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Experimental Investigation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composite
Available online at www.sciencedirect.com
ScienceDirect Materials Today: Proceedings 18 (2019) 4176–4181
www.materialstoday.com/proceedings
ICMPC-2019
Experimental Investigation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composite Vishnuvardhan Ra*, Rahul R Kotharia, Sivakumar Sa a
Department of Mechanical Engineering, Hindustan Institute of Technology and Science, Chennai-603103, India
Abstract Natural fiber reinforcement composites are replacing traditional materials and there is a increasing interest in research in use of these composites due to their availability in abundance and eco-friendliness. Natural fibers have many advantages over conventional materials like low cost, high strength to weight ratio, lightweight, high flexibility, stiffness properties, etc and have come a long way in replacing materials like metal, polymers and wood. In the present study, fiber reinforced composites is prepared with sisal fiber and epoxy resin as a binder. The composites prepared was tested to study its physical properties like tensile, flexural, impact, thermal properties and water absorption test. Scanning Electron Microscope (SEM) was used to study the surface morphology of the composite. Sisal fibers composite exhibit low-density and high specific properties and it is economically less expensive when compared to other synthetic fibers and hence can be used in automobile and transport industry. © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019 Keywords: Sisal fibre; epoxy resin; composite; mechanical tests; water absorption behavior; thermal test
1. Introduction Natural fibers (sisal, kenaf, jute etc) are on a replacing glass and carbon fiber because of their low-cost and easy availability. Other natural fibers such as hemp, banana and glass fibers composites or hybrid composites are proven to be better than individual composites[1]. Natural fibers have superior properties like low density, non-toxicity, renewability, biodegradability and relative non-adhesiveness[2]. However, these natural fibers suffer from some disadvantages such as low impact test, high brittleness and high moisture absorption properties. Natural fibers are preferred over glass fiber because the production of natural fiber has less environmental effects than glass fiber. As these natural fiber composites have lower density they are also lightweight so they improve fuel efficiency and also reduce emissions in automobile applications[3]. *Corresponding author. E-mail address: [email protected] 2214-7853© 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
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Kaewkuk [4]. the author studied about the physical properties of sisal fiber reinforced polypropylene composite and found that tensile modulus, water absorption properties and tensile strength, of the sisal fiber is directly proportional to the sisal fiber content but are inversely proportional to the impact strength and elongation at break. Hari om maurya [5]. the author tries to improve the mechanical property of sisal fiber reinforced epoxy composite by varying the fiber length and keeping the weight percent of sisal fiber content as constant. The tensile strength of the fiber was not increased by reinforcing the sisal fiber but tensile modulus, impact and flexural properties were improved. For composites with maximum fiber length, the impact properties were found maximum. Cristiane m[6]. the author has studied the effect of epoxy resin in the composite material. The epoxy resins have good mechanical properties but lack thermal properties. If these are exposed to high temperature then they can catch fire easily. This can result in complete failure of the composite material. To overcome this they are mixed with LDH which will act as a fire resistant in epoxy resin. By this, the fore problem of the epoxy resin can be controlled. In this present study mechanical properties, thermal property and water absorption property of sisal fiber reinforced epoxy composite with various fiber to resin ratio were investigated. 