research article enhancement of mechanical and dynamic...

Research ArticleEnhancement of Mechanical and DynamicMechanical Properties of Hydrophilic NanoclayReinforced Polylactic AcidPolycaprolactoneOilPalm Mesocarp Fiber Hybrid Composites

Chern Chiet Eng1 Nor Azowa Ibrahim1 Norhazlin Zainuddin1 Hidayah Ariffin2

Wan Md Zin Wan Yunus3 and Yoon Yee Then1

1 Department of Chemistry Faculty of Science University Putra Malaysia 43400 UPM Serdang Selangor Malaysia2 Department of Bioprocess Technology Faculty of Biotechnology and Biomolecular Sciences University Putra Malaysia43400 UPM Serdang Selangor Malaysia

3 Chemistry Department Centre for Defence Foundation Studies National Defence University of Malaysia Kem Sungai Besi57000 Kuala Lumpur Malaysia

Correspondence should be addressed to Nor Azowa Ibrahim norazowascienceupmedumy

Received 1 March 2014 Accepted 7 April 2014 Published 27 April 2014

Academic Editor Jan-Chan Huang

Copyright copy 2014 Chern Chiet Eng et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

In previous studies the effect of the addition of 1 wt hydrophilic nanoclay on polylactic acid (PLA)polycaprolactone (PCL)oilpalm mesocarp fiber (OPMF) biocomposites was investigated by tensile properties thermogravimetric analysis (TGA) andscanning electron microscopy (SEM) The current studies focus on the effect of addition of 1 wt hydrophilic nanoclay onmechanical (flexural and impact properties) and dynamicmechanical properties of compositesThe composites were characterizedby the Fourier transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA) FTIR spectra show that peakshifting occurs when 1 wt hydrophilic nanoclay was added to compositesThe addition of 1 wt hydrophilic nanoclay successfullyimproves the flexural properties and impact resistance of the biocomposites The storage modulus of biocomposites was decreasedwhen nanoclay was added which indicates that the stiffness of biocomposites was reduced The loss modulus curve shows that theaddition of nanoclay shift two t

119892in composites become closer to each other which indicates that the incorporation of nanoclay

slightly compatibilizes the biocomposites Tan 120575 indicated that hybrid composites dissipate less energy compared to biocompositesindicate that addition of clay to biocomposites improves fibermatrix adhesion Water sorption test shows that the addition ofnanoclay enhances water resistance of composites

1 Introduction

In our preliminary studies [1] we reported that the incor-poration 1 wt of hydrophilic nanoclay in polylactic Acid(PLA)polycaprolactone (PCL) blends successfully enhancethe morphology mechanical and thermal properties of theblends Therefore we choose incorporation of 1 wt ofhydrophilic nanoclay into PLAPCLoil palmmesocarp fiber(OPMF) biocomposites to study the effect of nanoclay onbiocomposites

In our previous paper [2] we reported that the addition of1 wt hydrophilic nanoclay to PLAPCLOPMF biocompos-ites increases the tensile strength and elongation at break ofbiocomposites around 848 and 3214 respectively at 10fiber loading Besides thermogravimetric analysis (TGA)results show that the presence of clay increases the thermalstability of the biocomposites Scanning electron microscopy(SEM) micrographs revealed that PLAPCLOPMF biocom-posites consist of cavity which indicated poor fibermatrixadhesion while micrographs of PLAPCLOPMFclay hybrid

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2014 Article ID 715801 8 pageshttpdxdoiorg1011552014715801

2 International Journal of Polymer Science

composites show better fibermatrix adhesion as no cavity ispresent at facture surfaces

Natural fiber as reinforcement filler in polymer com-posites has received increasing attention from researchers asnatural fibers havemany significant advantages over syntheticfibersThey are environmentally friendly fully biodegradableabundantly available renewable and cheap and have lowdensity [3] However there are some disadvantages suchas poor wetability incompatibility with some polymericmatrices and high moisture adsorption which restrict theirusage in polymer composites [4]

The oil palm (Elaeis guineensis) originates from SouthAfrica which grows well in all tropical areas of the world andit has become one of the main industrial crops Malaysianpalm oil industry has grown tremendously over the last25 years and has become the worldrsquos leading producer andexporter of palm oil [5] For every kg of palm oil producedapproximately 4 kg of dry biomass is produced excludingpalm oil mill effluent (POME) In 2010 the amount ofmesocarp fiber available was 1080Mtyear [6] Thereforethere is huge amount of fiber that can be utilized instead ofbeing discarded as waste Traditionally the mesocarp fiber ismixed with kernel shell and is being utilized as solid fuel togenerate electricity for the mill

