Experimental investigation of mechanical properties and morphology of bamboo-glass fiber-nanoclay reinforced epoxy hybrid composites

Abstract In the present work, the mechanical and morphological characterization of bamboo-glass fiber-nanoclay epoxy hybrid composites is carried out. Materials are prepared using a hand lay-up process with different wt.% of bamboo fiber, glass fiber, nanoclay, and epoxy. As per ASTM standards, fabricated composite laminates are cut and tested for tensile and flexural properties. The bamboo fiber epoxy composites (BFEC) display the tensile and flexural strength of 137 and 170 MPa, respectively. Hybrid composites, viz. bamboo-glass fibers epoxy composites (BGFEC), display improved tensile (180–240 MPa) and flexural (225 to 320 MPa) strengths compared to BFECs. Glass fiber epoxy composites (GFEC) display maximum tensile (265 MPa) and flexural (360 MPa) strengths among all the composites. Furthermore, the addition of nanoclay improves the tensile (by 6 to 8%) and flexural (by 8 to 10%) strengths of epoxy, BFEC, BGFEC, and GFECs. SEM analysis is conducted for fractured tensile specimens to understand the reasons for specimen failure.


Introduction
Natural fiber composites have gained worldwide importance over the past decade because of the recognition of the need for substitutes for synthetic fibers.These composites, reinforced with natural fibers, are relatively strong, lightweight, non-toxic, and biodegradable and thus hold promise for various applications, including those in domestic, construction, and automotive industries (Sanjay et al., 2018).Natural fibers offer various benefits such as biodegradability, renewability, low specific weight, good specific strength and stiffness, low cost, and safety in production and usage (Zaman & Khan, 2020).They do have some disadvantages, including lower impact strength, lower durability, and poor fiber-matrix adhesion (Rangappa et al., 2022).To address this, various authors have investigated the use of natural fibers, including but not limited to sisal (Bekele et al., 2022), banana (Ramachandran et al., 2016), oil palm (Ramlee et al., 2019), jute (Abu Shaid Sujon et al., 2020), hemp (Bollino et al., 2022), flax (Prabhu et al., 2023) and wood pulp (Tian & Xu, 2022), as reinforcements in polymer matrices.

Bamboo fiber-reinforced polymer composites
Bamboo fiber-reinforced polymer composites are made of bamboo fibers and polymer matrix to produce a strong and lightweight material.These composites are a desirable alternative for various applications because of their benefits over conventional materials like steel, concrete, or wood.The stems of bamboo plants are used to make bamboo fibers.Bamboo fibers offer excellent properties, viz., great strength, stiffness, and flexibility.Bamboo is an environmentally favorable option for composite materials due to its quick growth, renewability, and sustainability.Adding bamboo fibers to the polymer enhances the composite material's mechanical properties.The fibers increase the composite's strengths and impact resistance by serving as reinforcement.The low density of bamboo fibers helps to make the lightweight composite with an excellent strength-to-weight ratio.Construction, automotive, and consumer products industries are just a few industries that use Bamboo fiber-reinforced polymer composites.
Gupta et al. (Gupta et al., 2011) studied the impact of different wt.% of bamboo fiber on the epoxy's tensile strength.A bi-directional bamboo roving mat is utilized to fabricate the composite with varying weight percentages of 10, 20, 30, and 40.The results show that the tensile strength ranged from 118 to 138 MPa.Huang and Young (Huang & Bin Young, 2019) utilized the resin transfer molding technique to fabricate BFECs with 42 vol.%bamboo fiber.The epoxy displays a tensile strength and modulus of 79 MPa and 2.5 GPa, respectively.Meanwhile, the BFEC shows significant improvements in both properties, with values of approximately 169 MPa and 8.5 GPa, respectively.Chiu and Young (Chiu & Young, 2020) investigated the effect of unidirectional (UD) and bidirectional reinforcement (BD) on the BFEC's tensile properties.Both composites are fabricated using the resin transfer molding process with 50 wt% of reinforcement.The UD composite shows a tensile strength and modulus of 234 MPa and 14.89 GPa, respectively, while the BD composite has 128 MPa and 12.60 GPa.Wang et al (Wang et al., 2018), investigated the effect of different fiber volume fraction of bamboo fibers on the mechanical behavior of polylactidebased composites.As the volume fraction of fiber increases in the composites, the tensile modulus increases however failure strain decreases.