2. Materials and Composite Preparation In this present investigation sisal fiber (Agave Sisalana) are used for composite specimen along with epoxy AY 105 as a matrix. Sisal fibers and epoxy matrix were purchased from local source. Since epoxy is a thermosetting polymer it requires a hardener for cutting: HY95 hardener was used. The matrix was prepared with epoxy and hardener in the ratio 10:1 as recommended[7]. Sisal fibers are extracted from sisal plant through hand extraction machine with either serrated or non-serrated knives. A wood plank and knife are used to clamp the peel and then hand pulled through, thus removing the resinous material. The fibers which are extracted are sun dried which whitens the fiber after which the fibers are ready for knotting. For segregation bunch of fibers are mounted on a stick, each fiber is separated according to their fiber size and are grouped accordingly. After separation each fiber and knotted to the end of another fiber manually. This process is repeated until bunches of unknotted fibers are finished to form long unknotted strands. The specimen is prepared using compression moulding process. Dimensions of the specimen are cut as per ASTM standards using a diamond cutter. The composites with various wt % of fiber as designated S15 (15 wt% of sisal fiber), S20 (20 wt% of sisal fiber) and S25 (25 wt% of sisal fiber). 3. Testing and Characterization of Fibre The fabricated sisal fiber reinforced fiber epoxy composites were tested for mechanical properties, thermal properties and water absorption behavior. 3.1 Tensile Test The composite material fabricated is prepared as per the required dimension and the edges are finished for mechanical testing. As per the ASTM D638 standard the specimen is prepared with the specified dimensions, gauge length and cross-head speed. The test was carried out in tensile testing machine, the specimen is mounted in the machine and subjecting it to tension. The testing process involves placing the composite specimen in the testing machine and applying tension until it breaks (fractures). Multiple specimens with different fiber content were tested and the average values found are reported. 3.2 Flexural Test The flexural test also known as three-point bending test was carried out on Universal Testing Machine(UTM). The dimensions of the specimen were taken as per ASTM D79 standard. The deflection of the specimen was observed and measured, under the compressive load till the specimen cracks or breaks. During the experiment the top portion of the specimen was subjected to compression and the bottom portion was put through to tension. The middle portion of the specimen was put through to shear. Thus, flexural behavior was analyzed until the specimen breaks or cracks due to the combination of bending and shear. The specimens were tested for different sisal fiber content and the average values found are reported. 3.3 Impact Test The impact test specimen was fabricated to the required dimensions according to the ASTM A370 standard. One of the main problem with composites materials are they show a low value of impact strength compared to metals or alloys. The impact test was carried out using Charpy test, during the testing process the specimen is placed in the
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testing machine and the pendulum is allowed to move until it breaks or fractures. From the impact test results, the amount of energy or load needed to break or crack the material can be found and be used to measure the toughness and yield strength of the composite material. The average values for various fiber content of the tests was reported. 3.4 Water Absorption Behaviour The behavior of water absorption of sisal fiber reinforced epoxy composite has been studied. The absorption of water causes the degradation in the interface region of the fiber matrix, which results in poor mechanical properties along with the change in the dimension of composite. Water absorption of the composite material was investigated according to the ASTM D570 standard. Three types of water were used which is ordinary water, sea water and distilled water. The specimen was submerged in water to study the kinetics of water absorption in the fiber. The samples were taken out periodically and water on the surface of the samples are wiped out and the samples are weighed. The percentage of water absorption was calculated. 3.5 Thermal Test The thermal behaviour of the sisal fiber has been studied. The specimens are drilled using drilling machine and analyzed for thermal defects. The thermal defects may include cracks and/or forming of parallel air voids which can result in the reduction in mechanical properties. The specimens are drilled and then kept under SEM for studying in the change in the microstructure of the specimens, which is indicated in the figure 1(a) and (b) with the dimension of the air void. This is due to the heat generated during the drilling process which causes the material to expand and form air voids and internal cracks. This is one of the factors that affects the mechanical properties of the material.
(a)
b) SEM images of specimen after thermal testing Fig.1 (a) horizontal dimension of the air void (b) vertical dimension of the air void.
4. Microstructure Scanning Electron Microscope (SEM) images are taken to observe and study the internal structure, interfacial properties and internal cracks of the fractured surface of the composite material. Before observing the specimens through SEM they are coated with conducting material.