Polylactic acid (PLA) is biodegradable polymerwith goodmechanical properties thermal plasticity and biocompat-ibility However PLA is a comparatively brittle and stiffpolymer with low deformation at break Therefore modi-fication of PLA is needed in order to compete with otherflexible polymers such as polypropylene or polyethylene [7]Polycaprolactone (PCL) is flexible semicrystalline biodegrad-able polymer with low melting point and exceptional blendcompatibility High flexibility of PCL can be considered as agood plasticizer for PLA compared to low molecular weightplasticizers as it does notmigrate to the surface of the blendedsamples and the physical properties cannot be debased[8]

Recently many studies have been conducted by academicor industrial researcher on biodegradable polymer in orderto replace conventional nonbiodegradable polymer whichcauses major drawback to the environment However thecost of biodegradable polymer is comparatively higher thanpetrochemical based nonbiodegradable polymerwhich limitsits application The incorporation of cheap natural fibersas reinforcement filler into biodegradable polymer is analternative to reduce its cost

Hybrid composites are materials made by combiningtwo or more different types of fillers in a single matrixAlthough several fillers can be incorporated into the hybridsystem a combination of only two types of fillers wouldbe more beneficial By careful selection of the reinforcingfillersfibers the performance properties of the resultingcomposite can be significantly improved while the materialcost can be substantially reduced [9]The properties of hybridcomposites depend on the individual components in whichthere is a more favourable balance between the inherentadvantages and disadvantages Besides the advantages of onetype of filler could complement the other filler in hybridcomposite that contains two or more types of fillersThrough

proper material design a hybrid composite with balance incost and performance could be obtained [10]

Kord [11] investigates the effect of nanoclay on polypropy-lene (PP)hemp fiber composites The increment of nanoclayloading is up to 3 increase in tensile modulus tensilestrength and elongation at break of composites Howeverthe increment of nanoclay loading decreases the impactstrength Besides the increment of nanoclay loading signif-icantly decreases water absorption and swelling thicknessof composites The dynamic mechanical behaviour and fireproperties of composites were improved by the addition ofnanoclay X-ray diffraction (XRD) shows that the dispersionof nanoclay in the hemp fiberPP samples is not exfoliated

The aim of incorporation of cheap natural fiber (OPMF)into expensive biodegradable polymer (PLA and PCL) wasto reduce its cost The addition of hydrophilic fiber tohydrophobic matrix will reduce the mechanical strengthas incompatibility between fiber and matrix therefore theobjective of this paper is to investigate the effect of additionof 1 wt of hydrophilic nanoclay on mechanical dynamicmechanical morphology and water absorption propertiesof PLAPCLOPMFnanoclay hybrid composites by meltintercalation Various characterization techniques such asthe Fourier transform infrared spectroscopy (FTIR) anddynamic mechanical analysis (DMA) were used to studythe effect of addition of nanoclay on the properties ofPLAPCLOPMFnanoclay hybrid composites

2 Experimental

21 Materials All reactions were carried out by using reagentgrade chemicals (gt98 purity) without further purificationThe hydrophilic nanoclay (Nanomer PGV) was purchasedfrom Sigma-Aldrich and used as received Polylactide Resin4060Dwas supplied by NatureWorks while polycaprolactone(CAPA 650) was supplied by the Solvay caprolactone Oilpalm mesocarp fibers were obtained from Felda Palm IndSdn Bhd Serting Hilir

22 Preparation of Hybrid Composites The composites wereprepared by melt blending technique where the compositionof PLA and PCL was kept constant at 85wt and 15wtrespectively in blend while the clay content was constant at1 wt Only the content of OPMF varies from 0 to 30PLA PCL nanoclay and OPMF were manually premixed ina container and fed into Brabender Plastograph EC at 170∘Cwith rotor speed of 50 rpm for 10 minutesThe products werethen compression moulded into sheets of 1mm thickness byan electrically heated hydraulic press with a force of 1500 kNat 160∘C for 10 minutesThe sample sheets were then used forfurther characterization

23 The Fourier Transform Infrared Spectroscopy (FTIR)Perkin Elmer Spectrum 100 series spectrometer equippedwith attenuated total reflectance (ATR) was used to deter-mine the functional groups and types of the bonding of thesamples with the infrared spectra recorded in the range of

International Journal of Polymer Science 3

frequency of 280 to 4000 cmminus1 with the resolution of 4 cmminus1and number of scan being 16 scans

24 Tensile Properties Tensile properties measurement wasperformed by Instron machine model 4301 with grip attach-ment distance of 45mm Load of 10 kN was applied at con-stant crosshead speed of 5mmminminus1 Computerized Instron(Software series 9 national instruments GPIB PC22a andNI-4882) was used to process data Test specimens wereprepared and stamped in compliance with ASTM D638dumbbell parameters Sample thickness was measured withMitutoyo Digimatic Indicator type IDF-112 having measur-ing accuracy of plusmn0001mm

