Research Article Constructing Novel Fiber Reinforced

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2013 Article ID 470583 7 pageshttpdxdoiorg1011552013470583

Research ArticleConstructing Novel Fiber Reinforced Plastic (FRP)Composites through a Biomimetic Approach Connecting GlassFiber with Nanosized Boron Nitride by Polydopamine Coating

XueMei Wen12 ZaoZao Xiao1 Tao Jiang1 Jian Li1

Wei Zhang1 Lei Zhang13 and Huaiqi Shao1

1 School of Material Science and Chemical Engineering Tianjin University of Science and Technology Tianjin 300457 China2 Tianjin Synthetic Material Research Institute Tianjin 300220 China3 College of Marine Science and Engineering Tianjin University of Science and Technology Tianjin 300457 China

Correspondence should be addressed to Jian Li lijiantusteducn

Received 8 May 2013 Accepted 11 November 2013

Academic Editor Honggang Zhu

Copyright copy 2013 XueMei Wen 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

A biomimetic method was developed to construct novel fiber reinforced plastic (FRP) composites By mimicking mussel adhesiveproteins a monolayer of polydopamine was coated on glass fiber (GF) surface The polydopamine-treated GF (D-GF) adsorbedboron nitride (BN) nanoparticles while obtaining micronano multiscale hybrid fillers BN-D-GF Scanning electron microscopy(SEM) results showed that the strong interfacial interaction brought by the polydopamine benefits the loading amount as well asdispersion of the nano-BN on GFrsquos surface The BN-D-GF was incorporated into epoxy resin to construct ldquoFRP nanocompositesrdquoThe morphology dynamic mechanical and thermal characteristics of the FRP nanocomposites were analyzed SEM morphologyrevealed that BN-D-GF heterogeneous dispersed in epoxy matrix There was good adhesion between the polymer matrix and theBN-D-GF filler The dynamic modulus and mechanical loss were studied using dynamic mechanical analysis (DMA) Comparedwith neat epoxy and untreatedGF reinforced composites BN-D-GFepoxy andD-GFepoxy systems showed improvedmechanicalproperties The thermal conductivity Shore D hardness and insulation properties were also enhanced

1 Introduction

Epoxy resins are a class of high performance thermosettingpolymers for application in the automotive constructionand aerospace industries High specific stiffness dimensionalstability lightweight high corrosion resistance and excellentinsulating properties make them valuable in many electri-cal research areas especially for insulated packing [1ndash3]Recently using epoxy resin as the matrix for fiber-reinforcedplastic (FRP) composites has been increased significantly [4ndash6]The FRP composites are considered as ideal candidates foracademic research as well as industry applications becauseof their improved physicalchemical properties Glass fiber(GF) is usually used for preparing large varieties of FRPcomposites [7] The principal advantages of GF are low costhigh strength and modulus

For FRP composites the extent of adhesion of polymermatrix to the reinforcing fibers is very important It is wellknown that stress passes from the fibers to the matrixthrough the interface Therefore the adhesive force affectsthe strength and rigidity of the reinforced plastics and theirfracture behavior [8] In order to enhance affinity betweenGF and polymer matrix modification of the GF surfacecan be done by (a) coating fiber with a silane with reactiveend groups [9] (b) coating fiber with a rubber emulsion[10] (c) coating fiber with a solution of different polymerssuch as polyurethane and polystyrene [11] and (d) blendingwith nanoscopic materials such as carbon nanotube [12]graphene [13] and inorganic oxide nanoparticles [14]

Filling epoxy resin with nanomaterials especially ther-mally conductive nanofillers (Al

2O3[15] AlN [16] BN [17])

2 Journal of Nanomaterials

is emerged as an effective way to enhance the rather poorthermal conductivity of epoxy resin because the heat dissipa-tion in microelectronic packaging is becoming increasinglyimportant as the demands in denser and faster circuitsintensify For nanofillers their dispersion and interfacialinteractions with epoxy resin matrix are the most crucialfactor affecting the optimal properties of the nanocomposites[18 19] Nanofillers should be well dispersed in the matricesto obtain a high aspect ratio and large interfacial area betweenthe phases whereas strong interfacial interactions betweenthe nanofillers and epoxy resin matrices would facilitate thestress transformation and thermal conductivity

Many previous researches were interested in combiningthe advantages of microscale fibers and nanoscale particlesFor example Wan et al reported that multiscale rein-forcements consisting of clay and short glass fiber filledpolyamide 6 were prepared by a two-step melt compoundingprocess [20 21] The synergy of multiscale reinforcementsof clay and glass fiber provided better physical propertiesfor polymer-matrix composites than each of the individ-ual fillers Besides the above methods based on physicallyblending microscale fibers and nanoscale fillers [15ndash17 2021] a more effective method is to disperse nanofillers ontoglass fibers and then construct novel ldquoFRP nanocompositesrdquoThe advantages include (1) a better dispersion of thermallyconductive nanofillers in polymer matrix (2) an enhancedaffinity between fiber and matrix and (3) enhancing per-formance of FRP composites without marked increase incost due to small amount of nanofillers Traditional methodis to modify their surface in the presence of functionalcoupling agents such as silane coupling agents [22ndash24]However the amount of active groups on nanofillers orglass fibers is usually very small and the reactions requirestrict chemical conditions Furthermore the main caveat ofthis strategy is that the coupling agents are often materialspecific and thus lack efficacy across a broad range of FRPnanocomposites

