# Examine the Effectiveness of Fiber Addition and Its Length on the Mechanical Properties of Flax and Nanographene-Based Biocomposites

Authors: Norah Salem Alsaiari; S. Sivakumar; Selvam Annamalai; M. Thiyagu; M. Viji; Rahul Singh; Saikh Mohammed Wabaidur; A. H. Seikh; Agonafir Alemayehu
Journal: Journal of Nanomaterials
 (2022)

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## Abstract

Organic fiber biocomposites have figured prominently in various industries of commerce during the last 3 to 5 years owing to their remarkable physical and mechanical abilities. The main purpose of this experimental research is to evaluate the biomechanical and geomorphologic belongings of nanostructured substance under naturalistic situations. To accomplish such a cognitive approach, flaxseed strands are employed as reinforcing, nano-based graphene as an additive, and epoxy as a matrix phase, with the following restrictions in imagination: (i) fiber lengths, (ii) fiber volume fraction, and (iii) weight proportions of nanoparticles. The nanocomposites are combined by means of the hand lay-up process based on the Taguchi orthogonal specification. The material characteristics of the substance, like bending, tension, and shock characteristics, are assessed in line with the standard specification. The material properties of mixtures’ second levels are the highest when compared to all other configurations. The elastic modulus of nanoparticle biocomposites revealed that 2% graphene provides 32.39 percent, 4% graphene provides 36.39 percent, and 6% nanoparticle pertains to 31.23 percent. Fractured images captured using scanning electron microscope of cracked samples have been used to comprehend the overall failure mechanism of a composite in mechanical characterization.


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## Body

## 1. Introduction

Polymers are now employed in almost every aspect of daily life. Whenever the demand for a moderately priced, improved-strength material becomes critical for a variety of uses, polymers emerge. Polymer and polymer-based component development has acquired worldwide attention as a result of its properties [1, 2] Furthermore, because of their high strength-to-weight ratio, ease of processing, and lack of corrosion, fiber glass materials have developed popular alternatives to aluminum, ceramic, and metal. Additionally, they can be designed to have the necessary features. Because of the comprehensive invention and manufacturing of fiber glass produces global pollution as well as health consequences, an environmentally acceptable alternative is urgently needed [3]. Natural fibers are a cost-effective, compact, and environmentally sustainable replacement for glass fiber. This work [4] examined the natural life sequence evaluation of ordinary fiber and glass fiber composites and discovered that natural fibers are more ecologically friendly than glass fiber and that natural fabrics also minimize the number of polymers used as reinforcements. They [5] did some ground-breaking research employing natural fibers as reinforcement in polymer matrixes for usage in vehicle components. They [6] used jute to replace glass fiber acrylonitrile butadiene–styrene in vehicle panels. All of these experiments demonstrated that the organic material-based polymer composite had satisfactorily substituted glass fiber. They [7] investigated the mechanical characteristics of a short pineapple composite by varying the fiber length and content. According to research, fibers with a length of 25–30 mm and a fiber loading of 40% have superior mechanical characteristics. This work [8] deliberate the material characteristics of a pineapple strengthened hybrid and discovered a 5 : 1 favorable hybridization impact for strength properties. Furthermore, when powder material is utilized as the skin and jute is used as the base material, the composite’s shear test is improved. The work [9] investigated the elastic behavior of a pineapple composite material. When compared to pineapple and hybrid composites, the sisal/polyester composite exhibits the best damping behavior and the highest maximum impact strength. They [10] created the composite by using an epoxy matrix to reinforce woven banana fibers. Tensile testing revealed that the weaved type of reinforcement had greater strength, which was further validated using an analysis of variance approach, and the classifications, applications, and techniques are shown in Figure 1.Figure 1
Shows applications of fiber-reinforced polymer composites.Even with its economic and commercial distribution in the requisite form at a reasonable cost and equivalent superior mechanical qualities to those of glass fibers, flax fiber is regarded as the most potential material among such plant fabrics [11]. Flax fiber-reinforced composites have significantly lower rigidity and strength than glass and carbon fiber-reinforced composites, despite their superior dampening qualities. Flax-reinforced composites have been the subject of several investigations [12, 13]. Because of its remarkable mechanical characteristics, graphene and its compounds, such as graphene flake, oxide, and functionalized graphene oxide, have recently gained significant attention for increased composite applications. In their homogeneous suspensions, graphene compounds might be mass-produced in large quantities [14].Furthermore, due to their inherent organic compounds, such materials have superior chemical responsiveness and handling characteristics. Furthermore, using the nanoflocculation method, graphene-based and electrically conductive flakes can be formed in large quantities and used in smart nanocomposite applications. Earlier studies have shown that binding or mechanical interaction among fibers and nanoparticle flakes improves the mechanical and physical properties and capabilities of graphene-modified jute fibers and materials. Furthermore, graphene-based natural fibers have been produced for multipurpose smart composite uses, as evidenced by efficient electromagnetic interfering filtering. Such advancements may pave the way for the creation of efficient and environmentally friendly natural fibers for the next level of elevated industrial applications [15, 16]. Hybrid structures are made to keep the benefits of their components while removing some of the drawbacks. Hybridization of various fibers has been shown to be a good solution to the absence of flexibility in composites. One strategy for introducing slow breakdown in composites while also achieving better cost-effective components is hybridization. Interleaved continuous fibers, intermixed oriented short fibers, intermediate or laminated layers, and intralayer are all examples of fiber blending [17].The length and composition of the fibers are clearly critical aspects that determine the composite’s characteristics, as evidenced by the preceding literature reviews. The impact of fiber volume as well as length on the material characteristics of flax and nanographene-based hybrid epoxy composites is examined in this study. A fractography analysis is also accomplished on the shattered exterior of the composite by using scanning electron microscope.


