Mechanicaland water absorption behavior of continuous untreated and alkali treated Arecapalm leaf stalk fiber reinforced polymer composites. 1 N.

Shanmugasundaram,² I.Rajendran, 3M. Jayaraj and  4I.

Aravindhaguru 1,2 Department of Mechanical Engineering, Dr.Mahalingam College ofEngineering and Technology, Pollachi-642003, Tamilnadu, India 3,4 Department ofMechanical Engineering, PA College of Engineering and Technology,Pollachi-642002, Tamilnadu, India  ABSTRACT     The continuous untreated and alkalitreated areca palm leaf stalk fiber reinforced polymer composites werefabricated by compression mould technique. The composites were evaluated basedon mechanical properties such as tensile, flexural, impact and water absorptionbehavior. The weight fraction of the fiber and matrix was fixed as 30:70 in thecomposite. The mechanical property result shows that the alkali treatedcontinuous areca palm leaf stalk fiber composites gave good result compared toraw continuous areca palm leaf stalk fiber composites. The fracture behavior ofraw and alkali treated areca palm leaf stalk fiber composites were analyzed byscanning electron microscope (SEM).      Key words : Areca palm leaf stalk fiber,Mechanical properties, Weight fraction, Scanning Electron Microscope    Introduction      Eco friendly fiber composite materials are one such competent material which replaces the usual and synthetic materials for the light load applications where we require less weight and energy conservation.

The Global market is promptly moving towards the energy conservation and energy reduction process. Generally the natural fibers were frequently used to reduce the weight of the components i.e. the fibers are reinforced with the suitable matrix.

In the aspect of cost, renewable and biodegradability, the natural plant fibers have plenty of advantages when compare to the synthetic fibers. Several authors carried out their research in the area of natural fibers (SathishkumarT.P, Navaneethakrishnan.P et al.2012). Investigate the various of mechanical properties of tensile and flexural properties of randomly distributed unsaturated polyester resin with sisal/carbon fibre reinforced hybrid composites with different weight ratio fiber and compared with various natural fiber(P.

Noorunnisa Khanam et al.2010). Analysed the mechanical properties such as tensile, compressive, flexural, impact strength and water absorption of the alkali treated continuous Agave fibre reinforced epoxy composite (TCEC) and untreated continuous Agave fibre reinforced epoxy composite (UTCEC) (K.Mylsamy et.

al 2011). studied the effect of surface modifications on sisal fiber properties as well as on fiber/poly (lactic acid) (PLA) interface adhesion. (A. Orue et.al 2015)  The compared  mechanical properties were such as  tensile, flexural, and impact strengths of roselle and sisal fibers hybrid polyester composite at dried up and wet conditions were studied When length of the fiber            *Corresponding author: E-mail: [email protected]

com2were increased, the tensile andflexural strength of the composite improved (Athijayamania A,Thiruchitrambalamb M et. al 2009). Examine the manipulate of fibre morphologyof varous natural fibres on the composites physical and mechanical propertiesand on the fibre breakage due to extrusion process(Kristiina Oksman et.al 2009).Effect of properties due tothe  weaving patterns and randomorientatation on the properties of banana, kenaf and banana/kenaffiber-reinforced hybrid polyester composites.

 The maximum increase inmechanical strength was observed in the plain woven hybrid composites ratherthan in randomly oriented composites(Alavudeenet.al 2015). Studied the static and dynamic mechanical properties of alkalitreated continuous Palmyra Palm Leaf Stalk Fiber (PPLSF) and jute fibersreinforced  hybrid polyester composites. Increasing jute fiber loadingshowed a considerable increase in tensile and flexural properties of the hybridcomposites as compared to treated PPLSF composites(D. Shanmugam et.al 2013).