In nature marine mussel adhesive proteins (MAPs)contain large amounts of a particular amino acid known as34-dihydroxy-L-phenylalanine (dopamine DOPA) and haveattracted great attention owing to the amazing ability of mus-sels to adhere to various kinds of surfaces [25 26] In 2007Lee et al reported polydopamine (PDOPA) adhesive coatingson a wide variety of material surfaces including noble metalsoxides polymers semiconductors and ceramics prepared bymimicking MAPs [25]

Inspired by these works we hypothesized that if acatechol-rich polymer layer can be prepared as the interfacebetween nanofillers and GF the interfacial interactions maybe significantly enhanced and hence the physicalchemicalproperties of the FRP composites can be improved at very lownanofillers loadings To verify the hypothesis we prepareddopamine-modified glass fiber (D-GF) via a facile water-assisted process and then coated BN nanoparticles on thesurface The novel reinforcement (BN-D-GF) was incorpo-rated into an epoxy resin to form FRP nanocompositesSpecifically the structure morphology and thermomechan-ical properties of these novel materials were in detail investi-gated

2 Materials and Methods

21 Materials Epoxy resin based on diglycidyl ether ofbisphenol A (DGEBA E51) and triethylenetetramine (TETA)curing agent were purchased from Jiangtian Reagent Chemi-cals Co Ltd Short-cut glass fibers were supplied by OwensCorning Chemicals and 34-dihydroxyphenethylamine hy-drochloride (DOPA 98) was purchased from Sigma-Aldrich respectively All the other chemicals were purchasedlocally and of analytical reagent grade

22 Preparation of Modified Glass Fibers and FRP CompositesIn a typical experiment 5 g short-cut glass fiber (GF) wasmechanically stirred in 500mL 10mM Tris buffer solution(pH 85) [25] DOPA (1 g) was then added and the suspensionwas stirred for 8 h at roomambient conditionThe suspensionwas then centrifuged at 2500 rpm for 3min and then thedopamine coated glass fiber (D-GF) was obtained D-GFwas redispersed in 500mL 10mM Tris buffer solution (pH85) and then 05 g nano-BN was added The dark slurry-like product was washed with acetone and the solventwas removed by centrifuge The wash-centrifuge step wasrepeated three times and finally BN-D-GFacetone slurrywas obtained

To prepare the BN-D-GFepoxy FRP composites a cer-tain amount of E51was poured into the slurry followed by vig-orous stirring for 2 hThe acetonewas then removed by rotaryevaporation followed by drying in a vacuum oven at 50∘C for48 h The curing agent was then added at the epoxycuringagent ratio of 10013 (ww) The mixtures were mechanicallystirred degassed and cured at room temperature for 3 h andpostcured at 70∘C for 2 h For comparison a BNGFepoxycompositewas prepared using the sameprocedure except thatthe BN was physically adsorbed onto untreated GF withoutpolydopamine coating

23 Characterization

231 Scanning Electron Microscopy (SEM) Fiber sampleswere prepared by applying a drop of the particle suspension(in acetone) to a glass slide and then dried overnightThe samples were then sputtered with gold to increasetheir conductance for SEM observation Measurements wereconducted using Philips XL30 ESEM and Hitachi S-4800instrument at an operation voltage of 200 keV and 07 keV

232 Differential Scanning Calorimetry (DSC) Glass-transition temperatures (119879

119892) of the neat epoxy resin and FRP

composites were measured by using a differential scanningcalorimetry (DSC 200F3 Netzsch Germany) Samples wereheated from 20 to 250∘C at a heating rate of 10∘Cmin undernitrogen atmosphere

233 Dynamic Mechanical Analysis (DMA) A dynamicmechanical analysis (DMA) was performed with a DMA2980 Dynamical Mechanical Analyzer in the fixed frequencymode at 1Hz with an amplitude of 040mm The transversemechanical properties of the composites were measured

Journal of Nanomaterials 3

using the DMA Rectangular DMA specimens measuring 40times 10 times 3mmwere sawn and polished to uniform dimensionsTheDMA uses a flexural bending deformation to apply stressto the sample The sample undergoes a sinusoidal oscillationat a fixed frequency

24 Test of Neat Epoxy Resin and FRP Composites

241 Volume Resistivity A digital high resistance meter(6517A Keithley USA) was used to investigate the dc con-ductivity Samples with thickness of around 1mm were usedfor measurement The typical conductivity measurementinvolves a simple measurement of current under the sameambient atmosphere and a constant voltage (1 kV) Theelectric current was measured after applying the dc voltageto the specimens for 1min according to ASTM D257

