- Email: [email protected]
Evaluation of mechanical properties of banana and sisal fiber reinforced epoxy composites: Influence of glass fiber hybridization
Materials and Design 64 (2014) 194–202
Contents lists available at ScienceDirect
Materials and Design journal homepage: www.elsevier.com/locate/matdes
Technical Report
Evaluation of mechanical properties of banana and sisal fiber reinforced epoxy composites: Influence of glass fiber hybridization V.P. Arthanarieswaran ⇑, A. Kumaravel, M. Kathirselvam Department of Mechanical Engineering, K.S. Rangasamy College of Technology, Tiruchengode 637 215, Tamil Nadu, India
a r t i c l e
i n f o
Article history: Received 12 June 2014 Accepted 27 July 2014 Available online 4 August 2014
a b s t r a c t In this work, the effect of glass fiber hybridization with the randomly oriented natural fibers has been analyzed. The banana (B), sisal (S) fibers were chopped and woven E-glass (G) synthetic fibers were reinforced with epoxy matrix. Nine different kinds of laminates were prepared in the following stacking sequence of B, S, BS, G/B/G, G/S/G, G/BS/G, G/B/G/B/G, G/S/G/S/G and G/BS/G/BS/G. Mechanical properties like tensile strength, flexural strength and impact strength were evaluated and compared. Interfacial analysis was also carried out with the help of Scanning Electron Microscope (SEM) to study the micro structural behavior of the tested specimen. It was observed that the addition of two and three layer of glass fiber can improve the tensile strength by a factor of 2.34 and 4.13 respectively. The flexural properties were enhanced on banana–sisal fiber with two layers of glass fibers rather than three layers and the laminate with sisal and three glass ply offers better impact strength. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Natural fibers are found superior to the artificial fibers with the properties like less weight, low density, eco-friendly, high specific strength etc. However, it has some of the disadvantages like poor surface characteristics, more moisture absorption, quality variations, etc. These natural fiber composites are commonly used in an automobiles, packaging industries, aerospace, construction and so on. The tensile load carrying capacity of the natural fiber reinforced composites are found to be increasing with the fiber content up to an optimum level and then start declining [1]. Recent novel fibers such as Prosopis juliflora, sansevieria ehrenbergii can also be used as reinforcement material in the composite structure [2,3]. Now a days’ conventional material for the medium load applications are replaced by the composite materials. Studies by Prasad and Rao [4] suggested that the jowar fiber can be used for fabrication of light weight components used in housing sector, automobile body building, packaging industry, partition panels, etc. Banana empty fruit bunch fiber is better in tensile strength than the neat polyester resin and it can be used in industrial applications such as partition panels and packaging [5]. The replacements of the conventional material for curved pipes are succeeded by natural (hemp) and glass fiber together with 20% cost reduction and 23% weight reduction [6].
⇑ Corresponding author. Mobile: +91 9942522923; fax: +91 4288 274745. E-mail addresses: [email protected], [email protected] (V.P. Arthanarieswaran). http://dx.doi.org/10.1016/j.matdes.2014.07.058 0261-3069/Ó 2014 Elsevier Ltd. All rights reserved.
Many researchers have studied the performance of abaca fibers. The variation in the tensile behavior of abaca fiber with respect to height of the fiber stem shows that there is a great increase in its strength at a height of 1 m from bottom and then slightly decreasing afterwards [7] and studies by Venkateshwaran and Elayaperumal [8] revealed that abaca fiber with diameter of 200 lm shows better strength. Optimum weight percentage of the fiber content in the composite also determines its mechanical properties, the flexural properties are found to be increased linearly with fiber content up to 50 wt.% [9]. The combination of PLA bio composites with abaca and manmade cellulose fibers indicated that addition of 30 wt.% of abaca fibers increase the tensile strength and impact strength by a factor of 1.2 and 2.4 respectively [10]. The surface modified abaca fibers showed better performance than the untreated. Abaca fibers modified by fungamix and natural enzyme enhances the tensile strength and flexural strength whereas it reduces the water absorption characteristics to a certain extent [11]. The banana fibers which are alkali treated with 1% NaOH possess better mechanical properties [12] and studies by Paul et al. [13] exposed that treatment with 10% NaOH gives better thermo physical properties. The addition of maleated polypropylene (MAPP) as compatibilizer and MAH-PP promotes the interaction between abaca (Musa textilis) strands and polypropylene bio composites [14,15]. The dispersion of the filler in the matrix can be improved by surface treated abaca fiber with benzene diazonium salts [16]. Better mechanical properties on the Agave fibers are obtained with the particle reinforcement rather than short and long fiber
195
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
reinforced composites [17]. Attention on the irregular surface area of the sisal fibers was significant in the measurement of tensile properties and Young’s modulus value does not vary with respect to gauge length [18]. The surface treated sisal fibers improves the mechanical properties by enhancing adhesion between the sisal fibers and matrix as well as between cells [19–21] and in another study alkali treatment improved the crystalline fraction due to the removal of amorphous components [22]. As the fibers are exposed to different environmental condition, studies by Chow et al. [23] revealed that moisture absorption characteristics of the sisal fiber polypropylene composites induces the tensile strength starts to decline from the starting period of immersion and impact strength to increase initially followed by declining later. As single natural fiber composites are not having sufficient strength to replace the conventional materials, the hybrid combinations of natural fibers are preferred. The mechanical and thermal properties of the jute fiber reinforced epoxy composite are found to be increased with the addition of banana fiber up to 50% by weight [24]. With the combination of banana and sisal fiber, fiber length and weight percentage are the major factors in deciding the mechanical properties [25] and in another study, banana and sisal fiber with 50:50 weight percentage showed maximum tensile strength along with 40% weight fraction of total fiber content [26]. Paper can also be used as a hybrid material with the natural fibers and studies by Leburn et al. [27] revealed that the addition of paper with the hemp and flax fiber reinforced epoxy composites improves the strength and modulus capacity. The incorporation of the glass fibers with the natural one notably enhanced the mechanical properties of the composites. Incorporation of glass fiber up to 20% by mass with the bamboo fiber improved the tensile and flexural modulus by 12.5% and 10% respectively [28] and its moisture absorption and tensile strength degradation can be controlled by the coupling agent maleic anhydride polypropylene (MAPP) [29]. With the combination of glass and curaua fibers in the polyester resin, the maximum performance was observed with 30% of curaua and 70% glass fiber composites [30]. Addition of glass fiber as extreme plies in the jute fabrics considerably improved the flexural and interlaminar shear properties [31]. In another study, unidirectional glass and flax fiber composites showed superior interlaminar shear strength than the glass fibers and tensile properties can be enhanced with the addition of glass fibers [32]. The performance on tensile and flexural properties of the sisal fiber polypropylene composites with polypropylene grafted with maleic anhydride (PP-g-MA) as a compatibilizer are found to be increased with glass fiber hybridization [33]. Abaca and Jute fiber combination with the glass fiber exhibited better flexural properties and its mechanical properties are much affected by the fiber orientation in the laminates [34,35]. Glass fiber reinforced polymer composites can be replaced with the hybrid combination of sisal–jute with glass ply [36]. The above review obviously shows that there is small work have been done on the impact of stacking sequence and addition of glass fibers with two or more natural fibers. Hence, the present study is mainly focused on the influence of various stacking sequences on mechanical properties of hybrid combination of banana, sisal and glass fibers.
