# Investigation on the Mechanical Properties of Flax/False Banana Hybrid Fiber-Reinforced Polymer Composite

Authors: Alelign Zelalem Biresaw; Belete Sirahbizu Yigezu
Journal: Advances in Materials Science and Engineering
 (2022)

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## Abstract

The intent of this research is to develop new material from flax and false banana fiber hybrid reinforced polymer composite using polyester resin as a matrix to replace synthetic fiber-reinforced polymer composites for automotive interior bodies. The composite samples were fabricated based on the weight percentage of fibers/matrix and the orientation of the fibers that were combined with Taguchi’s experimental design using the hand layup fabrication process. And also, single flax and single false banana fiber-reinforced polymer composite was fabricated with the same composition and orientation alone. The composite was tested for tensile and flexural strength properties, and it had been discussed and specimens were prepared according to ASTM standards. As a result, false banana showed better flexural strength than false banana fiber-reinforced composite for tensile strength, whereas the hybrid composites of 25% of flax, 15% of false banana, and unidirectional orientation have shown the maximum tensile and flexural strength with a value of 113.4 MPa and 167.88 MPa, respectively.


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## Body

## 1. Introduction

In recent decades, fiber-reinforced composites have increasingly become the most widely used material in applications of automotive body panels, aerospace, construction industry (panels, false ceilings, partition boards), packaging, aerospace, railway coach interiors, sporting materials, storage devices, and so on [1]. The most common types of fibers used in advanced fiber-reinforced composites for structural and nonstructural applications are natural fibers and synthetic fibers [2]. Composites made of natural fibers have lightweight, low cost, bio-degradable, and environmentally friendly making them advantageous over synthetic fibers [3]. An important behavior of natural fiber among synthetic fibers is its carbon positive effect on the environment. Due to this, various academic and industrial researchers are conducting research on environmentally friendly, sustainable materials to replace conventional materials. These outstanding advantages, as well as the economic and environmental benefits of NF composites, made them predominant over synthetic fiber-reinforced composites for modern applications [4].Natural fibers are extracted from naturally available sources like plants, animals, and minerals. NFs are very easy to obtain and they are extensively available material in nature. Some of the commonly used natural fibers; particularly, plant fibers are seed fiber (cotton and coir), leaf fiber (sisal and pineapple), bast fiber (flax, ramie, and hemp), stalk fiber (rice), and grass fibers (rye and wheat) [5]. Generally, plant-based fibers become the most dominantly replacing reinforcement material for synthetic fibers in polymer matrix materials for structural and other engineering industrial applications and attracted interest due to severe ecological effects and the need for fabricating sustainable products [6, 7].Hybrid composites made from the blending of natural fibers alone or with synthetic fibers in a polymer matrix show a synergistic effect on properties that cannot be achieved from normal composites [8]. Composite materials are classified according to their content matrix material and reinforcement material. The reinforcements having high-strength fibers provide the polymer to substantially enhance the mechanical properties and make the FRPCs suitable for a large number of diverse applications ranging from aerospace to sports equipment [9]. The type, orientation, volume fraction, and size on the surface of the fibers influence the specific gravity, tensile/flexural strength and modulus, fatigue strength as well as fatigue failure mechanisms, and also the electrical and thermal conductivities [10]. The fibers can be chopped, woven, stitched, and braided. The most common types of fibers used in advanced composites for structural applications are natural fibers and synthetic fibers [11].Sivakumar et al. [12] experimented to study the mechanical properties of randomly oriented treated and untreated palmyra natural fiber-reinforced polyester composites using the hand layup fabrication method. Tensile strength and flexural strength were discussed for both the treated and untreated Palmyra. Thus, the mechanical properties of materials prepared from a chemical treated with potassium permanganate palmyra are found to be much stronger than those of untreated fiber. Not only this but also Saravana et al. [13] treated Carica Papaya with 5% of NaOH, and they found an improved mechanical property.Prasath et al. [14] studied the effect of fiber orientation on the performance of flax fiber-reinforced polymer composites. The composite was prepared by using a hand layup process by obtaining polyester resin from different layers of flax fibers in different orientations like 0°, 30°, 45°, 60°, and 90°. Results showed that 0° and 90° orientation exhibited better performance. However, as Ramesh and Sudharsan [15] examined experimentally the mechanical properties of flax-glass fiber, the maximum tensile strength of the composite material was found in a unidirectional orientation (0°) of the fibers in comparison with 90° orientation of the fibers. Demissie et al. [16] investigated the mechanical properties of false banana reinforced epoxy composite. During the investigation, it was observed that the mechanical properties will change with a change in the composition of fibers. Finally, it is concluded that the fabricated false banana epoxy composite is affected by the change in the loading of the fibers and it has been shown that a lightweight and improved mechanical properties.Meenakshi and Krishnamoorthy [17] prepared and characterized the mechanical properties of flax and glass fiber-reinforced polyester hybrid composite laminate by hand layup method. Laminated composites were prepared with different volumes of flax and glass fiber, and their mechanical properties like tensile strength, impact strength, flexural strength, and water absorption nature are tested. The tests are carried out on standard ASTM-sized samples and the results show that the hybrid composite is showing equally good performance to conventional glass fiber composite and overall better performance than the mono natural fiber composite. This paper is majorly concerned to develop new composite material, which aims to increase the use of available natural fibers as well as replace synthetic fibers by using flax/false banana fiber as a reinforcement material and polyester resin as a matrix and making the composite using hand lay up the method and experimentally investigating the tensile and flexural properties of the hybrid composite for the application of interior automotive bodies.