## 2. Experimental Works

### 2.1. Materials

The chemical structure of the filaments and the properties of the hybrid structure produced as a consequence have a considerable influence. The flax filaments were chopped to a variable length in order to employ fabric cutting machinery. Jevanthi Enterprises in Vellore provided the flaxseed fibers. Lokesh Chemicals in Chennai, Tamil Nadu, India, provided the graphene powder utilized in this study.


### 2.2. Composites Fabrication

The graphene employed in this work has been the standard material, with a purity of 90%. Serial dilutions of 2 to 6% filler material were used in successive augmentations of 0.3% through weight of a matrix material to create modified nanomaterials. To distribute graphene and flaxseed in resin, the ultrasonic irradiation procedure was applied. Furthermore, to distribute the graphene and flaxseed, a multiple shear mixing technique has been used, as well as the mixture being continually homogenized. Such continuous mixing is done for a certain duration of time until the solution is homogeneous. The epoxy and cure reagent combination were poured into a150×150×3−mm metal mold to manufacture hybrid composites. Table 1 shows how the composite products were produced based on the limitation settings. Table 2 shows the proportions of reinforcement and fillers, for conducting 9 experiments using L9 orthogonal array of hybrid composites.Table 1
Process variables and its phases for nanocomposite.
Sl. noProcess variablesPhasesP1P2P31Proportions of reinforcement1015202Length of reinforcement1530453Proportions of fillers246Table 2
L9 orthogonal array of hybrid composite.
Trail noReinforcement proportion (wt.%) AReinforcement length (mm) BProportions of fillers (wt.%) C110152210304310456415154515306615452720156820302920454


### 2.3. Testing of Composite Specimen

For tension tests, the produced laminate samples are cut to ASTM D 638-03 reproductions for bending tests to ASTM D-790 and also for impact testing to ASTM D-256.