2. Methodology 2.1. Materials 2.1.1. Sisal fiber and its extraction Sisal (Agave sisalana) plants are more familiar with the tropics and sub tropics region as they can grow better at a temperature of more than 25 °C. These plants consist of sword shaped leaves
of normally 1.5 m length and a typical plant produces around 150 leaves during its life span of 6 years. It contains about 500–800 fibers, which are normally used to make ropes, carpets etc. The matured leaves standing at an angle of more than 45° to the upright of the plant are cut. The next stage in which the leaves are initially crushed by the rollers of rounded knife edges followed by repetitive beaten is called decortication. During this process, the fibers are extracted by squeezing out the pulpy content of the leaf. Finally the fibers are dried in sunlight for 3–4 days after washing them in clean water to remove the dusts and unwanted contents in it. 2.1.2. Banana fiber and its extraction The banana fibers are extracted from the pseudo stem of the banana plant (Musa species). These are growing up to 5–10 feet depending upon the region and climatic conditions. The length of the stalk depends upon the height of the plant and its width is about 3–5 cm with a thickness of 1–2 cm. The fibers are located at the outer sheath of the stalk. The qualified stalk of the plant is cut to a length of 100 cm and its outer sheath is removed. Then these sections are crushed between two roller drums with scraping blades at its circumference to remove the pulpy material between the fibers. The process of stripping the fibers from the stalk is known as tuxies. Finally the fibers are completely cleaned in water to remove the waste materials and then dried in sunshine for a few days to remove the moisture content. Table 1 shows the physical properties of banana and sisal fiber. 2.1.3. E-Glass fiber E-Glass fiber is one of the most commonly used synthetic fibers, manufactured with the raw materials such as limestone, silica, clay, fluorspar, and dolomite. These ingredients are melted and extruded through bushings which have multiple small orifices to obtain filaments. The extruded filaments are coated with chemicals to obtain required size. The filaments are wounded together to form roving. The diameter of the filaments and the number of filaments in a roving determine its weight. The E-Glass fiber selected for this work is E-Glass woven roving of 400 gsm. 2.1.4. Epoxy Epoxy resin is a member of the epoxy oligomer class. It forms a three dimensional structure when it reacts with the hardener or curing agent. It is possible to change the properties of the epoxy resins with different epoxy oligomers and by choosing various curing agents. The epoxy-LY556 i.e., diglycidyl ether of biphenylA (DGEBA) with the hardener HY951 i.e., triethylenetetramine (TETA) is used as matrix material. The blending ratio of the resin with the hardener is 10:1 by weight. 2.2. Composite preparation The composite laminates for this work were fabricated by compression molding method. Initially, the qualified sunlight dried Table 1 Physical properties of banana and sisal fiber. Properties
Banana fiber
Sisal fiber
Density (kg/m3) Flexural modulus (GPa) Tensile strength (MPa) Young’s modulus (GPa) Elongation at break (%) Cellulose (%) Hemi cellulose (%) Lignin (%) Moisture content (%)
1350 4 56 3.5 2.6 62 18 5 11
1450 13.5 67 3.7 2.4 66 13 10 10
196
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
banana (B) and sisal (S) fibers are segregated and chopped. Nine different kinds of laminates were prepared with stacking sequences B (Laminate 1), G/B/G (Laminate 2), G/B/G/B/G (Laminate 3), S (Laminate 4), G/S/G (Laminate 5), G/S/G/S/G (Laminate 6), BS (Laminate 7), G/BS/G (Laminate 8) and G/BS/G/BS/G (Laminate 9) as shown in Fig. 1. The weighted quantity of banana, sisal, banana–sisal fibers and the epoxy resin were taken, the appropriate hardness also selected to fabricate the composites. The dimension of the mold used in the present work was 30 30 3 cm. This had to be placed over the fixed bottom jaw after placing a polythene sheet over it to avoid deposition of squeezing resin during the process. The mixture of epoxy resin with the hardener was applied to the mold, and then it was followed by the uniform deposition of the natural fiber premixed with a predetermined percentage of the resin mixture on the mold according to the laminates needed. Finally the resin was applied at the top before compressing the laminate with the DARRAGON hydraulic compression machine of 100 ton capacity. The pressure was applied gradually to ensure uniform distribution of resin throughout the laminate and also to remove the entrapped air. The laminate was kept under constant pressure for about nearly 12 h to guarantee absolute curing. The same process was repeated for the glass hybrid laminates with the e-glass woven fiber of 30 30 cm lamina placed agreeing to the stacking sequence. The weight percentage of natural fibers, E-glass fibers, epoxy resin mixture and the laminate was measured to calculate the weight and the volume fraction of the fibers listed in Table 2. After acquiring the compressed laminate from the compression molding machine, the burs on the rough edges were cut by using saw cutter and emery sheets were used to remove the rough edges.
2.3. Mechanical testing 2.3.1. Tensile test The ability of the material to stretch without breaking is termed as tensile strength. The tensile strength of the laminate was measured by the ASTM standard (American Society for Testing and Materials) ASTM: D3039. The specimen should ensure that the breakage should occur in the expected region and its necessity depends on the localization of the breakage. The ends of the specimen were clamped between the jaws. The movement of the jaw offers tensile force on the specimen. This force was recorded with respect to the change in gauge length. The tensile test was done on the FIE make Universal Testing Machine (UTM – Model UTE 40 with maximum load capacity of 400 kN). The samples were tested at a loading rate of 5 mm/min. Specimen which was cut from the three different types of laminates were subjected to tensile test
Table 2 Weight and volume fractions of natural and hybrid laminates. Laminate
Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate
Orientation
1 2 3 4 5 6 7 8 9
B G/B/G G/B/G/B/G S G/S/G G/S/G/S/G BS G/BS/G G/BS/G/BS/G
Fiber (wt.%)
Fiber (vol.%)
Banana
Sisal
Glass
Banana
Sisal
Glass
33 20 15 0 0 0 17 12 7
0 0 0 33 22 15 17 12 7
0 15 24 0 17 23 0 15 25
31 20 16 0 0 0 16 12 7
0 0 0 29 21 15 15 11 6
0 8 14 0 9 13 0 8 14
for five samples per laminate to get an average value. The tensile test specimens of various laminates are shown in Fig. 2.
2.3.2. Flexural test A flexural test imposes tensile stress on the convex side and compressive stress on the concave side of the specimen which causes a shear stress along the center line. It measured the force required to bend the beam. The flexural test was performed on the KALPAK UTM (Model no. KIC-2-0200-C with a capacity of 20 kN). The geometrical dimension of the nominal specimen was made according to the standard ASTM: D790. The specimens were placed between two supports at a distance of 50 mm and the load was applied at the center which is called as three point bending test. The load was applied at a rate of 5 mm/min till the specimen fractures and breaks. The fabricated specimen for the flexural test is shown in the Fig. 3. The maximum load at failure was used to calculate the flexural stress.
2.3.3. Impact test The capability of the material to withstand suddenly applied load is its impact strength. The impact strength of the laminates was tested by Izod impact test rig. This test measured the kinetic energy needed to initiate the fracture and to continue until the breakage of specimen. The standard dimension for the Izod test is ASTM: D4812. The test specimen was kept vertically with the help of grippers and the pendulum was blown from one side which strokes it with kinetic energy. The energy absorbed by the material before it fractured is recorded on the scale which was used to measure the toughness and ductility. The different Izod impact testing specimens are shown in Fig. 4.
Fig. 1. Stacking sequence of the laminates (a) B, (b) G/B/G, (c) G/B/G/B/G, (d) S, (e) G/S/G, (f) G/S/G/S/G, (g) BS, (h) G/BS/G and (i) G/BS/G/BS/G.
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
197
Fig. 2. Tensile test specimen with experimental setup.
Fig. 3. Flexural test specimen with experimental setup.
