International Review of Mechanical Engineering (I.RE.M.E.), Vol.
8, N. 1 ISSN 1970 - 8734January 2014 Manuscript received and
revised December 2013, accepted January 2014 Copyright 2014 Praise
Worthy Prize S.r.l. - All rights reserved 89 Material Properties of
Random Oriented Pressed Mat Coir Fibre/ Epoxy Composites Mohd
Amirul Abdul Rahman, Munaim Ali Omar Baki, Azmin Shakrine Mohd
Rafie, Renuganth A/L Vartharajoo
AbstractThematerialmechanicalpropertiesofcoirfibre/epoxycompositewereevaluated.
Highincreaseinconsumptionofcoconutfruitforfoodprocessingandotherindustrialusage
nowadays lead to increaseinth productionofcoconuttrashinthe
formofcoir fibre.Thesecoir fibres mostly disposed as unwanted waste
since there are not much further applications toutilize thecoir
fibres.Furthermore, theaerospace industries currentlyarelooking for
moreto optimize the performance of the existing materials (e.g.
metal and synthetic fibre composite) that would be introduced in
aircraft structurewhichrelativelycutthecostinproduction,
maintenance,and
in-serviceaircraft,eco-friendly,andlowinweightfactor.Therefore,naturalfibrereinforce
composite might be recommender answers to solve these
existingproblems wherebythis solution already been introduced in
the automotive and civil application. The existing raw coir fibres
used are inthe form of pressed matandoriginallyin therandomoriented
fibre form.They have been
useddirectlyinthecompressionmouldingprocesstogetherwithdifferentfibreweightratioof
20%to50%withepoxyresinsunderroomtemperatureandcontrolledpressureforcomposite
fabrication process. The fibres underwent no modification at all.
Then the fabricated panels have undergonemechanical material
tests;tensile,flexuralandtorsion testwith accordanceto ASTM
standardtoobtainmechanicalpropertiesofthematerialincludingtensilestrength,tensile
modulus and shear modulus. These properties data will be recorded
and might be used for further
analysissuchasaeroelasticanalysis.Theresultsshownthecompositewiththehigherfibre
percentage being more flexible (higher tensile strength) and less
than 50% of fibre loading, rigid composites were obtained.
Copyright 2014 Praise Worthy Prize S.r.l. - All rights reserved.
Keywords:
CoconutCoirFibre,MaterialMechanicalProperties,NaturalFibreComposites,
Epoxy Resin, Random Oriented Fibre Composite I.Introduction
Theintroductionofnaturalfibreinthedesignand
fabricationofcompositecouldbeaddedupasthe
advantageespeciallyintermoftheutilizationofgreen
technologyandlowincostmaterialinthemodern aircraft design process.
Natural fibres such as coconut fibres are the fibres that extracted
originally from coconut plant. The increment in
consumptionsofcoconutfruitforfoodprocessingand other industrial
usage in the presence day lead to increase
intheproductionofnon-recyclablecoconuttrashinthe form of coconut
husks. Therefore,anyrecommendedutilizationofthiswaste
coirfibrethatextractedfromcoconuthusksmightbe
seenasagoodrespondtomakeusethisabundantly
availablerawmaterial.Untilpresenceday,theyhave
beenusedforaseveralapplicationsincludingciviland mechanical
structures. Nowadays,theymightregardasoneofthe
significancevalueincommercialsectorsincetherapid
growthinpublicawarenesstowardstheutilizationof environmental
friendly materials. Thisgrowingenvironmentalconcernalsomight
attracttheaerospaceindustriesinthefuturefortheir application of
green technology ranging from design and
manufacturingtoin-serviceaircraft.Inaddition,other
criteriathatwouldaffectaircraftperformancesuchas
weightandcostreductionalsowouldbetakeninto
accountparticularlyinthematerialselectionprocessfor aircraft
primary structure. Coir fibre is the one of natural
fibresthatabundantlyavailableintropicalregions including India, Sri
Lanka, Philippines, and Malaysia [1]. Brown fibre that extracted
from matured coconuts are
thicker,stronger,andhigherabrasionresistance
comparedtowhitefibrethatextractedfromimmature coconuts. Brownfibre
is mostly used inengineering and
researchapplicationsandnormallyavailableinsemi-finishedproductformsnamelybristle(longfibres),
mattress(relativelyshort),anddecorticated(mixed fibres) [2].