(a)
(b) Fig. 2 SEM image of sisal fibre reinforced epoxy composite
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The SEM images are taken to observe and study the internal structure, interfacial properties and internal cracks of the fractured surface of the composite material. Before observing the specimens through SEM they are coated with conducting material. The fiber dispersion is clearly seen in the SEM images of sisal fiber reinforced composite. In figure 1 (a) and (b), the air gaps are clearly visible as shown in the image. These air gaps decreases the strength of the composites. In figure 2 (a-b), the fiber agglomeration is clearly visible. Agglomeration is collective stacking or collection of fibers in a matrix which results in non-uniform stress transfer and hence reduces the strength of the composite. The dispersion, orientation of fibers, presence of air voids and fiber agglomeration are the factors influencing for reduction in strength of the Sisal fiber reinforced composite. 5. Results and Discussion At present, the sisal fiber is used as reinforced in epoxy resin in various applications in automobile components, structures and in consumer goods. The main focus of this study is to find out the mechanical properties, thermal property and water absorption behavior of the sisal fiber reinforced epoxy composite. After the thermal test the specimen was examined under SEM and was found that due to non-uniform heating there was a parallel air void forming in the specimen, which can cause reduction in mechanical properties of the material. The tests results for the composite samples are present in the table 1.
Sisal fibre composite
Table 1. Mechanical Properties of Sisal Composites Tensile strength (MPa ) Flexural strength (MPa)
Impact strength (joules)
S15
30.36
81
10.1
S20
35.2
98
11.6
S25
41.65
120
12.8
5.1 Tensile Properties The tensile strength of the sisal fiber reinforced epoxy composite is mentioned in table 1. the tensile strength of the sisal composite is found to be increased with increasing the fiber content. The maximum value of tensile strength were found to be for composite S25 due to strong adhesiveness between sisal fiber and epoxy matrix, which allows a uniform transfer of stress fro fiber to matrix. It is noted that the tensile strength of the composite S25 is 41.65 which is 15% higher than those of S20 and S15 as shown in below Fig 3.
Fig. 3. Tensile Strength Comparison of Composite Material.
5.2 Flexural Properties Table 1 shows the flexural strength of sisal composites. It is found that fleural strength of the sisal composite is increasing with increase is fiber content up to 25 wt.%. due to strong adhesion with high fiber content the composite S25 offers maximum value of fleural strength. The maximum value of flexural strength is 81MPa for S25 which is 18% higher than those of S20 and S15 as shown in below Fig 4 .
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Fig.4. Flexural Strength Comparison of Composite Material
5.3 Impact Properties The impact strength of sisal composites is shown is table 1. Similar trend to Tensile and Flexural properties is also observed in impact properties of sisal fiber reinforced epoxy composite. The impact strength is found to be increasing with increasing the fiber content in the composite up to 25 wt.% in epoxy matrix. Impact strength for composite S25 is found to be 12.8 joules which is 10% higher than that those of composites S20 and S15 as shown in below Fig 5 and Below Table 2.
Fig. 5. Impact Strength Comparison of Composite Material. Table 2. Comparison of Water Absorption Sisal Fiber Composite Ordinary water Distilled water
Seawater
S15
5.3
5.76
5
S20
5.8
5.2
5.4
S25
6.1
6.2
5.89
5.4 Water Absorption Behaviour The percentage of water absorption for different kinds of water of sisal composites are plotted against the fiber content. It is found that on increasing the fiber content the amount of water absorbed also increases. Ordinary water had the higer water abosrption rates than distilled an sea water. This may be due to the prescence of air voids in the system. Due to the prescence of air void water molecules starts diffusing into the air voids till saturation state. The composite S25 showed the higher water absorption which are higher than those of S20 and S15. The increase in water absorption is due to hydrophilic nature of sisal fiber and greater interfacial area between matrix and fiber[8]. These fibers show hydrophilic nature due to the prescence of cellulose in them. On increasing the sisal fiber content
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weight fraction of fiber is increased which causes increase in amount of cellulose, air voids and interface surface area. The water absorption due to epoxy resin is negligible due to hydrophobic nature as shown in below Fig 6.
Fig. 6. Water Absorption Levels for Different Kinds of Water
6. Conclusion
Mechanical properties such as tensile, flexural and impact strength of sisal composite are found to be increasing with increase in fibre content in epoxy matrix. The composite S25 showed the maximum value for mechanical properties compared to other sisal composite.