### 2.4. Microstructural Analysis

SEM was carried out to examine the morphological examinations of cracked laminate material. Prior to SEM resolution, all samples were washed and chemically treated with nanometer silver to improve the electrochemical performance of the mixtures.


## 2.1. Materials

The chemical structure of the filaments and the properties of the hybrid structure produced as a consequence have a considerable influence. The flax filaments were chopped to a variable length in order to employ fabric cutting machinery. Jevanthi Enterprises in Vellore provided the flaxseed fibers. Lokesh Chemicals in Chennai, Tamil Nadu, India, provided the graphene powder utilized in this study.


## 2.2. Composites Fabrication

The graphene employed in this work has been the standard material, with a purity of 90%. Serial dilutions of 2 to 6% filler material were used in successive augmentations of 0.3% through weight of a matrix material to create modified nanomaterials. To distribute graphene and flaxseed in resin, the ultrasonic irradiation procedure was applied. Furthermore, to distribute the graphene and flaxseed, a multiple shear mixing technique has been used, as well as the mixture being continually homogenized. Such continuous mixing is done for a certain duration of time until the solution is homogeneous. The epoxy and cure reagent combination were poured into a150×150×3−mm metal mold to manufacture hybrid composites. Table 1 shows how the composite products were produced based on the limitation settings. Table 2 shows the proportions of reinforcement and fillers, for conducting 9 experiments using L9 orthogonal array of hybrid composites.Table 1
Process variables and its phases for nanocomposite.
Sl. noProcess variablesPhasesP1P2P31Proportions of reinforcement1015202Length of reinforcement1530453Proportions of fillers246Table 2
L9 orthogonal array of hybrid composite.
Trail noReinforcement proportion (wt.%) AReinforcement length (mm) BProportions of fillers (wt.%) C110152210304310456415154515306615452720156820302920454


## 2.3. Testing of Composite Specimen

For tension tests, the produced laminate samples are cut to ASTM D 638-03 reproductions for bending tests to ASTM D-790 and also for impact testing to ASTM D-256.


## 2.4. Microstructural Analysis

SEM was carried out to examine the morphological examinations of cracked laminate material. Prior to SEM resolution, all samples were washed and chemically treated with nanometer silver to improve the electrochemical performance of the mixtures.


## 3. Result and Discussion

### 3.1. Impact of Fiber Concentrations

Figure2(a) shows the effect of strand amount on mechanical properties of flax-based nanomaterials. It possesses 33.7 MPa stretching qualities, 38.19 MPa bending strength, and 27.41 Kg/m2 impact resistance. In comparison to 10 and 20 wt.% flaxseed fiber loading, 15 wt.% flaxseed fiber appears to be had outstanding material properties. The poor concert at first-level composite structures is owing to derisory stress transfer. This may be happened by the way of heterogeneity of fibers all matrices. By way of a consequence, the combination established a lattice section exhibiting poor fiber interaction [2]. This leads to a greater being removed easily from matrices while deposited in this conformation. This reveals that the flaxseed composite’s level one (10 wt.%) contribution is inadequate to withstand tensile strain. The elastic modulus of a combination is enhanced as the fiber volume fraction of the composite is between 10% and 15%. This is primarily attributable to the establishment of deep links between fiber and matrix as more than just a consequence of a thread’s ability to fill gaps in the composites through accommodating new shorter strands and spreading pressure uniformly. When 20 wt. percent fiber loading is used, the composite’s mechanical strength is reduced. This might be owing to a shortage of matrix volume percent, resulting in insufficient wettability between the matrix and reinforcement [18]. Figure 2(b) demonstrates the contour surface of tensile strength.Figure 2
(a) Strength of flax/graphene/epoxy composites; (b) contour surface of tensile strength.
(a)(b)


