Research Article Improvement of Interfacial Shear Strength...

Research ArticleImprovement of Interfacial Shear Strength ofMendong Fiber (Fimbristylis globulosa) Reinforced EpoxyComposite Using the AC Electric Fields

Heru Suryanto1 Eko Marsyahyo2 Yudy Surya Irawan3 Rudy Soenoko3 and Aminudin1

1Mechanical Engineering Department State University of Malang Jalan Semarang 5 Malang East Java 65145 Indonesia2Mechanical Engineering Department National Institute of Technology Jalan Sigura-Gura Malang East Java 65145 Indonesia3Mechanical Engineering Department University of Brawijaya Jalan Veteran Malang East Java 65145 Indonesia

Correspondence should be addressed to Heru Suryanto herusuryantoftumacid

Received 6 February 2015 Revised 23 April 2015 Accepted 14 May 2015

Academic Editor Adriana Gregorova

Copyright copy 2015 Heru Suryanto et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The effects of the AC electric field treatment on the interfacial shear strength of mendong fiber-reinforced epoxy composites wereinvestigated For this purpose the epoxy (DGEBA) with a cycloaliphatic amine curing agent was treated by the AC electric fieldduring the curing processThe heat generated during the epoxy polymerization process was monitored Structure of the epoxy wasstudied by X-ray diffraction Fourier transform infrared spectroscopy (FTIR) and Scanning Electron Microscope respectivelyThe interfacial shear strength (IFSS) was also measured using a single fiber pull-out test XRD analyzes indicated that the treatmentof AC electric fields was able to form a crystalline phase of epoxy IFSS of the mendong fiber-reinforced epoxy composites wasoptimum increased by 38 in the AC electric fields treatment of 750Vcm

1 Introduction

Natural fibers have been offering many advantages in therecent years The benefits of natural fiber composites thatcompared to composites with synthetic fiber reinforcementare low price low density being easily separated beingabundantly available being renewable being biodegradableand having no health hazard [1 2] Several alternatives to fibersources of crop as agricultural byproducts including wheatstraw [3] rice straw [4] switch grass [5] indian grass [6]napier grass [7] and mendong grass [8] have been used toproduce cellulose fibers Some of such fibers have applied inthe polymer composite

Diglycidyl ether of bisphenol A (DGEBA) is the mostcommon epoxy resin type It is used extensively in industrydue to its fluidity and ease of processing It possesses manydesirable properties such as high chemical and corrosionresistance excellent mechanical and thermal propertiesadhesion to various substrates low shrinkage upon cure andgood electrical insulating properties [9] DGEBA was able to

be processed under a variety of conditions and widely used asstructural and composite materials [10]

The physical properties of epoxy depend on the extent ofcure which depends on the curing conditions and time andtemperature of cure [11]The curing process is a processwherethe polymerization reaction occurs which determines themorphology of the matrix resin and properties of structures[12] It was conducted using an autoclave [13] radiationof ultraviolet [14] microwave [15] and electron beam [16]However that curing process uses a heat energy that causesthermal residual stress This stress was decreasing in theflexural strength of the epoxy compositematerial by 20 [17]the interfacial toughness by 40 [18] fatigue life by 10 [19]and delamination [17] For this reason efforts are necessaryto minimize the use of heat in the curing process such as byapplying an electric field during the curing process

When the epoxy was used as composite matrix thechanges of epoxy properties would influence its compositesThe change in the nature of the epoxy is strongly influencedby the structure and orientation of the molecular chains It

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2015 Article ID 542376 10 pageshttpdxdoiorg1011552015542376

2 International Journal of Polymer Science

may be done by adding a functional polymer matrix [20]like both plasticizers and rubber [21] modifying the structurethrough molecular orientation by using shear flow suchas injection molding and extrusion or using the externalfield such as electric field magnetic field and a combina-tion of both [22] The presence of the DC electric currentand electromagnetic fields cause an increase in the impactstrength of carbon fiber composite polymer by 247 and436 for DC current of 25A and 50A respectively [23]and also the interaction of static load and electromagneticfields able to decrease in defflection of the reinforced carboncomposite plate by 60 in electromagnetic infuluence of 1Tesla It indicates that the bending stiffness of the reinforcedcarbon composite plate was increasing [24] However thepresence of DC electric field is very high in the compositeglassepoxy cause of aging that causes delamination anddebonding between the glass fiber and epoxy matrix [25]In the composite compaction process the electric fieldexposure with AC and DC source is capable of modifyingthe epoxy resin in which the physical stability and strengthof the epoxy are increased by 100 and 50 in presenceof AC and DC fields respectively [10] The external electricfield causes the movement of electrons due to the intrinsicdipole arrangement of opposite charge [26] and settingthe orientation of the molecule [27] In polar moleculesthe polarity of the electric field can improve the surfaceand lead to increased adhesion properties of the polymerinterface PETgelatin [28] The electric field is also ableto convert hydrogen bonds [29] and capable of forming acovalent bond as the molecular interactions of polar andnon polar bond [30] The change of polarization also occursin the dielectric material due to the presence of an electricfield [31] and the presence of free-moving electrons at theinterface fibermatrix (interfacial polarization) that arises inthe process of making a composite [32] In epoxy curingnanolamellar microstructure was changed due to orientationof the microgel particle before gelation process occurs so thatthe epoxy surface topography becomes more rugged than nooriented epoxy [33] These physical changes will affect theinterfacial shear strength (IFSS) of compositesTherefore thisstudy was done to show the effects of exposure to AC electricfields during the curing process on IFSS of themendongfiber-epoxy matrix

2 Material and Methods

21 Material The research material was mendong fibersSamples were obtained from the cultivation land in thedistrict of Wajak Malang East Java Indonesia Samples wereselected in the harvest age of 5-6months and the straw lengthwas 1ndash12m The chemical properties contents of mendongfibers were 7214 cellulose 202 hemicellulose 344lignin 42 extractive compound and moisture of 42ndash52 Mendong fiber has tensile strength stiffness modulusand specific strength of 452MPa 17GPa and 507 kNsdotmkgrespectively [8]

The polymer matrix was diglycidyl ether of bisphenol-A(DGEBA) (brand name Eposchon PT Justus Kimia Raya

