Evaluation of Properties of Hybrid Natural Short Fiber Reinforced Composites

Transcription

1 Evaluation of Properties of Hybrid Natural Short Fiber Reinforced Coposites S. Vashikrishna Assistant Professor, Departent of Mechanical Engineering, Kaala Institute of Technology and Science, Karinagar TS, India. M. Pradeep Kuar Assistant Professor, Departent of Mechanical Engineering, Kaala Institute of Technology and Science, Karinagar TS, India. K. Vikra Kuar Assistant Professor, Departent of Mechanical Engineering, Kaala Institute of Technology and Science, Karinagar TS, India. Abstract Hybrid coposites have taken the attention of any researchers as a way to enhance echanical properties of coposites. However, hybrid coposites using natural fibers are less studied. And in such studies, the hybrid coposite often consists of natural fibers are ebedded in the resin atrix. The ai of present work is to prepare the lainas using the Hibiscus Cannabinus, Thespesia lapas short fiber polyester coposites fiber using general purpose unsaturated Isopthalic resin by hand lay-up process. The fibers without cheical treatent and with cheical treatent with sodiu hydroxide (NaOH) are considered in the work. The coposites are prepared using NaOH treated & untreated short fibers with polyester atrix at roo teperature between two thick glass plates. The prepared coposites are tested as per ASTM standards for flexural test and SEM analysis have been done to study the orphology of the hybrid coposite. Index Ters Hibiscus Cannabinus, Thespesia Lapas, Isopthalic resin. 1. INTRODUCTION A coposite is cobination of two aterials in which one of the aterials, called the reinforcing phase, is in the for of fibers, sheets, or particles, and is ebedded in the other aterials called the atrix phase. Coposites typically have a fiber or particle phase that is stiffer and stronger than the continuous atrix phase and serve as the principal load carrying ebers. The atrix acts as a load transfer ediu between fibers, and in less ideal cases where the loads are coplex, the atrix ay even have to bear loads transverse to the fiber axis. The atrix is ore ductile than the fibers and thus acts as a source of coposite toughness. The atrix also serves to protect the fibers fro environental daage before, during and after coposite processing. When designed properly, the new cobined aterial exhibits better strength than would each individual aterial. Coposites are used not only for their structural properties, but also for electrical, theral, tribological, and environental applications. Hybrid coposites are ore advanced coposites as copared to conventional FRP coposites. Hybrids can have ore than one reinforcing phase and a single atrix phase or single reinforcing phase with ultiple atrix phases or ultiple reinforcing and ultiple atrix phases. They have better flexibility as copared to other fiber reinforced coposites. Norally it contains a high odulus fiber with low odulus fiber. The high-odulus fiber provides the stiffness and load bearing qualities, whereas the low-odulus fiber akes the coposite ore daage tolerant and keeps the aterial cost low. The echanical properties of a hybrid coposite can be varied by changing volue ratio and stacking sequence of different plies. The interest in natural fiber-reinforced polyer coposite aterials is rapidly growing both in ters of their industrial applications and fundaental research. They are renewable, cheap, copletely or partially recyclable, and biodegradable. Plants, such as flax, cotton, hep, jute, sisal, kenaf, pineapple, raie, baboo, banana, etc., as well as wood, used fro tie ieorial as a source of lignocellulosic fibers, are ore and ore often applied as the reinforceent of coposites. Their availability, renewability, low density, and price as well as satisfactory echanical properties ake the an attractive ecological alternative to glass, carbon and an-ade fibers used for the anufacturing of coposites. The natural fiber Containing coposites are ore environentally friendly, and are used in transportation (autoobiles, railway coaches, aerospace), ilitary applications, building and construction industries (ceiling paneling, partition boards), packaging, consuer products, etc. ISSN: EverScience Publications 51