25 Flexural Properties The flexural strength and moduluswere measured with Instron Universal Testing Machine 4301according to ASTM D790 The size of the samples testingis 127mm times 127mm times 3mm The crosshead speed is13mmmin and the support span length is 48mm Datawas processed with computerized Instron (Software series 9national instruments GPIB PC22a and NI-4882)

26 The Izod Impact Strength The Izod impact test wascarried out according to ASTM D256 standard using animpact tester (The IZOD Impact Tester) The sample size is635 times 127 times 3mm while the notch length is 254mm Theenergy required to break the samples was divided by unit areaof residual cross section of sample to obtain impact resistancevalue The impact strength (Jm) was calculated by dividingthe energy obtained (J) with the thickness of specimen (m)

27 Thermogravimetric Analysis (TGA) TGA testing wasconducted in accordance with ASTM E1131 Perkin ElmerTGA7 was used for thermogravimetric analysis of sampleswhere about 15mg of the samples was heated from 35∘C to800∘C with the heating rate of 10∘Cmin Nitrogen gas waspumped with the flow rate of 20mLmin in order to let theanalysis be carried out in nitrogen atmosphere

28 Dynamic Mechanical Analysis (DMA) DMA testing wasconducted in accordance with ASTM D5023-07 The PerkinElmer Model Pyris Diamond DMA was used Samples weretested under the condition of static force 10N and dynamicforce 8N with 1Hz frequencies Scan was done from minus100∘Cto 130∘C at 2∘Cmin rate with sample dimensions being 1mmin thickness and 30mm in length by using bending mode

29 Scanning Electron Microscopy (SEM) The surface mor-phology of fracture surface was observed with SEM JEOLJSM-6400 The fracture surface was obtained from plainstrain fracture tensile tested specimens and was sputtercoated with gold using biorad coating system before viewing

210 Water Sorption Test Water absorption studies wereperformed following the ASTM D638 type M3 standardThe films were cut into dumbbell shapes and dried at roomtemperature overnight to reach the constantweightThen the

Rela

tive i

nten

sity

Wavenumber (cmminus1)

With 1wt clay

Without clay

3000 2000 1000

293983 cmminus1

174890 cmminus1

174554 cmminus1

294702 cmminus1

Figure 1 FTIR spectra of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites

samples were immersed at 25∘C of distilled water for up to 30daysMass uptakes of the samplesweremeasured periodicallyby removing them from the water bath The samples werewiped with the tissue paper to remove the surface water Themoisture uptake expressed in percent weight gain ΔM is

Δ119872 =119872119905 minus119872119900

119872119900

times 100 (1)

where Mt = mass of sample after immersion and Mo = massof sample before immersion

3 Results and Discussion

31 The Fourier Transform Infrared Spectroscopy (FTIR)FTIR spectra of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMF hybrid composites are shown inFigure 1 Both composites exhibit strong absorbance peakat 174890 cmminus1and 1745 cmminus1 respectively indicating thepresence of C=O stretching Besides CndashH stretching ispresent in both composites but the intensity of the peakfor PLAPCL1 wt clayOPMF hybrid composites is higherthan PLAPCLOPMF biocomposites with the peak at2939 cmminus1 and 2947 cmminus1 respectively Shifting of peaks inIR spectra is observed when there is strong interaction inpolymer blends [12] Therefore peak shifting is observedwhen 1wt of clay was incorporated into biocompositeswhich indicated that theremight be somephysical interactionbetween PLA PCL clay and OPMF in composites

32 Tensile Properties In our previous studies [2] wereported that the addition of 1 wt of nanoclay successfullyincreases the tensile strength and elongation at break butdecreases the tensile modulus of PLAPCLOPMF biocom-posites which is summarized in Table 1 PLAPCLOPMFbiocomposites show the highest tensile strength at 10 wtof the fiber loading and decrease with the increasing offiber loading which results from poor dispersion of fiberswhich leads to agglomeration of fillers Besides fiber actsas included filler in the resin matrix which weakens thecomposite due to poor interfacial adhesion and obstructsthe stress propagation which leads to reduction of tensilestrength as the filler loading increases The presence ofhydrophilic nanoclay increases the overall tensile strength


Table 1 Tensile properties of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMF hybrid composites

Sample Tensile strength (MPa) Elongation atbreak (mm) Tensile modulus (MPa)

PLA85PCL15 4594 plusmn 175 168 plusmn 030 90292 plusmn 5069

PLA85PCL1510 wt OPMF 3348 plusmn 244 056 plusmn 004 88480 plusmn 4416

PLA85PCL1520wt OPMF 2799 plusmn 134 040 plusmn 002 87873 plusmn 4479


PLA85PCL151 wt clay10 wt OPMF 3632 plusmn 122 074 plusmn 002 68580 plusmn 7132

PLA85PCL151 wt clay20wt OPMF 3232 plusmn 055 064 plusmn 010 66117 plusmn 4636


of hybrid composites which suggests that the presence ofhydrophilic nanoclay acts as physical compatibilizing agentsbetween hydrophilic fiber and hydrophobic matrix and thusimproves the fibermatrix adhesion of hybrid compositesThis might be due to the addition of nanoclay which suc-cessfully improves the miscibility of PLAPLA in blends [1]while at the same time the presence of hydrophilic nanoclayis more compatible with hydrophilic fiber which enhancesbetter physical interaction between fiber andmatrix resultingin better mechanical properties of hybrid composites