Fiber

minus +

2mm Epoxy

10mm

Figure 1 Treatment of AC electric fields during epoxy curing

Surabaya Indonesia) with an epoxy equivalent to 189plusmn5Thecuring agent was a modified cycloaliphatic amine contain-ing mainly 3-aminomethyl-355-trimethylcyclohexylamine(brand name EPH 555 from PT Justus Kimia Raya SurabayaIndonesia) with an amine hydrogen equivalent weight of 86and viscosity 05ndash1 Poise at room temperature Resin andcuring agent were carefully and homogeneously mixed at aratio of 2 1

22 Fiber Extraction Mendong fibers were extracted me-chanically The wet mendong straw was cut off 60 cm longfrom the base and the next piece to the top was removedMendong straw was repeatedly pounded and then cleanedusing water Then fibers were soaked in water for a weekMendong fibers were retrieved cleaned and allowed to dryup in ambient temperature Mendong fibers were mercerizedby immersion into 5 NaOH solution for 2 hours at ambienttemperature and then rinsed using an aquadest for five timesdried and kept in plastic wrap and put in a dry box withhumidity of 40 [8]

23 AC Electric Fields Treatment Treatment of anAC electricfield to pull-out tests was performed during the curingprocess of the epoxy from the liquid to solid This process isconducted by making a plastic mold with the size of 100 times10 times 2mmThen ten pieces of fibers with a length of 30mmwere prepared on a ruler that was attached on a digital heightgauge (002mm resolution) Furthermore epoxy was mixedwith the curing agent in the ratio 2 1 and then stirred andpoured into molds Fibers move down slowly into the epoxyliquid in the mold until the depth of the fiber embedded inan epoxymatrix reaches 200120583mand is recorded as embeddedfiber length as shown in Figure 1The exposure of AC electricfield was conducted between a pair of electrodes by frequency1 kHz and varying electric fields of 250Vcm 500Vcm750Vcm and 1000Vcm for 2 hours After the epoxy wassolid the epoxy that contains the fiber is cutwith a razor bladeto the size of 5 times 5 times 2mm3

24 Measurement of Heat Generated during the Epoxy Poly-merization 20 g epoxy was mixed with 10 g curing agents

International Journal of Polymer Science 3

in beaker glass and then stirred at 150 rpm for 30 s 15 g ofthis mixture was poured into tube with diameter of 25mmand then exposed to the AC electric fields by frequency1 kHz and varying AC electric fields of 250Vcm 500Vcm750Vcm and 1000Vcm The heat was generated while theepoxy polymerization was measured by a temperature sensorof LM15 type (resolution 001∘C National SemiconductorUSA) that linked to microcontrol and computer The sensorwas placed in the middle of epoxy tube and temperature wasmeasured for 110min

25 X-Ray Diffraction Analysis X-ray diffraction studieswere performed under room conditions using PanAnalyticaltype X-Pert Pro Diffractometer system with CuK120572 radiation(120582 = 154 A) Flat sample was used for X-ray diffractionanalysis The diffracted intensity of CuK120572 radiation wasrecorded between 5∘ and 80∘ (2120579 angle range) at 40 kV and30mA

26 FTIR Analysis Infrared spectra were recorded in Shi-madzu IR Prestige-21 FTIR spectrometer Epoxy sample wasin the formof flat with 01mm thick IR spectra were recordedin the spectral range of 4000ndash400 cmminus1 with resolution of2 cmminus1

27 Fiber Pull-Out Test The single fiber pull-out test wasconducted for determining IFSS of the fiber-matrix interfaceHolder pull-out test samples weremade by gluing fiber on thethick paper with a distance of 6mm from the epoxy matrixas shown in Figure 2 Pull-out tests were carried out by usinga fiber tensile testing device with force gauge 5N with 1mNresolution Tensile test was performedwith a crosshead speedof 35mmmin at ambient temperature Each treatment willtake 10 samples of the test

28 Morphological Studies The morphological structure ofthe epoxywas observed using FEI Inspect-S50 type ScanningElectron Microscope (SEM) All specimens were sputteredwith a 10 nm layer of gold before the SEM observations

3 Result and Discussion

31 Temperature Profile during Curing Process The curingprocess starts from mixing epoxy resin and hardener tobegin a chemical reaction that transforms the epoxy liquidinto a solid This process involves a complex process asdifferent chemical reactions and an exothermic chemicalreaction In general both gelation and vitrification are themost significant phenomena of this process [34] Profile oftemperature during the curing process of epoxy in the ACelectric fields was shown in Figure 3

From the measurements of the temperature during thecuring process of epoxy that exposed by the AC electric fieldshows the total exothermic heat of chemical reaction waslower than epoxy without the treatment The polymerizationhas strongly influenced the molecular response to the ACelectric fields [35] Meir et al [36] demonstrate that an exter-nal electric field can act as an accessory catalyst or an inhibitor

Fiber

RestraintRestraint

Card

Tensionforce

Glue

02mmSample

6mm

2mm

5mm

Figure 2 Single fiber pull-out test

2020 30 40 50 60 70 80 90 100 110100

2530354045505560657075808590

Curing time (min)

Tem

pera

ture

(∘C)

No treatment250Vcm500Vcm

750Vcm1000Vcm

Figure 3 Temperature profiles at the center point of 3 cm diameterof the tube

for organic reactions like Diels-Alders reaction When theelectric fields were oriented along the ldquoreaction axisrdquo thebarrier of the reactions is lowered by a significant amountSimply flipping the electric fieldsrsquo direction has the oppositeeffect and the electric fields act as an inhibitor Additionallyan electric field oriented perpendicular to the ldquoreactionaxisrdquo in the direction of the individual molecule dipoles canchange the endothermic or exothermic selectivity In thiscase treatments of AC electric field in curing process wereable to reduce the occurrence of the epoxy polymerizationreaction It was indicated by a reduction in the temperature ofexothermic reaction of the epoxy polymerization The reac-tion temperature is 737 697 609 545 and 51∘C for the AC


Inte

nsity

(au

)