## 2. Materials and Methods

### 2.1. Materials

The materials used to prepare flax/false banana hybrid composite are flax fiber, false banana fiber, polyester resin, methyl ethyl ketone peroxide(MEKP), and Honey Wax® 250 as mold releasing agent. False banana fiber extracted from a plant native to Ethiopia is often referred to as the false banana because not surprisingly it resembles the banana plant. The fiber is extracted from this fiber by hand using wood lumber and other sharp wood. In Table1, the physical and mechanical properties of the false banana fiber are described.Table 1
Physical and mechanical properties of false banana fiber [18].
PropertiesFalse banana fiberDensity (g/cm3)1.4–1.6Modulus of elasticity (GPa)543.3Tensile strength (MPa)543Modulus (GPa)67.3Elongation at break (%)4–6Flax fiber is one of the most exciting fiber types in natural fibers, and it is used in advance to produce composite material with different reinforcing elements. Flax fiber had purchased from the commercial market at Merkato, Addis Ababa, Ethiopia, and its properties are indicated in Table 2.Table 2
Physical and mechanical properties of flax fiber [19].
PropertiesFlax fiberDensity (g/cm3)1.45Specific tensile strength (MPa/(g/cm3))245–1334Specific Young’s modulus (GPa/(g/cm3))11–53Dry elongation (%)0.6–1.8Wet elongation (%)0.7–2.2Tensile strength (MPa)343–2000Modulus (MPa)15–80Elongation at break (%)3.08Alkali treatment of fiber materials: Alkaline treatment greatly improves the mechanical behavior of natural fibers, especially fiber strength and stiffness, and hence the mechanical properties of the resulting composite [20]. The addition of aqueous sodium hydroxide (NaOH) to natural fiber promotes the ionization of the hydroxyl group to the alkoxide. The alkali reaction between flax and false banana fiber and NaOH is as follows [21].(1)Fiber–OH+N2OH⟶Fiber–O–Na++H2O.In alkali treatment of surface modification, the flax-false/banana fibers were soaked in a 5% NaOH solution maintained at room temperature. The fibers were kept immersed in the alkali solution for 24 hrs. Those fibers had then washed several times with fresh water to remove any NaOH solution that is stuck to the fiber surface and finally washed again with distilled water. The fibers were then dried at room temperature for two days.


### 2.2. Hybrid Composite Sample Fabrication

The composites were fabricated based on the mass percentage ratio of fiber and matrix, and orientation of flax and false banana fiber by using the hand layup method. Before going to fabrication, the fibers are treated using NaOH solution, and then, it was dried for a specified time. After that, fibers will be cut into a required length depending on the size of the mold that it would be prepared for the fabrication of hybrid samples. Then, eleven samples were fabricated in the different mass percentages of flax fiber and false banana fiber, polyester resin matrix using the calculated value, and by obtaining different orientations of hybrid fibers based on experimental design.