The addition of fiber decreases the elongation at breakof composites from 168mm to 056mm (PLAPCLOPMFbiocomposites) and 074mm (PLAPCLOPMF1 wt clayhybrid composites) respectively at 10 wt fiber loading Theaddition of fiber into matrix causes composites to becomestiffer and harder as the segment mobility of the compositesis reduced which leads to low elongation On the otherhand the addition of hydrophilic nanoclay improves thefibermatrix adhesion of hybrid composites and also stresstransfer within hybrid composites which enhance the flexi-bility of the composites Therefore PLAPCLOPMF1 wtclay hybrid composites show better elongation at break thanPLAPCLOPMF biocomposites

Tensile modulus of PLAPCLOPMF biocomposites andPLAPCLOPMF1 wt clay hybrid composites indicates thatthe overall tensile modulus of biocomposites is higher thanhybrid compositesTherefore this implies that the addition ofhydrophilic nanoclay decreases the stiffness of the compositesas the flexibility of composites increase which leads to lowertensile modulus

33 Flexural Properties Flexural strength of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMFhybrid composites is illustrated in Figure 2 The addition of1 clay in hybrid compositesshows better flexural strength(3653MPa) compared to biocomposites (2145MPa) at10 wt fiber loading Therefore the addition of clay haspositive effect on flexural strength of hybrid composites dueto better interfacial adhesion betweenmatrix and filler whichwill improve stress transfer from matrix to filler resultingin higher values of flexural strength Weak fibermatrixinterfacial bonding results in poor flexural properties [13]When higher amount of fiber is incorporated into thecomposites flexural strength decreases This is due to theincrement of population of fiber defects and fiber ends with

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20 25 30 35

Flex

ural

stre

ngth

(MPa

)

Fiber loading ()

Without clayWith 1wt clay

Figure 2 Flexural strength of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites

increased fiber content The fiber defects could act as sourceof stress concentration in composites [14]

Figure 3 shows flexuralmodulus of PLAPCLOPMF bio-composites and PLAPCL1 wt clayOPMF hybrid compos-ites The biocomposites show increment in flexural modulusfrom 243780MPa to 279700MPa while hybrid compositesdo not show changes in flexural modulus (243320MPa)when 10wt of fiber was added When the amount offiber increases the flexural modulus of hybrid compositesincreases and flexural modulus of biocomposites decreasesThe increasing trend in flexural modulus with the incrementamount of fiber for hybrid composites due to the addition offillers with higher stiffness than matrix is mentioned by [15]However biocomposites showdecrement of flexuralmoduluswith increment of fiber loading due to poor interfacialadhesion between fiber andmatrixwhich leads to lowflexuralmodulus

34 The Izod Impact Strength Impact strength of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMF


0

0 5 10 15 20 25 30 35

Fiber loading ()


500

1000

1500

2000

2500

3000

3500

Flex

ural

mod

ulus

(MPa

)

Figure 3 Flexural modulus of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites

hybrid composites is illustrated in Figure 4 The impactstrength decreases from 18870 Jm (PLA85PCL15) to8237 Jm and 9544 Jm for biocomposites and hybrid com-posites respectively at 10 wt fiber loading When fiber isincorporated into matrix poor energy absorbing capabilityof fiber inhibit deformation and ductile mobility of polymermolecules which lower the ability of composites to absorbenergy during crack propagation Besides less energy isrequired to initiate a crack as fiber creates high stress concen-tration regions [16] However the impact strength of hybridcomposites is higher than biocomposites as the addition ofclay improves impact strength of hybrid composites due tobetter fibermatrix adhesion in hybrid composites comparedto biocomposites

35 Thermogravimetric Analysis (TGA) Previously wereported that incorporation of nanoclay improves thethermal stability of PLAPCLOPMF biocomposites [2] ThePLAPCLOPMF biocomposites show onset temperature of19601∘C which increases to 22112∘C when clay is added tothe biocomposites Table 2 shows the thermal properties ofPLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMF hybrid compositesThe increment of thermal stabilityof hybrid composites due to clay can hinder the permeabilityof volatile degradation products out of the materials Thedispersed clay forms a barrier which delays the release ofthermal degradation products compared to the neat polymer[17]

36 Dynamic Mechanical Analysis (DMA) The storagemodulus (1198661015840) of PLAPCLOPMF biocomposites and

0 5 10 15 20 25 30 35

Fiber loading ()