Hybrid composites
Although natural fiber composites are typically limited to non-structural or sub-structural applications due to their weaker mechanical properties, various methods are developed to improve their properties.These methods include modifying the matrix and fibers through chemical or physical means and combining natural fibers with high-strength synthetic fibers or adding the nanoparticle (Hemath et al., 2020;Vinay et al., 2021) or microparticles (Jenish et al., 2022;Prabhu et al., 2023) to produce hybrid composites.Hybridization offers the advantage of customizing material properties according to specific requirements.Recently a new approach is introduced to enhance the properties of hybrid composites using carbon/glass fabrics as skin layers with plant and animal fibers (Rangappa et al., 2022).
Glass fibers are famous for reinforcing thermoplastics and thermosets due to their affordability, superior tensile strength, chemical resistance, dimensional stability, and excellent insulation characteristics.Kumar et al. (Kumar et al., 2021) studied the effect of different wt.% hybridization of bamboo fiber (BF) and glass fibers (GF) on the epoxy-based polymer composite.The findings indicate that increasing the weight percentage of GF resulted in an 88% improvement in the composite's tensile strength.Supian et al. (Supian et al., 2021) explored the hybrid of date palm fibers and bamboo fibers as reinforcements for polymeric composites in automotive interior components.The hybrid composite exhibits superior mechanical properties, making it promising for non-structural and semi-structural applications.Aruchamy et al (Aruchamy et al., 2020).compared cotton and cotton-bamboo fabrics epoxy composites.Composites are prepared utilizing compression molding.Mechanical properties are assessed under various fiber loading conditions (30 to 50 wt.%).The cotton-bamboo hybrid composite with 45 wt.% loadings shows the most remarkable mechanical properties, attributed to the presence of bamboo yarn in the weft direction.
Many researchers have incorporated different nanoparticles into polymer resin to fabricate natural fiber hybrid composite materials.Nanoparticles can significantly improve the mechanical properties of composites (Hemath et al., 2020;Vinay et al., 2021).The presence of nanoparticles allows for better load transfer within the composite material.When stress is applied, the nanoparticles can efficiently distribute and transfer the load to neighboring matrix material.This helps prevent the propagation of cracks and enhances the overall load-carrying capacity of the composite.Also, nanoparticles can increase the stiffness of composites by restricting the movement of polymer chains or matrix material (Bajić et al., 2023).Nanoparticles can act as barriers to crack propagation.When a crack attempts to propagate through the composite, it encounters obstacles in the form of nano-fillers, which can hinder its progress.This makes the composite more resistant to crack initiation and growth (Kini et al., 2023).

Chemical-treated natural fiber-reinforced polymer composites
Chemical treatment of natural fibers is essential to improve adhesion, surface, and mechanical properties.Common chemical treatments for natural fibers include alkali treatment (using sodium hydroxide or potassium hydroxide), silane treatment (using organosilane compounds), and acetylation (introducing acetyl groups onto the surface of fiber).The specific treatment chosen depends on the type of fiber, the polymer, and the anticipated composite properties.Different chemical treatments on fibers can significantly reduce amorphous components such as hemicellulose, lignin, and other impurities, making them less resistive to water molecules (Madhu et al., 2020).Alkali treatment is a simple, cost-efficient, and highly successful method for treating a large number of fibers (Sanjay et al., 2019).
Zhang et al. (Zhang et al., 2015) investigated the influence of surface modification on bamboo fibers' microstructure and thermo-mechanical properties.The SEM analysis reveals that an alkali treatment increases the fiber surface area available for interlocking adhesion with the matrix resin, resulting in superior interfacial bonding over untreated ones.Further results show that the average fracture strength of treated fiber on the condition of 4 wt % NaOH for one hour is increased by 10% compared to the untreated fibers.Alkali treatment can reduce the hydrophilicity of bamboo fiber, which might, in turn, improve the interfacial bonding.Dinesh et al (Dinesh et al., 2020).explored the mechanical properties of hybrid composite materials using banana and S2 glass fiber epoxy composites.Two sets of specimens are prepared: one with NaOH-treated banana fiber and another without chemical treatment.The results show that the NaOH-treated sample exhibited higher tensile and flexural strength, with SEM images revealing well-defined bonding structures.Kaima et al (Kaima et al., 2023).investigated the impact of different alkali solutions, concentrations, and soaking times on bamboo fiber bundle tensile strength for biodegradable composite materials.Bamboo strips from rough giant bamboo are soaked in NaOH, KOH, and ash solutions at various times at 5%, 10%, and 20% concentrations.The optimal soaking time is 48 hours for all solutions and concentrations.Concentrations above 5% KOH and NaOH destroyed bamboo fiber bundles, while ash solutions and 5% KOH and NaOH yielded similar tensile strength to distilled water.Alkali solutions protected bamboo fibers from fungus growth compared to water.
The literature lacks comprehensive documentation on how combining bamboo fibers, glass fibers, and nanoclay influences the mechanical properties of epoxy-based composites.This factor seems to have noteworthy implications for broadening the range of potential uses for fiber-reinforced polymers (FRPs), particularly within construction, automotive manufacturing, and consumer goods.The present work explores the influence of hybridizing bamboo fiber, glass fiber, and nanoclay on epoxy-based composites' tensile and flexural properties.Moreover, the current study reports and assesses the impact of the different wt.% of glass and bamboo fiber on the tensile and flexural properties.The study also explores the influence of the addition of nanoclay on the properties of epoxy, BFEC, GFEC, and BGFECs.In addition, the tensile test specimens' fractured surface is explored using SEM analysis to understand the causes for specimen failure under tensile load.