3. Results and discussions 3.1. Tensile properties The tensile strength capabilities of the nine different kinds of laminates are determined by testing in the UTM. The tensile properties of the laminates are listed in Table 3. It has been clear that the tensile strength is increased with the addition of the glass fibers with the natural one. The elongation at break is much higher for the laminates having two glass fibers placed as the skin layers than that of the three glass fiber laminate, i.e., one at center layer and the remaining two as outer layers. The sample load vs displacement curve for the G/BS/G/BS/G laminate is shown in Fig. 5. It seems that the displacement is directly proportional to the load applied till the specimen fractures. The tensile modulus of the laminates is obtained by measuring the corresponding values of the stress strain values from the graph. The typical stress vs strain curve generated from the UTM for the G/BS/G/BS/G combination laminate is shown in Fig. 6. When the specimen reaches its yield strength, it starts to behave as a brittle material which initiates it to break. The comparative plot of the load vs displacement curve for all the laminates is shown in Fig. 7. The tensile strength of the pure banana (B) and sisal (S) natural laminates are 21 MPa and 23 MPa respectively, while the laminate having randomly
mixed banana–sisal fiber (BS) is around 25 MPa indicating that mixing of banana and sisal fibers together in equal weight ratios improves the tensile properties of the laminates and it is found to be 19% and 8.7% higher than banana (B) and sisal fiber (S). There is gradual increase in the tensile strength of the natural hybrid composites with the incorporation of glass fibers [30,32]. The addition of two layers of glass ply to the banana (G/B/G), sisal (G/S/G) and banana–sisal (G/BS/G) improves the tensile strength by 119%, 126% and 156% respectively. Similarly, strength of the sisal (G/S/G/S/G) and banana–sisal fiber (G/BS/G/BS/G) with three layers of woven glass fiber is increased by 5.6% and 18.2% than the banana fiber (G/B/G/B/G) hybrid laminates. Fig. 8 shows the stress–strain curve comparison of all the types of combinations in which the natural fiber laminates are showing the least value among all. The elongation of the banana–sisal fiber laminate having two layers of glass fibers has 1.4 times than the natural one and 1.1 times higher than the three layers of glass fiber laminates. Similar kinds of results were obtained with the tensile modulus behavior. Thus from all these observations it is clear that the addition of glass fiber increases the tensile properties of the sisal laminates [33] and mixing the banana and sisal fiber collectively with equal weight ratios [26] improves its tendency to withstand more tensile force. The maximum tensile strength is obtained by hybridizing banana–sisal with glass fibers rather than banana or sisal with glass fibers [34].
Fig. 4. Impact test specimen with experimental setup.
198
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
Table 3 Mechanical properties of the composites. Laminate
Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate
1 2 3 4 5 6 7 8 9
Tensile strength (MPa)
Tensile modulus (GPa)
Flexural strength (MPa)
Impact energy (J)
21 46 88 23 52 93 25 64 104
0.62 1.42 1.94 0.67 1.57 2.21 0.75 1.63 2.35
56 132 176 61 159 184 62 192 163
7.6 10.2 12.5 8.4 11.7 13.3 7.4 11.3 12.8
Fig. 7. Load vs displacement plot of the laminates.
Fig. 5. Load vs deflection curve of G/BS/G/BS/G.
Fig. 8. Stress vs strain plot of the laminates.
Fig. 6. Stress vs strain graph of G/BS/G/BS/G.
The comparison of the maximum displacement and elongation of the different combinations are compared in Fig. 9. 3.2. Flexural properties The flexural strength measured with the UTM machine is summarized in Table 3. It reveals that the banana and sisal fiber as a sandwich material between glass fibers is showing more strength than the other combinations. During the gradual application of load, it is evenly distributed between the fibers and matrix in the laminates and it starts to ruptures when the load exceeds its limit. The crack begins where the adhesion between the fiber and matrix is poor and starts to propagate over the entire length of the cross section of laminates. The flexural strength of the natural fiber combination ranges between 56 MPa and 62 MPa. Nearly equal
strength is obtained between the sisal (S) and banana–sisal fiber (BS) composites. The addition of two layers of glass ply to the banana (G/B/G), sisal (G/S/G) and banana–sisal combinations (G/ BS/G) improves the flexural strength by 135%, 160% and 209% respectively, whereas the addition of one more layer of glass fiber to the same groupings (G/B/G/B/G), (G/S/G/S/G) and (G/BS/G/BS/G) increases its value by 214%, 201% and 163% respectively. Hence maximum strength of 192 MPa is observed in the banana–sisal fiber with two glass ply (G/BS/G) as extreme layers of reinforcement [31]. Fig. 10 shows the comparison of flexural strength of all laminates. The glass hybrid laminates is better than the pure natural laminates and the properties seems to be increasing with the addition of the glass fibers; while the addition beyond a particular limit affects its strength absorbing characteristics. The improvement in the flexural properties of the banana–sisal groupings with three layers of glass fibers (G/BS/G/BS/G) is not as much as witnessed in the two layers of glass (G/BS/G) relatively. This was
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
199
Fig. 9. Elongation and maximum displacement of the laminates.
mainly due to the reason that the load transfer capability of the laminates i.e., compressive load at the top layer and tensile load at the bottom layer as well as the shearing force in the intermediate layers, were not uniform throughout the length when there are more number of diversity layers. 3.3. Impact properties The impact test is carried out for analyzing the impact capability of nine different laminates. The energy loss is found using Izod impact test machine. The energy absorbed while a specimen is impacted by a heavy blow is listed in the Table 3. It shows that the hybrid combinations of fibers with three layers of glass fibers are much better than the natural fibers. Breakage of the specimen starts with the crack propagation due to loss of adhesion between fibers and matrix and then initiates fiber breakage and pullout. The impact strength of the banana (B), sisal (S) and banana–sisal fiber (BS) laminate is around 7.6 J, 8.4 J and 7.4 J respectively, while the maximum strength of 13.3 J is shown by sisal fibers arrangement with three layers of glass fiber (G/S/G/S/G). The impact energy of
the natural fiber laminates is found to be lesser than the hybrid combination with the glass fibers. The impact energy of the banana (B) and banana–sisal fiber (BS) laminates exhibits nearly the same values. There is a sharp increase in the impact properties with the addition of the glass fibers with the natural. The impact performance is enhanced by 34%, 39% and 53% for the two layer glass ply addition as extreme ply to the banana (G/B/G), sisal (G/S/G) and banana–sisal (G/BS/G) laminates. Maximum impact energy is observed by three layer glass fiber samples with sisal fiber (G/S/ G/S/G) which is 3.1% and 6.4% greater than the glass hybrid banana (G/B/G/B/G) and banana–sisal fiber (G/BS/G/BS/G) laminates respectively. As the laminate has alternate layers of sisal and glass fibers, much amount of energy is absorbed by the glass fibers. The effect of the banana and sisal fibers together with equal weight ratios does not have positive trend on the impact performance [34] as obtained in the tensile and flexural properties. As the load travels in the transverse direction on the arrangement of fiber layers, impact properties starts declining with more diversified natural fiber layers than the symmetrical layers. Fig. 11 shows the
Fig. 10. Comparison of flexural strength of the laminates.
200
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
Fig. 11. Impact energy of the laminates.
Fig. 12. Fiber pullout in tensile test specimen.
Fig. 13. Occurrence of voids in the tested specimen.
comparison among the impact energy absorption characteristics of the various kinds of laminates.
observed that, the crack was mainly due to the inappropriate adhesion between fibers and matrix and the poor load transferring capacity between the fibers. The SEM image of the natural fiber with three alternate layers of glass fibers subjected to flexural test is as shown in Fig. 15. In hybrid combinations, the glass fiber plays a vital role in determining flexural properties. The majority of the load was absorbed by these fibers, after its failure the remaining load was transferred to the banana and sisal fibers. From the above studies, it is evident that the presence of voids, improper adhesions between the fibers and matrix, fiber pull out are the major causes for the laminate failure [25,36].
3.4. Interfacial analysis (SEM analysis) SEM studies have been performed to study the failure analysis of the tested specimen. The region which has to be scanned is coated with a layer of gold before inspection. The tensile test specimen image illustrates the fiber pullout characteristics of the glass fiber and fiber breakage of the banana and sisal fibers and it is shown in Fig. 12. The glass and natural fibers absorbs the majority of loads in the vertical direction only rather than the horizontal direction. The glass fiber alone shares some of the energy with the fibers in horizontal orientation as it was in woven form. From Fig. 13, it is observed that the formation of the void between the fibers and matrix is greatly affecting the mechanical properties of the laminates. In the Izod impact test, crack formation is initiated at the micro level as depicted in Fig. 14, which is the specimen of laminate having three alternate layers of E-glass fibers. It has been
4. Conclusions The mechanical properties of the hybrid combination of glass with banana, sisal and banana–sisal were studied in this work. The laminates were manufactured by the compression molding process and tested according to ASTM standard. From the obtained results, the following conclusions are derived.
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
201
References
Fig. 14. Presence of micro cracks in impact test specimen.