### 2.3. Experimental Design

Two samples will be done for the comparison of flax fiber-reinforced polyester composite and false banana fiber-reinforced polyester composite out of the designed details with the same fraction and fiber orientation with the same fabrication method, whereas nine samples have been fabricated based on TaguchiL9 orthogonal array. L9 orthogonal array of DOE is used for combining the factors and levels by using Minitab 18.1 version software. Based on this method, Tables 3–5 consist of control factors and their levels; corresponding experimental runs and their composite designation; and composition of composite designations, respectively.Table 3
Control factors and their levels.
Control factorsUnitsLevels123Flax fiber(%)51525False banana fiber(%)51525Orientation of fibers(°)[0, 0][90, 0][0, 90]Table 4
Corresponding experimental runs and their composite designation.
Experimental runsComposite designationFlax fiber (wt%)False banana fiber (wt%)Orientation of the fibersFlax fiber (wt%)False banana fiber (wt%)Orientation of the fibers1FFBHPC 111155[0, 0]2FFBHPC 2122515[90, 0]3FFBHPC 3133525[0, 90]4FFBHPC 4212155[90, 0]5FFBHPC 52231515[0, 90]6FFBHPC 62311525[0, 0]7FFBHPC 7313255[0, 90]8FFBHPC 83212515[0, 0]9FFBHPC 93322525[90, 0]Table 5
Composition of composite designations.
Composite designationFlax/false banana/matrix (%)Flax/false banana orientations (°)FFBRHPC 15/5/90[0, 0]FFBRHPC 25/15/80[90, 0]FFBRHPC 35/25/70[0, 90]FFBRHPC 415/5/80[90, 0]FFBRHPC 515/15/70[0, 90]FFBRHPC 615/25/60[0, 0]FFBRHPC 725/5/70[0, 90]FFBRHPC 825/15/60[0, 0]FFBRHPC 925/25/50[90, 0]


### 2.4. Characterization of Prepared Samples

Composites that were fabricated had gone to different mechanical property tests to characterize the material based on the American Society for Testing and Materials (ASTM). Tests that were performed are tensile strength property using ASTM D3039 and flexural strength property using ASTM D790. For every test of the composite samples to characterize their properties, three test specimens had prepared for the same composition. Then, it is tested using a universal testing machine (UTM). UTM testing systems are highly integrated testing packages that can be configured to meet different testing needs. It includes a load unit with an integrally mounted actuator and servo valves, a hydraulic power unit, and a control system. The standard specimen used for tensile testing of fiber-reinforced composites is a flat rectangular coupon. During the test, a uniaxial load is applied through both ends of the specimen. The size of the specimen prepared for the tensile strength test is 250 × 25 × 4 mm. It is a three-point bending test in which the maximum bending stress that the test specimen can sustain before it yields. The flexural test is carried out on flat specimens to determine flexural strength. For each sample, three specimens with the size of 170 × 25 × 4 mm are prepared. The test follows ASTM standards, and it was performed on UTM; it is equipped with bend fixtures and closed-loop controllers are recommended to run flexural testing.The maximum bending stress can be calculated as follows:(2)σbf=Mb,maxWb=3FmaxL2BH2,where σbf = bending stress in the outer specimen at the midpoint.(3)Mb,max=Maximumbendingmoment=FmaxL4,(4)Wb=Sectionmodulus=BH26,whereFmax = load at a given point on the load-deflection curve, L = length of span, B = width of the sample, and H = depth of the sample.