0

50

100

150

200

250

Impa

ct st

reng

th (J

m)

Figure 4 Impact strength of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites

PLAPCL1 wt clayOPMF hybrid composites is illustratedin Figure 5 All the fiber loading in composites for DMAtesting is 10 wt Increment of 1198661015840 after addition of fibersis due to incorporation of high modulus fibers in thematrix The value of storage modulus decreases at highertemperature due to loss in stiffness of the fibers [18] The 1198661015840results show agreement with the flexural modulus resultsas biocomposites show higher tensile modulus than hybridcomposites The addition of clay shows considerable effecton the elastic properties of hybrid composites by reducingthe stiffness of the hybrid composites

Figure 6 shows the loss modulus (11986610158401015840) of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMFhybrid composites All the fiber loading in compositesfor DMA testing is 10 wt Loss modulus indicates thematerialrsquos ability to dissipate energy in the form of heat ormolecular rearrangements during the deformation [19] Theloss modulus accounts for the viscous component of thecomplex modulus or the out of phase component with theapplied strain which normally increases with the additionof filler [20] The addition of fiber increases the 11986610158401015840 ofbiocomposites and hybrid composites at the temperaturearound minus68∘C and then decreases at 48∘C The addition ofclay to biocomposites slightly shifts Tg of biocomposites fromminus677∘C to minus670∘C at PCL region and also from 476∘C to465∘C at PLA region which suggests that the incorporationof clay slightly compatibilizes the biocomposites resultingin better mechanical properties of hybrid composites thanbiocomposites

Figure 7 illustrated the loss factor (tan 120575) of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMFhybrid composites All the fiber loading in composites for


Table 2 Thermal properties of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMF hybrid composites

Sample Onset temperature (∘C) Offset temperature (∘C) of degradationPLAPCLOPMF 19601 47384 7278PLAPCL1 wt clayOPMF 22112 45836 7108

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

minus150 minus100 minus50 0 50 100 150

Temperature (∘C)

PLAPCL (8515)Without clayWith 1wt clay

Stor

age m

odul

usG

998400(P

a)

Figure 5 Storage modulus of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites

0

1000

2000

3000

4000

5000

6000

7000

8000

9000


Temperature (∘C)


Loss

mod

ulus

G998400998400

(Pa)

Figure 6 Loss modulus of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites


Temperature (∘C)


0

05

1

15

2

25

3

Tan120575

Figure 7 Tan 120575 of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMF hybrid composites

DMA testing is 10 wt The addition of fiber decreases tan 120575in the glass transition region because molecular mobilityof the composites decreased and the mechanical loss toovercome interfriction between molecular chains is reducedNormally damping of the polymer is much greater thanfibers Therefore the addition of fibers to polymer matrixwill increase the elasticity and decrease the viscosity andhence less energy will be used to overcome the frictionalforces between molecular chains as to decrease mechanicalloss [21] The higher the damping at the interface the poorerthe interfacial adhesion between fiber and matrix [22]Besides composites with poor interfacial bonding tendto dissipate more energy compared with composites withgood interfacial bonding Therefore addition of clay tobiocomposites improves fibermatrix adhesion as hybridcomposites show lower tan 120575 than biocomposites

37 Scanning Electron Microscopy (SEM) In our previouspaper [2] we reported that PLAPCLOPMF biocompos-ites consist of cavity as fiber has been pulled out frommatrix which indicated poor fibermatrix adhesion as fibercould not provide an efficient stress transfer from thematrix to the filler causing them to have lower mechan-ical properties in response to stress On the other hand


PLAPCLOPMF1 wt clay hybrid composites show betterfibermatrix adhesion as no cavity is present and fiberbreakage could be seen on facture surfaces indicating betterfibermatrix adhesion Therefore the SEM results supportthe tensile properties results as the biocomposites show lowstrength due to poor stress transfer between matrix andfiber in composites which cause the composites to becomebrittle On the other hand SEM results also support thetensile properties results that hybrid composites show bettermechanical properties than biocomposites

38 Water Sorption Test Water absorption of PLAPCLOPMF biocomposites and PLAPCL1 wt clayOPMFhybrid composites is shown in Figure 8 The fiber absorbswater due to the presence of hydroxyl groups which absorbwater through the formation of hydrogen bonding [23] Allcomposites show a sharp increment in water absorption atthe beginning and then remain constant around 10 dayswith the maximum water absorption being 581 and 529for biocomposites and hybrid composites respectivelyWater absorption of all composites is typical type of theFickian diffusion behaviour In Fickrsquos law the concentrationgradient is the driving force for diffusion and amount ofthe component diffused in a function of time Generallymoisture absorption process follows the prediction of Fickrsquoslaw as the mass of water absorbed increases linearly withsquare root of time until reach equilibrium plateau [24]Biocomposites show higher water absorption than hybridcomposites which might be due to the weak fibermatrixadhesion leads to more void in composites which can act aspathways for water diffusion into the composites Thereforeaddition of clay improves fibermatrix adhesion whileenhancing water resistance of composites at the same time