The water uptake of sisal fibre is found to be increasing with increase in sisal fibre content. The composite S25 showed the maximum uptake compared to other sisal composite.
Natural fiber composites have good mechanical properties and are slowly replacing synthetic fibers and are helping to reduce environmental impacts caused by synthetic fiber.
Mechanical properties can be attained by using treated fibers and correct method of fabrication.
Acknowledgments The Authors are thankful to the Editor and Anonymous Reviewers for several constructive suggestions. We also would like to express our sincere gratitude to Dr. Ashish Selokar, Accendere, CL Educate Pvt. Ltd. for his valuable comments that led to substantial improvements on an earlier version of this manuscript. References [1] Deenalayan, S.Sivakumar, R. Vishnuvardhan, R. Sathish kumar, International J. Engg. Tech, 7 (2.31) (2018)208-211. [2]Silva Flavio de Andrade, Filho Romildo Dias Toledo, Filho Joao de Almeida Melo, Fairbairn Eduardo de Moraes rego. J.Construct.& Build. Mater. 2010; 24:777–85. [3] S V Joshi, L T Drzal, A K Mohanty and S Arora 2004 Composites: Part A J. Appl. Sci. Manf. 35371. [4] S Kaewkuk, W Sutapun & K Jarukumjorn, Compos. Part B, 45 (2013) 544. [5] Hari Om Maurya, M.K. Gupta, R.K. Srivastava, H. Singh. Mat. Today: Proc. 2; 2015; 1347 – 1355. [6]Cristiane M. Becker, Teo A.Dick, Fernando Wypych, Henri S. Schrekker, Sandro C. Amico. Polymer Testing 31 (741-747). [7] N Venkateshwaran, A Elyaya Perumal, A Alavudeen & M Thiruchitrambalam, Mater. Des. 32(2011) 4017. [8] M K Gupta & R K Srivastava, American. J. Polym. Sci. Engg. 3 (2015) 208.
ScienceDirect Materials Today: Proceedings 18 (2019) 4176–4181
www.materialstoday.com/proceedings
ICMPC-2019
Experimental Investigation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composite Vishnuvardhan Ra*, Rahul R Kotharia, Sivakumar Sa a
Department of Mechanical Engineering, Hindustan Institute of Technology and Science, Chennai-603103, India
Abstract Natural fiber reinforcement composites are replacing traditional materials and there is a increasing interest in research in use of these composites due to their availability in abundance and eco-friendliness. Natural fibers have many advantages over conventional materials like low cost, high strength to weight ratio, lightweight, high flexibility, stiffness properties, etc and have come a long way in replacing materials like metal, polymers and wood. In the present study, fiber reinforced composites is prepared with sisal fiber and epoxy resin as a binder. The composites prepared was tested to study its physical properties like tensile, flexural, impact, thermal properties and water absorption test. Scanning Electron Microscope (SEM) was used to study the surface morphology of the composite. Sisal fibers composite exhibit low-density and high specific properties and it is economically less expensive when compared to other synthetic fibers and hence can be used in automobile and transport industry. © 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019 Keywords: Sisal fibre; epoxy resin; composite; mechanical tests; water absorption behavior; thermal test
1. Introduction Natural fibers (sisal, kenaf, jute etc) are on a replacing glass and carbon fiber because of their low-cost and easy availability. Other natural fibers such as hemp, banana and glass fibers composites or hybrid composites are proven to be better than individual composites[1]. Natural fibers have superior properties like low density, non-toxicity, renewability, biodegradability and relative non-adhesiveness[2]. However, these natural fibers suffer from some disadvantages such as low impact test, high brittleness and high moisture absorption properties. Natural fibers are preferred over glass fiber because the production of natural fiber has less environmental effects than glass fiber. As these natural fiber composites have lower density they are also lightweight so they improve fuel efficiency and also reduce emissions in automobile applications[3]. *Corresponding author. E-mail address: [email protected] 2214-7853© 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the 9th International Conference of Materials Processing and Characterization, ICMPC-2019
R. Vishnuvardhan et al. / Materials Today: Proceedings 18 (2019) 4176–4181