Thebenefitsofcoirfibresincludeprovideexcellent
insulationagainsttemperatureandsound,noteasily combustible,
flame-retardant, unaffected by moisture and
dampness,toughanddurable,resilient,springbackto Mohd Amirul Abdul
Rahman et al. Copyright 2014 Praise Worthy Prize S.r.l. - All
rights reserved International Review of Mechanical Engineering,
Vol. 8, N. 1 90 shape even after constant use, totally static free,
and easy toclean[2].Epoxyresin(thermosetresingroup)isone
ofthecommonlyusedmatrixmaterialsandhavethe advantages of low in
densities, good corrosion resistance,
lowthermalandelectricalconductivities,translucence, and aesthetis
colour effects while the limitations of them
arelowintransversestrengthandoperational temperature limits
[3]-[4]. Inaddition,thecuringtimeofepoxyresinismuch
higherthanpolyesterresinsandithasagreaterbinding
property.Incaseofcoirfibrereinforcedcomposites,
thereareseveralreportedworksdoneonthem.Arylmis
etal.[5]workedonpreparationofcoircompositepanel
forautomotiveinteriorapplications.Hefoundthe
optimaluseofcompositecontentsforthatspecific purpose are 60% wt
coir fibre,37% PPpowder,and 3% MAPP.
Mujahidetal.[6]cameoutwiththedynamic
characteristicsofthecoconutcoirfibrereinforced
compositearegreatlydependentonthevolume percentage of fibre by
using experimental modal analysis
[EMA]onthecompositesamplebuttheincreaseof fibres will make
composite tend to have low stiffness and
ductility.Aireddyetal[7]studiedcoirdustreinforced
epoxymatrixcompositesofdifferentcompositions.The
experimentalresultsshownthat,theabrasivewear
resistanceofthecompositedependsonthecoirdust concentration, sliding
distance, and applied normal load.The abrasive wear resistance
decreased with increased innormal load andcoir dustconcentration.
Lai etal. [8] havedonetheexperimentoncoirfiber-reinforced
polypropylenecompositeandhasfoundoutthe
compositewithtreatedcoirfiberhaveahighertensile modulus and greater
flexural strength than untreated one.
Vermaet.al[4]statethatchemicalmodificationsare
commonlyconsideredtooptimizetheinterfacial
propertiesbetweennaturalfibreandpolymermatrix
becauseofthehydrophilicnatureofnaturalfibers. However, the others
research done on fiber treatment had
reportedthattheusualfibertreatmentssofardidnot significantly modify
the mechanical performance of coir-polyester composites as reviewed
by Monteiro [9]. Razzoqiet.al[12]havestudiedtheinfluenceof
compressionpressureonmechanicalpropertiesof
ceramicmatrixcompositeandfoundoutthatthe
mechanicalpropertiesimprovedforallcomposites
generallyatincreasingofcompressingpressure.Lynda
andFaycal[13]investigatedtheeffectsofshear
deformationonthenaturalfrequenciesofantisymmetric cross-ply and
angle-ply laminated composite plates.
Thesheardeformationshowedaconsiderableeffect on the natural
frequencies for composite plates. Bourouis and Mili [14] studied
the effect of the fibre orientation on
staticfailureofcompositesandwichbeams
carbon/epoxy,kevlarepoxy,glassepoxyofstacking -3s, [0/90] 3s and
[45/-45] 3s.Theyfoundoutthatthesandwichbeamswith carbon/epoxy, and
glass epoxy face sheets shows the best
characteristicscomparedtokevlar/epoxywhichfacing
lowmechanicalresistanceinbothtensileand
compressive.Thepurposesofthisresearchareto
evaluateandestablishpreliminarydataformaterial
mechanicalpropertiesfromstandardmechanicaltest;
tensile,flexuralandtorsiontestontherandom oriented and non-modify
pressed mat coir fibre/epoxy
composite.Theincreaseofcostduetothetreatment of the fibres should
be a point of concern. Thepreliminarydataobtainedmightbeservedin
theaerospaceresearchareaincludingaeroelasticand
ballisticanalysisorcanbeusedasareplacementin automotive components
and construction products.Thedetailsofresearchmethodologyandresult
analysis will be discussed in the next section. II.Materials and
Methods Acommerciallyavailablesemi-finishedproductof
rawbrowncoirfubresasshowninFig.1wereusedin
theformofpressedmatandoriginallyintherandom
orientedfibreform.Thefibreswereuntreated(no surface modification).