Control250Vcm500Vcm

750Vcm1000Vcm

62

123214164

237

2120579 (deg)5 10 15 20 25 30 35 40 45 50

Figure 4 Diffractogram of epoxy cured in AC electric fields

electric fields 0Vcm (nontreatment) 250Vcm 500Vcm750Vcm and 1000Vcm respectively Genge [37] mentionsthat the reduction in the polymerization reaction was dueto inhibition of the initiation of the polymerization processby AC electric field within a certain range (1500ndash4000Vcm)and due to the reduced reactivity of themonomers to producea polymerization reaction

Besides physical treatment inhibition of polymeriza-tion reaction of epoxy (oxirane reaction) can be done byadding a stabilizer such as caprolactam salicylamide NN-dimethylformamide and monooctadecenyl urea with theaim of lowering the excessive polymerization which canreduce the flexibility of epoxy [38] and adding a plasticizerThe decreasing on cure temperature produces a linear poly-mer chains low cross-link density and decreased in shrinkageand crack propagation [39] This causes the epoxy to becomemore ductile [40]

32 XRD Analysis It is commonly understood that amor-phous chain segments can have some long-range order XRDis used for the conformation analysis of chain segmentorderingThe 2120579 scans for four different treatments on epoxysamples are shown in Figure 4 There are significant peaksthat can be attributed to crystalline phase The treatment ofAC electric fields of 250 500 and 750Vcm results in a newcrystal phase peak by the 2120579 angle 62∘ 123∘ 164∘ 214∘ and237∘ Peak intensity was increased to treatment of AC electricfields 750Vcm It indicates that epoxy structurewas undergoorientation However by higher field strength (1000Vcm)peak intensity was disappearing at an angle 2120579 = 214∘ Itindicates that epoxy crystal has not formed yet at higherelectric fields

Inhibition of the polymerization reaction in epoxy (Fig-ure 3) was resulting in a reduction of branching chain

structure and the chains were regularly organized by electricfields The portion of the polymer chain which was regularlyorganized should be noted as a crystalline structure [41]The electric field can increase the nucleation and growth ofcrystals [42] In the macromolecules the influence of theelectric field on the crystal growth can occur in the fieldstrength 104ndash106 Vm and could also occur in an electric fieldwith a value less than the specified threshold It was alsoexplained that the electric field can decrease or increase thefree energy formation of phases depending on the initial andfinal phase of the dielectric constant When the final phaseof the dielectric constant was lower than the initial phasean increase in the nucleation process for the free energyof formation of a new phase was decreased and vice versa[43 44]

The change in the intensity of the crystal peak signifiesthat the crystal phase segments reoriented by electric fieldsThe peak of the crystal increases proportionally to theincrement in the electric field strength Li and Kessler [45]show that the liquid crystalline thermoset was able to beoriented by a magnetic field at the crystal peaks at angles 2120579= 5∘ The arrangement of polymer chains due to the workof the external field causes changes in the polymer chainaxis and the microstructure [46] The chain arrangement isa result of the orientation of the dipole matrix derived fromthe movement of polar group matrix [47] This orientationof the crystal structure produces anisotropic materials whichdiffering in physical and mechanical properties

The molecular orientation of a structure is strongly influ-enced by the dipole moment contained in the structure andthe activity of the dipole moment is greatly influenced by thefrequency of the applied electric field At the low frequenciesall dipoles were oriented and permittivity material will beincreased but at the high frequency the dipole is not able tofollow the electric field so that orientation does not happen[48] This orientation process that occurs lasted until thestructure is locked due to the cross-link reaction that takesplace simultaneously with the orientation process [49]

Basically the dipole moments in a hydrogen bond cangenerate the electric field strength in the core The electricfield gradient at the nucleus also appears from the orien-tation of the dipole moment of the molecules around itSo the change of the dipole moment will alter the degreeof relationship of proton transfer and the change in dipolemoment of the hydrogen bonds can change the resonantfrequency of the bond [50] The protonelectron transfer canform a bondwhich forms a supramolecularmotif (synthons)This motif can undergo molecular fragments that affect thecrystallinity of the material [51] Partial crystallization ofmacromolecules based on bisphenol A has been done byannealing techniques the addition of organic solvents andthe use of supercritical CO

2and steam and electrostatic

field In a nanofiber manufacturing the phenomenon ofpartial crystallization of macromolecules has been observedto improve their mechanical properties [52]

33 FTIR Analysis FTIR was used to study the changes inthe epoxy peaks which occur when the curing reaction took


0

DGEBA monomer

OH group

102030405060708090

100110120

Wave number (1cm)

Tran

smitt

ance

()

4000 3500 3000 2500 2000 1500 1000 500

No treatment250Vcm500Vcm750Vcm

1000Vcm

compoundAromatic

862915 ring

Epoxy

Figure 5 FTIR spectra of epoxy cured in AC electric fields

place The spectrum of epoxy system exposed to the ACelectric field during curing process is shown in Figure 5

The prominent features that occurred during polymeriza-tion were the decreasing of the epoxy ring at 915 cmminus1 and862 cmminus1 [53] In the treatment of the AC electric field ofboth 500Vcm and 750Vcm there is a striking change inabsorption intensity as shown in Figure 5 A simple aromaticcompound in DGEBA monomer is observed between 2000and 1700 cmminus1 [54] In these treatments these peaks wererather similar to DGEBA monomer It means that some ofthe monomers were inhibited to react with hardener It wasalso observed in peaks of 3400ndash3600 cmminus1 which shows OHabsorbance is low It means the formation of the secondaryamine and the hydroxyl groups during cure was decreased

Based on the results of the FTIR and XRD analysisepoxy structure was crystallized and oriented Crystallineepoxy was similar to solidification of pure DGEBA thatforms a crystalline phase [55] The occurrence of a moleculeorientation is caused by interactions between molecules ina polymer chain Interaction of both polar and nonpolarmolecules was occurring due to fluctuations in the den-sity distribution of electronsprotons in the molecule Itdepended on the molecule polarizability and the change ofpolarization depends on temperature and direction of theorientation of the polar molecule [56]