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Kaewkuk [4]. the author studied about the physical properties of sisal fiber reinforced polypropylene composite and found that tensile modulus, water absorption properties and tensile strength, of the sisal fiber is directly proportional to the sisal fiber content but are inversely proportional to the impact strength and elongation at break. Hari om maurya [5]. the author tries to improve the mechanical property of sisal fiber reinforced epoxy composite by varying the fiber length and keeping the weight percent of sisal fiber content as constant. The tensile strength of the fiber was not increased by reinforcing the sisal fiber but tensile modulus, impact and flexural properties were improved. For composites with maximum fiber length, the impact properties were found maximum. Cristiane m[6]. the author has studied the effect of epoxy resin in the composite material. The epoxy resins have good mechanical properties but lack thermal properties. If these are exposed to high temperature then they can catch fire easily. This can result in complete failure of the composite material. To overcome this they are mixed with LDH which will act as a fire resistant in epoxy resin. By this, the fore problem of the epoxy resin can be controlled. In this present study mechanical properties, thermal property and water absorption property of sisal fiber reinforced epoxy composite with various fiber to resin ratio were investigated. 2. Materials and Composite Preparation In this present investigation sisal fiber (Agave Sisalana) are used for composite specimen along with epoxy AY 105 as a matrix. Sisal fibers and epoxy matrix were purchased from local source. Since epoxy is a thermosetting polymer it requires a hardener for cutting: HY95 hardener was used. The matrix was prepared with epoxy and hardener in the ratio 10:1 as recommended[7]. Sisal fibers are extracted from sisal plant through hand extraction machine with either serrated or non-serrated knives. A wood plank and knife are used to clamp the peel and then hand pulled through, thus removing the resinous material. The fibers which are extracted are sun dried which whitens the fiber after which the fibers are ready for knotting. For segregation bunch of fibers are mounted on a stick, each fiber is separated according to their fiber size and are grouped accordingly. After separation each fiber and knotted to the end of another fiber manually. This process is repeated until bunches of unknotted fibers are finished to form long unknotted strands. The specimen is prepared using compression moulding process. Dimensions of the specimen are cut as per ASTM standards using a diamond cutter. The composites with various wt % of fiber as designated S15 (15 wt% of sisal fiber), S20 (20 wt% of sisal fiber) and S25 (25 wt% of sisal fiber). 3. Testing and Characterization of Fibre The fabricated sisal fiber reinforced fiber epoxy composites were tested for mechanical properties, thermal properties and water absorption behavior. 3.1 Tensile Test The composite material fabricated is prepared as per the required dimension and the edges are finished for mechanical testing. As per the ASTM D638 standard the specimen is prepared with the specified dimensions, gauge length and cross-head speed. The test was carried out in tensile testing machine, the specimen is mounted in the machine and subjecting it to tension. The testing process involves placing the composite specimen in the testing machine and applying tension until it breaks (fractures). Multiple specimens with different fiber content were tested and the average values found are reported. 3.2 Flexural Test The flexural test also known as three-point bending test was carried out on Universal Testing Machine(UTM). The dimensions of the specimen were taken as per ASTM D79 standard. The deflection of the specimen was observed and measured, under the compressive load till the specimen cracks or breaks. During the experiment the top portion of the specimen was subjected to compression and the bottom portion was put through to tension. The middle portion of the specimen was put through to shear. Thus, flexural behavior was analyzed until the specimen breaks or cracks due to the combination of bending and shear. The specimens were tested for different sisal fiber content and the average values found are reported. 3.3 Impact Test The impact test specimen was fabricated to the required dimensions according to the ASTM A370 standard. One of the main problem with composites materials are they show a low value of impact strength compared to metals or alloys. The impact test was carried out using Charpy test, during the testing process the specimen is placed in the