242 Dielectric Loss Dielectric properties measurementswere performed using an impedance analyzer (Aglient4294A USA) with 16451B Dielectric Test Fixture in the fre-quency range of 102ndash107Hz All measurements were carriedout at room temperature with voltage amplitude of 05 VThe data of impedance and phase angle measured wereconverted into the relative dielectric constant and dielectricloss considering the appropriate geometric coefficient

243 Dielectric Breakdown Strength Dielectric breakdownstrength was measured using an AHDZ-10100 alternating-current dielectric strength tester (Shanghai LanpotronicsCorporation China) according to ASTM D 149-2004 Thespecimens were placed between two 10-mm-diameter copperball electrodes and the electrode system containing themeasured sample was immersed in the pure silicone oil toprevent the surface flashover The test voltage was appliedacross two ball-typed electrodes and was increased until thesample was punctured Five breakdown tests were repeatedlyperformed on each specimen All of the measurements wereperformed under the same humidity and temperature

244 Thermal Conductivity LFA 447 Nanoflash (NetzschGermany) was employed to determine the thermal conduc-tivity according to ASTM E1461 Samples were prepared incylindrical shape of 130mm in diameter and 10ndash20mm inthickness

245 Shore D Hardness Shore D hardness testing wasperformed according toASTMD2240 using aWoltest SD 300equipment

3 Results and Discussion

31 Characterization Figure 1(a) showed that nano-BN waseasily aggregated and had relatively round shapes with afine size of 15ndash50 nm Figure 1(b) indicated that when glassfibers were not treated with nano-BN their surfaces wererather smooth Dopamine treatment of glass fiber surfacesresulted in rather improved adherence between nano-BNand GF Different processes of BN modification of GF

were indicated in Figures 1(c) and 1(d) which showed theformation of reinforcement through physical adsorption aswell as dopamine adhesion In Figure 1(c) the smooth surfaceindicated that less BN was adhered onto fibers because of theweak physical adsorptionThus in BNGFepoxy compositeit indicated insufficient adherence to the epoxy matrix whileFigure 1(e) showed that ldquofiber pulloutsrdquo occurred due to theweak interface between epoxy and glass fibers Additionallypart of nano-BN aggregated and formedmicrosized particlesHowever it was different for specimens that dopaminedomains acted as coupling agent and adhered to the glassfiber surfaces (BN-D-GF) In Figures 1(d) and 1(f) BN-D-GF showed continuous and rough surfaces due to dopaminetreatment as well as nano-BN adhesion Therefore this alsoincreased the interaction at the fiberepoxy matrix interfacewhile ldquofiber pulloutsrdquo nearly disappeared in BN-D-GFepoxycomposites

FTIR spectra of the dopamine GF and D-GF wereshown in Figure 2 The characteristic peak at 1608 cmminus1 and1508 cmminus1 found in D-GF further confirmed that dopaminehad been polymerized into polydopamine on surface of GF

DSC was used to investigate the thermal properties ofthe neat epoxy and FRP composites The DSC curves shownin Figure 3 indicate an increase in the glass transitiontemperature of the epoxy resin with the GF loading Theintroduction of GF was thought to restrict the mobility of theepoxy molecules The obvious effect on increasing the glasstransition temperature indicated a strong interaction at themolecular level between the epoxy molecules and dopamineor BN layers which could come only from the dopamine-treated samples (D-GFepoxy and BN-D-GFepoxy)

32 Dynamic Mechanical Behavior of Composites Dynamicmechanical properties of FRP composites depend on variousfactors such as fiber loading fiber orientation and the natureof fiber-matrix interface region Dynamic tests are especiallysensitive to all kinds of transitions and relaxation processes ofmatrix resin and also to themicrostructure of the composites

Dynamic storage modulus (1198641015840) is the most importantproperty to assess the load bearing capacity of a compositematerial The variation of storage modulus as a function oftemperature of epoxy resin or FRP composites was given inFigure 4 There was a prominent increase in the modulusof the matrix with the incorporation of glass fibers over theentire region This may be due to the increase in the stiffnessof the matrix with the reinforcement effect imparted by thefibers that allowed for a greater degree of stress transfer atthe interface [27] The maximum 1198641015840 value was exhibited byD-GFepoxy composite The value was 37624MPa whereasthe1198641015840 value for unreinforced cured neat resinwas 21446MPaat room temperature It was clear that the room temperaturestoragemodulus of thematrix enhancedmore than 75uponthe addition of dopamine coating fiber Previous researchhad proved that it was due to physical cross-linking causedby the hydrogen bonds between the epoxy molecules anddopamine coating filler where the catechol groups act asproton donors while the CndashOndashC groups in the epoxy actas proton acceptors [28] For BN-D-GFepoxy composites


(a) (b)

(c) (d)

Fiber pullouts

Fiber pullouts

Fiber pullouts Fiber pullouts

Nano-BN aggregation

(e) (f)