34 Surface Morphology of Epoxy The exposure of ACelectric field with a frequency of 1 kHz was able to changethe epoxy surface topography (Figure 6) Epoxy with notreatment has a smooth surface (Figure 6(a)) On exposureto the AC electric field of 250Vcm a change in the structureis shown by the presence of the needle-shaped epoxy phase(dendrites) on the surface (Figure 6(b)) In the exposureof the AC electric field (500 and 750Vcm) epoxy phasewas becoming more widespread in certain regions that have

relatively the same direction (Figures 6(c) and 6(d)) In theAC electric field exposure of 1000Vcm the phase changesinto a wider structure with phase dendrites at its widest side(Figure 6(e)) These surface morphology changes are causedby both the crystallization and the reorientation of epoxystructure in certain areas until the structure has been lockedbecause the solidification process is complete It is shownthat the peak emergence in the diffractogram is due to theexposure of AC electric fields by several diffraction angles(Figure 4)

The intense exposure of AC electric fields was able tochange the electrical properties and microstructure of thepolymer The effects of electric fields exposure to epoxycause the surface topography to become rugged Roughnesswas suspected because of the oriented interplane Thesechanges result from ionization instability associated with thegeneration of currents resulting from electrostatic [33 57]

35 Interfacial Shear Strength (IFSS) Figure 7 shows theinterface strength values at varying AC electric field treat-ment on epoxy during the curing process

The interface shear strength (IFSS) is an indicator of theeffectiveness of the bond between the fibers with the matrixEpoxy without treatment using the AC electric fields duringcuring process has IFSS of mendong fiber-epoxy matrixby 111MPa After the AC electric field exposure the IFSSof mendong fiber-epoxy matrix was increased to 12MPa142MPa 152MPa and 141MPawith percentage of 8 2838 and 27 by AC electric fields exposure of 250 500 750and 1000Vcm respectively The IFSS mendong fiber-epoxymatrix was optimum through treatment of the AC electricfield of 750Vcm with increasing value of 38

The increasing of the IFSS was related to the changeof the epoxy cross-link during AC electric field treatmentThe high cross-link density makes epoxy brittle and weak inadhesion strength [21] Improved interface shear stress hasbeen associated with changes in the nature of the matrix dueto a decrease in cross-link density of epoxy This reductionis indicated by the exothermic heat generated during theprocess of lower cross-link (Figure 3) A lightly cross-linkedamine cured epoxy polymer to the fiber surface creates abeneficial interphase resulting in a substantial increase inadhesion of fiber-matrix [58] Cross-link density reductioncauses an epoxy more ductile tough [59] and flexible [21]

The significant changes in the material properties canbe achieved through the formation of molecular arrange-ment producing a heterogeneous morphology caused by thepresence a crystal phase [60] In this study formation ofcrystal phase was improving the IFSS of mendong fiber-epoxy matrix Formed crystal in this system was functioningas a particle that toughens the epoxy This improvementmechanismwas known as second phase-toughened system Itwas already applied using plasticizer [21] and rubber [61] andrigid crystalline particle [62] Crystalline phase in polymerinduces changes in mechanical properties (effective Youngrsquosmodulus residual stresses practical adhesion durabilityetc) [63] The increase of crystallinity also can improvethe efficiency of stress transfer at the interface [64] and


20120583m

(a)

20120583m

(b)

20120583m

(c)

20120583m

(d)

20120583m

(e)

Figure 6 Surface morphology of epoxy exposure by AC electric fields with the following AC electric fields strength 0Vcm (no treatment)(a) 250Vcm (b) 500Vcm (c) 750Vcm (d) 1000Vcm (e)

strengthen the bond adhesion as in polypropylene laminationprocess [65] The crystals in polymer have functioned as across-link bond and act as filler in the polymerThe change incrystallinity of the matrix causes changes in shear modulusThe higher the shear modulus of the matrix the greater theIFSS [66]

Figure 8(a) shows the fiber pull-out specimens andFigures 8(b) and 8(c) show the hole in the epoxy block afterpull-out test

Overview of the mendong fiber embedded in epoxy aftera pull-out test showed that the mendong fiber embedded inepoxy without electric field treatment (Figure 8(b)) exhibiteda rough surface in some parts of the epoxy surface rupture

It indicates that the properties of the epoxy showed a brittlefracture At the mendong fiber embedded in epoxy withAC electric field treatment (Figure 8(c)) the surface ruptureexhibited a smooth surface in some parts of the epoxy surfacerupture and epoxy had undergone stretching It indicatesthat the properties of the epoxy tend to be ductile The effectof fiber as a reinforcing will be the maximum when it usesa matrix that is more ductile [67] As shown in Figure 3the treatment of AC electric fields on epoxy during a curingprocess was able to reduce the cross-link density In DGEBAsystems the lower the cross-link densities the lower theshrinkageThe total shrinkage is smaller because the numberof covalent bonds formed per unit volume is smaller [68]


No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)

Electric field (Vcm)250 500 750 1000

Figure 7 The influence of the AC electric fields treatment on the IFSS between mendong fiber and epoxy thermoset (119873 = 10)

50120583m

(a)

50120583m

(b)

50120583m

(c)

Figure 8 SEMmicrographs of amendong fiber pull-out specimen (a) Fiber embedded in epoxy (b) cavity in nontreated epoxy after pull-outtest and (c) cavity in treated epoxy using AC electric fields 750Vcm after pull-out test

and the lower volume shrinkage implied the higher adhesionstrength of resin since the internal stress was minimized[69 70] Besides that the lower cross-linked epoxy resinsresult the better mobility of the polymer chain which makesthe epoxymatrixmore ductile comparedwith high cross-linkepoxy [40]

4 Conclusion

The present work reports the effects of AC electric fieldtreatment during the curing process to interface strength ofmendong fiber-reinforced epoxy composites The materialshave been characterized by X-ray diffraction studies FTIR


spectroscopy single fiber pull-out test and SEM micro-scopies The application of AC electric fields during thecuring process of epoxy decreases the exotherm reactiontemperature from 737∘C to 51∘C for nontreatment to electricfield treatment of 1000Vcm respectively and functionalgroup of epoxy had undergone a polarization in the presenceof electric fieldsThe crystalline phase in epoxy structure wasformed and shown at diffractogrampeak by the 2120579 angle 62∘123∘ 164∘ 214∘ and 237∘ with the presence of the needle-shaped epoxy phase in the epoxy structure morphology As aresult the interface strength of the mendong fiber-reinforcedepoxy composites was optimum increased by 38 in theAC electric fields treatment of 750Vcm Finally it is worthnoting that further research is still required to evaluate theeffect of frequency and waveform of AC electric fields incuring epoxy to develop nonthermal curing methods forbetter interface fiber-matrix strength