Fig. 15. Fiber breakage in flexural test specimen.
The maximum tensile strength of 104 MPa is observed for the laminate having banana–sisal hybrid combination with three layers of glass fiber. The laminates with banana–sisal fibers as a sandwich and glass fibers at the extreme layers shows better performance on the flexural strength and it withstands up to 192 MPa. Better impact energy of 13.3 J is obtained in the sisal fiber laminate with three alternate layers of glass fiber. The interfacial analysis (SEM) revealed that tensile, flexural and impact performances are affected by the factors such as poor adhesion between fiber and matrix, formation of micro cracks, presence of voids and fiber pullout. From the observations, the hybrid composite laminates are showing moderate performance than the glass fiber composites. Hence it is suitable for the medium load applications such as welding helmet, chair, table, roof, and automobile body panels.
[1] Ku H, Wang H, Pattarachaiyakoop N, Trada M. A review on the tensile properties of natural fiber reinforced polymer composites. Composites Part B 2011;42:856–73. [2] Saravanakumar SS, Kumaravel A, Nagarajan T, Sudhakar P, Baskaran R. Characterization of a novel natural cellulosic fiber from Prosopis juliflora bark. Carbohydr Polym 2013;92:1928–33. [3] Sathishkumar TP, Navaneethakrishnan P, Shankar S, Rajasekar R. Characterization of new cellulose sansevieria ehrenbergii fibers for polymer composites. Compos Inter 2013;20:575–93. [4] Prasad AVR, Rao KM. Mechanical properties of natural fibre reinforced polyester composites: Jowar, sisal and bamboo. Mater Des 2011;32: 4658–63. [5] Prasad AVR, Rao KM, Nagasrinivasulu G. Mechanical properties of banana empty fruit bunch fiber reinforced polyester composites. Indian J Fibre Text Res 2009;34:162–7. [6] Cicala G, Cristaldi G, Recca G, Ziegmann G, El-Sabbagh A, Dickert M. Properties and performances of various hybrid glass/natural fibre composites for curved pipes. Mater Des 2009;30:2538–42. [7] Liu K, Takagi H, Yang Z. Dependence of tensile properties of abaca fiber fragments and its unidirectional composites on the fragment height in the fiber stem. Composites Part A 2013;45:14–22. [8] Venkateshwaran N, Elayaperumal A. Banana fiber reinforced polymer composites – a review. J Reinf Plast Compos 2010;29:2387–96. [9] Girones J, Lopez JP, Vilaseca F, Bayer JR, Herrera-Franco PJ, Mutje P. Biocomposites from Musa textilis and polypropylene: evaluation of flexural properties and impact strength. Compos Sci Technol 2011;71:122–8. [10] Bledzki AK, Jaszkiewicz A, Scherzer D. Mechanical properties of PLA composites with man-made cellulose and abaca fibres. Composites Part A 2009;40:404–12. [11] Bledzki AK, Mamun AA, Jaszkiewicz A, Erdmann K. Polypropylene composites with enzyme modified abaca fibre. Compos Sci Technol 2010;70:854–60. [12] Venkateshwaran N, Elayaperumal A, Arunsundaranayagam D. Fiber surface treatment and its effect on mechanical and visco-elastic behavior of banana/ epoxy composite. Mater Des 2013;47:151–9. [13] Paul SA, Boudenne A, Ibos L, Candau Y, Joseph K, Thomas S. Effect of fiber loading and chemical treatments on thermophysical properties of banana fiber/polypropylene commingled composite materials. Composites Part A 2008;39:1582–8. [14] Vilaseca F, Valadez-Gonzalez A, Herrera-Franco PJ, Pelach MA, Lopez JP, Mutje P. Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties. Bioresour Technol 2010;101:387–95. [15] Bledzki AK, Mamun AA, Faruk O. Abaca fibre reinforced PP composites and comparison with jute and flax fibre PP composites. eXPRESS Polym Lett 2007;1(11):755–62. [16] Rahman MR, Huque MM, Islam MN, Hasan M. Mechanical properties of polypropylene composites reinforced with chemically treated abaca. Composites Part A 2009;40:511–7. [17] Singha AS, Rana RK. Natural fiber reinforced polystyrene composites: effect of fiber loading, fiber dimensions and surface modification on mechanical properties. Mater Des 2012;41:289–97. [18] Silva FA, Chawla N, Toledo Filho RD. Tensile behavior of high performance natural (sisal) fibers. Compos Sci Technol 2008;68:3438–43. [19] Ronga MZ, Zhangb MQ, Liub Y, Yangb GC, Zengb HM. The effect of fiber treatment on the mechanical properties of unidirectional sisal-reinforced epoxy composites. Compos Sci Technol 2001;61:1437–47. [20] Dwivedi UK, Chand N. Influence of MA-g-PP on abrasive wear behaviour of chopped sisal fibre reinforced polypropylene composites. J Mater Proc Technol 2009;209:5371–5. [21] Sangthong S, Pongprayoon T, Yanumet N. Mechanical property improvement of unsaturated polyester composite reinforced with admicellar-treated sisal fibers. Composites Part A 2009;40:687–94. [22] Barreto ACH, Rosa DS, Fechine PBA, Mazzetto SE. Properties of sisal fibers treated by alkali solution and their application into cardanol-based biocomposites. Composites Part A 2011;42:492–500. [23] Chow CPL, Xing XS, Li RKY. Moisture absorption studies of sisal fibre reinforced polypropylene composites. Compos Sci Technol 2007;67:306–13. [24] Boopalan M, Niranjanaa M, Umapathy MJ. Study on the mechanical properties and thermal properties of jute and banana fiber reinforced epoxy hybrid composites. Composites Part B 2013;51:54–7. [25] Venkateshwaran N, ElayaPerumal A, Alavudeen A, Thiruchitrambalam M. Mechanical and water absorption behaviour of banana/sisal reinforced hybrid composites. Mater Des 2011;32:4017–21. [26] Venkateshwaran N, Elayaperumal A, Sathiya GK. Prediction of tensile properties of hybrid-natural fiber composites. Composites Part B 2012;43: 793–6. [27] Lebrun G, Couture A, Laperriere L. Tensile and impregnation behavior of unidirectional hemp/paper/epoxy and flax/paper/epoxy composites. Compos Struct 2013;103:151–60. [28] Thwe M, Liao K. Effects of environmental aging on the mechanical properties of bamboo–glass fiber reinforced polymer matrix hybrid composites. Composites Part A 2002;33:43–52. [29] Thwe MM, Liao K. Durability of bamboo–glass fiber reinforced polymer matrix hybrid composites. Compos Sci Technol 2003;63:375–87.
202
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
[30] Almeida Junior JHS, Amico SC, Botelho EC, Amado FDR. Hybridization effect on the mechanical properties of curaua/glass fiber composites. Composites Part B 2013;55:492–7. [31] Ahmed KS, Vijayarangan S. Tensile, flexural and interlaminar shear properties of woven jute and jute–glass fabric reinforced polyester composites. J Mater Process Technol 2008;207:330–5. [32] Zhang Y, Li Y, Ma H, Yu T. Tensile and interfacial properties of unidirectional flax/glass fiber reinforced hybrid composites. Compos Sci Technol 2013;88:172–7. [33] Jarukumjorn K, Suppakarn N. Effect of glass fiber hybridization on properties of sisal fiber–polypropylene composites. Composites Part B 2009;40:623–7.
[34] Ramnath BV, Kokan SJ, Raja RN, Sathyanarayanan R, Elanchezhian C, Prasad AR, et al. Evaluation of mechanical properties of abaca–jute–glass fibre reinforced epoxy composite. Mater Des 2013;51:357–66. [35] Ramnath BV, Manickavasagam VM, Elanchezhian C, Krishna CV, Karthik S, Saravanan K. Determination of mechanical properties of intra-layer abaca– jute–glass fiber reinforced composite. Mater Des 2014;60:643–52. [36] Ramesh M, Palanikumar K, Reddy KH. Mechanical property evaluation of sisal– jute–glass fiber reinforced polyester composites. Composites Part B 2013;48:1–9.