Figure 1 SEM image of BNnanoparticles (a) untreatedGF (b) BNGF (c) BN-D-GF (d) BNGFepoxy composite (e) and BN-D-GFepoxycomposite (f)

the value was 33784MPa which was 57 higher than neatresin As the temperature increases 1198641015840 decreases and thenthere was a sharp decline in the1198641015840 value at the glass transitionregionThis behavior could be attributed to the increase in themolecular mobility of the polymer chains above 119879

119892

Loss modulus (11986410158401015840) is a measure of the energy dissipatedas heat per cycle under deformation Or it is the viscousresponse of the material Figure 5 showed the trends of

variation of loss modulus for the neat epoxy and FRPcomposites with variation of temperature From the figure itwas clear that the incorporation of fiber causes broadeningof the loss modulus peak The peak broadening could beattributed to the inhibition of relaxation process within thecomposites [29] This might be due to the increase in thenumber of chain segments as well as more free volumeupon fiber addition The loss modulus value in the transition


Table 1 Tests of neat epoxy and FRP composites

Thermal conductivity(WmsdotK)

Volume resistivity(times1016Ωsdotcm)

Dielectric losstangent

Dielectric breakdown strength(kvmm)

Shore Dhardness

Neat epoxy 0252 300 253 311 71GFepoxy 0287 214 24 248 78D-GFepoxy 0308 267 214 273 80BNGFepoxy 0294 377 219 258 79BN-D-GFepoxy 0393 686 201 277 82

0 500 1000 1500 2000 2500 3000 3500 4000 4500

1618

Dopamine

GF

D-GF

1508

Wavenumber (cmminus1)

Figure 2 FTIR spectra of dopamine and glass fibers

20 40 60 80 100 120 140 160 180 200 220

D-GFepoxy

Neat epoxy

BNGFepoxy

GFepoxy

Hea

t flow

(Wg

)

BN-D-GF epoxy

Temperature (∘C)

1104∘C

1085∘C

1183∘C

1037∘C

1178∘C

Figure 3 DSC curves of neat epoxy resin and FRP composites

region was much high for composites when compared tothe neat resin The higher modulus at this temperature wasdue to the increase in internal friction that enhances thedissipation of energy Additionally the presence of highmodulus glass fibers reduced the flexibility of the materialby introducing constraints on the segmental mobility of thepolymeric molecules at the relaxation temperatures [30]

33Thermal Conductivity Themeasurements of the thermalconductivity of the GF-reinforced epoxy resin were shown

0 50 100 150 200 250

0

100

200

300

400

Neat epoxyBN-D-GFepoxyGFepoxy

D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400

(MPa

)

Figure 4 Dynamic storage modulus of neat epoxy and FRPcomposites

in Table 1 In the same figure the measurements of thethermal conductivity of the epoxy resin were shown forcomparison purposes It can be seen that reinforcing thepolymer with the untreated GF resulted approximately in a13 increase in the thermal conductivity The slight increasemay be a result of the relatively better conducting nature ofthe glass fibers compared to the epoxy-resin matrix Mea-surements on BNGFepoxy samples show that the physicalblending of the BN with glass fibers had no real effect onthe thermal conductivity It seemed that the discontinuousnature of the nano-BN in the matrix probably nullifies itsthermal conductivityThe thermal conductivity of compositeincreased slightly from 0287WmK for untreated GF filledcomposite to 0308WmK for D-GF filled composite Thedopamine layer on the GF surface had rendered the surfacemore organophilic with greater wettability of the epoxy resinThis led to greater interfacial adhesion between the filler andthe polymer matrix leading to more efficient heat transferacross the interface and hence the increase in the thermalconductivity of the D-GF filled composites Reinforcing theepoxy resin with both BN-D-GF produced a 56 of thermalconductivity increase It was possible that the nano-BNhas created a better conductive pathway between the glassfibers and polymer matrix and thus the observed increase


0 50 100 150 200 250

0

10

20

30

40


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400998400

(MPa

)

Figure 5 Loss modulus of neat epoxy and FRP composites

in thermal conductivity A previous study had investigatednanotube-reinforced GF composites and reported that themultiwall carbon nanotubes (C-MWNTs) were repelled bythe glass fibers [31] In a word thermal conductivity of aFRP composite strongly depends on the efficiency of heattransfer through the interface between the filler and thematrix Hence any treatment which enhances the interfacialadhesion between the filler and the matrix could be expectedto increase the overall thermal conductivity of the compositeas well

34 Electrical Properties Dielectric breakdown strength ofthe neat epoxy as well as FRP composites was summarizedin Table 1 One can see that (i) all the FRP compositesshowed lower dielectric strength in comparisonwith the pureepoxy and (ii) the composites with dopamine-treated GFshowed higher values of breakdown strength when comparedwith the composites with untreated GF The embedding ofinorganic fillers into insulating polymers could introducedifferent kinds of defects and then result in lower dielectricbreakdown strength There existed two possible reasonscausing lower dielectric strength in the FRP composites withuntreated GF The first was incompatible interface betweenthe untreated fibers and epoxy which can introduce voids inthe composites causing the decrease of dielectric strengthThe second was that the agglomeration of the BN could resultin electromagnetic interactions among the nanoparticleswhich can distort severely the field and in turn cause lowerbreakdown strength