Conflict of Interests

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

Acknowledgments

This work was supported by the Ministry of ResearchTechnology and Higher Education Indonesia throughthe Fundamental Research Program with Contract no943UN3214LT2015

References

[1] X Li L G Tabil and S Panigrahi ldquoChemical treatments ofnatural fiber for use in natural fiber-reinforced composites areviewrdquo Journal of Polymers and the Environment vol 15 no 1pp 25ndash33 2007

[2] Q Mu C Wei and S Feng ldquoStudies on mechanical propertiesof sisal fiberphenol formaldehyde resin in-situ compositesrdquoPolymer Composites vol 30 no 2 pp 131ndash137 2009

[3] N Reddy and Y Yang ldquoPreparation and characterization oflong natural cellulose fibers from wheat strawrdquo Journal ofAgricultural and Food Chemistry vol 55 no 21 pp 8570ndash85752007

[4] N Reddy and Y Yang ldquoProperties of high-quality long naturalcellulose fibers from rice strawrdquo Journal of Agricultural and FoodChemistry vol 54 no 21 pp 8077ndash8081 2006

[5] N Reddy andY Yang ldquoNatural cellulose fibers from switchgrasswith tensile properties similar to cotton and linenrdquo Biotechnol-ogy and Bioengineering vol 97 no 5 pp 1021ndash1027 2007

[6] W Liu A K Mohanty P Askeland L T Drzal and MMisra ldquoInfluence of fiber surface treatment on properties ofIndian grass fiber reinforced soy protein based biocompositesrdquoPolymer vol 45 no 22 pp 7589ndash7596 2004

[7] K O Reddy C U Maheswari D J P Reddy and A V RajululdquoThermal properties of Napier grass fibersrdquo Materials Lettersvol 63 no 27 pp 2390ndash2392 2009

[8] H Suryanto EMarsyahyo Y S Irawan andR Soenoko ldquoEffectof alkali treatment on crystalline structure of cellulose fiberfrom mendong (Fimbristylis globulosa) strawrdquo Key EngineeringMaterials vol 594-595 pp 720ndash724 2014

[9] J P B Souza and J M Reis ldquoThermal behavior of DGEBA(Diglycidyl Ether of Bisphenol A) adhesives and its influenceon the strength of jointsrdquo Applied Adhesion Science vol 1 no 1article 6 10 pages 2013

[10] G Babich and G Cherevashchenko ldquoModification of theepoxy resin by use of electric fieldrdquo in Proceedings of thePEGASUSAIAA Student Conference

[11] M S Islam K L Pickering andN J Foreman ldquoCuring kineticsand effects of fibre surface treatment and curing parameters onthe interfacial and tensile properties of hempepoxy compos-itesrdquo Journal of Adhesion Science and Technology vol 23 no 16pp 2085ndash2107 2009

[12] J Chen and M Hojjati ldquoMicrodielectric analysis and curingkinetics of an epoxy resin systemrdquo Polymer Engineering ampScience vol 47 no 2 pp 150ndash158 2007

[13] M M Thomas B Joseph and J L Kardos ldquoExperimentalcharacterization of autoclave-cured glass-epoxy composite lam-inates cure cycle effects upon thickness void content andrelated phenomenardquo Polymer Composites vol 18 no 3 pp 283ndash299 1997

[14] A Endruweit M S Johnson and A C Long ldquoCuring of com-posite components by ultraviolet radiation a reviewrdquo PolymerComposites vol 27 no 2 pp 119ndash128 2006

[15] R Yusoff M K Aroua A Nesbitt and R J Day ldquoCuring ofpolymeric composites using microwave Resin Transfer Mould-ing (RTM)rdquo Journal of Engineering Science and Technology vol2 no 2 pp 151ndash163 2007

[16] J Raghavan andMR Baillie ldquoElectron beam curing of polymercompositesrdquo Polymer Composites vol 21 no 4 pp 619ndash6292000

[17] S S KimHMurayama K Kageyama K Uzawa andMKanaildquoStudy on the curing process for carbonepoxy composites toreduce thermal residual stressrdquo Composites Part A AppliedScience and Manufacturing vol 43 no 8 pp 1197ndash1202 2012

[18] J A Nairn C Liu D Mendels and S Zhandarov ldquoFracturemechanics analysis of the single-fiber pull-out test and themicrobond test including the effects of friction and thermalstressesrdquo in Proceedings of the 16th Annual Technical Conferencepp 1ndash12 American Society for Composites Blacksburg VaUSA September 2001

[19] W Kim and N Kim ldquoReduction of residual stress in compositepatchrdquo in Proceedings of the 13th International Conference onComposite Materials pp 1ndash8 Beijing China June 2001

[20] K Renner J Moczo P Suba and B Pukanszky ldquoMicromechan-ical deformations in PPlignocellulosic filler composites effectof matrix propertiesrdquo Composites Science and Technology vol70 no 7 pp 1141ndash1147 2010

[21] D Ratna ldquoModification of epoxy resins for improvement ofadhesion a critical reviewrdquo Journal of Adhesion Science andTechnology vol 17 no 12 pp 1655ndash1668 2003

[22] M Tehrani M Al-Haik H Garmestani and D Li ldquoEffect ofmoderate magnetic annealing on the microstructure quasi-static and viscoelastic mechanical behavior of a structuralepoxyrdquo Journal of Engineering Materials and Technology vol134 no 1 Article ID 010907 pp 1ndash10 2012

[23] R L Sierakowski I Y Telichev and O I Zhupanska ldquoA studyof composite strengthening through application of an electricfieldrdquo in Proceedings of the ASME International MechanicalEngineering Congress and Exposition (IMECE rsquo06) November2006


[24] O I Zhupanska and R L Sierakowski ldquoEffects of an elec-tromagnetic field on the mechanical response of compositesrdquoJournal of Composite Materials vol 41 no 5 pp 633ndash652 2007

[25] M N Ajour The effect of high voltage fields on epoxy laminates[PhD dissertation] Department of Engineering University ofLeicester 2003