Contents lists available at ScienceDirect
Materials and Design journal homepage: www.elsevier.com/locate/matdes
Technical Report
Evaluation of mechanical properties of banana and sisal fiber reinforced epoxy composites: Influence of glass fiber hybridization V.P. Arthanarieswaran ⇑, A. Kumaravel, M. Kathirselvam Department of Mechanical Engineering, K.S. Rangasamy College of Technology, Tiruchengode 637 215, Tamil Nadu, India
a r t i c l e
i n f o
Article history: Received 12 June 2014 Accepted 27 July 2014 Available online 4 August 2014
a b s t r a c t In this work, the effect of glass fiber hybridization with the randomly oriented natural fibers has been analyzed. The banana (B), sisal (S) fibers were chopped and woven E-glass (G) synthetic fibers were reinforced with epoxy matrix. Nine different kinds of laminates were prepared in the following stacking sequence of B, S, BS, G/B/G, G/S/G, G/BS/G, G/B/G/B/G, G/S/G/S/G and G/BS/G/BS/G. Mechanical properties like tensile strength, flexural strength and impact strength were evaluated and compared. Interfacial analysis was also carried out with the help of Scanning Electron Microscope (SEM) to study the micro structural behavior of the tested specimen. It was observed that the addition of two and three layer of glass fiber can improve the tensile strength by a factor of 2.34 and 4.13 respectively. The flexural properties were enhanced on banana–sisal fiber with two layers of glass fibers rather than three layers and the laminate with sisal and three glass ply offers better impact strength. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction Natural fibers are found superior to the artificial fibers with the properties like less weight, low density, eco-friendly, high specific strength etc. However, it has some of the disadvantages like poor surface characteristics, more moisture absorption, quality variations, etc. These natural fiber composites are commonly used in an automobiles, packaging industries, aerospace, construction and so on. The tensile load carrying capacity of the natural fiber reinforced composites are found to be increasing with the fiber content up to an optimum level and then start declining [1]. Recent novel fibers such as Prosopis juliflora, sansevieria ehrenbergii can also be used as reinforcement material in the composite structure [2,3]. Now a days’ conventional material for the medium load applications are replaced by the composite materials. Studies by Prasad and Rao [4] suggested that the jowar fiber can be used for fabrication of light weight components used in housing sector, automobile body building, packaging industry, partition panels, etc. Banana empty fruit bunch fiber is better in tensile strength than the neat polyester resin and it can be used in industrial applications such as partition panels and packaging [5]. The replacements of the conventional material for curved pipes are succeeded by natural (hemp) and glass fiber together with 20% cost reduction and 23% weight reduction [6].
⇑ Corresponding author. Mobile: +91 9942522923; fax: +91 4288 274745. E-mail addresses: [email protected], [email protected] (V.P. Arthanarieswaran). http://dx.doi.org/10.1016/j.matdes.2014.07.058 0261-3069/Ó 2014 Elsevier Ltd. All rights reserved.
Many researchers have studied the performance of abaca fibers. The variation in the tensile behavior of abaca fiber with respect to height of the fiber stem shows that there is a great increase in its strength at a height of 1 m from bottom and then slightly decreasing afterwards [7] and studies by Venkateshwaran and Elayaperumal [8] revealed that abaca fiber with diameter of 200 lm shows better strength. Optimum weight percentage of the fiber content in the composite also determines its mechanical properties, the flexural properties are found to be increased linearly with fiber content up to 50 wt.% [9]. The combination of PLA bio composites with abaca and manmade cellulose fibers indicated that addition of 30 wt.% of abaca fibers increase the tensile strength and impact strength by a factor of 1.2 and 2.4 respectively [10]. The surface modified abaca fibers showed better performance than the untreated. Abaca fibers modified by fungamix and natural enzyme enhances the tensile strength and flexural strength whereas it reduces the water absorption characteristics to a certain extent [11]. The banana fibers which are alkali treated with 1% NaOH possess better mechanical properties [12] and studies by Paul et al. [13] exposed that treatment with 10% NaOH gives better thermo physical properties. The addition of maleated polypropylene (MAPP) as compatibilizer and MAH-PP promotes the interaction between abaca (Musa textilis) strands and polypropylene bio composites [14,15]. The dispersion of the filler in the matrix can be improved by surface treated abaca fiber with benzene diazonium salts [16]. Better mechanical properties on the Agave fibers are obtained with the particle reinforcement rather than short and long fiber
195
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
reinforced composites [17]. Attention on the irregular surface area of the sisal fibers was significant in the measurement of tensile properties and Young’s modulus value does not vary with respect to gauge length [18]. The surface treated sisal fibers improves the mechanical properties by enhancing adhesion between the sisal fibers and matrix as well as between cells [19–21] and in another study alkali treatment improved the crystalline fraction due to the removal of amorphous components [22]. As the fibers are exposed to different environmental condition, studies by Chow et al. [23] revealed that moisture absorption characteristics of the sisal fiber polypropylene composites induces the tensile strength starts to decline from the starting period of immersion and impact strength to increase initially followed by declining later. As single natural fiber composites are not having sufficient strength to replace the conventional materials, the hybrid combinations of natural fibers are preferred. The mechanical and thermal properties of the jute fiber reinforced epoxy composite are found to be increased with the addition of banana fiber up to 50% by weight [24]. With the combination of banana and sisal fiber, fiber length and weight percentage are the major factors in deciding the mechanical properties [25] and in another study, banana and sisal fiber with 50:50 weight percentage showed maximum tensile strength along with 40% weight fraction of total fiber content [26]. Paper can also be used as a hybrid material with the natural fibers and studies by Leburn et al. [27] revealed that the addition of paper with the hemp and flax fiber reinforced epoxy composites improves the strength and modulus capacity. The incorporation of the glass fibers with the natural one notably enhanced the mechanical properties of the composites. Incorporation of glass fiber up to 20% by mass with the bamboo fiber improved the tensile and flexural modulus by 12.5% and 10% respectively [28] and its moisture absorption and tensile strength degradation can be controlled by the coupling agent maleic anhydride polypropylene (MAPP) [29]. With the combination of glass and curaua fibers in the polyester resin, the maximum performance was observed with 30% of curaua and 70% glass fiber composites [30]. Addition of glass fiber as extreme plies in the jute fabrics considerably improved the flexural and interlaminar shear properties [31]. In another study, unidirectional glass and flax fiber composites showed superior interlaminar shear strength than the glass fibers and tensile properties can be enhanced with the addition of glass fibers [32]. The performance on tensile and flexural properties of the sisal fiber polypropylene composites with polypropylene grafted with maleic anhydride (PP-g-MA) as a compatibilizer are found to be increased with glass fiber hybridization [33]. Abaca and Jute fiber combination with the glass fiber exhibited better flexural properties and its mechanical properties are much affected by the fiber orientation in the laminates [34,35]. Glass fiber reinforced polymer composites can be replaced with the hybrid combination of sisal–jute with glass ply [36]. The above review obviously shows that there is small work have been done on the impact of stacking sequence and addition of glass fibers with two or more natural fibers. Hence, the present study is mainly focused on the influence of various stacking sequences on mechanical properties of hybrid combination of banana, sisal and glass fibers.