Studies on the behavior of pineapple leaf fibers treated with NaOH and modifiedwith two different functionalities were attempted by (Threepopnatkul et. al 2009).Based on the above literature survey the fibers were treated with 5%NaOHsolution and the effects on mechanical and water absorption behavior  of treated continuous Areca palm leaf stalkfiber composites were studied and the results are compared with raw continuousAreca palm leaf stalk fiber composites. Methods and Materials Polyester Resin The isopthallic unsaturated polyesterresin is used as a matrix to fabricate the composites. The curing agent’saccelerator (Methyl Ethyl Ketone Peroxide) and the catalyst (CobaltNaphthalene) are used to cure the resin. The chemicals were procured form CovaiSeenu and Company, Coimbatore, India.

The mechanical properties of isophthallicresin are very high and water absorption property was very low compare to otherresin.  Extraction of fiber  The Areca palm leaf stalk fibers wereextracted from Areca palm leaf stalks. The required quantities of stalks werecollected and leaves were removed and dried at the sunlight for a week. After aweek the stalks were trimmed into separate pieces and immersed in the water   for four weeks and the fibers wereextracted by mechanical retting process. Alkali treatment of fiber  The continuously untreated areca palmleaf stalk fibers were immersed with 5% sodium hydroxide (NaOH) solution for30min.The fibers were washed with flow water and then washed with very dilutehydrochloric acid (HCI) continuously till the fibers were free from alkali.Then the continuously treated areca palm leaf stalk fibers were dried at roomtemperature for 2 to 3 days.

 Fabrication of composites The rectangular mild steel plate of200x 150x10mm3 was used to fabricate the composites. The mould was assembledwith top and bottom plate. The continuous fibers were longitudinallydistributed inside the bottom plate and cover with top plate to compress themould for 15mintues to produce a fiber mat of 5mm thickness.

The mat was takenaway from the mould and kept separate. Then the mould was cleaned and releasingagent was applied on the mould to easy removal of composite after curing. Thematrix was prepared with adding of accelerator and catalyst in isophthallicresin to stir continuously to ensure homogeneity. The fiber mat is placed againin the bottom plate and the matrix was poured in the bottom die and top plateis used to cover the bottom plate. The uniform pressure of 1ton was applied for12 hours continuously to top and bottom plate to compress the composite. Afterthat the composite plate was taken away from the mould and cut into ASTMstandard size for different tests. The continuous untreated areca palm leafstalk fiber composites were named as UAFC for treated areca palm leaf stalkfiber composites were named as TAFC.  Tensile test  The tensile tests of the compositeswere determined according to ASTM D 638-Type I.

Initially the tensile specimenswere cut from the fabricated composite plate. The test was conducted usingInstron tensile testing machine with crosshead speed of 5mm/min with gaugelength of 57mm. Five specimens were tested and average values were showed.

   Flexural test  The three pointbending tests of the composites were conducted according to ASTM D 790. Thesize of 127 X12.7 X5mm3 was cut from the fabricated composite plate. The Lloyd instrument LR with100 KN was used to conduct the flexural strength with cross head speed of1mm/min. Five specimens were tested and average values were calculated.

 Impact test The Izod impacttester was used to conducted impact tests according to ASTM D 256. The size of64X13X5mm3 was cut from fabricated composite plate. Five specimens were testedand average values were reported. Water absorption test  The specimens werecut from the fabricated composite plates according to the ASTM D 570-98. Thesize of the specimen was 76.2X25.4X5 mm3 used to conduct the tests. Initiallythe dry specimen’s weight was noted using electronic balancing machine withaccuracy of 0.

00001mg. The specimens were immersed in the distilled water andremoved from the water at regular interval of time. Then the specimens werecleaned using issue paper to remove the excess water present on the specimensurface and the measure the weight of the samples. The initial weight of thedry sample to final weight of wet sample provides the percentage of waterabsorbed by the composite.    Scanning electron microscopy The scanningelectron microscopy(SEM) model JEOL 6390 at accelerating voltage of 10 kV wereused to analyze the fracture behavior of continuous areca palm leaf stalk untreated and treated fiber compositessurfaces.  Results and discussions Tensile properties        The effects of alkali treatment ontensile properties of continuous areca palm leaf stalk fiber reinforcedcomposites were explored.