### 3.2. Outcome of Reinforcement Lengths

Figure3(a) illustrates the effect of flaxseeds reinforcement length on the material characteristics of flax-based nanomaterials. The mechanical characteristics of small sisal fiber/polyethylene composites were examined [4], as well as the impacts of fiber quantity, length, and orientation on processing steps. In this investigation, the sliced fiber spreading in matrix was haphazard; consequently, the reinforcement could not endure the tension once the matrix was moved. According to [19], the length of the fibers influences the structural properties of fiber-based materials and [20] investigated the investigational and theoretic values of ductile characteristics for PALF fiber-based composites, discovering that the comparison over the decree of amalgamation flops to deliver such an adequate contest, and the distinction grows as the fiber volume percent rises. The presence of cavities throughout the aggregates, and the reality that such threads were not correctly oriented, may have even contributed to the poor findings. Material strength improved as length to a high of 33.70 MPa tension, 38.19 MPa bending, and 27.41 Kg/m2 impact resistance at 20 mm. The chemical process at the convergence zones will most probably be sufficiently intense to convey overall strain, resulting in improved material properties for such combinations. Even as threading length is increased, the fracture toughness of the fibers diminishes. This is owing to a small crack generated throughout nanocomposite manufacture leading to a shortage of adhesion between epoxy as well as the strand. Composite contact failures are produced through matrices breakage, matrices and fibers delamination, or fibers pulling out. Regardless of the fact the strand pulling out is established as a prominent residual stress in nanocomposites, spalling happens whenever the maximum stress is surpassed. As an outcome, the composite’s interfacial interaction strength decreases [21]. Whenever the stressful situations exceed the forces exerted, a fiber intensity fracture is a break. The shattered fibers may be yanked out from the polymer, causing aerodynamic drag. Figure 3(b) exhibit the contour surface of flexural strength of nanocomposites.Figure 3
(a) Strength of flax/graphene/epoxy composites; (b) contour surface of bending strength.
(a)(b)


### 3.3. Impact of Filler Additions

Figures4(a) and 4(b) show how graphene filler concentrations affect tension, bending, and impacting characteristics. The 4 percent graphene additives revealed higher elastic modulus (38.54 MPa tension, 42.34 MPa bending, and 33.68 kg/m2 impacting) than 2 and 6 percent graphene additives. The improved structural properties of graphene in resins at 5% concentration may be related to expanding stress distribution networks. This inclusion of additional packed graphene into a polymer matrix changed the clear point interaction between matrix and fiber by raising the number and diameter of pores. As a result, at a quantity of 4 wt.%, the resin, flaxseed, and graphene compositions provide satisfactory stickiness bonding among interface contractures [14, 15]. However, introducing 2 and 6 wt.% graphene resulted in declining outcomes, indicating a decrease in mechanical characteristics. Additionally, greater and lower axial loads of 2 wt.% or 6 wt.% of flaxseed and resin were seen in poor boundary adhering of fiber matrix, culminating in aggregating and inferior combination toughness qualities. Figure 4(b) illustrates the impact of graphene fillers on material properties. The two weight percentage graphene provides 32.39 percentage of elastic modulus, while 4 wt.% graphene provides 36.38 percentage, as well as the 6 wt.% graphene provides 31.23%.Figure 4
(a) Strength of flax/graphene/epoxy composites; (b) contribution of nanographene.
(a)(b)


### 3.4. Microstructural Examinations

Several fractured interfacial of a natural fiber epoxy matrix laminate after mechanical failures are depicted in Figure5. Figure 5(a) shows a scanning electron microscope representation of the surface regions of a flaxseed filament-based polymer nanocomposite following ductile failure. The fibers were displaced from polymeric contact as a result of the lower interfacial interaction, as shown in Figure 5(b). The roughness of the permeate side of the membrane indicates that there has been minimal contact between the threads as well as the resin structures. Figure 5(c) shows a flaxseed fiber separating from the substrate. Additionally, increasing the length of a strand to 20 mm might improve interoperability. Whenever the fiber length is extended between 10 and 20 mm, interfacial breaking is minimized. As a result, at a quantity of 4 wt.%, the resin and flaxseed as well as graphene compositions create satisfactory adhesive interaction among epidermal contractures. However, introducing 2 and 6 wt.% graphene leads to a negative outcome, indicating a decrease in structural rigidity. Moreover, greater or lower concentrations of 2 wt.% to 6 wt.% in flaxseed and resin were seen in poor interface sticking of reinforcement and resin, leading to coagulation due to poor stickiness with poor combination toughness qualities.Figure 5
Morphological examination of flax/graphene/epoxy-based hybrid composites.
(a)(b)(c)