4 Conclusion

In these studies the addition of 1 wt hydrophilic nanoclaysuccessfully improves the overall flexural strength and impactstrength of PLAPCLOPMF biocomposites DMA analysisshows decrement in storage modulus when nanoclay wasadded indicating that addition of nanoclay has considerableeffect on the elastic properties of hybrid composites byreducing the stiffness of the hybrid composites Lossmodulusshows that the addition of nanoclay to biocomposites slightlyshifts Tg of biocomposites from minus677∘C to minus670∘C at PCLregion and also from 476∘C to 465∘C at PLA region whichsuggests that the incorporation of nanoclay slightly com-patibilizes the biocomposites resulting in better mechanicalproperties of PLAPCL1 wt clayOPMF hybrid compositesthan biocomposites Tan 120575 indicated that hybrid compositesdissipate less energy compared to biocomposites indicatingthat addition of clay to biocomposites improves fibermatrixadhesion Water sorption test shows that the addition ofnanoclay improves fibermatrix adhesion while enhancingwater resistance of composites at the same time Thereforethe addition of nanoclay in hybrid composites makes hybridcomposites possess good strength and properties whichis comparable with some conventional plastics Besides

0

1

2

3

4

5

6

0 10 20 30 40

Wat

er ab

sorp

tion

()

Time (days)


Figure 8Water absorption of PLAPCLOPMF biocomposites andPLAPCL1 wt clayOPMF hybrid composites

the incorporation of natural fibers in hybrid compositeslowering the cost of biodegradable polymer which widerthe application of biodegradable polymer based compositesThe applications of the hybrid composites might be moresuitable for single-use materials that do not require veryhigh strength while at the same time biodegradability andenvironment friendly are one of the concerns of selection ofmaterials

Conflict of Interests

The authors declare that there is no conflict of interests withany financial organization regarding the materials discussedin the paper

Acknowledgments

The authors would like to thank the Research UniversityGrant Scheme (RUGS) UPM for its financial support Allthe technical staff in the Department of Chemistry Faculty ofScience Universiti Putra Malaysia are greatly acknowledgedfor their assistance

References

[1] C C Eng N A Ibrahim N Zainuddin et al ldquoEnhance-ment of mechanical and thermal properties of polylacticacidpolycaprolactone blends by hydrophilic nanoclayrdquo IndianJournal of Materials Science vol 2013 Article ID 816503 11pages 2013


[2] C C Eng N A Ibrahim N Zainuddin H Ariffin W M ZWan Yunus and Y Y Then ldquoEffect of hydrophilic nanoclay onmorphology thermal and mechanical properties of polylacticacidpolycaprolactoneoil palmmesocarp fiber biocompositesrdquoInternational Journal of the Institute of Materials Malaysia vol1 no 1 pp 51ndash70 2014

[3] P Wambua J Ivens and I Verpoest ldquoNatural fibres can theyreplace glass in fibre reinforced plasticsrdquo Composites Scienceand Technology vol 63 no 9 pp 1259ndash1264 2003

[4] J E Riccieri L H de Carvalho and A Vazquez ldquoInterfacialproperties and initial step of the water sorption in unidirec-tional unsaturated polyestervegetable fiber compositesrdquo Poly-mer Composites vol 20 no 1 pp 29ndash37 1999

[5] M A AMohammed A SalmiatonW A K GWanAzlinaMS Mohammad Amran A FakhrursquoL-Razi and Y H Taufiq-YapldquoHydrogen rich gas from oil palm biomass as a potential sourceof renewable energy in Malaysiardquo Renewable and SustainableEnergy Reviews vol 15 no 2 pp 1258ndash1270 2011

[6] W P Q Ng H L Lam F Y Ng M Kamal and J H ELim ldquoWaste-to-wealth green potential from palm biomass inMalaysiardquo Journal of Cleaner Production vol 34 pp 57ndash652012

[7] H Balakrishnan A Hassan M U Wahit A A Yussuf and SB A Razak ldquoNovel toughened polylactic acid nanocompositemechanical thermal and morphological propertiesrdquo Materialsand Design vol 31 no 7 pp 3289ndash3298 2010

[8] J T Yeh C JWu C H Tsou et al ldquoStudy on the crystallizationmiscibility morphology properties of poly(lactic acid)poly(120576-caprolactone) blendsrdquo PolymermdashPlastics Technology and Engi-neering vol 48 no 6 pp 571ndash578 2009

[9] K Majeed M Jawaid A Hassan et al ldquoPotential materialsfor food packaging from nanoclaynatural fibres filled hybridcompositesrdquoMaterials amp Design vol 46 pp 391ndash410 2013