[26] Y Chen and C-Y Shew ldquoConformational behavior of polarpolymer models under electric fieldsrdquo Chemical Physics Lettersvol 378 no 1-2 pp 142ndash147 2003

[27] M S Mehata K Awasthi T Iimori and N Ohta ldquoElectricfield effects on state energy and molecular orientation of 2-hydroxyquinoline in solid polymer filmsrdquo Journal of Photo-chemistry and Photobiology A Chemistry vol 204 no 1 pp 39ndash45 2009

[28] L Lavielle K Nakajima and J Schultz ldquoInfluence of an electricfield on polar-group orientation and adhesion at poly(ethyleneterephthalate) surfacesrdquo Journal of Applied Polymer Science vol46 no 6 pp 1045ndash1050 1992

[29] G A Puchkovskaya Y A Reznikov A A Yakubov OV Yaroshchuk and A V Glushchenko ldquoTransformation ofhydrogen bonding of a liquid crystal-aerosil system under theinfluence of an electric fieldrdquo Journal ofMolecular Structure vol381 no 1ndash3 pp 133ndash139 1996

[30] D Rai A D Kulkarni S P Gejji and R K Pathak ldquoIs highelectric field capable of selectively inducing a covalent-like bondbetween polar and non-polar molecular speciesrdquo TheoreticalChemistry Accounts vol 123 no 5-6 pp 501ndash511 2009

[31] S Wen and D D L Chung ldquoElectric polarization in carbonfiber-reinforced cementrdquoCement and Concrete Research vol 31no 1 pp 141ndash147 2001

[32] I B Amor Z Ghallabi H Kaddami M Raihane M Arousand A Kallel ldquoExperimental study of relaxation process inunidirectional (epoxypalm tree fiber) compositerdquo Journal ofMolecular Liquids vol 154 no 2-3 pp 61ndash68 2010

[33] J Duan J Zhang and P Jiang ldquoEffect of external electricfield on morphologies and properties of the cured epoxy andepoxyacrylate systemsrdquo Journal of Applied Polymer Science vol125 no 2 pp 902ndash914 2012

[34] L Nunez-Regueira S Gomez-Barreiro and C A Gracia-Fernandez ldquoStudy of the influence of isomerism on the curingproperties of the epoxy system DGEBA (119899 = 0)12 DCH byDEA andMDSCrdquo Journal ofThermal Analysis and Calorimetryvol 82 no 3 pp 797ndash801 2005

[35] A Shiota and C K Ober ldquoOrientation of liquid crystallineepoxides under ac electric fieldsrdquo Macromolecules vol 30 no15 pp 4278ndash4287 1997

[36] R Meir H Chen W Lai and S Shaik ldquoOriented electricfields accelerate diels-alder reactions and control the endoexoselectivityrdquo ChemPhysChem vol 11 no 1 pp 301ndash310 2010

[37] C A Genge The Effect of Alternating Electrical Fields on thePolymerization of StyreneMcGillUniversityMontreal Canada1947

[38] R Johnson H ChicagoW Young and T Findley ldquoPolymeriza-tion inhibition in oxirane containing fatty acid estersrdquoUSPatentNo 3230189 1966

[39] G Guven Shear band propagation in cross linked epoxies[Thesis] Polymer Science and Engineering Lehigh University1998

[40] T M Prozonic The effect of epoxy network structure on tough-enability [Thesis] Polymer Science and Engineering LehighUniversity 2012

[41] B Fahlman Material Chemistry Springer Science+BusinessMedia New York NY USA 2nd edition 2011

[42] W Liu J Tang B Huang and Y Du ldquoElectric-field-enhancedcrystallization of amorphous Fe

86Zr7B6Cu1alloyrdquo Journal of

Alloys and Compounds vol 420 no 1-2 pp 171ndash174 2006[43] K V Saban and G Varghese ldquoThermodynamics of crystal

nucleation in drops hanging or sitting in an external electricfieldrdquo Indian Journal of Pure and Applied Physics vol 40 no 8pp 552ndash555 2002

[44] K V Saban J Thomas P A Varughese and G VargheseldquoThermodynamics of crystal nucleation in an external electricfieldrdquo Crystal Research and Technology vol 37 no 11 pp 1188ndash1199 2002

[45] Y Li andM R Kessler ldquoLiquid crystalline epoxy resin based onbiphenyl mesogen effect of magnetic field orientation duringcurerdquo Polymer vol 54 no 21 pp 5741ndash5746 2013

[46] M Tehrani M Al-Haik H Garmestani and D Li ldquoEffect ofmoderate magnetic annealing on the microstructure quasi-static and viscoelastic mechanical behavior of a structuralepoxyrdquo Journal of Engineering Materials and Technology vol134 no 1 Article ID 010907 2012

[47] H Z Akbas H Durmus andG Ahmetli ldquoDielectric propertiesof cured epoxy with tetardquoOzean Journal of Applied Science vol2 no 4 pp 443ndash449 2009

[48] J P Eloundou ldquoDipolar relaxations in an epoxy-amine systemrdquoEuropean Polymer Journal vol 38 no 3 pp 431ndash438 2002

[49] M S Al-Haik H Garmestani D S Li et al ldquoMechanicalproperties of magnetically oriented epoxyrdquo Journal of PolymerScience Part B Polymer Physics vol 42 no 9 pp 1586ndash16002004

[50] P Huyskens L Sobczyk and I Majerz ldquoOn a hardsofthydrogen bond interactionrdquo Journal of Molecular Structure vol615 no 1ndash3 pp 61ndash72 2002

[51] B Miroslaw A E Koziol A Bielenica K Dziuba and MStruga ldquoSubstituent effect on supramolecular motifs in seriesof succinimide polycyclic keto derivativesmdashspectroscopic the-oretical and crystallographic studiesrdquo Journal of MolecularStructure vol 1074 pp 695ndash702 2014

[52] C-C Liao C-C Wang K-C Shih and C-Y Chen ldquoElectro-spinning fabrication of partially crystalline bisphenol A poly-carbonate nanofibers effects on conformation crystallinity andmechanical propertiesrdquoEuropean Polymer Journal vol 47 no 5pp 911ndash924 2011