Epoxyresin(ZeepoxyHL002TA)andhardener (Zeepoxy HL002 TB) that
generally being used for hand lay-up that cure at room temperature
were used as matrix of the composites. The low viscosity of the
resins allows easyhandlingandgivesgoodwettingofreinforcement
andsubstrates.Otherspecialfeaturesofthisresinare
longpot-life,highheatdistortiontemperature,andgood mechanical
properties. Custom made mould made from two rectangular mild steel
sheets having dimensions of 600mm x 600mm with
rectangularframewithuniformframewidthof40mm and thickness of 3 mm
were prepared. Thefunctionsoftheseplatesandframeareto
compressthefibreafterepoxyisapplied,maintain
specimenthickness,andalsoasacovertoavoidthe
debrisfromenteringintocompositepartsduringthe
curingtime.Themouldthenwascleanedandrelease
agent(wax)wasappliedonthe mouldbeforebeinglay-up with the fibre.
Fig. 1. Semi-finished product of coconut coir fibre pressed mat
Mohd Amirul Abdul Rahman et al. Copyright 2014 Praise Worthy Prize
S.r.l. - All rights reserved International Review of Mechanical
Engineering, Vol. 8, N. 1 91 Epoxy resin and epoxy hardener with
weight ratio 2:1 were thoroughly mixed together before uniformly
poured onthefibre.Thecurewasdonewhenfibreandepoxy
mixturebeingcompressedusingcompressedmachine
withappliedpressure1.64MPaforcuringtimeof48 hours at room
temperature (303K). Fig.2showsthesampleoffabricatedpanel.Six
categoriesofsampleswerepreparedfordifferentfibre
weightratiorangingfrom20%,25%,30%,35%,40% and 50% with epoxy
resins. Fig. 2. Random oriented pressed mat coir fibre/epoxy
composite Thefabricatedsampleswerecutintotherequired sizes and
numbers prescribed in the standard mechanical
testandundergonetensile,flexuralandtorsiontestwith accordance to
ASTM D 3039, ASTM D 790, and ASTM
D198relativelytoobtainmechanicalpropertiesofthe
materialincludingtensilestrength,tensilemodulusand shear modulus.
The data have been recorded.
Forthetensiletest,thesampleswhichdimensionof 250 mm 25 mm 2.5 mm
were prepared and test under
roomtemperatureandtestspeedof2mm/minona10 kN InstronUniversal
TestingMachinetoobtainaverage
YoungModulusforeachfiberweightpercentage.The
threepointflexuraltestwasdonebyusing5kNInstron Universal Testing
Machine test speed of 2 mm/min under room temperature. Figs. 3.
Mechanical tests: (a) tensile test(b) flexural test (c) torsion
test Thesampledimensionusedforthetestis100mmx
25mmx2.5mmandflexuralmodulusandflexural
strengthdatawererecorded.Shearmodulus,Gdata
wererecordedfromtorsiontestbyusingNorwood50
NmTorsionalTestingMachineunderroomtemperature
andrateoftwistof(0.16rad/m)/min.Allthetestsare
repeatedforeachfibreweightpercentagetoobtainthe
averagevaluesforeachtypeofmechanicalproperties data. III.Results
and Discussion TableIbelowpresentsthecalculatedaveragetensile
modulusandflexuralfor20%to50%weightcoirfibre
compositecompositions.Theresultshadshownthe
compositeswith25%fiberloadingpercentagerecorded
averagehighesttensilemodulus,Ewhichis17.42MPa while the lowest is
1.754 MPa that belongs to 40% fiber
loadingpercentagesample.Oneshouldsaythereis
decrementinvalueofEforincreasingamountoffiber loading and
decreasing amount of epoxy
resins.Therefore,thegreaterfibreloadingcomposition,the
stifferthecompositeorthehighercompositeresistance to elastic
deformation that results from the application of a given stress.