## 2.1. Materials

The materials used to prepare flax/false banana hybrid composite are flax fiber, false banana fiber, polyester resin, methyl ethyl ketone peroxide(MEKP), and Honey Wax® 250 as mold releasing agent. False banana fiber extracted from a plant native to Ethiopia is often referred to as the false banana because not surprisingly it resembles the banana plant. The fiber is extracted from this fiber by hand using wood lumber and other sharp wood. In Table1, the physical and mechanical properties of the false banana fiber are described.Table 1
Physical and mechanical properties of false banana fiber [18].
PropertiesFalse banana fiberDensity (g/cm3)1.4–1.6Modulus of elasticity (GPa)543.3Tensile strength (MPa)543Modulus (GPa)67.3Elongation at break (%)4–6Flax fiber is one of the most exciting fiber types in natural fibers, and it is used in advance to produce composite material with different reinforcing elements. Flax fiber had purchased from the commercial market at Merkato, Addis Ababa, Ethiopia, and its properties are indicated in Table 2.Table 2
Physical and mechanical properties of flax fiber [19].
PropertiesFlax fiberDensity (g/cm3)1.45Specific tensile strength (MPa/(g/cm3))245–1334Specific Young’s modulus (GPa/(g/cm3))11–53Dry elongation (%)0.6–1.8Wet elongation (%)0.7–2.2Tensile strength (MPa)343–2000Modulus (MPa)15–80Elongation at break (%)3.08Alkali treatment of fiber materials: Alkaline treatment greatly improves the mechanical behavior of natural fibers, especially fiber strength and stiffness, and hence the mechanical properties of the resulting composite [20]. The addition of aqueous sodium hydroxide (NaOH) to natural fiber promotes the ionization of the hydroxyl group to the alkoxide. The alkali reaction between flax and false banana fiber and NaOH is as follows [21].(1)Fiber–OH+N2OH⟶Fiber–O–Na++H2O.In alkali treatment of surface modification, the flax-false/banana fibers were soaked in a 5% NaOH solution maintained at room temperature. The fibers were kept immersed in the alkali solution for 24 hrs. Those fibers had then washed several times with fresh water to remove any NaOH solution that is stuck to the fiber surface and finally washed again with distilled water. The fibers were then dried at room temperature for two days.


## 2.2. Hybrid Composite Sample Fabrication

The composites were fabricated based on the mass percentage ratio of fiber and matrix, and orientation of flax and false banana fiber by using the hand layup method. Before going to fabrication, the fibers are treated using NaOH solution, and then, it was dried for a specified time. After that, fibers will be cut into a required length depending on the size of the mold that it would be prepared for the fabrication of hybrid samples. Then, eleven samples were fabricated in the different mass percentages of flax fiber and false banana fiber, polyester resin matrix using the calculated value, and by obtaining different orientations of hybrid fibers based on experimental design.


## 2.3. Experimental Design

Two samples will be done for the comparison of flax fiber-reinforced polyester composite and false banana fiber-reinforced polyester composite out of the designed details with the same fraction and fiber orientation with the same fabrication method, whereas nine samples have been fabricated based on TaguchiL9 orthogonal array. L9 orthogonal array of DOE is used for combining the factors and levels by using Minitab 18.1 version software. Based on this method, Tables 3–5 consist of control factors and their levels; corresponding experimental runs and their composite designation; and composition of composite designations, respectively.Table 3
Control factors and their levels.
Control factorsUnitsLevels123Flax fiber(%)51525False banana fiber(%)51525Orientation of fibers(°)[0, 0][90, 0][0, 90]Table 4
Corresponding experimental runs and their composite designation.
Experimental runsComposite designationFlax fiber (wt%)False banana fiber (wt%)Orientation of the fibersFlax fiber (wt%)False banana fiber (wt%)Orientation of the fibers1FFBHPC 111155[0, 0]2FFBHPC 2122515[90, 0]3FFBHPC 3133525[0, 90]4FFBHPC 4212155[90, 0]5FFBHPC 52231515[0, 90]6FFBHPC 62311525[0, 0]7FFBHPC 7313255[0, 90]8FFBHPC 83212515[0, 0]9FFBHPC 93322525[90, 0]Table 5
Composition of composite designations.
Composite designationFlax/false banana/matrix (%)Flax/false banana orientations (°)FFBRHPC 15/5/90[0, 0]FFBRHPC 25/15/80[90, 0]FFBRHPC 35/25/70[0, 90]FFBRHPC 415/5/80[90, 0]FFBRHPC 515/15/70[0, 90]FFBRHPC 615/25/60[0, 0]FFBRHPC 725/5/70[0, 90]FFBRHPC 825/15/60[0, 0]FFBRHPC 925/25/50[90, 0]