2. Methodology 2.1. Materials 2.1.1. Sisal fiber and its extraction Sisal (Agave sisalana) plants are more familiar with the tropics and sub tropics region as they can grow better at a temperature of more than 25 °C. These plants consist of sword shaped leaves
of normally 1.5 m length and a typical plant produces around 150 leaves during its life span of 6 years. It contains about 500–800 fibers, which are normally used to make ropes, carpets etc. The matured leaves standing at an angle of more than 45° to the upright of the plant are cut. The next stage in which the leaves are initially crushed by the rollers of rounded knife edges followed by repetitive beaten is called decortication. During this process, the fibers are extracted by squeezing out the pulpy content of the leaf. Finally the fibers are dried in sunlight for 3–4 days after washing them in clean water to remove the dusts and unwanted contents in it. 2.1.2. Banana fiber and its extraction The banana fibers are extracted from the pseudo stem of the banana plant (Musa species). These are growing up to 5–10 feet depending upon the region and climatic conditions. The length of the stalk depends upon the height of the plant and its width is about 3–5 cm with a thickness of 1–2 cm. The fibers are located at the outer sheath of the stalk. The qualified stalk of the plant is cut to a length of 100 cm and its outer sheath is removed. Then these sections are crushed between two roller drums with scraping blades at its circumference to remove the pulpy material between the fibers. The process of stripping the fibers from the stalk is known as tuxies. Finally the fibers are completely cleaned in water to remove the waste materials and then dried in sunshine for a few days to remove the moisture content. Table 1 shows the physical properties of banana and sisal fiber. 2.1.3. E-Glass fiber E-Glass fiber is one of the most commonly used synthetic fibers, manufactured with the raw materials such as limestone, silica, clay, fluorspar, and dolomite. These ingredients are melted and extruded through bushings which have multiple small orifices to obtain filaments. The extruded filaments are coated with chemicals to obtain required size. The filaments are wounded together to form roving. The diameter of the filaments and the number of filaments in a roving determine its weight. The E-Glass fiber selected for this work is E-Glass woven roving of 400 gsm. 2.1.4. Epoxy Epoxy resin is a member of the epoxy oligomer class. It forms a three dimensional structure when it reacts with the hardener or curing agent. It is possible to change the properties of the epoxy resins with different epoxy oligomers and by choosing various curing agents. The epoxy-LY556 i.e., diglycidyl ether of biphenylA (DGEBA) with the hardener HY951 i.e., triethylenetetramine (TETA) is used as matrix material. The blending ratio of the resin with the hardener is 10:1 by weight. 2.2. Composite preparation The composite laminates for this work were fabricated by compression molding method. Initially, the qualified sunlight dried Table 1 Physical properties of banana and sisal fiber. Properties
Banana fiber
Sisal fiber
Density (kg/m3) Flexural modulus (GPa) Tensile strength (MPa) Young’s modulus (GPa) Elongation at break (%) Cellulose (%) Hemi cellulose (%) Lignin (%) Moisture content (%)
1350 4 56 3.5 2.6 62 18 5 11
1450 13.5 67 3.7 2.4 66 13 10 10
196
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
banana (B) and sisal (S) fibers are segregated and chopped. Nine different kinds of laminates were prepared with stacking sequences B (Laminate 1), G/B/G (Laminate 2), G/B/G/B/G (Laminate 3), S (Laminate 4), G/S/G (Laminate 5), G/S/G/S/G (Laminate 6), BS (Laminate 7), G/BS/G (Laminate 8) and G/BS/G/BS/G (Laminate 9) as shown in Fig. 1. The weighted quantity of banana, sisal, banana–sisal fibers and the epoxy resin were taken, the appropriate hardness also selected to fabricate the composites. The dimension of the mold used in the present work was 30 30 3 cm. This had to be placed over the fixed bottom jaw after placing a polythene sheet over it to avoid deposition of squeezing resin during the process. The mixture of epoxy resin with the hardener was applied to the mold, and then it was followed by the uniform deposition of the natural fiber premixed with a predetermined percentage of the resin mixture on the mold according to the laminates needed. Finally the resin was applied at the top before compressing the laminate with the DARRAGON hydraulic compression machine of 100 ton capacity. The pressure was applied gradually to ensure uniform distribution of resin throughout the laminate and also to remove the entrapped air. The laminate was kept under constant pressure for about nearly 12 h to guarantee absolute curing. The same process was repeated for the glass hybrid laminates with the e-glass woven fiber of 30 30 cm lamina placed agreeing to the stacking sequence. The weight percentage of natural fibers, E-glass fibers, epoxy resin mixture and the laminate was measured to calculate the weight and the volume fraction of the fibers listed in Table 2. After acquiring the compressed laminate from the compression molding machine, the burs on the rough edges were cut by using saw cutter and emery sheets were used to remove the rough edges.
2.3. Mechanical testing 2.3.1. Tensile test The ability of the material to stretch without breaking is termed as tensile strength. The tensile strength of the laminate was measured by the ASTM standard (American Society for Testing and Materials) ASTM: D3039. The specimen should ensure that the breakage should occur in the expected region and its necessity depends on the localization of the breakage. The ends of the specimen were clamped between the jaws. The movement of the jaw offers tensile force on the specimen. This force was recorded with respect to the change in gauge length. The tensile test was done on the FIE make Universal Testing Machine (UTM – Model UTE 40 with maximum load capacity of 400 kN). The samples were tested at a loading rate of 5 mm/min. Specimen which was cut from the three different types of laminates were subjected to tensile test
Table 2 Weight and volume fractions of natural and hybrid laminates. Laminate
Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate
Orientation
1 2 3 4 5 6 7 8 9
B G/B/G G/B/G/B/G S G/S/G G/S/G/S/G BS G/BS/G G/BS/G/BS/G
Fiber (wt.%)
Fiber (vol.%)
Banana
Sisal
Glass
Banana
Sisal
Glass
33 20 15 0 0 0 17 12 7
0 0 0 33 22 15 17 12 7
0 15 24 0 17 23 0 15 25
31 20 16 0 0 0 16 12 7
0 0 0 29 21 15 15 11 6
0 8 14 0 9 13 0 8 14
for five samples per laminate to get an average value. The tensile test specimens of various laminates are shown in Fig. 2.
2.3.2. Flexural test A flexural test imposes tensile stress on the convex side and compressive stress on the concave side of the specimen which causes a shear stress along the center line. It measured the force required to bend the beam. The flexural test was performed on the KALPAK UTM (Model no. KIC-2-0200-C with a capacity of 20 kN). The geometrical dimension of the nominal specimen was made according to the standard ASTM: D790. The specimens were placed between two supports at a distance of 50 mm and the load was applied at the center which is called as three point bending test. The load was applied at a rate of 5 mm/min till the specimen fractures and breaks. The fabricated specimen for the flexural test is shown in the Fig. 3. The maximum load at failure was used to calculate the flexural stress.
2.3.3. Impact test The capability of the material to withstand suddenly applied load is its impact strength. The impact strength of the laminates was tested by Izod impact test rig. This test measured the kinetic energy needed to initiate the fracture and to continue until the breakage of specimen. The standard dimension for the Izod test is ASTM: D4812. The test specimen was kept vertically with the help of grippers and the pendulum was blown from one side which strokes it with kinetic energy. The energy absorbed by the material before it fractured is recorded on the scale which was used to measure the toughness and ductility. The different Izod impact testing specimens are shown in Fig. 4.
Fig. 1. Stacking sequence of the laminates (a) B, (b) G/B/G, (c) G/B/G/B/G, (d) S, (e) G/S/G, (f) G/S/G/S/G, (g) BS, (h) G/BS/G and (i) G/BS/G/BS/G.
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
197
Fig. 2. Tensile test specimen with experimental setup.
Fig. 3. Flexural test specimen with experimental setup.