Materials
"Atul Polymers, India" supplies commercially available epoxy (L-12) resin and hardener (K-6) in a 10:1 mixing ratio.Epoxy (L-12) is an intermediate viscosity (9 K-12 K mPa.s) non-modified liquid resin.K-6 is a lower-viscosity hardener that cures at ambient temperature."Yuje Enterprises, Bengaluru, India" provides an E-glass fiber reel with bi-directional orientation and 360 GSM."Shreenath Weaving Industries, Gandhinagar, India" provides the 150 GSM bi-directional bamboo fiber reel."Sigma Aldrich, India" supplies the surface-modified nanoclay (Montmorillonite clay).Nanoclay has a "sheet-like" structure with lateral dimensions varying from 200 to 600 nm and a few nanometers thick.

Surface treatment of bamboo fiber
Bamboo fibers are treated with 5 wt.%NaOH solution for 1 hour at room temperature (Wong et al., 2010).The mass ratio of solution and bamboo fiber is maintained at 30:1.The treated bamboo fibers are rinsed in with water several times before drying the treated bamboo fiber at ambient temperature.Untreated and treated bamboo fibers are used to prepare two different bamboo fiber epoxy composites with 50 wt.%fibers, respectively.The detailed procedure to prepare composites is mentioned in section 2.3, and the properties of untreated and treated bamboo fiber epoxy composites are compared and discussed in section 3.1.

Preparation of composites
The epoxy and nanoclay epoxy composite specimens are prepared by general casting technique.Further, the hand lay-up technique is employed to prepare bamboo fiber epoxy, glass fiber epoxy, and hybrid composite laminates, which are subsequently compression molded.The composite laminates are cured for 24 hours at room temperature before being cut into specimens according to ASTM standards.Figure 1 outlines the specific steps taken to prepare the laminates.A detailed explanation pertaining to the preparation of composites is provided in our previous work (Shettar et al., 2020).Two types of laminates are produced.,viz., one without nanoclay and one with nanoclay, each with varying weight percentages of treated bamboo fiber, glass fiber, and epoxy, as specified in Tables 1 and 2. The treated bamboo fibers are used to prepare bamboo-fiber epoxy and bamboo-glass fiber epoxy composites.

Tensile test
Using a computerized "Universal Testing Machine" (UTM) (Z020, ZWICK-ROELL, India) and in accordance with ASTM D638 (For epoxy and Nanoclay-epoxy composites) and D3039 (For fiberreinforced composites) standards, tensile tests are carried out.The UTM specimen arrangement is depicted in Figure 2.

SEM analysis
After conducting the tensile test, the fractured specimens are examined using a EVO18 ZEISS SEM (Carl Zeiss Microscopy, Germany).To prepare the specimens for imaging, they are cut to the required dimensions and mounted onto the microscope holder.A thin film of conductive material is employed onto the specimen surface using a "mini sputter coater machine", which utilizes an 80:20 gold-palladium sputtering target to achieve high-quality images.The coating process lasted for approximately 10 Mins.

Flexural test
The computerized UTM (Z020, ZWICK-ROELL, India) is used to conduct a flexural test on five specimens of each composite type as per ASTM D790 (For epoxy and Nanoclay-epoxy composites) and D7264 (For fiber-reinforced composites) standards.The testing setup is portrayed in Figure 3.    them more responsive to bonding with the polymer.This improved interaction between the treated fibers and the polymer results in greater adhesion and load transfer, increasing composite strength and stiffness (Supian et al., 2021).