2 . LITERATURE REVIEW K.V. Arun, S. Basavarajappa, B.S. Sherigara [1] carried out experiental analysis on glass/textile fabric reinforced hybrid coposites under noral condition and sea water environents have been reported. The critical stress intensity factor, interlainar shear strength and ipact toughness have been evaluated, both in interlainar and translainar directions. The atrix aterial used was a ediu viscosity epoxy resin and fibers are plain weave E-glass fabric and silk based textile fabric. Yi Zou, Shah Huda, Yiqi Yang [] studied the tensile strength, flexural strength, ipact strength and sound absorption properties of lainas ade of Whole and split wheat straws (WS) have been used with polypropylene (PP). Supranee Sangthong, Thirawudh Pongprayoon, Nantaya Yanuet [3] studied the echanical property iproveent of unsaturated polyester coposite reinforced with adicellartreated sisal fibers. P. Tyhreepopnatkul, N. Kaerkitcha, N. Athipongarporn [4] studied the echanical properties like tensile strength, ipact strength, And therogravietric analysis (TGA). The odified fiber identified using a Fourier transfor infrared spectroscopy (FTIR) of lainas ade of pineapple leaf fiber (PALF) polycarbonate coposites. Y-Xu, S.Kawata, K.Hosoi, K.kawai and S.Kuroda [5] studied the dynaic thero echanical properties of the salinized-kenaf polystyrene coposites. The polyeric coupling agent treatent of the kenaf fiber increased the fiber atrix interaction. The DMA results showed that the odified fiber coposites have higher storage odulus and lower loss factor. Byoung-Ho Lee, Hyun-Joong Ki, and Woong-Ryeol Yu [6] studied about Fabrication of Long and Discontinuous Natural Fiber Reinforced Polypropylene Biocoposites and Their Mechanical Properties. Mehdi Jonoobi, Jalaludin Harun,Alireza Shakeri,Manjusri Misra and Kristiina Oksan [7] studied the cheical, crystallinity and theral degradation of bleached and unbleached Hibiscus cannabinus pulp and nanofibers. Theral stability increased in the aterial having undergone cheo-echanical treatents. A.S. Singha and Vijay Kuar Thakur [8] studied theral and echanical properties of Grewia optiva fiber reinforced Urea- Foraldehyde (UF) atrix based polyer coposites. Mechanical properties such as: tensile strength, copressive strength and wear resistance of urea - foraldehyde resin increases to a significant extent when reinforced with Grewia optiva fiber. Morphological and Theral studies of the atrix and fiber reinforced biocoposites have also been carried out. Therogravietric analysis (TGA) of aterials such as raw Grewia optiva fiber, polyeric UF resin and biocoposites was investigated as a function of % weight loss with the increase in teperature. Morsyleide F. Rosa, Bor-sen Chiou, Eliton S. Medeiros, Delilah F. Wood, Tina G. Willias, Luiz H.C. Mattoso, Willia J. Orts, Syed H. Ia[9] studied the Coir fibers which received three treatents, naely washing with water, alkali treatent (ercerization) and bleaching. Treated fibers were incorporated in starch/ethylene vinyl alcohol copolyers (EVOH) blends. Mechanical and theral properties of starch/evoh/coir biocoposites were evaluated.treatents produced surface odifications and iproved the theral stability of the fibers and consequently of the coposites. 3. TREATMENT OF FIBER The quality of a fiber reinforced coposite depends considerably on the fiber-atrix interface because the interface acts as a binder and transfers stress between the treatents of fibers using cheical agent like sodiu hydroxide (NaOH). For treatent process water by volue is taken along with % of NaOH. The fibers are soaked in the water for 4 hours as shown in Figure 1, and then the fibers are washed thoroughly with distilled water to reove the final residues of alkali. Good bonding is expected due to iproved wetting of fibers with the atrix. In order to develop coposites with better echanical properties and good environental perforance, it is necessary to ipart fibers by cheical treatents. The extracted fibres treated, untreated and chopped fibres are shown in figure (a) and figure (b) Figure 1 Treatent of Fiber in % NaOH solution Figure (a) Treated and Untreated fibers Figure (b) Chopped fiber ISSN: EverScience Publications 5