## 3.1. Impact of Fiber Concentrations

Figure2(a) shows the effect of strand amount on mechanical properties of flax-based nanomaterials. It possesses 33.7 MPa stretching qualities, 38.19 MPa bending strength, and 27.41 Kg/m2 impact resistance. In comparison to 10 and 20 wt.% flaxseed fiber loading, 15 wt.% flaxseed fiber appears to be had outstanding material properties. The poor concert at first-level composite structures is owing to derisory stress transfer. This may be happened by the way of heterogeneity of fibers all matrices. By way of a consequence, the combination established a lattice section exhibiting poor fiber interaction [2]. This leads to a greater being removed easily from matrices while deposited in this conformation. This reveals that the flaxseed composite’s level one (10 wt.%) contribution is inadequate to withstand tensile strain. The elastic modulus of a combination is enhanced as the fiber volume fraction of the composite is between 10% and 15%. This is primarily attributable to the establishment of deep links between fiber and matrix as more than just a consequence of a thread’s ability to fill gaps in the composites through accommodating new shorter strands and spreading pressure uniformly. When 20 wt. percent fiber loading is used, the composite’s mechanical strength is reduced. This might be owing to a shortage of matrix volume percent, resulting in insufficient wettability between the matrix and reinforcement [18]. Figure 2(b) demonstrates the contour surface of tensile strength.Figure 2
(a) Strength of flax/graphene/epoxy composites; (b) contour surface of tensile strength.
(a)(b)


## 3.2. Outcome of Reinforcement Lengths

Figure3(a) illustrates the effect of flaxseeds reinforcement length on the material characteristics of flax-based nanomaterials. The mechanical characteristics of small sisal fiber/polyethylene composites were examined [4], as well as the impacts of fiber quantity, length, and orientation on processing steps. In this investigation, the sliced fiber spreading in matrix was haphazard; consequently, the reinforcement could not endure the tension once the matrix was moved. According to [19], the length of the fibers influences the structural properties of fiber-based materials and [20] investigated the investigational and theoretic values of ductile characteristics for PALF fiber-based composites, discovering that the comparison over the decree of amalgamation flops to deliver such an adequate contest, and the distinction grows as the fiber volume percent rises. The presence of cavities throughout the aggregates, and the reality that such threads were not correctly oriented, may have even contributed to the poor findings. Material strength improved as length to a high of 33.70 MPa tension, 38.19 MPa bending, and 27.41 Kg/m2 impact resistance at 20 mm. The chemical process at the convergence zones will most probably be sufficiently intense to convey overall strain, resulting in improved material properties for such combinations. Even as threading length is increased, the fracture toughness of the fibers diminishes. This is owing to a small crack generated throughout nanocomposite manufacture leading to a shortage of adhesion between epoxy as well as the strand. Composite contact failures are produced through matrices breakage, matrices and fibers delamination, or fibers pulling out. Regardless of the fact the strand pulling out is established as a prominent residual stress in nanocomposites, spalling happens whenever the maximum stress is surpassed. As an outcome, the composite’s interfacial interaction strength decreases [21]. Whenever the stressful situations exceed the forces exerted, a fiber intensity fracture is a break. The shattered fibers may be yanked out from the polymer, causing aerodynamic drag. Figure 3(b) exhibit the contour surface of flexural strength of nanocomposites.Figure 3
(a) Strength of flax/graphene/epoxy composites; (b) contour surface of bending strength.
(a)(b)