The variation of volume resistivity for the neat epoxyas well as FRP composites was summarized in Table 1 Itcan be seen that (i) the volume resistivity value of the FRPcomposites with untreated GF was slightly lower than thatof the neat epoxy and (ii) the volume resistivity value of theFRP composites with dopamine-treated GF was higher thanthat of the neat epoxyThe decreased volume resistivitymightoriginate from the contribution of impurity ions as well as

hydroxyl groups which existed in the surface of glass fibersPrevious results had proved that the surface treatment bymeans of silane can replace the hydroxyl groups to remove themolecularly absorbed water hydrogen bonded to the surfaceof the AlN nanoparticles which reduced the conductivity ofthe AlN nanoparticles and the nanocomposites [32] Becausethe BN ceramic nanoparticles used for FRP composite prepa-ration were dielectric materials like AlN BN-D-GFepoxysample showed that highest volume resistivity value

The dielectric loss tangent of the neat epoxy as well asFRP composites was summarized in Table 1 One can seethat (i) all the FRP composite samples showed lower valuesof dielectric loss in comparison with the neat epoxy and (ii)the values of dielectric loss tangent of epoxy nanocompositeswith dopamine-treated glass fibers were obviously lower thanthose epoxy nanocomposites with untreated GF especiallyconnected with BN It was proposed that the incorporation ofBN-D-GF can result in polymer chain entanglement becauseof the good dispersion of the nanofiller which in turncauses immobility of charge carriers or reduction in electricalconductivity thus causing a reduction of dielectric loss

35 Shore D Hardness Shore D hardness of the neat epoxyas well as FRP composites was summarized in Table 1 AllFRP composites benefited from the GF presence so that thehardness value was increasing more than 10The dopaminecoating affected a certain extent while the value of GFepoxyand BNGFepoxy was slightly increased

4 Conclusions

Thepresent study reported a biomimetic approach to success-fully coat a monolayer of PDOPA onto GF Compared withuntreated GF the PDOPA coating greatly benefited the inter-facial interaction hence leading to enhanced loading amountand homogenous distribution of BN nanoparticles (about40 nm) on GF BN-D-GF micronano multiscale hybrid fillerwas also demonstrated as an appropriate reinforcement forepoxy resin The FRP nanocomposites BN-D-GFepoxyresin showed drastically enhanced volume resistance andthermal conductivity It is expected that the present approachcan be extended to preparing a variety of FRP composite sys-tems which include fiber reinforcement polymer matricesand functional nanomaterialsThis would pave a new way fordiverse applications such as adhesive building materials andopto- and microelectronics devices

Acknowledgments

The authors acknowledge the financial support from theNational Natural Science Foundation of China (21306139U1162114) Natural Science Foundation of Tianjin (no12JCQNJC06000) Tianjin City High School Science ampTechnology Fund Planning Project (20110505 20130509)Lab Opening Foundation of Tianjin University of Scienceamp Technology (1103A207) and National UndergraduateTraining Programs for Innovation and Entrepreneurship(201310057118)


References

[1] L T Drazal Advances in Polymer Science vol 75 SpringerBerlin Germany 1986

[2] H D Middleton Composite Materials in Aircraft StructureLongman New York NY USA 1990

[3] A A Baker R Jones and R J Callinan ldquoDamage tolerance ofgraphiteepoxy compositesrdquo Composite Structures vol 4 no 1pp 15ndash44 1985

[4] W K Goertzen and M R Kessler ldquoDynamic mechanicalanalysis of carbonepoxy composites for structural pipelinerepairrdquo Composites B vol 38 no 1 pp 1ndash9 2007

[5] S Sirivedin D N Fenner R B Nath and C Galiotis ldquoEffectsof inter-fibre spacing and matrix cracks on stress amplificationfactors in carbon-fibreepoxymatrix composites Part II hexag-onal array of fibresrdquo Composites A vol 37 no 11 pp 1936ndash19432006

[6] W K Goertzen and M R Kessler ldquoCreep behavior of carbonfiberepoxymatrix compositesrdquoMaterials Science and Engineer-ing A vol 421 no 1-2 pp 217ndash225 2006

[7] N Hameed P A Sreekumar B Francis W Yang and SThomas ldquoMorphology dynamic mechanical and thermal stud-ies on poly(styrene-co-acrylonitrile)modified epoxy resinglassfibre compositesrdquo Composites A vol 38 no 12 pp 2422ndash24322007

[8] Y T Liao and K C Lee ldquoEffect of interface properties on thestatic and dynamic properties of unidirectional compositesrdquoJournal of Applied Polymer Science vol 44 pp 933ndash936 1992