3 4. PREPARATION OF LAMINA The coposites are prepared by hand layup technique shown in the figure 3. The hand layup is the one of the Fabrication technique. First Wax polish is applied on the surfaces of the base plates and poly vinyl alcohol (PVA) is applied with a brush and allowed to dry for few inutes to for a thin layer. These two ites will help in easy reoval of the lainate fro the base plates. Figure 5 Isopthalic, Glass Plate, Surface Plate. Figure 3 Hand Lay-Up Method The fiber piles were cut to size fro the Kenaf and thespesia lapas. The appropriate nubers of fiber plies were taken two for each. Then the fibers were weighed and accordingly the resin and hardeners were weighed. Isopathlic and hardener were ixed by using glass rod in a bowl. Care was taken to avoid foration of bubbles. Because the air bubbles were trapped in atrix ay result failure in the aterial. The subsequent fabrication process consisted of first putting a releasing fil on the ould surface. Next a polyer coating was applied on the sheets. Then fiber ply of one kind was put and proper rolling was done. Then resin was again applied, next to it fiber ply of another kind was put and rolled. Rolling was done using cylindrical ild steel rod. This procedure was repeated until eight alternating fibers have been laid. On the top of the last ply a polyer coating is done which serves to ensure a good surface finish. Finally a releasing sheet was put on the top; a light rolling was carried out. Then a 0 kgf weight was applied on the coposite. It was left for 4 hrs to allow sufficient tie for curing and subsequent hardening. The various additives used for the process are shown in the figure 4 and 5. Figure 6 shows coposites after preparation. Figure 6 Hybrid coposites 5. SPECIMEN PREPARATION AND TESTING Flexural Test Specien Speciens for flexural test are cut fro lainas as per ASTM D790 standards [10]. The standard diensions for test specien are shown in the Figure 7 and the actual speciens are shown in Figure 8. Figure 7 ASTM D790 Flexural Test Specien Details. [10] Figure 4 Wax, Accelerator, MEKP Testing a) Flexural Test: Figure 8 Flexural Test Speciens Flexural strength is the ability of the aterial to withstand bending forces applied perpendicular to its longitudinal axis. ISSN: EverScience Publications 53

4 Soetie it is referred as cross breaking strength where axiu stress developed when a bar-shaped test piece, acting as a siple bea, is subjected to a bending force perpendicular to the bar. This stress decreased due to the flexural load is a cobination of copressive and tensile stresses. There are two ethods that cover the deterination of flexural properties of aterial: three-point loading syste and four point loading syste. As described in ASTM D790, threepoint loading syste applied on a supported bea was utilized. Flexural test is iportant for designer as well as anufacturer in the for of a bea. If the service failure is significant in bending, flexural test is ore relevant for design and specification purpose than tensile test. Figure 9 (a & b) Flexural Test Setup. Flexural test was done by copression testing achine supplied by Hydraulic and Engineering Instruents, New Delhi, with a cross head speed of 1.5 /inute at standard laboratory atosphere of 3 C ± C (73.4 F ± 3.6 F) and 50 ± 5 percent relative huidity. There were two iportant paraeters being deterined in the flexural test, they are flexural strength and tangent odulus of elasticity in bending. σ f = 3PL bd (1) Where σ f = Stress in the outer specien at idpoint, MPa N Flexural Modulus P = Load at a given point on the load deflection curve, L = Support span, b = width of bea tested, d = depth of bea tested, Flexural odulus or Modulus of elasticity is a easure of the stiffness during the initial of the bending process. This tangent odulus is the ratio within the elastic liit of stress to corresponding strain. A tangent line will be drawn to the steepest initial straight line portion of the load deflection curve and the value can be calculated using equation E B = L3 4bd () Where E B = odulus of elasticity in bending (MPa) L = support span = slope of the tangent to the initial straight line portion of the load deflection curve of deflection (N/) b) Morphology b = width of bea tested d = depth of bea tested For orphological study, Scanning Electron Microscope (SEM) was used to reveal the nature of the bond between the fibers and atrix. It is an instruent for obtaining icro structural iages using a scanning electron bea. In the SEM, a sall electron bea spot (usually circa 1μ) is scanned repeatedly over the surface area of the saple. The iportance of SEM is it produces iage that likes a visual iage of a large scale piece which allows the irregular surface of the aterial to be observed. Figure 10: Flexural Test Speciens after Testing. Flexural Strength Flexural strength is the axiu stress in the outer specien at the oent of break. When the hoogeneous elastic aterial is tested with three-point syste, the axiu stress occurs at the idpoint. This stress can be evaluated for any point on the load deflection curve using equation. Figure 11 EVOMA15 Scanning Electron Microscope [11] ISSN: EverScience Publications 54