## 3.3. Impact of Filler Additions

Figures4(a) and 4(b) show how graphene filler concentrations affect tension, bending, and impacting characteristics. The 4 percent graphene additives revealed higher elastic modulus (38.54 MPa tension, 42.34 MPa bending, and 33.68 kg/m2 impacting) than 2 and 6 percent graphene additives. The improved structural properties of graphene in resins at 5% concentration may be related to expanding stress distribution networks. This inclusion of additional packed graphene into a polymer matrix changed the clear point interaction between matrix and fiber by raising the number and diameter of pores. As a result, at a quantity of 4 wt.%, the resin, flaxseed, and graphene compositions provide satisfactory stickiness bonding among interface contractures [14, 15]. However, introducing 2 and 6 wt.% graphene resulted in declining outcomes, indicating a decrease in mechanical characteristics. Additionally, greater and lower axial loads of 2 wt.% or 6 wt.% of flaxseed and resin were seen in poor boundary adhering of fiber matrix, culminating in aggregating and inferior combination toughness qualities. Figure 4(b) illustrates the impact of graphene fillers on material properties. The two weight percentage graphene provides 32.39 percentage of elastic modulus, while 4 wt.% graphene provides 36.38 percentage, as well as the 6 wt.% graphene provides 31.23%.Figure 4
(a) Strength of flax/graphene/epoxy composites; (b) contribution of nanographene.
(a)(b)


## 3.4. Microstructural Examinations

Several fractured interfacial of a natural fiber epoxy matrix laminate after mechanical failures are depicted in Figure5. Figure 5(a) shows a scanning electron microscope representation of the surface regions of a flaxseed filament-based polymer nanocomposite following ductile failure. The fibers were displaced from polymeric contact as a result of the lower interfacial interaction, as shown in Figure 5(b). The roughness of the permeate side of the membrane indicates that there has been minimal contact between the threads as well as the resin structures. Figure 5(c) shows a flaxseed fiber separating from the substrate. Additionally, increasing the length of a strand to 20 mm might improve interoperability. Whenever the fiber length is extended between 10 and 20 mm, interfacial breaking is minimized. As a result, at a quantity of 4 wt.%, the resin and flaxseed as well as graphene compositions create satisfactory adhesive interaction among epidermal contractures. However, introducing 2 and 6 wt.% graphene leads to a negative outcome, indicating a decrease in structural rigidity. Moreover, greater or lower concentrations of 2 wt.% to 6 wt.% in flaxseed and resin were seen in poor interface sticking of reinforcement and resin, leading to coagulation due to poor stickiness with poor combination toughness qualities.Figure 5
Morphological examination of flax/graphene/epoxy-based hybrid composites.
(a)(b)(c)


## 4. Conclusion

The hybrid composites were successfully fabricated by using flaxseed fiber as a reinforcement and inorganic graphene powder as filler through the hand lay-up method. The composite exhibits the highest value of mechanical strength, and the detailed findings were listed out. Whenever the fabric weighting was raised be approximately to 15%, the material strength of flaxseed as well as nanoparticles polymer nanocomposite improved. It has the greatest tensile properties of 38.54 MPa and the maximum flexural value of 42.34 MPa as well as the maximum impact value of 33.68 kg/m2. In comparison to the first level and third levels, the second level of reinforcement length has superior mechanical qualities. Since the fibers in second-level flaxseeds are dispersed equally throughout the polymeric matrix, it minimized void development in lightweight materials. The intermediate ranges of filler contributions demonstrated enhanced material strength as compared to the upper and lower levels, since the impacts of cavities were offset by the occurrence of regulated filler additives. The morphology examination of flax-based nanocomposites demonstrates that poor adherence is the primary cause of material property degradation.



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