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testing machine and the pendulum is allowed to move until it breaks or fractures. From the impact test results, the amount of energy or load needed to break or crack the material can be found and be used to measure the toughness and yield strength of the composite material. The average values for various fiber content of the tests was reported. 3.4 Water Absorption Behaviour The behavior of water absorption of sisal fiber reinforced epoxy composite has been studied. The absorption of water causes the degradation in the interface region of the fiber matrix, which results in poor mechanical properties along with the change in the dimension of composite. Water absorption of the composite material was investigated according to the ASTM D570 standard. Three types of water were used which is ordinary water, sea water and distilled water. The specimen was submerged in water to study the kinetics of water absorption in the fiber. The samples were taken out periodically and water on the surface of the samples are wiped out and the samples are weighed. The percentage of water absorption was calculated. 3.5 Thermal Test The thermal behaviour of the sisal fiber has been studied. The specimens are drilled using drilling machine and analyzed for thermal defects. The thermal defects may include cracks and/or forming of parallel air voids which can result in the reduction in mechanical properties. The specimens are drilled and then kept under SEM for studying in the change in the microstructure of the specimens, which is indicated in the figure 1(a) and (b) with the dimension of the air void. This is due to the heat generated during the drilling process which causes the material to expand and form air voids and internal cracks. This is one of the factors that affects the mechanical properties of the material.
(a)
b) SEM images of specimen after thermal testing Fig.1 (a) horizontal dimension of the air void (b) vertical dimension of the air void.
4. Microstructure Scanning Electron Microscope (SEM) images are taken to observe and study the internal structure, interfacial properties and internal cracks of the fractured surface of the composite material. Before observing the specimens through SEM they are coated with conducting material.
(a)
(b) Fig. 2 SEM image of sisal fibre reinforced epoxy composite
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The SEM images are taken to observe and study the internal structure, interfacial properties and internal cracks of the fractured surface of the composite material. Before observing the specimens through SEM they are coated with conducting material. The fiber dispersion is clearly seen in the SEM images of sisal fiber reinforced composite. In figure 1 (a) and (b), the air gaps are clearly visible as shown in the image. These air gaps decreases the strength of the composites. In figure 2 (a-b), the fiber agglomeration is clearly visible. Agglomeration is collective stacking or collection of fibers in a matrix which results in non-uniform stress transfer and hence reduces the strength of the composite. The dispersion, orientation of fibers, presence of air voids and fiber agglomeration are the factors influencing for reduction in strength of the Sisal fiber reinforced composite. 5. Results and Discussion At present, the sisal fiber is used as reinforced in epoxy resin in various applications in automobile components, structures and in consumer goods. The main focus of this study is to find out the mechanical properties, thermal property and water absorption behavior of the sisal fiber reinforced epoxy composite. After the thermal test the specimen was examined under SEM and was found that due to non-uniform heating there was a parallel air void forming in the specimen, which can cause reduction in mechanical properties of the material. The tests results for the composite samples are present in the table 1.
Sisal fibre composite
Table 1. Mechanical Properties of Sisal Composites Tensile strength (MPa ) Flexural strength (MPa)
Impact strength (joules)
S15
30.36
81
10.1
S20
35.2
98
11.6
S25
41.65
120
12.8
5.1 Tensile Properties The tensile strength of the sisal fiber reinforced epoxy composite is mentioned in table 1. the tensile strength of the sisal composite is found to be increased with increasing the fiber content. The maximum value of tensile strength were found to be for composite S25 due to strong adhesiveness between sisal fiber and epoxy matrix, which allows a uniform transfer of stress fro fiber to matrix. It is noted that the tensile strength of the composite S25 is 41.65 which is 15% higher than those of S20 and S15 as shown in below Fig 3.
Fig. 3. Tensile Strength Comparison of Composite Material.
5.2 Flexural Properties Table 1 shows the flexural strength of sisal composites. It is found that fleural strength of the sisal composite is increasing with increase is fiber content up to 25 wt.%. due to strong adhesion with high fiber content the composite S25 offers maximum value of fleural strength. The maximum value of flexural strength is 81MPa for S25 which is 18% higher than those of S20 and S15 as shown in below Fig 4 .