5 In this testing EVOMA15 Scanning Electron Microscope was used. The photo of this equipent is shown in Figure 11. The fractured speciens were placed on a stub, coated with platinu and inserted into the scanning barrel. The inter condition of the scanning barrel were vacuued to prevent interference of scanning picture due to the presence of air. Magnification, focus, contrast and brightness of the result were adjusted to produce the best icrographs. Flexural Testing 6. RESULTS AND DISCUSSIONS Table 1 Flexure Test observations for Hybrid fiber 4 T coposite Specien specien specien Table Mean values of flexure test observations for Hybrid fiber 4 T coposite. Mean Load Stress in outer fiber (N/ ) Table: 3 Flexure Test observations for hybrid fiber 4 UT coposite Specien 1 Specien Specien Table 4 Mean values of flexure test observations for 4 hybrid fiber 4 UT coposite. Mean Load Stress in outer fiber (N/ ) Table 5 Flexure Test observations for hybrid fiber 6 T coposite Specien 1 Specien Specien Table 6: Mean values of flexure test observations for hybrid fiber 6 T coposite. Mean Load Stress in outer fiber (N/ ) ISSN: EverScience Publications 55

6 Table 7 Flexure Test observations for hybrid fiber 6 UT coposite specien 1 specien Table 8: Mean values of flexure test observations for hybrid fiber 6 UT laina. Mean Stress in outer Load fiber (N/ ) specien 3 Figure 1 Flexural Stress Curve. The figure shows Curve between flexural stress (N/ ) and deflection. Treated laina have flexural strength is higher copare to untreated hybrid laina. Table 9: Flexural strength, Specific flexural strength, Flexural Modulus and specific Flexural Modulus for different coposites Treatent Untreate d Alkali Treated Length Flexural Strength (MPa) Specific Flexural strength Flexural Modulus (MPa) Specific Flexural Modulus (MPa/ g/c³) Figure 13 Flexural length of fiber ISSN: EverScience Publications 56

7 Figure 14 Flexural Strength for Different coposites. It is observed that 8 fiber length coposites were optial flexural strength than 4 and 6 fiber length coposites. Further it is observed that treated coposites possess higher aforeentioned properties than untreated. This is due to the alkali treatent iproves the adhesive characteristics kenaf and thespesia fiber surface by reoving heicellulose and lignin. This surface offers the excellent fiber-atrix interface adhesion as a results iproved echanical properties. Figure 17: Specific Flexural Modulus for Different lainas. Morphological Analysis Figure 15: Specific Flexural Strength for Different coposites. Figure 18 Micrograph of 4-UT Coposite Morphology of the coposites is studied using EVOMA15 sart SEM icrographs. Figure 18 shows the untreated fractured surface of the coposites. In case of untreated coposite laina, the fiber pullout can be observed in fractured surface due to poor bonding between fiber and resin. Figure 16: Flexural Modulus for Different coposites. Figure 19: icrograph of 4-T Coposite ISSN: EverScience Publications 57