The TAFC shows better improvement in tensile strengthand tensile modulus compared to UAFC. The UAFC showed 15% increased in tensilestrength compared to neat resin. The tensile stress vs tensile curves showed (Figure1) that the load increases to certain limit the UAFC failed due to poor bondingbetween fiber and matrix. (D.

Shanmugam et. al 2012).   The TAFC showed(Figure 2) around 38% and 55% improvement in tensile strength and tensilemodulus (Figure 3) compared to matrix and UAFC.  3             Fig 1.Tensile stress vs tensilestrain for UAFC and TAFC             Fig 2.

Tensile strength of UAFC andTAFC                 Fig 3.Tensile strengthof UAFC and TAFC Flexural properties Theflexural strength and flexural modulus of UAFC and TAFC were shown in Figure 4and 5. The TAFC were increased 28% and 11% of flexural strength compared tomatrix and UAFC.4  It is interesting to observe thatthe chemical bonding between the fiber and the matrix in the TAFC showed morestrength because of more shrinkage and toughness inbuilt in the composites. Theflexural modulus increased by 51% and 34% than matrix and TAFC.                    Fig 4.

Flexural strengthof UAFC and TAFC   This indicates that the fiberorientation in the longitudinal direction increase the areas of contact betweenfiber and matrix and improves the adhesion (Nam TH et. al 2011)    The impact properties of thecomposites were highly correlated to adhesion strength between matrix andreinforcement, the properties of matrix and reinforcement (Sreenivasan VS,Ravindran D et. al 2012) The TAFC had 67% and 43% increase in impact energyabsorbed for failure which corresponds to 58% and 32% increase in impactstrength compared to matrix.               Fig 6.

Impact energy ofUAFC and TAFC   In the case TAFC, better interlocking among the fiber and matrix has allowed for more energy absorption and to stop the propagation of crack resulting in a notable improvement in impact properties (impact strength and impact energy) compared to matrix and UAFC.   Water absorption properties   The natural fibers as reinforcement in polymer matrix is more sensitive to water which will cause the poor dimensional stability (Dhakal HN et. al 2001) and will reduce the mechanical properties of the composite. Figure 8 shows the function of water                     Fig 7.Impact Strengthof UAFC and TAFC           Fig 5. Flexural Modulusof UAFC and TAFC Impact properties The surfacemodification of the fiber influence the impact energy and impact strength ofthe composites is shown in Figure 6 and Figure 7. absorptionproperties of UAFC and TAFC.

The results were recorded for every 30min intervaland results shows that TAFC absorb less water compared to UAFC.            Fig 8.Water absorptionof UAFC and TAFC The UAFC uptakemore water due to the high amount of hemicellouse, lignin and other impuritiespresent in the fiber. The alkali treatment removes the hemicellouse, lignin andother impurities and leading to good mechanical bonding between fiber and matrix.The water absorption in the composites was found to be 8%, 5% for UAFC after180min. Conclusions The influence ofalkai treatments on mechanical and water absorption behaviour of continuousareca palm leaf stalk fiber composites were experimentally determined and thefollowing conclusions are arrived.

 The alkali treatedcontinuous areca palm leaf stalk fiber  composites (TAFC) had an increased by 38% in tensile strength andtensile modulus increased by 55% respectively, compared to untreated continuousareca palm leaf stalk fiber composites (UAFC) due to better load transferbetween the fibers and matrix. The alkali treatedcontinuous areca palm leaf stalk fiber composites (TAFC) had better flexuraland impact properties compared to untreated continuous areca palm leaf stalkfiber composites (UAFC) which was due to better interfacial adhesion betweenthe fibers and matrix. The alkali treatedcontinuous areca palm leaf stalk fiber composites (TAFC) have decreased theamount of water absorption compared to untreated continuous areca palm leafstalk fiber composites (UAFC).

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