SEM analysis
Figure 5 shows the SEM images of the fracture surface of untreated and treated BFECs under tensile load.It is evident from Figure 5 that untreated and treated bamboo fibers show entirely diverse surface morphologies.Figure 5(a, b) shows minimal epoxy resin bonding to the surface of the untreated bamboo fiber, indicating a weak connection between the fiber and epoxy due to inadequate interfacial adhesion.This is primarily attributed to the untreated fibers carrying numerous hydrophilic elements on their surface and possessing a relatively smooth and irregular surface structure (Singh et al., 2020).However, as depicted in Figure 5(c, d), the treated bamboo fibers exhibit enhanced compatibility with the resin, resulting in a higher presence of epoxy observed on the fiber surface.This indicates that treating bamboo fiber improves adhesion between the fibers and the matrix, resulting in more uniform and intimate contact (Wang et al., 2019), which improves stress transfer between the matrix and the fibers.Also, in treated BFECs, the interfacial region among the fibers and the matrix might show signs of increased mechanical interlocking (Figure 5(c, d)).This can be seen as a more intricate and tightly bonded interface.The explanations above are the reasons for the display of better mechanical properties by treated BFECs, as shown in Figure 4.

Tensile properties
The tensile strength and tensile modulus of epoxy, BFEC, BGFEC, and GFECs are shown in Figure 6.The epoxy's tensile strength and tensile modulus are 54 MPa and 0.75 GPa, respectively.Bamboo fiber-reinforced epoxy composites (50BF50E) display improved tensile strength and tensile modulus, i.e., 137 MPa and 2.1 GPa, compared to pure epoxy (100E).Adding bamboo fibers to epoxy resin can enhance its tensile properties due to the unique characteristics of bamboo fibers and their interaction with the epoxy matrix.Bamboo fibers are known for their impressive strength-toweight ratio.They are lightweight yet exceptionally strong.Also, treated bamboo fibers possess a rough surface, which can promote better adhesion and bonding with the epoxy resin (Khan et al., 2017).This substantial interfacial bonding transfers stress more effectively between the fibers and the matrix, preventing premature debonding or fiber pull-out during tensile loading (Huang et al., 2021).
Figure 6 shows hybrid composites, viz., bamboo-glass fibers reinforced epoxy composites (25BF25GF50E, 20BF30GF50E, 5BF45GF50E) display improved tensile properties compared to BFECs (50BF50E).Hybridizing the bamboo and glass fiber enhances the tensile strength by 31 to 75% and tensile modulus by 26 to 119%, respectively.Also, a gradual increase in the tensile strength and tensile modulus is observed in hybrid composites due to increased wt.% of glass fiber, which is the major load-bearing constituent.Glass fibers are known for their high tensile strength and stiffness, while bamboo fibers offer natural strength and flexibility.When combined, the hybrid composite can benefit from the superior strength of glass fiber and the flexibility of bamboo fiber, resulting in a balanced material with improved overall tensile properties (Ng, 2022).Also, the hybrid structure can lead to a better load distribution throughout the composite, reducing the risk of localized stress concentrations and improving tensile properties (Al-Maharma & Sendur, 2018).
GFECs (50GF50E) display the maximum tensile strength and tensile modulus, i.e., 265 MPa and 5.35 GPa, respectively, compared to all other types of composites and epoxy.This is related to glass fiber's higher strength and stiffness than other constituents.

