20] O V Erokhina A V Artemov L S GalrsquoBraikh G A Vikhor-eva and A A Polyutov ldquoState of lithium cation in a solution ofpolyurethane in deviethylformamiderdquo Fibre Chemistry vol 38no 6 pp 447ndash449 2006


[21] F Cengiz-Callioglu O Jirsak and M Dayik ldquoInvestigationinto the relationships between independent and dependentparameters in roller electrospinning of polyurethanerdquo TextileResearch Journal vol 83 no 7 pp 718ndash729 2013

[22] P P Rastogi ldquoA study on ion-dipole interaction energy ofsome alkali metal cations halide anions and symmetricaltetraalkylammonium ions in different solventsrdquo Zeitschrift furPhysikalische Chemie vol 75 no 3-4 pp 202ndash206 1971

[23] A Karmakar and A Ghosh ldquoDielectric permittivity and elec-tric modulus of polyethylene oxide (PEO)-LiClO

4composite

electrolytesrdquo Current Applied Physics vol 12 no 2 pp 539ndash5432012

[24] G Collins J Federici Y Imura and L H Catalani ldquoChargegeneration charge transport and residual charge in the elec-trospinning of polymers a review of issues and complicationsrdquoJournal of Applied Physics vol 111 no 4 Article ID 044701 2012

[25] H Kliem K Schroeder and W Bauhofer ldquoHigh dielectricpermittivity of polyethylene oxide in humid atmospheresrdquo inProceedings of the Annual Conference on Electrical Insulationand Dielectric Phenomena pp 12ndash15 October 1996

[26] C Fanggao G A Saunders E F Lambson et al ldquoFrequencydependence of the complex dielectric constant of poly(ethyleneoxide) under hydrostatic pressurerdquo Il Nuovo Cimento D vol 16no 7 pp 855ndash864 1994

[27] M W Jernegan ldquoBenjamin Franklinrsquos lsquoelectrical kitersquo and light-ning rodrdquoTheNew England Quarterly vol 1 no 2 pp 180ndash1961928

[28] V Cooray Lightning Protection The Institution of Engineeringand Technology 2009

[29] J L G Lussac Instruction Sur Les Paratonnerres KessingerPublishing LLC Paris France 1824

[30] M Nayel ldquoInvestigation of lightning rod shielding anglerdquo inProceedings of the IEEE Industry Applications Society AnnualMeeting (IAS rsquo10) pp 1ndash4 IEEE Houston Tex USA October2010

[31] A V Rakov and M A Uman Lightning Physics and EffectsCambridge University Press Cambridge UK 2003

[32] M A Uman All about Lightning Dover Publications NewYork NY USA 1987

[33] C F Wagner G D McCann and G L MacLane ldquoShielding oftransmission linesrdquo Electrical Engineering vol 60 pp 313ndash3281941

[34] X Zhang L Dong J He S Chen and R Zeng ldquoStudy on theeffectiveness of single lightning rods by a fractal approachrdquoJournal of Lightning Research vol 1 no 1 pp 1ndash8 2009

[35] D Lukas A Sarkar L Martinova et al ldquoPhysical principles ofelectrospinning (electrospinning as a nano-scale technology ofthe twenty-first century)rdquo Textile Progress vol 41 no 2 pp 59ndash140 2009

[36] D Lukas A Sarkar and P Pokorny ldquoSelf-organization ofjets in electrospinning from free liquid surface a generalizedapproachrdquo Journal of Applied Physics vol 103 no 8 Article ID084309 2008

[37] M Komarek and L Martinova ldquoDesign and evaluation of meltelectrospinning electrodesrdquo in Proceedings of the 2nd NanoconInternational Conference Tanger Ed pp 72ndash77 OlomoucCzech Republic October 2010

[38] A T DaoThe role of rheological properties of polymer solutionsin needleless electrostatic spinning [PhD thesis] Technical Uni-versity of Liberec Liberec Czech Republic 2010

[39] J R Melcher and G I Taylor ldquoElectrohydrodynamicsmdashareview of role of interfacial shear stressesrdquo Annual Review ofFluid Mechanics vol 1 no 1 pp 111ndash146 1969

[40] P K Bahattacharjee and G C Rutledge ldquoElectrospinning andpolymer nanofibers process fundamentalsrdquo in ComprehensiveBiomaterials vol 1 pp 497ndash512 2011