[9] K Sever M Sarikanat Y Seki and I H Tavman ldquoCon-centration effect of 120574-glycidoxypropyl-trimethoxysilane on themechanical properties of glass fiber-epoxy compositesrdquo Poly-mer Composites vol 30 no 9 pp 1251ndash1257 2009

[10] M R Dadfar and F Ghadami ldquoEffect of rubber modificationon fracture toughness properties of glass reinforced hot curedepoxy compositesrdquo Materials and Design vol 47 pp 16ndash202013

[11] F Tarlochan S Ramesh and S Harpreet ldquoAdvanced compositesandwich structure design for energy absorption applicationsblast protection and crashworthinessrdquoComposites B vol 43 pp2198ndash2208 2012

[12] M M Rahman S Zainuddin M V Hosur et al ldquoEffect ofNH2-MWCNTs on crosslink density of epoxy matrix and ILSSproperties of e-glassepoxy compositesrdquo Composite Structuresvol 95 pp 213ndash221 2013

[13] F Yavari M A Rafiee J Rafiee Z-Z Yu and N KoratkarldquoDramatic increase in fatigue life in hierarchical graphenecompositesrdquoACS AppliedMaterials and Interfaces vol 2 no 10pp 2738ndash2743 2010

[14] N Shahid R G Villate and A R Barron ldquoChemically func-tionalized alumina nanoparticle effect on carbon fiberepoxycompositesrdquo Composites Science and Technology vol 65 no 14pp 2250ndash2258 2005

[15] G-W Lee M Park J Kim J I Lee and H G Yoon ldquoEnhancedthermal conductivity of polymer composites filled with hybridfillerrdquo Composites A vol 37 no 5 pp 727ndash734 2006

[16] M Ya-nan L Guozheng G Aijuan Z Feipeng and Y LildquoThermally conductive aluminum nitride-multiwalled carbonnanotubecyanate ester composites with high flame retardancyand low dielectric lossrdquo Industrial and Engineering ChemistryResearch vol 52 pp 3342ndash3353 2013

[17] H B Cho M Mitsuhashi T Nakayama et al ldquoThermalanisotropy of epoxy resin-based nano-hybrid films containing

BN nanosheets under a rotating superconducting magneticfieldrdquo Materials Chemistry and Physics vol 139 pp 355ndash3592013

[18] S Sinha Ray and M Okamoto ldquoPolymerlayered silicatenanocomposites a review from preparation to processingrdquoProgress in Polymer Science vol 28 no 11 pp 1539ndash1641 2003

[19] I Zaman Q-H Le H-C Kuan et al ldquoInterface-tunedepoxyclay nanocompositesrdquo Polymer vol 52 no 2 pp 497ndash504 2011

[20] T Wan S Liao K Wang P Yan and M Clifford ldquoMulti-scalehybrid polyamide 6 composites reinforced with nano-scale clayand micro-scale short glass fibrerdquo Composites A vol 50 pp 31ndash38 2013

[21] M J Clifford and T Wan ldquoFibre reinforced nanocompositesmechanical properties of PA6clay and glass fibrePA6claynanocompositesrdquo Polymer vol 51 no 2 pp 535ndash539 2010

[22] N N Herrera J-M Letoffe J-L Putaux L David and EBourgeat-Lami ldquoAqueous dispersions of silane-functionalizedlaponite clay platelets a first step toward the elaboration ofwater-based polymerclay nanocompositesrdquo Langmuir vol 20no 5 pp 1564ndash1571 2004

[23] K A Carrado L Xu R Csencsits and J V Muntean ldquoUseof organo- and alkoxysilanes in the synthesis of grafted andpristine claysrdquo Chemistry of Materials vol 13 no 10 pp 3766ndash3773 2001

[24] N N Herrera J-M Letoffe J-P Reymond and E Bourgeat-Lami ldquoSilylation of laponite clay particles with monofunctionaland trifunctional vinyl alkoxysilanesrdquo Journal of MaterialsChemistry vol 15 no 8 pp 863ndash871 2005

[25] H Lee B P Lee and P B Messersmith ldquoA reversible wetdryadhesive inspired by mussels and geckosrdquo Nature vol 448 no7151 pp 338ndash341 2007

[26] H Lee S M Dellatore W M Miller and P B MessersmithldquoMussel-inspired surface chemistry for multifunctional coat-ingsrdquo Science vol 318 no 5849 pp 426ndash430 2007

[27] P V Joseph G Mathew K Joseph G Groeninckx and SThomas ldquoDynamic mechanical properties of short sisal fibrereinforced polypropylene compositesrdquo Composites A vol 34no 3 pp 275ndash290 2003

[28] L Yang S L Phua J K H Teo et al ldquoA biomimetic approach toenhancing interfacial interactions polydopamine-coated clayas reinforcement for epoxy resinrdquo ACS Applied Materials andInterfaces vol 3 no 8 pp 3026ndash3032 2011