3. Results and discussions 3.1. Tensile properties The tensile strength capabilities of the nine different kinds of laminates are determined by testing in the UTM. The tensile properties of the laminates are listed in Table 3. It has been clear that the tensile strength is increased with the addition of the glass fibers with the natural one. The elongation at break is much higher for the laminates having two glass fibers placed as the skin layers than that of the three glass fiber laminate, i.e., one at center layer and the remaining two as outer layers. The sample load vs displacement curve for the G/BS/G/BS/G laminate is shown in Fig. 5. It seems that the displacement is directly proportional to the load applied till the specimen fractures. The tensile modulus of the laminates is obtained by measuring the corresponding values of the stress strain values from the graph. The typical stress vs strain curve generated from the UTM for the G/BS/G/BS/G combination laminate is shown in Fig. 6. When the specimen reaches its yield strength, it starts to behave as a brittle material which initiates it to break. The comparative plot of the load vs displacement curve for all the laminates is shown in Fig. 7. The tensile strength of the pure banana (B) and sisal (S) natural laminates are 21 MPa and 23 MPa respectively, while the laminate having randomly
mixed banana–sisal fiber (BS) is around 25 MPa indicating that mixing of banana and sisal fibers together in equal weight ratios improves the tensile properties of the laminates and it is found to be 19% and 8.7% higher than banana (B) and sisal fiber (S). There is gradual increase in the tensile strength of the natural hybrid composites with the incorporation of glass fibers [30,32]. The addition of two layers of glass ply to the banana (G/B/G), sisal (G/S/G) and banana–sisal (G/BS/G) improves the tensile strength by 119%, 126% and 156% respectively. Similarly, strength of the sisal (G/S/G/S/G) and banana–sisal fiber (G/BS/G/BS/G) with three layers of woven glass fiber is increased by 5.6% and 18.2% than the banana fiber (G/B/G/B/G) hybrid laminates. Fig. 8 shows the stress–strain curve comparison of all the types of combinations in which the natural fiber laminates are showing the least value among all. The elongation of the banana–sisal fiber laminate having two layers of glass fibers has 1.4 times than the natural one and 1.1 times higher than the three layers of glass fiber laminates. Similar kinds of results were obtained with the tensile modulus behavior. Thus from all these observations it is clear that the addition of glass fiber increases the tensile properties of the sisal laminates [33] and mixing the banana and sisal fiber collectively with equal weight ratios [26] improves its tendency to withstand more tensile force. The maximum tensile strength is obtained by hybridizing banana–sisal with glass fibers rather than banana or sisal with glass fibers [34].
Fig. 4. Impact test specimen with experimental setup.
198
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
Table 3 Mechanical properties of the composites. Laminate
Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate Laminate
1 2 3 4 5 6 7 8 9
Tensile strength (MPa)
Tensile modulus (GPa)
Flexural strength (MPa)
Impact energy (J)
21 46 88 23 52 93 25 64 104
0.62 1.42 1.94 0.67 1.57 2.21 0.75 1.63 2.35
56 132 176 61 159 184 62 192 163
7.6 10.2 12.5 8.4 11.7 13.3 7.4 11.3 12.8
Fig. 7. Load vs displacement plot of the laminates.
Fig. 5. Load vs deflection curve of G/BS/G/BS/G.
Fig. 8. Stress vs strain plot of the laminates.
Fig. 6. Stress vs strain graph of G/BS/G/BS/G.
The comparison of the maximum displacement and elongation of the different combinations are compared in Fig. 9. 3.2. Flexural properties The flexural strength measured with the UTM machine is summarized in Table 3. It reveals that the banana and sisal fiber as a sandwich material between glass fibers is showing more strength than the other combinations. During the gradual application of load, it is evenly distributed between the fibers and matrix in the laminates and it starts to ruptures when the load exceeds its limit. The crack begins where the adhesion between the fiber and matrix is poor and starts to propagate over the entire length of the cross section of laminates. The flexural strength of the natural fiber combination ranges between 56 MPa and 62 MPa. Nearly equal
strength is obtained between the sisal (S) and banana–sisal fiber (BS) composites. The addition of two layers of glass ply to the banana (G/B/G), sisal (G/S/G) and banana–sisal combinations (G/ BS/G) improves the flexural strength by 135%, 160% and 209% respectively, whereas the addition of one more layer of glass fiber to the same groupings (G/B/G/B/G), (G/S/G/S/G) and (G/BS/G/BS/G) increases its value by 214%, 201% and 163% respectively. Hence maximum strength of 192 MPa is observed in the banana–sisal fiber with two glass ply (G/BS/G) as extreme layers of reinforcement [31]. Fig. 10 shows the comparison of flexural strength of all laminates. The glass hybrid laminates is better than the pure natural laminates and the properties seems to be increasing with the addition of the glass fibers; while the addition beyond a particular limit affects its strength absorbing characteristics. The improvement in the flexural properties of the banana–sisal groupings with three layers of glass fibers (G/BS/G/BS/G) is not as much as witnessed in the two layers of glass (G/BS/G) relatively. This was
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
199
Fig. 9. Elongation and maximum displacement of the laminates.
mainly due to the reason that the load transfer capability of the laminates i.e., compressive load at the top layer and tensile load at the bottom layer as well as the shearing force in the intermediate layers, were not uniform throughout the length when there are more number of diversity layers. 3.3. Impact properties The impact test is carried out for analyzing the impact capability of nine different laminates. The energy loss is found using Izod impact test machine. The energy absorbed while a specimen is impacted by a heavy blow is listed in the Table 3. It shows that the hybrid combinations of fibers with three layers of glass fibers are much better than the natural fibers. Breakage of the specimen starts with the crack propagation due to loss of adhesion between fibers and matrix and then initiates fiber breakage and pullout. The impact strength of the banana (B), sisal (S) and banana–sisal fiber (BS) laminate is around 7.6 J, 8.4 J and 7.4 J respectively, while the maximum strength of 13.3 J is shown by sisal fibers arrangement with three layers of glass fiber (G/S/G/S/G). The impact energy of
the natural fiber laminates is found to be lesser than the hybrid combination with the glass fibers. The impact energy of the banana (B) and banana–sisal fiber (BS) laminates exhibits nearly the same values. There is a sharp increase in the impact properties with the addition of the glass fibers with the natural. The impact performance is enhanced by 34%, 39% and 53% for the two layer glass ply addition as extreme ply to the banana (G/B/G), sisal (G/S/G) and banana–sisal (G/BS/G) laminates. Maximum impact energy is observed by three layer glass fiber samples with sisal fiber (G/S/ G/S/G) which is 3.1% and 6.4% greater than the glass hybrid banana (G/B/G/B/G) and banana–sisal fiber (G/BS/G/BS/G) laminates respectively. As the laminate has alternate layers of sisal and glass fibers, much amount of energy is absorbed by the glass fibers. The effect of the banana and sisal fibers together with equal weight ratios does not have positive trend on the impact performance [34] as obtained in the tensile and flexural properties. As the load travels in the transverse direction on the arrangement of fiber layers, impact properties starts declining with more diversified natural fiber layers than the symmetrical layers. Fig. 11 shows the
Fig. 10. Comparison of flexural strength of the laminates.
200
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
Fig. 11. Impact energy of the laminates.
Fig. 12. Fiber pullout in tensile test specimen.
Fig. 13. Occurrence of voids in the tested specimen.
comparison among the impact energy absorption characteristics of the various kinds of laminates.
observed that, the crack was mainly due to the inappropriate adhesion between fibers and matrix and the poor load transferring capacity between the fibers. The SEM image of the natural fiber with three alternate layers of glass fibers subjected to flexural test is as shown in Fig. 15. In hybrid combinations, the glass fiber plays a vital role in determining flexural properties. The majority of the load was absorbed by these fibers, after its failure the remaining load was transferred to the banana and sisal fibers. From the above studies, it is evident that the presence of voids, improper adhesions between the fibers and matrix, fiber pull out are the major causes for the laminate failure [25,36].
3.4. Interfacial analysis (SEM analysis) SEM studies have been performed to study the failure analysis of the tested specimen. The region which has to be scanned is coated with a layer of gold before inspection. The tensile test specimen image illustrates the fiber pullout characteristics of the glass fiber and fiber breakage of the banana and sisal fibers and it is shown in Fig. 12. The glass and natural fibers absorbs the majority of loads in the vertical direction only rather than the horizontal direction. The glass fiber alone shares some of the energy with the fibers in horizontal orientation as it was in woven form. From Fig. 13, it is observed that the formation of the void between the fibers and matrix is greatly affecting the mechanical properties of the laminates. In the Izod impact test, crack formation is initiated at the micro level as depicted in Fig. 14, which is the specimen of laminate having three alternate layers of E-glass fibers. It has been
4. Conclusions The mechanical properties of the hybrid combination of glass with banana, sisal and banana–sisal were studied in this work. The laminates were manufactured by the compression molding process and tested according to ASTM standard. From the obtained results, the following conclusions are derived.
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
201
References
Fig. 14. Presence of micro cracks in impact test specimen.
Fig. 15. Fiber breakage in flexural test specimen.