SEM analysis
The epoxy's fracture surface (depicted in Figure 7(a)) displays smooth, river-like patterns, suggesting a brittle fracture pattern, which signifies relatively lower fracture toughness.The lines along which the fractures propagate are almost parallel, indicating rapid and direct crack propagation.Although slight variations exist in the cracks, their predominant direction remains consistent.The fracture surface of the pure epoxy exhibits a uniform, glassy, and unvaried appearance, indicative of minimal matrix displacement-a feature typical of a homogeneous and brittle material (Kini et al., 2019;Sun et al., 2023).
Figures 7(b-d) present the SEM images of fractured specimens from the tensile testing of BFEC, BGFEC, and GFEC, respectively.Within these figures, it becomes evident that the specimen failure is attributed to a combination of factors, including matrix rupture, breakage of fibers, delamination between fibers and matrix, and the pull-out of fibers due to tensile loading.The fibers in the images exhibit a clean appearance, with no traces of residual matrix material observed.Notably, Figure 7(d) displays a broken fiber end, clearly showing the separation between the fiber and the epoxy, indicating a debonding phenomenon.(100E).Bamboo fibers act as load-bearing elements.They resist deformation and carry applied loads, thereby increasing the overall strength and stiffness of the material.The present work agrees with the findings of Chin et al (Chin et al., 2020), which reveals that adding bamboo fibers enhanced the flexural properties of three thermoset resins, viz., epoxy, polyester, and vinyl ester.Figure 8 indicates that hybrid composites, i.e., BGFECs (25BF25GF50E, 20BF30GF50E, 5BF45GF50E), outperform BFECs (50BF50E).Hybridizing the bamboo and glass fiber enhances flexural strength by 32 to 88% and flexural modulus by 40 to 130%, respectively.In addition, increased wt.% of glass fiber, a key load-bearing constituent, causes a steady rise in flexural strength and flexural modulus in hybrid composites.Glass fibers are known for their high strength and stiffness, which can complement the bamboo fibers in hybrid composites.Including glass fibers adds an additional layer of reinforcement, boosting the overall strength and stiffness of the composite beyond what bamboo fibers alone can provide (Shi et al., 2023).In a hybrid composite, bamboo fibers and glass fibers distribute loads differently.Bamboo fibers can absorb energy and help disperse forces across the material, while glass fibers carry a significant portion of the load due to their high strength.This combination prevents localized stress concentrations and enhances the composite's ability to handle bending forces (Samal et al., 2009).

Flexural properties
Similar to tensile properties, GFECs (50GF50E) display maximum flexural strength and flexural modulus, i.e., 360 MPa and 11.46 GPa, respectively, compared to epoxy, BFEC, and BGFECs.A similar trend in results is witnessed by Latha et al. (Latha et al., 2016) in their work.

Tensile properties
Figure 9 illustrates the improvement in tensile strength and tensile modulus of epoxy, BFEC, BGFEC, and GFECs by adding the 2 wt.% nanoclay.The addition of nanoclay enhances the tensile strength and tensile modulus epoxy to 57 MPa and 0.81 GPa, respectively, compared to pure epoxy, i.e., 54 MPa and 0.75 GPa.A similar trend in results is seen by Shettar et al. (Shettar et al., 2022) in their work.Incorporating surface-modified nanoclay results in an elevation of the epoxy's cross-linking density.This, in turn, causes an augmentation in the epoxy's toughness and tensile properties.This improvement arises due to the transfer of load from the epoxy matrix to the reinforcing nanoclay, fostering interaction between the two.The elongated structure of the nanoclay contributes to enhancing the tensile properties of the polymer matrix, facilitating a more robust interaction near the nanoclay interface (Guo et al., 2018).Within the realm of epoxy-nanoclay composites, nanoclay plays an active role as a stress transfer agent.This active participation leads to plastic deformation within the epoxy, subsequently culminating in an increase in tensile properties.However, it's important to note that an elevated cross-linking density could potentially reduce the epoxy's fracture toughness.This reduction is attributable to the emergence of internal stresses during the epoxy-curing process.In high cross-link density epoxies, susceptibility to crack initiation is notably diminished, and the expansion of voids due to plastic deformation is restricted.Interestingly, the nanoclay hinders crack propagation through the generation of substantial plastic deformation (Fakhreddini-Najafabadi et al., 2021).
Similarly, adding nanoclay increases the tensile properties of BFEC, BGFEC, and GFECs.The tensile strength and tensile modulus of aforesaid composites are increased by 5 to 7% and 7 to 13%, respectively.The observed outcomes could be ascribed to the subsequent factors (Senthil Kumar et al., 2018;Withers et al., 2015;Zabihi et al., 2018): 1) Nanoclay platelets function as interlocking mediators between the fibers and epoxy, thereby potentially amplifying their interfacial adhesion; 2) The inclusion of nanoclay into the epoxy has enhanced the overall mechanical properties of the epoxy; 3) Nanoclay's positive influence on the epoxy's properties could fortify the epoxy's capacity to bear loads, ultimately resulting in a reduction of stress intensity on the fibers.