[29] E M Woo and J C Seferis ldquoViscoelastic characterization ofhigh performance epoxy matrix compositesrdquo Polymer Compos-ites vol 12 pp 273ndash280 1991

[30] M A Lopez-Manchado J Biagitti and J M Kenny ldquoCompara-tive study of the effects of different fibers on the processing andproperties of ternary composites based on PP-EPDM blendsrdquoPolymer Composites vol 23 no 5 pp 779ndash789 2002

[31] M H G Wichmann J Sumfleth F H Gojny M QuaresiminB Fiedler and K Schulte ldquoGlass-fibre-reinforced compositeswith enhanced mechanical and electrical properties benefitsand limitations of a nanoparticle modified matrixrdquo EngineeringFracture Mechanics vol 73 no 16 pp 2346ndash2359 2006

[32] S Kume I Yamada K Watari I Harada and K MitsuishildquoHigh-thermal-conductivity AlN filler for polymerceramicscompositesrdquo Journal of the American Ceramic Society vol 92supplement 1 pp S153ndashS156 2009

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


is emerged as an effective way to enhance the rather poorthermal conductivity of epoxy resin because the heat dissipa-tion in microelectronic packaging is becoming increasinglyimportant as the demands in denser and faster circuitsintensify For nanofillers their dispersion and interfacialinteractions with epoxy resin matrix are the most crucialfactor affecting the optimal properties of the nanocomposites[18 19] Nanofillers should be well dispersed in the matricesto obtain a high aspect ratio and large interfacial area betweenthe phases whereas strong interfacial interactions betweenthe nanofillers and epoxy resin matrices would facilitate thestress transformation and thermal conductivity

Many previous researches were interested in combiningthe advantages of microscale fibers and nanoscale particlesFor example Wan et al reported that multiscale rein-forcements consisting of clay and short glass fiber filledpolyamide 6 were prepared by a two-step melt compoundingprocess [20 21] The synergy of multiscale reinforcementsof clay and glass fiber provided better physical propertiesfor polymer-matrix composites than each of the individ-ual fillers Besides the above methods based on physicallyblending microscale fibers and nanoscale fillers [15ndash17 2021] a more effective method is to disperse nanofillers ontoglass fibers and then construct novel ldquoFRP nanocompositesrdquoThe advantages include (1) a better dispersion of thermallyconductive nanofillers in polymer matrix (2) an enhancedaffinity between fiber and matrix and (3) enhancing per-formance of FRP composites without marked increase incost due to small amount of nanofillers Traditional methodis to modify their surface in the presence of functionalcoupling agents such as silane coupling agents [22ndash24]However the amount of active groups on nanofillers orglass fibers is usually very small and the reactions requirestrict chemical conditions Furthermore the main caveat ofthis strategy is that the coupling agents are often materialspecific and thus lack efficacy across a broad range of FRPnanocomposites

In nature marine mussel adhesive proteins (MAPs)contain large amounts of a particular amino acid known as34-dihydroxy-L-phenylalanine (dopamine DOPA) and haveattracted great attention owing to the amazing ability of mus-sels to adhere to various kinds of surfaces [25 26] In 2007Lee et al reported polydopamine (PDOPA) adhesive coatingson a wide variety of material surfaces including noble metalsoxides polymers semiconductors and ceramics prepared bymimicking MAPs [25]

Inspired by these works we hypothesized that if acatechol-rich polymer layer can be prepared as the interfacebetween nanofillers and GF the interfacial interactions maybe significantly enhanced and hence the physicalchemicalproperties of the FRP composites can be improved at very lownanofillers loadings To verify the hypothesis we prepareddopamine-modified glass fiber (D-GF) via a facile water-assisted process and then coated BN nanoparticles on thesurface The novel reinforcement (BN-D-GF) was incorpo-rated into an epoxy resin to form FRP nanocompositesSpecifically the structure morphology and thermomechan-ical properties of these novel materials were in detail investi-gated

2 Materials and Methods

21 Materials Epoxy resin based on diglycidyl ether ofbisphenol A (DGEBA E51) and triethylenetetramine (TETA)curing agent were purchased from Jiangtian Reagent Chemi-cals Co Ltd Short-cut glass fibers were supplied by OwensCorning Chemicals and 34-dihydroxyphenethylamine hy-drochloride (DOPA 98) was purchased from Sigma-Aldrich respectively All the other chemicals were purchasedlocally and of analytical reagent grade

22 Preparation of Modified Glass Fibers and FRP CompositesIn a typical experiment 5 g short-cut glass fiber (GF) wasmechanically stirred in 500mL 10mM Tris buffer solution(pH 85) [25] DOPA (1 g) was then added and the suspensionwas stirred for 8 h at roomambient conditionThe suspensionwas then centrifuged at 2500 rpm for 3min and then thedopamine coated glass fiber (D-GF) was obtained D-GFwas redispersed in 500mL 10mM Tris buffer solution (pH85) and then 05 g nano-BN was added The dark slurry-like product was washed with acetone and the solventwas removed by centrifuge The wash-centrifuge step wasrepeated three times and finally BN-D-GFacetone slurrywas obtained