The maximum tensile strength of 104 MPa is observed for the laminate having banana–sisal hybrid combination with three layers of glass fiber. The laminates with banana–sisal fibers as a sandwich and glass fibers at the extreme layers shows better performance on the flexural strength and it withstands up to 192 MPa. Better impact energy of 13.3 J is obtained in the sisal fiber laminate with three alternate layers of glass fiber. The interfacial analysis (SEM) revealed that tensile, flexural and impact performances are affected by the factors such as poor adhesion between fiber and matrix, formation of micro cracks, presence of voids and fiber pullout. From the observations, the hybrid composite laminates are showing moderate performance than the glass fiber composites. Hence it is suitable for the medium load applications such as welding helmet, chair, table, roof, and automobile body panels.
[1] Ku H, Wang H, Pattarachaiyakoop N, Trada M. A review on the tensile properties of natural fiber reinforced polymer composites. Composites Part B 2011;42:856–73. [2] Saravanakumar SS, Kumaravel A, Nagarajan T, Sudhakar P, Baskaran R. Characterization of a novel natural cellulosic fiber from Prosopis juliflora bark. Carbohydr Polym 2013;92:1928–33. [3] Sathishkumar TP, Navaneethakrishnan P, Shankar S, Rajasekar R. Characterization of new cellulose sansevieria ehrenbergii fibers for polymer composites. Compos Inter 2013;20:575–93. [4] Prasad AVR, Rao KM. Mechanical properties of natural fibre reinforced polyester composites: Jowar, sisal and bamboo. Mater Des 2011;32: 4658–63. [5] Prasad AVR, Rao KM, Nagasrinivasulu G. Mechanical properties of banana empty fruit bunch fiber reinforced polyester composites. Indian J Fibre Text Res 2009;34:162–7. [6] Cicala G, Cristaldi G, Recca G, Ziegmann G, El-Sabbagh A, Dickert M. Properties and performances of various hybrid glass/natural fibre composites for curved pipes. Mater Des 2009;30:2538–42. [7] Liu K, Takagi H, Yang Z. Dependence of tensile properties of abaca fiber fragments and its unidirectional composites on the fragment height in the fiber stem. Composites Part A 2013;45:14–22. [8] Venkateshwaran N, Elayaperumal A. Banana fiber reinforced polymer composites – a review. J Reinf Plast Compos 2010;29:2387–96. [9] Girones J, Lopez JP, Vilaseca F, Bayer JR, Herrera-Franco PJ, Mutje P. Biocomposites from Musa textilis and polypropylene: evaluation of flexural properties and impact strength. Compos Sci Technol 2011;71:122–8. [10] Bledzki AK, Jaszkiewicz A, Scherzer D. Mechanical properties of PLA composites with man-made cellulose and abaca fibres. Composites Part A 2009;40:404–12. [11] Bledzki AK, Mamun AA, Jaszkiewicz A, Erdmann K. Polypropylene composites with enzyme modified abaca fibre. Compos Sci Technol 2010;70:854–60. [12] Venkateshwaran N, Elayaperumal A, Arunsundaranayagam D. Fiber surface treatment and its effect on mechanical and visco-elastic behavior of banana/ epoxy composite. Mater Des 2013;47:151–9. [13] Paul SA, Boudenne A, Ibos L, Candau Y, Joseph K, Thomas S. Effect of fiber loading and chemical treatments on thermophysical properties of banana fiber/polypropylene commingled composite materials. Composites Part A 2008;39:1582–8. [14] Vilaseca F, Valadez-Gonzalez A, Herrera-Franco PJ, Pelach MA, Lopez JP, Mutje P. Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties. Bioresour Technol 2010;101:387–95. [15] Bledzki AK, Mamun AA, Faruk O. Abaca fibre reinforced PP composites and comparison with jute and flax fibre PP composites. eXPRESS Polym Lett 2007;1(11):755–62. [16] Rahman MR, Huque MM, Islam MN, Hasan M. Mechanical properties of polypropylene composites reinforced with chemically treated abaca. Composites Part A 2009;40:511–7. [17] Singha AS, Rana RK. Natural fiber reinforced polystyrene composites: effect of fiber loading, fiber dimensions and surface modification on mechanical properties. Mater Des 2012;41:289–97. [18] Silva FA, Chawla N, Toledo Filho RD. Tensile behavior of high performance natural (sisal) fibers. Compos Sci Technol 2008;68:3438–43. [19] Ronga MZ, Zhangb MQ, Liub Y, Yangb GC, Zengb HM. The effect of fiber treatment on the mechanical properties of unidirectional sisal-reinforced epoxy composites. Compos Sci Technol 2001;61:1437–47. [20] Dwivedi UK, Chand N. Influence of MA-g-PP on abrasive wear behaviour of chopped sisal fibre reinforced polypropylene composites. J Mater Proc Technol 2009;209:5371–5. [21] Sangthong S, Pongprayoon T, Yanumet N. Mechanical property improvement of unsaturated polyester composite reinforced with admicellar-treated sisal fibers. Composites Part A 2009;40:687–94. [22] Barreto ACH, Rosa DS, Fechine PBA, Mazzetto SE. Properties of sisal fibers treated by alkali solution and their application into cardanol-based biocomposites. Composites Part A 2011;42:492–500. [23] Chow CPL, Xing XS, Li RKY. Moisture absorption studies of sisal fibre reinforced polypropylene composites. Compos Sci Technol 2007;67:306–13. [24] Boopalan M, Niranjanaa M, Umapathy MJ. Study on the mechanical properties and thermal properties of jute and banana fiber reinforced epoxy hybrid composites. Composites Part B 2013;51:54–7. [25] Venkateshwaran N, ElayaPerumal A, Alavudeen A, Thiruchitrambalam M. Mechanical and water absorption behaviour of banana/sisal reinforced hybrid composites. Mater Des 2011;32:4017–21. [26] Venkateshwaran N, Elayaperumal A, Sathiya GK. Prediction of tensile properties of hybrid-natural fiber composites. Composites Part B 2012;43: 793–6. [27] Lebrun G, Couture A, Laperriere L. Tensile and impregnation behavior of unidirectional hemp/paper/epoxy and flax/paper/epoxy composites. Compos Struct 2013;103:151–60. [28] Thwe M, Liao K. Effects of environmental aging on the mechanical properties of bamboo–glass fiber reinforced polymer matrix hybrid composites. Composites Part A 2002;33:43–52. [29] Thwe MM, Liao K. Durability of bamboo–glass fiber reinforced polymer matrix hybrid composites. Compos Sci Technol 2003;63:375–87.
202
V.P. Arthanarieswaran et al. / Materials and Design 64 (2014) 194–202
[30] Almeida Junior JHS, Amico SC, Botelho EC, Amado FDR. Hybridization effect on the mechanical properties of curaua/glass fiber composites. Composites Part B 2013;55:492–7. [31] Ahmed KS, Vijayarangan S. Tensile, flexural and interlaminar shear properties of woven jute and jute–glass fabric reinforced polyester composites. J Mater Process Technol 2008;207:330–5. [32] Zhang Y, Li Y, Ma H, Yu T. Tensile and interfacial properties of unidirectional flax/glass fiber reinforced hybrid composites. Compos Sci Technol 2013;88:172–7. [33] Jarukumjorn K, Suppakarn N. Effect of glass fiber hybridization on properties of sisal fiber–polypropylene composites. Composites Part B 2009;40:623–7.
[34] Ramnath BV, Kokan SJ, Raja RN, Sathyanarayanan R, Elanchezhian C, Prasad AR, et al. Evaluation of mechanical properties of abaca–jute–glass fibre reinforced epoxy composite. Mater Des 2013;51:357–66. [35] Ramnath BV, Manickavasagam VM, Elanchezhian C, Krishna CV, Karthik S, Saravanan K. Determination of mechanical properties of intra-layer abaca– jute–glass fiber reinforced composite. Mater Des 2014;60:643–52. [36] Ramesh M, Palanikumar K, Reddy KH. Mechanical property evaluation of sisal– jute–glass fiber reinforced polyester composites. Composites Part B 2013;48:1–9.