[10] M J John and S Thomas ldquoBiofibres and biocompositesrdquoCarbohydrate Polymers vol 71 no 3 pp 343ndash364 2008

[11] B Kord ldquoEffect of nanoparticles loading on properties of poly-meric composite based on hemp fiberpolypropylenerdquo JournalofThermoplastic CompositeMaterials vol 25 no 7 pp 793ndash8062012

[12] B K Kim and C H Choi ldquoMelt blends of poly(methyl meth-acrylate) with a phenoxyrdquo Polymer vol 37 no 5 pp 807ndash8121996

[13] H P S Abdul Khalil A M Issam M T Ahmad Shakri RSuriani and A Y Awang ldquoConventional agro-composites fromchemically modified fibresrdquo Industrial Crops and Products vol26 no 3 pp 315ndash323 2007

[14] M A Sawpan K L Pickering and A Fernyhough ldquoFlexuralproperties of hemp fibre reinforced polylactide and unsaturatedpolyester compositesrdquo Composites A Applied Science and Man-ufacturing vol 43 no 3 pp 519ndash526 2012

[15] C R Reddy A P Sardashti and L C Simon ldquoPreparationand characterization of polypropylene-wheat straw-clay com-positesrdquo Composites Science and Technology vol 70 no 12 pp1674ndash1680 2010

[16] B D Park and J J Balatinecz ldquoMechanical properties of wood-fibertoughened isotactic polypropylene compositesrdquo PolymerComposites vol 18 no 1 pp 79ndash89 1997

[17] T Agag T Koga and T Takeichi ldquoStudies on thermaland mechanical properties of polyimide-clay nanocompositesrdquoPolymer vol 42 no 8 pp 3399ndash3408 2001

[18] D Shanmugam and M Thiruchitrambalam ldquoStatic anddynamic mechanical properties of alkali treated unidirectionalcontinuous Palmyra Palm Leaf Stalk Fiberjute fiber reinforcedhybrid polyester compositesrdquo Materials amp Design vol 50 pp533ndash542 2013

[19] F Rezaei R Yunus andN A Ibrahim ldquoEffect of fiber length onthermomechanical properties of short carbon fiber reinforcedpolypropylene compositesrdquoMaterials and Design vol 30 no 2pp 260ndash263 2009

[20] S Singh A K Mohanty and M Misra ldquoHybrid bio-compositefrom talc wood fiber and bioplastic fabrication and character-izationrdquo Composites A Applied Science and Manufacturing vol41 no 2 pp 304ndash312 2010

[21] W Liu M Misra P Askeland L T Drzal and A K MohantyldquolsquoGreenrsquo composites from soy based plastic and pineapple leaffiber Fabrication and properties evaluationrdquo Polymer vol 46no 8 pp 2710ndash2721 2005

[22] S Dong and R Gauvin ldquoApplication of dynamic mechanicalanalysis for the study of the interfacial region in carbonfiberepoxy composite materialsrdquo Polymer Composites vol 14no 5 pp 414ndash420 1993

[23] H P S Abdul Khalil H Ismail M N Ahmad A Ariffinand K Hassan ldquoThe effect of various anhydride modificationson mechanical properties and water absorption of oil palmempty fruit bunches reinforced polyester compositesrdquo PolymerInternational vol 50 no 4 pp 395ndash402 2001

[24] V Vilay M Mariatti R Mat Taib and M Todo ldquoEffect of fibersurface treatment and fiber loading on the properties of bagassefiber-reinforced unsaturated polyester compositesrdquo CompositesScience and Technology vol 68 no 3-4 pp 631ndash638 2008

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NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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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


composites show better fibermatrix adhesion as no cavity ispresent at facture surfaces

Natural fiber as reinforcement filler in polymer com-posites has received increasing attention from researchers asnatural fibers havemany significant advantages over syntheticfibersThey are environmentally friendly fully biodegradableabundantly available renewable and cheap and have lowdensity [3] However there are some disadvantages suchas poor wetability incompatibility with some polymericmatrices and high moisture adsorption which restrict theirusage in polymer composites [4]

The oil palm (Elaeis guineensis) originates from SouthAfrica which grows well in all tropical areas of the world andit has become one of the main industrial crops Malaysianpalm oil industry has grown tremendously over the last25 years and has become the worldrsquos leading producer andexporter of palm oil [5] For every kg of palm oil producedapproximately 4 kg of dry biomass is produced excludingpalm oil mill effluent (POME) In 2010 the amount ofmesocarp fiber available was 1080Mtyear [6] Thereforethere is huge amount of fiber that can be utilized instead ofbeing discarded as waste Traditionally the mesocarp fiber ismixed with kernel shell and is being utilized as solid fuel togenerate electricity for the mill