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


761 055

Take-upcylinder

Rotating cylinder

Air

Input ofconditioned air

High voltagesupplier

Nanoweb

Nanofiber

Output ofair

Collectorelectrode Supporting material

Roller

Air

Incondi

Figure 1 Diagram of the roller electrospinning system

polyurethane (PU) and polyethylene oxide (PEO) polymerswith various concentrations of tetraethylammonium bro-mide (TEAB) and lithium chloride (LiCl) salts We chose PUin this work for two reasons First the PU used in this studyis pure and industrially produced Second much informationon this polymer is available from previous studies includinginformation on optimum spinning conditions

In the current work PEO was used with both TEAB andLiCl salts In case of PEO adding salt decreases its spinningperformance similar to PVA solutions Moreover PEO isproduced in better purity than PVA One of the aims ofthis study is to determine the different spinning behavioursof both water-soluble and -insoluble polymers Using PVAwhich ismostly used in electrospinning is possible AlthoughPVA has been studied by many researchers PEO was chosenin this work for its more stable quality and better purityThe possible salt-polymer salt-solvent and solvent-polymerrelations are explained in the following section

2 Experimental

21 Materials Polyurethane Larithane LS 1086 (Novo-tex Italy) which is an aliphatic elastomer composed of2000 gmol linear polycarbonate diol and isophorone diiso-cyanate and extended by isophorone diamine was chosen asthe second polymer

Most PUs are block polymers prepared with a diiso-cyanate which is a short diol such as 14-butanediol or 16-hexanediol a diamine (the chain extender) and a diol with amolecular weight of 500 to 4000 based on a polyetherpolyester or polycarbonate Preparation is usually performedin two steps the reaction of the longer polyol with isocyanate

in the first stage and that with the chain extender in thesecond stage [17] PU has excellent damping properties goodmechanical and physical properties even at low temperatureshigh combustion resistance and low thermal conductivity[18] DMF (Fluka Switzerland) was used as the solvent

Water-soluble PEOwithmolecularweight of 400 kDawaspurchased from Scientific Polymers Inc USA Distilledwater was used as the solvent PEO is a water-soluble andnon-ionic polymer PEOs are also commonly studied in elec-trospinning They are available in a large range of molecularweights PEOs can be applied in areas such as textile appli-cations cosmetics antifoaming agents and food industryamong others PEOs are produced by the polymerization ofethylene oxide and they have a structural polyether unit ofndashCH2ndashCH2ndashOndash They are a good candidate for an electro-

spinning system because of their high spinnability and watersolubility

Tetraethylammonium bromide was purchased fromFluka (Switzerland) and LiCl from Lach-Ner sro (CzechRepublic) Based on previous works 6 PEO and 175 PUwere chosen as the constant polymer concentrations Variousamounts of salt were used according to themolar ratio of saltThe nomenclature of solutions is tabulated as shown inNomenclature and Symbols of Solutions according to saltcontent We used a small amount of LiCl salt content for thePEO solution because the fibre diameter increases withincreased amount of salt

22 Methods

221 Spinning Conditions The solutions were spun usinga spinning device as shown in Figure 1 All the measured



Sample Voltage(kV)

Distance(mm)

Roller speed(rpm)

RH()

Temperature(∘C)

Roller length(mm)

Roller diameter(mm)



Sample Voltage(kV)

Distance(mm)

Roller speed(rpm)

RH()

Temperature(∘C)

Roller length(mm)

Roller diameter(mm)












119891

119871119903

gminm (1)







119903lowast 60

Nc gh (2)








PU

TEABLiCl

00010

15

20

25

30

35

40

45

Surfa

ce te

nsio

n (m

Nm

)


008

(a)

PEO

TEABLiCl

000

50

45

60

55

65

Surfa

ce te

nsio

n (m

Nm

)


008 010 012 014

(b)


100000

04

08

12

16

2000 3000

PUPUL1PUL2PUL3

PUT1PUT2PUT3

4000Shear rate (1s)

Visc

osity

(Pamiddot

s)

1000 2000 3000 4000Shear rate (1s)

PEOPEOL1PEOL2PEOL3

PEOT1PEOT2PEOT3

00

02

04

06

08

Visc

osity

(Pamiddot

s)





C C

HH

+ Li+

Li+

+ ClminusN N

O

O O


|O|




4N+ and Et

4N+) are sur-






4N+ in DMF solvent










999448999471

1198962

ion pair119896119889

999448999471

119896119891

free ions (3)




119889is





2H2Olarrrarr H

3O+ +OHminus (4)