8 Figure 19 shows the treated fractured surface of coposite. For treated coposite fiber surface treatent increased the bonding between fiber resin interfaces and the fracture of the fiber occurred instead of fiber pullout. Figure 0 Micrograph of 6-UT coposite Figure 0 shows the untreated, fractured surface of coposites. In this case the fiber pullout can be observed in fractured surface in figure 19 due to poor bonding between fiber and resin. Figure 1: Micrograph of 6-T coposite Figure 1 shows the treated fractured surface of coposites. For treated coposite laina the fiber surface treatent increased the bonding between fiber-resin interfaces and the fracture if fiber occurred instead of fiber pullout. 7. CONCLUSION The kenaf and Thespisa lapas fibers was successfully used to fabricate hybrid natural coposites with 30% fiber and 70 % resin, these fibers are bio degradable and highly crystalline with well aligned structure. So it has been known that they also have higher tensile strength than other natural and synthetic coposites and in turn it would not induce any serious environental proble like in synthetic fibers The variation of echanical properties like flexural test, and SEM analysis of Isopathalic based kenaf-thespeisia lapas hybrid coposites has been studied as function of fiber length. It is observed that 8 fiber length hybrid coposites are observed optial flexural than 4 and 6. Fro SEM icrograph it is clearly visible that fiber is nicely ebedded with atrix. These coposites ay find applications as structural aterials where higher strength and cost considerations are iportant. REFERENCES [1] K. V. Arun, S. Basavarajappa, B.S. Sherigara, Daage characterisation of glasstextile fabric polyer hybrid coposites in sea water environent. Materials and Design 31 (010), pp [] Yi Zou, Shah Huda, Yiqi Yang, Lightweight coposites fro long wheat straw and polypropylene web. Bioresource Technology 101 (010), pp [3] Supranee Sangthong, Thirawudh Pongprayoon, Nantaya Yanuet, Mechanical property iproveent of unsaturated polyester coposite reinforced with adicellar-treated sisal fibers. Coposites: Part A 40 (009), pp [4] P. Threepopnatkul, N. Kaerkitcha, N. Athipongarporn, Effect of surface treatent on perforance of pineapple leaf fiber polycarbonate coposites. Coposites: Part B 40 (009), pp [5] Y-Xu, S.Kawata, K.kawai and S.Kuroda Theroechanical properties of the silanized-kenaf/polystyrene coposites express Polyer Letters Vol.3, No.10 (009) [6] Byoung-Ho Lee, Hyun-Joong Ki, and Woong-Ryeol Yu Fabrication of Long and Discontinuous Natural Fiber Reinforced Polypropylene Biocoposites and Their Mechanical Properties Fibers and Polyers 009, Vol.10, No.1, [7] Mehdi Jonoobi.; Jalaludin Harun.; Alireza Shakeri.;,Manjusri Misra and Kristiina Oksan.; Cheical, Crystallinity, and Theral degradation of Bleached and Unnleached Hibiscus cannabinus pulp and Nanofibers, BioResources, 009, vol 4(), pp [8] Singha A.S.; and Vijay Kuar Thakur; Grewia optiva Fiber Reinforced Novel, Low Cost Polyer Coposites, 009, vol 6(1), pp [9] Morsyleide F. Rosa.; Bor-sen Chiou.; Eliton S. Medeiros.; Delilah F. Wood.; Tina G. Willias.; Luiz H.C. Mattoso.; Willia J. Orts.; and Syed H. Ia.; Effect of fiber treatents on tensile and theral properties of starch/ethylene vinyl alcohol copolyers/coir biocoposites, Bioresource Technology, 009, pp [10] ASTM D , Standard ethod of test for Flexural properties of Plastics, Aerican Society for Testing Materials (1961). [11] EVOMA15 Scanning Electron Microscope ANNA university Chennai. ISSN: EverScience Publications 58