## 2.4. Characterization of Prepared Samples

Composites that were fabricated had gone to different mechanical property tests to characterize the material based on the American Society for Testing and Materials (ASTM). Tests that were performed are tensile strength property using ASTM D3039 and flexural strength property using ASTM D790. For every test of the composite samples to characterize their properties, three test specimens had prepared for the same composition. Then, it is tested using a universal testing machine (UTM). UTM testing systems are highly integrated testing packages that can be configured to meet different testing needs. It includes a load unit with an integrally mounted actuator and servo valves, a hydraulic power unit, and a control system. The standard specimen used for tensile testing of fiber-reinforced composites is a flat rectangular coupon. During the test, a uniaxial load is applied through both ends of the specimen. The size of the specimen prepared for the tensile strength test is 250 × 25 × 4 mm. It is a three-point bending test in which the maximum bending stress that the test specimen can sustain before it yields. The flexural test is carried out on flat specimens to determine flexural strength. For each sample, three specimens with the size of 170 × 25 × 4 mm are prepared. The test follows ASTM standards, and it was performed on UTM; it is equipped with bend fixtures and closed-loop controllers are recommended to run flexural testing.The maximum bending stress can be calculated as follows:(2)σbf=Mb,maxWb=3FmaxL2BH2,where σbf = bending stress in the outer specimen at the midpoint.(3)Mb,max=Maximumbendingmoment=FmaxL4,(4)Wb=Sectionmodulus=BH26,whereFmax = load at a given point on the load-deflection curve, L = length of span, B = width of the sample, and H = depth of the sample.


## 3. Results and Discussions

### 3.1. Discussion on Tensile Strength

The results of tensile strength properties were recorded during the observation of specimens fabricated in different fiber volume ratios, matrices, and orientations of the fibers. After testing each specimen, the tensile strength of the composites was evaluated and the average value of the property that was observed has been calculated for each sample. The testing process is continued until the specimen fractures. For comparison, pure flax fiber-reinforced and false banana reinforced composite were prepared. Composite samples were fabricated from single fiber alone, that is, flax fiber only and false banana fiber only, and hybrid flax and false banana fiber. FFRPC and FBFRPC had fabricated with 10% fiber and 90% matrix percentage ratio for both samples with zero degrees orientation of the fibers. The tensile strength properties of these samples were compared to exhibit the effect of hybridization of fibers in the composite material.Figure1 shown above describes the comparisons of the average tensile strength of FFRPC and FBFRPC composite samples. Thus, FFRPC attained the maximum tensile strength with the value of 35.43 MPa than FBFRPC having 30.63 MPa with the same fiber volume ratio and matrix volume ratio with the same fiber orientation. From this, it is possible to summarize flax fiber has a more positive effect on the tensile strength properties of fabricated composite sample materials than false banana fiber based on the results it had been shown. Similarly, FFRPC can withstand more tensile load on the account of having flax fiber than FBFRPC.Figure 1
Comparisons of the average tensile strength of FFRPC and FBFRPC composite samples.Also, these samples are compared with FFBHRPC 1 to see the effect of the hybridization of fibers. FFBHRPC 1 had fabricated with 5%/5%/90% (flax/false banana/matrix) constituents by using the same orientation of fibers, which were used. The tensile strength value of this composite is 33.26 MPa. It is lower than the tensile strength of FFRPC but is greater than FBFRPC. Thus, the hybridization of these two fibers improves the tensile strength of the composite samples.Every sample test has been accomplished by repeating three times (for the same composition) to have an exact result, and the average is taken as the final finding. Based on the results tabulated the average tensile strength, strain at break and maximum force obtained from samples of FFBRHPC 1, FFBRHPC 2, FFBRHPC 3, FFBRHPC 4, FFBRHPC 5, FFBRHPC 6, FFBRHPC 7, FFBRHPC 8, and FFBRHPC 9 have discussed. These composites were fabricated with different fiber/matrix ratios and orientations that were combined using the Taguchi method. The following figure shows the comparison of the tensile strength of these samples.In the above Figure2, it is shown that the effects of fiber/matrix ratios and orientations of the fiber have a vital role in the tensile strength properties of fabricated composite materials. These samples were tested according to ASTM standards by the use of UTM. Thus, as the graph is shown, FFBHRPC 8 indicated the maximum tensile strength of all the composites. This sample was prepared with 25% of flax fiber, 15% of false banana, and 60% of polyester resin with the orientation of [0° flax and 0° false banana] at a room temperature of 25°C by using a hand layup method and cured for 24 hr using a hydraulic press machine. This sample has a tensile strength of 113.4 MPa. It is the highest value recorded during the observation of the results. The important thing to get this value is that the orientation of the fibers is arranged in the direction of the applied tensile load. Next to this sample, FFBHRPC 5 has the highest tensile strength 88.7 MPa among the other composite results. It was prepared in the different orientations of the fiber [0° flax and 90° false banana] to that of FFBHRPC 8. This sample has an improved tensile strength due to having a high tensile modulus of flax fiber, and it is arranged 0° orientation, this thing made the sample better properties than other samples. Thus, the increase in flax fiber orientation contributes to the decrease in tensile strength.Figure 2
Comparison of average tensile strength of fabricated samples.To sum up the observation, the tensile strength of the composites that were fabricated has different values of the property. This is due to the variation in weight percentage of flax, false banana fiber, and polyester resin as well as the orientation of fibers. Especially, flax fiber orientation (to be zero degrees) shows a positive effect on the tensile strength of the composite. Even if the weight percentage of flax fiber increases and it is arranged in 90° fiber orientation to false banana fiber and the load is applied perpendicular to it during the test the tensile strength of the composite decreases. And the decrease in false banana fiber weight percentage helps to increase the tensile strength of the material.