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Fig.4. Flexural Strength Comparison of Composite Material
5.3 Impact Properties The impact strength of sisal composites is shown is table 1. Similar trend to Tensile and Flexural properties is also observed in impact properties of sisal fiber reinforced epoxy composite. The impact strength is found to be increasing with increasing the fiber content in the composite up to 25 wt.% in epoxy matrix. Impact strength for composite S25 is found to be 12.8 joules which is 10% higher than that those of composites S20 and S15 as shown in below Fig 5 and Below Table 2.
Fig. 5. Impact Strength Comparison of Composite Material. Table 2. Comparison of Water Absorption Sisal Fiber Composite Ordinary water Distilled water
Seawater
S15
5.3
5.76
5
S20
5.8
5.2
5.4
S25
6.1
6.2
5.89
5.4 Water Absorption Behaviour The percentage of water absorption for different kinds of water of sisal composites are plotted against the fiber content. It is found that on increasing the fiber content the amount of water absorbed also increases. Ordinary water had the higer water abosrption rates than distilled an sea water. This may be due to the prescence of air voids in the system. Due to the prescence of air void water molecules starts diffusing into the air voids till saturation state. The composite S25 showed the higher water absorption which are higher than those of S20 and S15. The increase in water absorption is due to hydrophilic nature of sisal fiber and greater interfacial area between matrix and fiber[8]. These fibers show hydrophilic nature due to the prescence of cellulose in them. On increasing the sisal fiber content
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weight fraction of fiber is increased which causes increase in amount of cellulose, air voids and interface surface area. The water absorption due to epoxy resin is negligible due to hydrophobic nature as shown in below Fig 6.
Fig. 6. Water Absorption Levels for Different Kinds of Water
6. Conclusion
Mechanical properties such as tensile, flexural and impact strength of sisal composite are found to be increasing with increase in fibre content in epoxy matrix. The composite S25 showed the maximum value for mechanical properties compared to other sisal composite.
The water uptake of sisal fibre is found to be increasing with increase in sisal fibre content. The composite S25 showed the maximum uptake compared to other sisal composite.
Natural fiber composites have good mechanical properties and are slowly replacing synthetic fibers and are helping to reduce environmental impacts caused by synthetic fiber.
Mechanical properties can be attained by using treated fibers and correct method of fabrication.
Acknowledgments The Authors are thankful to the Editor and Anonymous Reviewers for several constructive suggestions. We also would like to express our sincere gratitude to Dr. Ashish Selokar, Accendere, CL Educate Pvt. Ltd. for his valuable comments that led to substantial improvements on an earlier version of this manuscript. References [1] Deenalayan, S.Sivakumar, R. Vishnuvardhan, R. Sathish kumar, International J. Engg. Tech, 7 (2.31) (2018)208-211. [2]Silva Flavio de Andrade, Filho Romildo Dias Toledo, Filho Joao de Almeida Melo, Fairbairn Eduardo de Moraes rego. J.Construct.& Build. Mater. 2010; 24:777–85. [3] S V Joshi, L T Drzal, A K Mohanty and S Arora 2004 Composites: Part A J. Appl. Sci. Manf. 35371. [4] S Kaewkuk, W Sutapun & K Jarukumjorn, Compos. Part B, 45 (2013) 544. [5] Hari Om Maurya, M.K. Gupta, R.K. Srivastava, H. Singh. Mat. Today: Proc. 2; 2015; 1347 – 1355. [6]Cristiane M. Becker, Teo A.Dick, Fernando Wypych, Henri S. Schrekker, Sandro C. Amico. Polymer Testing 31 (741-747). [7] N Venkateshwaran, A Elyaya Perumal, A Alavudeen & M Thiruchitrambalam, Mater. Des. 32(2011) 4017. [8] M K Gupta & R K Srivastava, American. J. Polym. Sci. Engg. 3 (2015) 208.