H3C

H3C

H3C

H3C

H3C H3C

CH3

CH3

CH3

CH3 CH3

CH3

Ominus

H3C

H3C Ominus

Ominus

H3C CH3

Ominus

Ominus

H3C CH3

Ominus

+ Li+

Ominus

CH3

CH3Ominus

N

N

N

N N

N NNN

C

C C

C C

C CC


NC C

O

C

O

O O + LiCl

Lithium chlorideH

N

HHPolyurethane

H

C

H

H

C C C C

OO

CNN

H H

HHHHH

H

C

H

H

O OC

H

H

C

H

H

Li+

Clminus


0000

1

3

4

5

TEABLiCl

Con

duct

ivity

(mS

cm)


2



0000

4

6

8

10

TEABLiCl

Con

duct

ivity

(mS

cm)


2





TEABLiCl


008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl


kVDC

+

++

+ ++

++

+















50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Sample Voltage(kV)

Distance(mm)

Roller speed(rpm)

RH()

Temperature(∘C)

Roller length(mm)

Roller diameter(mm)



Sample Voltage(kV)

Distance(mm)

Roller speed(rpm)

RH()

Temperature(∘C)

Roller length(mm)

Roller diameter(mm)












119891

119871119903

gminm (1)







119903lowast 60

Nc gh (2)








PU

TEABLiCl

00010

15

20

25

30

35

40

45

Surfa

ce te

nsio

n (m

Nm

)


008

(a)

PEO

TEABLiCl

000

50

45

60

55

65

Surfa

ce te

nsio

n (m

Nm

)


008 010 012 014

(b)


100000

04

08

12

16

2000 3000

PUPUL1PUL2PUL3

PUT1PUT2PUT3

4000Shear rate (1s)

Visc

osity

(Pamiddot

s)

1000 2000 3000 4000Shear rate (1s)

PEOPEOL1PEOL2PEOL3

PEOT1PEOT2PEOT3

00

02

04

06

08

Visc

osity

(Pamiddot

s)





C C

HH

+ Li+

Li+

+ ClminusN N

O

O O


|O|




4N+ and Et

4N+) are sur-






4N+ in DMF solvent










999448999471

1198962

ion pair119896119889

999448999471

119896119891

free ions (3)




119889is





2H2Olarrrarr H

3O+ +OHminus (4)





H3C

H3C

H3C

H3C

H3C H3C

CH3

CH3

CH3

CH3 CH3

CH3

Ominus

H3C

H3C Ominus

Ominus

H3C CH3

Ominus

Ominus

H3C CH3

Ominus

+ Li+

Ominus

CH3

CH3Ominus

N

N

N

N N

N NNN

C

C C

C C

C CC


NC C

O

C

O

O O + LiCl

Lithium chlorideH

N

HHPolyurethane

H

C

H

H

C C C C

OO

CNN

H H

HHHHH

H

C

H

H

O OC

H

H

C

H

H

Li+

Clminus


0000

1

3

4

5

TEABLiCl

Con

duct

ivity

(mS

cm)


2



0000

4

6

8

10

TEABLiCl

Con

duct

ivity

(mS

cm)


2





TEABLiCl


008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl


kVDC

+

++

+ ++

++

+















50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




PU

TEABLiCl

00010

15

20

25

30

35

40

45

Surfa

ce te

nsio

n (m

Nm

)


008

(a)

PEO

TEABLiCl

000

50

45

60

55

65

Surfa

ce te

nsio

n (m

Nm

)


008 010 012 014

(b)


100000

04

08

12

16

2000 3000

PUPUL1PUL2PUL3

PUT1PUT2PUT3

4000Shear rate (1s)

Visc

osity

(Pamiddot

s)

1000 2000 3000 4000Shear rate (1s)

PEOPEOL1PEOL2PEOL3

PEOT1PEOT2PEOT3

00

02

04

06

08

Visc

osity

(Pamiddot

s)





C C

HH

+ Li+

Li+

+ ClminusN N

O

O O


|O|




4N+ and Et

4N+) are sur-






4N+ in DMF solvent










999448999471

1198962

ion pair119896119889

999448999471

119896119891

free ions (3)




119889is





2H2Olarrrarr H

3O+ +OHminus (4)