### 3.2. Discussion on Flexural Strength

The results of flexural strength were conducted by using UTM like that of compressive, tensile, and impact strength, and not only this one but also the fabrication systems like fiber/matrix ratio and orientation of the fibers were the same. Comparisons were also done between FFRPC and FBFRPC, and the other samples that were fabricated by the Taguchi combination of the constituents.The flexural strength of FFRPC and FBFRPC is illustrated in Figure3. False banana fiber-reinforced polymer composite showed better strength with a value of 74.73 MPa compared with flax fiber-reinforced polymer composites. Thus, FBFRPC can resist more flexural load than FFRPC. The composites were fabricated with 10% of fibers for both samples and 90% of matrices with the same manufacturing method. From the comparison, false banana actuates more in flax/false banana fiber hybrid reinforced polymer composites to enhance the property. FFBRHPC 1 has the same percentage ratio of fiber/matrix as FFRPC and FBFRPC, but the difference in the case of FFBRHPC 1 is the hybrid of the two fibers. The flexural strength put down for FFBRHPC 1 is 82.22 MPa. It is indicated that the hybridization of flax/false banana fiber commodities is a positive thing in flax/false banana fiber hybrid reinforced polymer composite.Figure 3
Comparison of average flexural strength of fabricated samples.Figure4 shows the comparison of flexural strength of Taguchi-based fabricated samples. Nine samples are fabricated with the same fiber/matrix ratio and orientation as that of samples performed for tensile and compressive strength. FFBRHPC 8 points out the maximum flexural strength with the value of 167.88 MPa. This sample also showed the maximum tensile strength as it is discussed above. For tensile strength, the maximum strength was attained due to the presence of a high tensile modulus of flax fiber, whereas in the case of flexural strength, the presence of false banana fiber helps to improve the property in the longitudinal orientation of the fibers. FFBRHRPC 3 settled second place next to FFBRHRPC 8 due to the maximum amount of false banana fiber available in the composite, but the orientation is different. The value obtained for FFBRHRPC 3 is 106.25 MPa, and its orientation of fiber arrangement is 0° of flax and 90° of false banana fiber.Figure 4
Comparison of average flexural strength of fabricated samples.By and large, the flexural strength comparisons of the different combinations of the flax/false banana fiber-reinforced composites are presented in the above figure. The results indicated that the orientation and fiber volume has a great influence on flax/false banana hybrid reinforced polymer composites. In the end, when the weight of false banana fiber increased in fiber/matrix ratio greatly improves the flexural strength, this is due to the reason that the nature of the false banana fiber.