Polylactic acid (PLA) is biodegradable polymerwith goodmechanical properties thermal plasticity and biocompat-ibility However PLA is a comparatively brittle and stiffpolymer with low deformation at break Therefore modi-fication of PLA is needed in order to compete with otherflexible polymers such as polypropylene or polyethylene [7]Polycaprolactone (PCL) is flexible semicrystalline biodegrad-able polymer with low melting point and exceptional blendcompatibility High flexibility of PCL can be considered as agood plasticizer for PLA compared to low molecular weightplasticizers as it does notmigrate to the surface of the blendedsamples and the physical properties cannot be debased[8]

Recently many studies have been conducted by academicor industrial researcher on biodegradable polymer in orderto replace conventional nonbiodegradable polymer whichcauses major drawback to the environment However thecost of biodegradable polymer is comparatively higher thanpetrochemical based nonbiodegradable polymerwhich limitsits application The incorporation of cheap natural fibersas reinforcement filler into biodegradable polymer is analternative to reduce its cost

Hybrid composites are materials made by combiningtwo or more different types of fillers in a single matrixAlthough several fillers can be incorporated into the hybridsystem a combination of only two types of fillers wouldbe more beneficial By careful selection of the reinforcingfillersfibers the performance properties of the resultingcomposite can be significantly improved while the materialcost can be substantially reduced [9]The properties of hybridcomposites depend on the individual components in whichthere is a more favourable balance between the inherentadvantages and disadvantages Besides the advantages of onetype of filler could complement the other filler in hybridcomposite that contains two or more types of fillersThrough

proper material design a hybrid composite with balance incost and performance could be obtained [10]

Kord [11] investigates the effect of nanoclay on polypropy-lene (PP)hemp fiber composites The increment of nanoclayloading is up to 3 increase in tensile modulus tensilestrength and elongation at break of composites Howeverthe increment of nanoclay loading decreases the impactstrength Besides the increment of nanoclay loading signif-icantly decreases water absorption and swelling thicknessof composites The dynamic mechanical behaviour and fireproperties of composites were improved by the addition ofnanoclay X-ray diffraction (XRD) shows that the dispersionof nanoclay in the hemp fiberPP samples is not exfoliated

The aim of incorporation of cheap natural fiber (OPMF)into expensive biodegradable polymer (PLA and PCL) wasto reduce its cost The addition of hydrophilic fiber tohydrophobic matrix will reduce the mechanical strengthas incompatibility between fiber and matrix therefore theobjective of this paper is to investigate the effect of additionof 1 wt of hydrophilic nanoclay on mechanical dynamicmechanical morphology and water absorption propertiesof PLAPCLOPMFnanoclay hybrid composites by meltintercalation Various characterization techniques such asthe Fourier transform infrared spectroscopy (FTIR) anddynamic mechanical analysis (DMA) were used to studythe effect of addition of nanoclay on the properties ofPLAPCLOPMFnanoclay hybrid composites

2 Experimental

21 Materials All reactions were carried out by using reagentgrade chemicals (gt98 purity) without further purificationThe hydrophilic nanoclay (Nanomer PGV) was purchasedfrom Sigma-Aldrich and used as received Polylactide Resin4060Dwas supplied by NatureWorks while polycaprolactone(CAPA 650) was supplied by the Solvay caprolactone Oilpalm mesocarp fibers were obtained from Felda Palm IndSdn Bhd Serting Hilir

22 Preparation of Hybrid Composites The composites wereprepared by melt blending technique where the compositionof PLA and PCL was kept constant at 85wt and 15wtrespectively in blend while the clay content was constant at1 wt Only the content of OPMF varies from 0 to 30PLA PCL nanoclay and OPMF were manually premixed ina container and fed into Brabender Plastograph EC at 170∘Cwith rotor speed of 50 rpm for 10 minutesThe products werethen compression moulded into sheets of 1mm thickness byan electrically heated hydraulic press with a force of 1500 kNat 160∘C for 10 minutesThe sample sheets were then used forfurther characterization

23 The Fourier Transform Infrared Spectroscopy (FTIR)Perkin Elmer Spectrum 100 series spectrometer equippedwith attenuated total reflectance (ATR) was used to deter-mine the functional groups and types of the bonding of thesamples with the infrared spectra recorded in the range of










Rela

tive i

nten

sity


With 1wt clay

Without clay

3000 2000 1000

293983 cmminus1

174890 cmminus1

174554 cmminus1

294702 cmminus1



Δ119872 =119872119905 minus119872119900

119872119900

times 100 (1)



















0

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ural

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ngth

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Acknowledgments


References

































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












Rela

tive i

nten

sity


With 1wt clay

Without clay

3000 2000 1000

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174890 cmminus1

174554 cmminus1

294702 cmminus1



Δ119872 =119872119905 minus119872119900

119872119900

times 100 (1)



















0

5

10

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CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials

















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Acknowledgments


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CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

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CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






0

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30000

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CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






4 Conclusion


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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 enhancement of mechanical and dynamic...

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