TABLE I AVERAGE FLEXURAL MODULUS AND TENSILE MODULUS OF ELASTICITY
Weight % of coir fiber Flexural Modulus of Elasticity (Mpa) Tensile
Modulus of Elasticity (Mpa) 2042.89.906 2574.0217.423 3044.6615.324
3512.4511.868 407.0431.622 5013.3271.754 The similar pattern also
shown in the flexural modulus and flexural strength data as
depicted in Table I and Fig.
4wheretheamountofcoirfibreinfluencedthe mechanical properties
recorded. Theflexuralstrengthandmodulustendstodecrease with the
amount of fibre and the highest flexural modulus
is74.02MPaandthehighestflexuralstrengthis58.59 MPa,both belongto25%
fibreloadingwhile the lowest
belongsto40%fibreloading.Asafirstcomment,the
higherthan35%coirfiberloadingpanelsshownthe
higherflexibilitybehaviourwhicharesoftand deformable while the less
than 35% wt coir fibre loading
panelsshowmorerigidbehaviourwhicharestiffand relatively hard.
Therefore,upto35%fibresloadingthefabricated composite panels is
structural-like materials while above
thispercentage,theepoxyresinsdoesnotproperly impregnate the fibres.
Lackofefficientreinforcementbycoirfibresmight
attributetotheirlowmodulusofelasticityascommon behaviour for other
natural fibres. Mohd Amirul Abdul Rahman et al. Copyright 2014
Praise Worthy Prize S.r.l. - All rights reserved International
Review of Mechanical Engineering, Vol. 8, N. 1 92 Fig. 4. Variation
of the flexural strength with the mass fraction of coir fibre The
resultsthan compared to theflexural strength for
pressedmatcoirfiber-polyestercompositeundertwo different
fabrication compression pressures which are 2.6 MPa and 5.2 MPa
that was done by Monteiro et. al [9] as
showninFig.5.Thissuggeststhestrengthtendsto
decreasewiththeamountoffiberandrevealsthatthe
randomlyorientedcoirfibersarenotreinforcingneither
epoxymatrixnorpolyestermatrixatall.Several
measurementpoints(25%and35%wtfibre)hadnot
beenincludedinMonteirowork.Besidesthat,the different in pressures
didnot be a major influence to the value of flexural strength
compared to the difference type of matrix that has been used. Fig.
5. Variation of the flexural strength with the mass fraction of
coir fibre for different compression fabrication pressures
TableIshowsthecomparisonbetweenflexural
modulusofelasticityandtensilemodulusofelasticity.
Generally,theelasticmoduliachievedfromtheflexural
testaregenerallyclosetotheelasticmodulusobtained from tensile test
using the same material.
However,thereareseveralfactorsthatmightaffect
theelasticmodulus,whichare1)elasticandplastic
deformationattherollersatthesupportsortheloading
pointsmightnotbesufficientlysmallincomparisonto
thebeamdeflection;2)ifashortspecimenisflexural
tested,deformationduetoshearstressmaytakeplace,
whicharenotidealforthecalculationaccordingtothe
beamtheory;3)materialsmighthavedifferentelastic modulus under
flexural and tension. Therefore,theaverageelasticmodulusinflexural
shouldbeidentifiedtoanyavoidconfusionsforthe interpretation of the
mechanical behaviour of the material
[10]-[11].Thedeterminationoftorsionalproperties, shear modulus, G
was done by using torsion test.
FromFig.6oftheaverageshearmodulusforeach
fibreloadingpercentage,the20%fibreloading
percentagerecordedhighestaverageshearmodulus while 50% fibre
loading percentage recorded the lowest.The imposition of torsional
stresses also evokes elastic
behavioursameliketensionstresssincetherandomly
orientedfibrescompositecouldbeconsideredasan isotropic materials.
Therefore,theshearmodulusdataobtainedcouldbe
usedforfurthersupportingthetensilemodulusand
flexuralmodulusdataobtainedwhichagreedthatthe
higherthan35%coirfiberloadingpanelsshownthe
higherflexibilitybehaviourwhicharesoftand deformable while the less
than 35% wt coir fiber loading
panelsshowmorerigidbehaviourwhicharestiffand relatively hard. Fig.