## 3.1. Discussion on Tensile Strength

The results of tensile strength properties were recorded during the observation of specimens fabricated in different fiber volume ratios, matrices, and orientations of the fibers. After testing each specimen, the tensile strength of the composites was evaluated and the average value of the property that was observed has been calculated for each sample. The testing process is continued until the specimen fractures. For comparison, pure flax fiber-reinforced and false banana reinforced composite were prepared. Composite samples were fabricated from single fiber alone, that is, flax fiber only and false banana fiber only, and hybrid flax and false banana fiber. FFRPC and FBFRPC had fabricated with 10% fiber and 90% matrix percentage ratio for both samples with zero degrees orientation of the fibers. The tensile strength properties of these samples were compared to exhibit the effect of hybridization of fibers in the composite material.Figure1 shown above describes the comparisons of the average tensile strength of FFRPC and FBFRPC composite samples. Thus, FFRPC attained the maximum tensile strength with the value of 35.43 MPa than FBFRPC having 30.63 MPa with the same fiber volume ratio and matrix volume ratio with the same fiber orientation. From this, it is possible to summarize flax fiber has a more positive effect on the tensile strength properties of fabricated composite sample materials than false banana fiber based on the results it had been shown. Similarly, FFRPC can withstand more tensile load on the account of having flax fiber than FBFRPC.Figure 1
Comparisons of the average tensile strength of FFRPC and FBFRPC composite samples.Also, these samples are compared with FFBHRPC 1 to see the effect of the hybridization of fibers. FFBHRPC 1 had fabricated with 5%/5%/90% (flax/false banana/matrix) constituents by using the same orientation of fibers, which were used. The tensile strength value of this composite is 33.26 MPa. It is lower than the tensile strength of FFRPC but is greater than FBFRPC. Thus, the hybridization of these two fibers improves the tensile strength of the composite samples.Every sample test has been accomplished by repeating three times (for the same composition) to have an exact result, and the average is taken as the final finding. Based on the results tabulated the average tensile strength, strain at break and maximum force obtained from samples of FFBRHPC 1, FFBRHPC 2, FFBRHPC 3, FFBRHPC 4, FFBRHPC 5, FFBRHPC 6, FFBRHPC 7, FFBRHPC 8, and FFBRHPC 9 have discussed. These composites were fabricated with different fiber/matrix ratios and orientations that were combined using the Taguchi method. The following figure shows the comparison of the tensile strength of these samples.In the above Figure2, it is shown that the effects of fiber/matrix ratios and orientations of the fiber have a vital role in the tensile strength properties of fabricated composite materials. These samples were tested according to ASTM standards by the use of UTM. Thus, as the graph is shown, FFBHRPC 8 indicated the maximum tensile strength of all the composites. This sample was prepared with 25% of flax fiber, 15% of false banana, and 60% of polyester resin with the orientation of [0° flax and 0° false banana] at a room temperature of 25°C by using a hand layup method and cured for 24 hr using a hydraulic press machine. This sample has a tensile strength of 113.4 MPa. It is the highest value recorded during the observation of the results. The important thing to get this value is that the orientation of the fibers is arranged in the direction of the applied tensile load. Next to this sample, FFBHRPC 5 has the highest tensile strength 88.7 MPa among the other composite results. It was prepared in the different orientations of the fiber [0° flax and 90° false banana] to that of FFBHRPC 8. This sample has an improved tensile strength due to having a high tensile modulus of flax fiber, and it is arranged 0° orientation, this thing made the sample better properties than other samples. Thus, the increase in flax fiber orientation contributes to the decrease in tensile strength.Figure 2
Comparison of average tensile strength of fabricated samples.To sum up the observation, the tensile strength of the composites that were fabricated has different values of the property. This is due to the variation in weight percentage of flax, false banana fiber, and polyester resin as well as the orientation of fibers. Especially, flax fiber orientation (to be zero degrees) shows a positive effect on the tensile strength of the composite. Even if the weight percentage of flax fiber increases and it is arranged in 90° fiber orientation to false banana fiber and the load is applied perpendicular to it during the test the tensile strength of the composite decreases. And the decrease in false banana fiber weight percentage helps to increase the tensile strength of the material.