To prepare the BN-D-GFepoxy FRP composites a cer-tain amount of E51was poured into the slurry followed by vig-orous stirring for 2 hThe acetonewas then removed by rotaryevaporation followed by drying in a vacuum oven at 50∘C for48 h The curing agent was then added at the epoxycuringagent ratio of 10013 (ww) The mixtures were mechanicallystirred degassed and cured at room temperature for 3 h andpostcured at 70∘C for 2 h For comparison a BNGFepoxycompositewas prepared using the sameprocedure except thatthe BN was physically adsorbed onto untreated GF withoutpolydopamine coating

23 Characterization

231 Scanning Electron Microscopy (SEM) Fiber sampleswere prepared by applying a drop of the particle suspension(in acetone) to a glass slide and then dried overnightThe samples were then sputtered with gold to increasetheir conductance for SEM observation Measurements wereconducted using Philips XL30 ESEM and Hitachi S-4800instrument at an operation voltage of 200 keV and 07 keV

232 Differential Scanning Calorimetry (DSC) Glass-transition temperatures (119879

119892) of the neat epoxy resin and FRP

composites were measured by using a differential scanningcalorimetry (DSC 200F3 Netzsch Germany) Samples wereheated from 20 to 250∘C at a heating rate of 10∘Cmin undernitrogen atmosphere

233 Dynamic Mechanical Analysis (DMA) A dynamicmechanical analysis (DMA) was performed with a DMA2980 Dynamical Mechanical Analyzer in the fixed frequencymode at 1Hz with an amplitude of 040mm The transversemechanical properties of the composites were measured

















(a) (b)

(c) (d)

Fiber pullouts

Fiber pullouts


Nano-BN aggregation

(e) (f)



119892









Shore Dhardness


0 500 1000 1500 2000 2500 3000 3500 4000 4500

1618

Dopamine

GF

D-GF

1508



20 40 60 80 100 120 140 160 180 200 220

D-GFepoxy

Neat epoxy

BNGFepoxy

GFepoxy

Hea

t flow

(Wg

)

BN-D-GF epoxy

Temperature (∘C)

1104∘C

1085∘C

1183∘C

1037∘C

1178∘C




0 50 100 150 200 250

0

100

200

300

400


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400

(MPa

)




0 50 100 150 200 250

0

10

20

30

40


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400998400

(MPa

)








4 Conclusions


Acknowledgments



References









































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



















(a) (b)

(c) (d)

Fiber pullouts

Fiber pullouts


Nano-BN aggregation

(e) (f)



119892









Shore Dhardness


0 500 1000 1500 2000 2500 3000 3500 4000 4500

1618

Dopamine

GF

D-GF

1508



20 40 60 80 100 120 140 160 180 200 220

D-GFepoxy

Neat epoxy

BNGFepoxy

GFepoxy

Hea

t flow

(Wg

)

BN-D-GF epoxy

Temperature (∘C)

1104∘C

1085∘C

1183∘C

1037∘C

1178∘C




0 50 100 150 200 250

0

100

200

300

400


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400

(MPa

)




0 50 100 150 200 250

0

10

20

30

40


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400998400

(MPa

)








4 Conclusions


Acknowledgments



References









































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)

Fiber pullouts

Fiber pullouts


Nano-BN aggregation

(e) (f)



119892









Shore Dhardness


0 500 1000 1500 2000 2500 3000 3500 4000 4500

1618

Dopamine

GF

D-GF

1508



20 40 60 80 100 120 140 160 180 200 220

D-GFepoxy

Neat epoxy

BNGFepoxy

GFepoxy

Hea

t flow

(Wg

)

BN-D-GF epoxy

Temperature (∘C)

1104∘C

1085∘C

1183∘C

1037∘C

1178∘C




0 50 100 150 200 250

0

100

200

300

400


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400

(MPa

)




0 50 100 150 200 250

0

10

20

30

40


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400998400

(MPa

)








4 Conclusions


Acknowledgments



References









































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials









Shore Dhardness


0 500 1000 1500 2000 2500 3000 3500 4000 4500

1618

Dopamine

GF

D-GF

1508



20 40 60 80 100 120 140 160 180 200 220

D-GFepoxy

Neat epoxy

BNGFepoxy

GFepoxy

Hea

t flow

(Wg

)

BN-D-GF epoxy

Temperature (∘C)

1104∘C

1085∘C

1183∘C

1037∘C

1178∘C




0 50 100 150 200 250

0

100

200

300

400


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400

(MPa

)




0 50 100 150 200 250

0

10

20

30

40


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400998400

(MPa

)








4 Conclusions


Acknowledgments



References









































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 50 100 150 200 250

0

10

20

30

40


D-GFepoxyBNGFepoxy

Temperature (∘C)

E998400998400

(MPa

)








4 Conclusions


Acknowledgments



References









































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




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



Documents

Research Article Constructing Novel Fiber Reinforced