6. Variation of the average shear modulus with the mass fraction of
coir fibre Forthefurthercommercialandresearchinterest,the
coirfibrecompositemightbefurtherusedasa
alternativesreplacementmaterialfornon-critical
structureforfurniture,buildingfurnished,automotive
andaerospaceparts.Itmightbetailored,modified,or
hybridizeintootherconventionalcompositeormaterial
inordertoincreasethematerialperformanceforthe future works and use
depending on the purposes. IV.Conclusion
Itcanbeconcludedthattheamountofcirfibre
loadingplayedanimportantroleindeterminationof
stiffnesslevelofthecomposite.Tthelessthan35%wt
coirfiberloadingpanelsshowmorerigidbehaviour which are stiff and
relatively hard while greater than 35%
coirfiberloadingpanelsshownthehigherflexibility behaviour which are
soft and deformable. Thecoirfibreshowsthecommonbehavioursimilar
likesothernaturalplantfibrewhichislackofefficient
reinforcementthatleadtotheirlowstiffnesslevel 0204060800 20 40
60Weight of Coir Fiber (wt.%)0204060800 20 40 60Weight of Cor Fiber
(wt.%)Pressure 1.3MPaPressure 2.6MPaPressure
5.2MPa00,0010,0020,0030,0040 20 40 60Fiber wt. (%) Mohd Amirul
Abdul Rahman et al. Copyright 2014 Praise Worthy Prize S.r.l. - All
rights reserved International Review of Mechanical Engineering,
Vol. 8, N. 1 93 comparedtootherconventionalcomposites.The
preliminarydataestablishedinthisresearchmightbe served as a
reference for further studies. Acknowledgements
Theauthoracknowledgeallthemembersofthe research for their support.
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information MohdAmirulAbdulRahmanbornin14
November1986inMuar,Johor,Malaysia.He
obtainedhisBachelorDegreeinEngineering
(Aerospace)in2010fromInternationalIslamic University
Malaysia.Currently studyingMaster
ofScienceAerosapceEngineeringbyresearch in Universiti Putra
Malaysia, Serdang, Selangor, Malaysia.Hismajorfieldofstudyis
experimental aeroelasticity and natural composite. E-mail:
[email protected] MunaimAliOmarBakiwasbornin1985.
Theauthorstartedhistertiaryeducationat matriculation level in 2003
at Kolej Matrikulasi Johor,Tangkak,johor.Heobtainedhis
BachelorDegreeofAircraftEngineering
Technology(Mechanical)in2011atUniKL
MalaysiaInstituiteofAviationTechnology
(MIAT),Dengkil,Selangor.Currentlystudying
MasterofScienceAerospaceEngineeringbyresearchinUniversiti
PutraMalaysia,Serdang,Selangor,Malaysia.Heconcentratingin study of
ballisctic impact and natural composite. E-mail:
[email protected] Dr.AzminShakrineMohdRafieisalecturer
inAerospaceengineeringdepartmentat
UniversitiPutraMalaysia.Hewasenrolledto
Dip.Eng.Programin1192atUniversiti
TeknologiMalaysiaforthreeyears.Thenhe
continuedhisstudynbachelorprograminthe
sameiuniversity.Hegraduatedin1998with B.Eng in Mechanical
Engineering (Aeronautic). He joined the same university as a
research assistant from 1998 to 2001
andatthesametimeenrolledthemasterprograminaeronautic engineering.
In 2002 he obtained his M.Eng Degree and joint Universiti
PutraMalaysiaastutor.InNovember2003,hefurtherhisstudiedin PhD
program in aerospace engineering at Universiti Putra Malaysia. He
thenreceivedhisPhDin2007.Hisresearchdedicatedtothe
ExperimentalAerodynamicandAeroelasticity.Hehisamongthe
pioneerindevelopingtheexperimentalworkonaeroelasticityfieldin
Malaysia.Hiscurrentresearchinterestisprimarilyindeveloping
experimentalaeroelasticityandaerodynamicespeciallyincomposite
material. E-mail: [email protected]
RenuganthVaratharajooreceivedPh.D.In
SpacecraftSysytemsfromDresdenUniversity
ofTechnology(germany)in2003.Heis
currentlyalecturer/reseacrcheratUniversity
PutraMalaysia.Heteachessapcerealted
courses.Hisresearchfocuseson1)spacecraft
navifgationandcontrol;2)combinedattitude
controlsystems;and3)rockettrajectory
optimisation.Hehasauthorednumerouspublicationsonthesubject matter.
He is also acting as a reviewer for a few aerospace journals.
E-mail: [email protected]