[53] B Bolasodun O Rufai and S Durowaiye ldquoInfrared studies ofcuring of araldite DLS 7724 41015840 DDS and araldite LY 50524 41015840DDS epoxy systems using conventional andmicrowave energyrdquoInternational Journal of Engineering Science vol 3 no 1 pp 11ndash23 2014

[54] J Coates ldquoInterpretation of infrared spectra a practicalapproachrdquo in Encyclopedia of Analytical Chemistry R MeyersEd pp 10815ndash10837 JohnWiley amp Sons Chichester UK 2000

[55] A Boukenter E Duval and H M Rosenberg ldquoRaman scatter-ing in amorphous and crystalline materials a study of epoxyresin and DGEBArdquo Journal of Physics C Solid State Physics vol21 no 15 pp 541ndash547 1988

[56] D Freude ldquoMolecules in electric and magnetic fieldsrdquo inMolecular Physics pp 1ndash26 2005

[57] M T Darestani T C Chilcott and H G L Coster ldquoChangingthe microstructure of membranes using intense electric fieldsdielectric strength studiesrdquo Journal of Membrane Science vol452 pp 367ndash378 2014


[58] L Xu and L T Drzal ldquoImprovement of adhesion betweenvinyl ester resin and carbon fibersrdquo in Proceedings of the 13thInternational Conference on Composite Materials (ICCM rsquo01)pp 1ndash10 Beijing China September 2001

[59] R A Pearson A F Yee D Building andAArbor ldquoTougheningmechanisms in elastomer-modified epoxiesrdquo Journal of Materi-als Science vol 24 pp 2571ndash2580 1989

[60] H Lutzen T M Gesing and A Hartwig ldquoNucleation as a newconcept for morphology adjustment of crystalline thermoset-ting epoxy polymersrdquo Reactive and Functional Polymers vol 73no 8 pp 1038ndash1045 2013

[61] F J Guild A J Kinloch and A C Taylor ldquoParticle cavitationin rubber toughened epoxies the role of particle sizerdquo Journalof Materials Science vol 45 no 14 pp 3882ndash3894 2010

[62] J K Kim and R E Robertson ldquoToughening of thermosetpolymers by rigid crystalline particlesrdquo Journal of MaterialsScience vol 27 no 1 pp 161ndash174 1992

[63] M Aufray and A Andre Roche ldquoEpoxy-aminemetal inter-phases influences from sharp needle-like crystal formationrdquoInternational Journal of Adhesion and Adhesives vol 27 no 5pp 387ndash393 2007

[64] B S Hsiao and E J Chen ldquoTranscrystalline interphase inadvanced polymer compositesrdquo in Controlled Interphases inComposite Materials Proceedings of the Third InternationalConference on Composite Interfaces (ICCI-III) held on May 21ndash24 1990 in Cleveland Ohio USA pp 613ndash622 Springer ChamSwitzerland 1990

[65] J Song A Bringuier S Kobayashi A M Baker and C WMacosko ldquoAdhesion between polyethylenes and different typesof polypropylenesrdquo Polymer Journal vol 44 no 9 pp 939ndash9452012

[66] L T Drzal ldquoThe effect of polymeric matrix mechanical prop-erties on the fiber-matrix interfacial shear strengthrdquo MaterialsScience and Engineering A vol 126 no 1-2 pp 289ndash293 1990

[67] D Nwabunma and T Kyu Polyolefin Composites JohnWiley ampSons New Jersey NJ USA 2008

[68] K P Pang and J K Gillham ldquoAnomalous behavior of curedepoxy resins density at room temperature versus time andtemperature of curerdquo Journal of Applied Polymer Science vol 37no 7 pp 1969ndash1991 1989

[69] T H Chiang and T-E Hsieh ldquoA study of monomerrsquos effect onadhesion strength of UV-curable resinsrdquo International Journalof Adhesion and Adhesives vol 26 no 7 pp 520ndash531 2006

[70] M Zarrelli A A Skordos and I K Partridge ldquoInvestigation ofcure induced shrinkage in unreinforced epoxy resinrdquo PlasticsRubber and Composites vol 31 no 9 pp 377ndash384 2002

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



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CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

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Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

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Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


may be done by adding a functional polymer matrix [20]like both plasticizers and rubber [21] modifying the structurethrough molecular orientation by using shear flow suchas injection molding and extrusion or using the externalfield such as electric field magnetic field and a combina-tion of both [22] The presence of the DC electric currentand electromagnetic fields cause an increase in the impactstrength of carbon fiber composite polymer by 247 and436 for DC current of 25A and 50A respectively [23]and also the interaction of static load and electromagneticfields able to decrease in defflection of the reinforced carboncomposite plate by 60 in electromagnetic infuluence of 1Tesla It indicates that the bending stiffness of the reinforcedcarbon composite plate was increasing [24] However thepresence of DC electric field is very high in the compositeglassepoxy cause of aging that causes delamination anddebonding between the glass fiber and epoxy matrix [25]In the composite compaction process the electric fieldexposure with AC and DC source is capable of modifyingthe epoxy resin in which the physical stability and strengthof the epoxy are increased by 100 and 50 in presenceof AC and DC fields respectively [10] The external electricfield causes the movement of electrons due to the intrinsicdipole arrangement of opposite charge [26] and settingthe orientation of the molecule [27] In polar moleculesthe polarity of the electric field can improve the surfaceand lead to increased adhesion properties of the polymerinterface PETgelatin [28] The electric field is also ableto convert hydrogen bonds [29] and capable of forming acovalent bond as the molecular interactions of polar andnon polar bond [30] The change of polarization also occursin the dielectric material due to the presence of an electricfield [31] and the presence of free-moving electrons at theinterface fibermatrix (interfacial polarization) that arises inthe process of making a composite [32] In epoxy curingnanolamellar microstructure was changed due to orientationof the microgel particle before gelation process occurs so thatthe epoxy surface topography becomes more rugged than nooriented epoxy [33] These physical changes will affect theinterfacial shear strength (IFSS) of compositesTherefore thisstudy was done to show the effects of exposure to AC electricfields during the curing process on IFSS of themendongfiber-epoxy matrix