## 3.2. Discussion on Flexural Strength

The results of flexural strength were conducted by using UTM like that of compressive, tensile, and impact strength, and not only this one but also the fabrication systems like fiber/matrix ratio and orientation of the fibers were the same. Comparisons were also done between FFRPC and FBFRPC, and the other samples that were fabricated by the Taguchi combination of the constituents.The flexural strength of FFRPC and FBFRPC is illustrated in Figure3. False banana fiber-reinforced polymer composite showed better strength with a value of 74.73 MPa compared with flax fiber-reinforced polymer composites. Thus, FBFRPC can resist more flexural load than FFRPC. The composites were fabricated with 10% of fibers for both samples and 90% of matrices with the same manufacturing method. From the comparison, false banana actuates more in flax/false banana fiber hybrid reinforced polymer composites to enhance the property. FFBRHPC 1 has the same percentage ratio of fiber/matrix as FFRPC and FBFRPC, but the difference in the case of FFBRHPC 1 is the hybrid of the two fibers. The flexural strength put down for FFBRHPC 1 is 82.22 MPa. It is indicated that the hybridization of flax/false banana fiber commodities is a positive thing in flax/false banana fiber hybrid reinforced polymer composite.Figure 3
Comparison of average flexural strength of fabricated samples.Figure4 shows the comparison of flexural strength of Taguchi-based fabricated samples. Nine samples are fabricated with the same fiber/matrix ratio and orientation as that of samples performed for tensile and compressive strength. FFBRHPC 8 points out the maximum flexural strength with the value of 167.88 MPa. This sample also showed the maximum tensile strength as it is discussed above. For tensile strength, the maximum strength was attained due to the presence of a high tensile modulus of flax fiber, whereas in the case of flexural strength, the presence of false banana fiber helps to improve the property in the longitudinal orientation of the fibers. FFBRHRPC 3 settled second place next to FFBRHRPC 8 due to the maximum amount of false banana fiber available in the composite, but the orientation is different. The value obtained for FFBRHRPC 3 is 106.25 MPa, and its orientation of fiber arrangement is 0° of flax and 90° of false banana fiber.Figure 4
Comparison of average flexural strength of fabricated samples.By and large, the flexural strength comparisons of the different combinations of the flax/false banana fiber-reinforced composites are presented in the above figure. The results indicated that the orientation and fiber volume has a great influence on flax/false banana hybrid reinforced polymer composites. In the end, when the weight of false banana fiber increased in fiber/matrix ratio greatly improves the flexural strength, this is due to the reason that the nature of the false banana fiber.


## 4. Conclusion

The fabricated composite samples were prepared for different mechanical properties. Tests like tensile strength and flexural strength properties of the composites that were fabricated are investigated. Thus, it was observed that composites made with 10% of flax fiber alone and 25% flax fiber, and 15% false banana fiber showed the maximum tensile and flexural strength with a unidirectional orientation of the fibers with the value of 35.43 MPa and 113.4 MPa, respectively, in comparison with the other composite samples. Additionally, during the test flax fiber shows better tensile strength and less flexural strength compared with false banana fiber, and in the hybridization process, the flexural strength was improved compared to tensile strength. False banana fiber alone and 25% flax fiber and 15% of false banana fiber have a maximum flexural strength and the results recorded were 74.73 MPa and 167.88 MPa, respectively. Generally, according to the properties required and the results found that this new flax/false banana hybrid reinforced composite has a comparable property, while it is compared to the previous works and it can be used in different applications of automotive interior bodies.



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*Source: 5696758-2022-08-13.xml*