H3C

H3C

H3C

H3C

H3C H3C

CH3

CH3

CH3

CH3 CH3

CH3

Ominus

H3C

H3C Ominus

Ominus

H3C CH3

Ominus

Ominus

H3C CH3

Ominus

+ Li+

Ominus

CH3

CH3Ominus

N

N

N

N N

N NNN

C

C C

C C

C CC


NC C

O

C

O

O O + LiCl

Lithium chlorideH

N

HHPolyurethane

H

C

H

H

C C C C

OO

CNN

H H

HHHHH

H

C

H

H

O OC

H

H

C

H

H

Li+

Clminus


0000

1

3

4

5

TEABLiCl

Con

duct

ivity

(mS

cm)


2



0000

4

6

8

10

TEABLiCl

Con

duct

ivity

(mS

cm)


2





TEABLiCl


008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl


kVDC

+

++

+ ++

++

+















50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





4N+ and Et

4N+) are sur-






4N+ in DMF solvent










999448999471

1198962

ion pair119896119889

999448999471

119896119891

free ions (3)




119889is





2H2Olarrrarr H

3O+ +OHminus (4)





H3C

H3C

H3C

H3C

H3C H3C

CH3

CH3

CH3

CH3 CH3

CH3

Ominus

H3C

H3C Ominus

Ominus

H3C CH3

Ominus

Ominus

H3C CH3

Ominus

+ Li+

Ominus

CH3

CH3Ominus

N

N

N

N N

N NNN

C

C C

C C

C CC


NC C

O

C

O

O O + LiCl

Lithium chlorideH

N

HHPolyurethane

H

C

H

H

C C C C

OO

CNN

H H

HHHHH

H

C

H

H

O OC

H

H

C

H

H

Li+

Clminus


0000

1

3

4

5

TEABLiCl

Con

duct

ivity

(mS

cm)


2



0000

4

6

8

10

TEABLiCl

Con

duct

ivity

(mS

cm)


2





TEABLiCl


008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl


kVDC

+

++

+ ++

++

+















50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




H3C

H3C

H3C

H3C

H3C H3C

CH3

CH3

CH3

CH3 CH3

CH3

Ominus

H3C

H3C Ominus

Ominus

H3C CH3

Ominus

Ominus

H3C CH3

Ominus

+ Li+

Ominus

CH3

CH3Ominus

N

N

N

N N

N NNN

C

C C

C C

C CC


NC C

O

C

O

O O + LiCl

Lithium chlorideH

N

HHPolyurethane

H

C

H

H

C C C C

OO

CNN

H H

HHHHH

H

C

H

H

O OC

H

H

C

H

H

Li+

Clminus


0000

1

3

4

5

TEABLiCl

Con

duct

ivity

(mS

cm)


2



0000

4

6

8

10

TEABLiCl

Con

duct

ivity

(mS

cm)


2





TEABLiCl


008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl


kVDC

+

++

+ ++

++

+















50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




TEABLiCl


008

PU

00

02

04

06

08

10

12

14

16C

ondu

ctiv

ity (m

Scm

)

0000

4

6

8

10

12

Con

duct

ivity

(mS

cm)


2

PEO

TEABLiCl


kVDC

+

++

+ ++

++

+















50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





50

20

40

60

80

100

100

150

200

250N

umbe

r of j

et

Num

ber o

f jet

s

004 006 008

PUT1PUT2PUT3

PUL3

PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1














Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Spin

ning

per

form

ance

(gm

inm

)

05

10

15

20


PUT1PUT2PUT3

PUL3PUL2PUL1

Spin

ning

per

form

ance

(gm

inm

)

00

03

06

09

PEOT1PEOT2PEOT3

PEOL3PEOL2

PEOL1



PUT1PUT2PUT3

PUL3PUL2PUL1 PEOT1

PEOT2PEOT3

PEOL3PEOL2

PEOL1


000

005

010

015

020

SPje

t (g

h)

SPje

t (g

h)


000000

003

006

009

012

004 012008



4 Conclusion




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Fibr

e dia

met

er (n

m)

0

100

200

300

400


PUT1PUT2PUT3

PUL1PUL2PUL3

006

(a)Fi

bre d

iam

eter

(nm

)

PEOT1PEOT2PEOT3

PEOL1PEOL2PEOL3

0

100

200

300

400


(b)


PUT1PUT2PUT3

PUL3

PUL2PUL1


0

2

4

Non

fibro

us ar

ea (

)

004 006 008

(a)

PEOT1PEOT2PEOT3

PEOL3PEO

PEOL2

PEOL1

60

30

0

90

Non

fibro

us ar

ea (

)


(b)






Future Works














Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials















Acknowledgments


References


























4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







4composite


























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



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Research Article Influence of Salts on Electrospinning of ...F : Surface tension of polymer...

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