SEM analysis
The fracture surface of the nanoclay-epoxy composite exhibits an intricate and winding trajectory, accompanied by an enhanced degree of surface irregularity, as depicted in Figure 10(a).This distinctive feature suggests that the advancement of crack propagation encounters considerable resistance, leading to increased tensile properties.Incorporating nanoclay into the epoxy matrix effectively impedes the crack's progression.Several distinct mechanisms for energy absorption are identified within the nanoclay-epoxy composite, contributing to the elevation of its tensile properties.Notable mechanisms encompass crack deflection, pinning, and arresting.As a collective result of these fractographic attributes, the crack path before ultimate failure takes on a convoluted course, ultimately amplifying the energy absorbed prior to failure and thereby enhancing the composite's tensile properties (Nguyen et al., 2020).
Illustrations presented in Figures 10(b-d) provide corroboration that the incorporation of nanoclay leads to a bolstered interfacial bonding among the fiber and the matrix, thereby signifying an enhancement in the composite's tensile properties.Within SEM images, large clusters of resin are observable, signifying a robust bonding among the fiber and matrix.Even post-fracture, minimal degrees of relative detachment are observed between the fibers and the matrix.This observation underscores the increased bonding resulting from the introduction of nanoclay into the composites, particularly at the interface of fiber and matrix (Sand Chee & Jawaid, 2019).

Flexural properties
Similar to tensile properties, adding nanoclay improves the flexural properties of epoxy, bamboo fiber epoxy, BFEC, BGFEC, and GFECs (Figure 11).The addition of nanoclay enhances the flexural strength and flexural modulus epoxy by 10 and 17%, respectively.A similar trend of results is noticed by Suresh et al. (Suresh et al., 2023) in their work.The increase in flexural properties is ascribed to the enhanced interfacial bonding responsible for stress transmission and elastic deformation when nanoclay particles are present.The neighboring matrix gains strength and rigidity through the incorporation of nanoclay (Arulmurugan & Venkateshwaran, 2016).Additionally, nanoclay can establish physical cross-links between epoxy chains, leading to enhanced strength in specific regions.Leveraging its sheet-like arrangement, nanoclay permits the realignment of clay layers along the stress axis, culminating in a more potent reinforcement effect (Hamim & Singh, 2014).
Similarly, adding nanoclay enhances the flexural properties of bamboo fiber epoxy, bambooglass fibers epoxy, and glass fiber epoxy composites.The flexural strength and flexural modulus of these mentioned composites experience an elevation ranging from 7 to 12% and 12 to 20%, respectively.It is recognized that the presence of nanoclay improves the bonding property of the epoxy, facilitating improved interfacial adhesion within the composites.This enhanced interfacial adhesion results in improved stress transmission among the constituents, ultimately leading to the augmentation of flexural properties (Jeyakumar et al., 2017).

Conclusions
(1) The tensile and flexural properties of bamboo fiber are improved by the NaOH treatment.
Treated bamboo fiber epoxy composites display around 30% improvement in mechanical properties compared to untreated bamboo fiber epoxy composites.
(5) Adding nanoclay improves the tensile and flexural properties of bamboo fiber epoxy, bamboo-glass fibers epoxy, and glass fiber epoxy composites.
(6) The reasons for the failure of the specimen under tensile load are determined by SEM analysis of the fracture surface.

Figure
Figure 1.Preparation of composites.

Figures 4
Figures4(a, b) show the tensile and flexural properties of treated and untreated BFECs.Untreated and treated BFEC (50BF50E) exhibit tensile strength of 102 MPa and 137 MPa, respectively.The tensile strength of treated composites is 34.31% higher than untreated composites.Similarly, there is an increment of 30.7% in flexural strength of treated BFEC compared to untreated BFEC.Similarly, tensile modulus of 1.6 and 2.1 GPa and flexural modulus of 3.17 and 4 GPa are obtained for treated and untreated composites, respectively.Treating bamboo fiber with NaOH, a strong alkaline solution, can increase mechanical properties in polymer composites.Removing lignin and hemicellulose from the bamboo fibers by NaOH treatment increases their surface area and makes

Figure
Figure 2. Loading arrangement of tensile specimen in UTM.

Figure
Figure 4. Properties of untreated and treated BFECS a) tensile and b) flexural properties.
Figure 5. SEM images of fracture surface under tensile load (a, b) untreated (c, d) treated bamboo fiber epoxy composites.

Figure 8
Figure 8 depicts the flexural strength and modulus of epoxy, BFEC, BGFEC, and GFECs.The flexural strength and flexural modulus of epoxy are 110 MPa and 2.16 GPa, respectively.BFECs (50BF50E) display better flexural strength and flexural modulus, i.e., 170 MPa and 4 GPa, than pure epoxy

Figure 7 .
Figure 7. SEM images of fracture surface under tensile load.

Figure 10 .
Figure 10.SEM images fracture surface under tensile load.

Figure
Figure 11.Flexural strength and flexural modulus.