2 Material and Methods

21 Material The research material was mendong fibersSamples were obtained from the cultivation land in thedistrict of Wajak Malang East Java Indonesia Samples wereselected in the harvest age of 5-6months and the straw lengthwas 1ndash12m The chemical properties contents of mendongfibers were 7214 cellulose 202 hemicellulose 344lignin 42 extractive compound and moisture of 42ndash52 Mendong fiber has tensile strength stiffness modulusand specific strength of 452MPa 17GPa and 507 kNsdotmkgrespectively [8]

The polymer matrix was diglycidyl ether of bisphenol-A(DGEBA) (brand name Eposchon PT Justus Kimia Raya

Fiber

minus +

2mm Epoxy

10mm

Figure 1 Treatment of AC electric fields during epoxy curing

Surabaya Indonesia) with an epoxy equivalent to 189plusmn5Thecuring agent was a modified cycloaliphatic amine contain-ing mainly 3-aminomethyl-355-trimethylcyclohexylamine(brand name EPH 555 from PT Justus Kimia Raya SurabayaIndonesia) with an amine hydrogen equivalent weight of 86and viscosity 05ndash1 Poise at room temperature Resin andcuring agent were carefully and homogeneously mixed at aratio of 2 1

22 Fiber Extraction Mendong fibers were extracted me-chanically The wet mendong straw was cut off 60 cm longfrom the base and the next piece to the top was removedMendong straw was repeatedly pounded and then cleanedusing water Then fibers were soaked in water for a weekMendong fibers were retrieved cleaned and allowed to dryup in ambient temperature Mendong fibers were mercerizedby immersion into 5 NaOH solution for 2 hours at ambienttemperature and then rinsed using an aquadest for five timesdried and kept in plastic wrap and put in a dry box withhumidity of 40 [8]

23 AC Electric Fields Treatment Treatment of anAC electricfield to pull-out tests was performed during the curingprocess of the epoxy from the liquid to solid This process isconducted by making a plastic mold with the size of 100 times10 times 2mmThen ten pieces of fibers with a length of 30mmwere prepared on a ruler that was attached on a digital heightgauge (002mm resolution) Furthermore epoxy was mixedwith the curing agent in the ratio 2 1 and then stirred andpoured into molds Fibers move down slowly into the epoxyliquid in the mold until the depth of the fiber embedded inan epoxymatrix reaches 200120583mand is recorded as embeddedfiber length as shown in Figure 1The exposure of AC electricfield was conducted between a pair of electrodes by frequency1 kHz and varying electric fields of 250Vcm 500Vcm750Vcm and 1000Vcm for 2 hours After the epoxy wassolid the epoxy that contains the fiber is cutwith a razor bladeto the size of 5 times 5 times 2mm3

24 Measurement of Heat Generated during the Epoxy Poly-merization 20 g epoxy was mixed with 10 g curing agents










Fiber

RestraintRestraint

Card

Tensionforce

Glue

02mmSample

6mm

2mm

5mm


2020 30 40 50 60 70 80 90 100 110100

2530354045505560657075808590

Curing time (min)

Tem

pera

ture

(∘C)


750Vcm1000Vcm




Inte

nsity

(au

)

Control250Vcm500Vcm

750Vcm1000Vcm

62

123214164

237

2120579 (deg)5 10 15 20 25 30 35 40 45 50














0

DGEBA monomer

OH group

102030405060708090

100110120

Wave number (1cm)

Tran

smitt

ance

()

4000 3500 3000 2500 2000 1500 1000 500


1000Vcm

compoundAromatic

862915 ring

Epoxy













20120583m

(a)

20120583m

(b)

20120583m

(c)

20120583m

(d)

20120583m

(e)







No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)



50120583m

(a)

50120583m

(b)

50120583m

(c)



4 Conclusion






Acknowledgments


References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












Fiber

RestraintRestraint

Card

Tensionforce

Glue

02mmSample

6mm

2mm

5mm


2020 30 40 50 60 70 80 90 100 110100

2530354045505560657075808590

Curing time (min)

Tem

pera

ture

(∘C)


750Vcm1000Vcm




Inte

nsity

(au

)

Control250Vcm500Vcm

750Vcm1000Vcm

62

123214164

237

2120579 (deg)5 10 15 20 25 30 35 40 45 50














0

DGEBA monomer

OH group

102030405060708090

100110120

Wave number (1cm)

Tran

smitt

ance

()

4000 3500 3000 2500 2000 1500 1000 500


1000Vcm

compoundAromatic

862915 ring

Epoxy













20120583m

(a)

20120583m

(b)

20120583m

(c)

20120583m

(d)

20120583m

(e)







No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)



50120583m

(a)

50120583m

(b)

50120583m

(c)



4 Conclusion






Acknowledgments


References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Inte

nsity

(au

)

Control250Vcm500Vcm

750Vcm1000Vcm

62

123214164

237

2120579 (deg)5 10 15 20 25 30 35 40 45 50














0

DGEBA monomer

OH group

102030405060708090

100110120

Wave number (1cm)

Tran

smitt

ance

()

4000 3500 3000 2500 2000 1500 1000 500


1000Vcm

compoundAromatic

862915 ring

Epoxy













20120583m

(a)

20120583m

(b)

20120583m

(c)

20120583m

(d)

20120583m

(e)







No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)



50120583m

(a)

50120583m

(b)

50120583m

(c)



4 Conclusion






Acknowledgments


References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

DGEBA monomer

OH group

102030405060708090

100110120

Wave number (1cm)

Tran

smitt

ance

()

4000 3500 3000 2500 2000 1500 1000 500


1000Vcm

compoundAromatic

862915 ring

Epoxy













20120583m

(a)

20120583m

(b)

20120583m

(c)

20120583m

(d)

20120583m

(e)







No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)



50120583m

(a)

50120583m

(b)

50120583m

(c)



4 Conclusion






Acknowledgments


References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




20120583m

(a)

20120583m

(b)

20120583m

(c)

20120583m

(d)

20120583m

(e)







No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)



50120583m

(a)

50120583m

(b)

50120583m

(c)



4 Conclusion






Acknowledgments


References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




No treatment0

2

4

6

8

10

12

14

16

18

20

IFSS

(MPa

)



50120583m

(a)

50120583m

(b)

50120583m

(c)



4 Conclusion






Acknowledgments


References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







Acknowledgments


References


















































































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



Research Article Improvement of Interfacial Shear Strength...

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Transcript of Research Article Improvement of Interfacial Shear Strength...