Abstract

The intention of this research is to recapitulate the two different fillers like E glass fiber and nanocarbon fiber, which were utilized to fabricate the polymer matrix composites by the assistance of epoxy resin. The mechanical compression molding was influenced to produce the polymer-based nanocomposites under consideration of optimal process parameters. There are three different weight fractions E glass fiber (40%, 45%, and 50%), nanocarbon fiber (10%, 15%, and 20%), and epoxy concentrations (30%, 40%, and 50%), respectively, that were used to produce the polymer matrix composites. Those processing parameters were designed by the L9 Taguchi with DOE technique to conduct the mechanical tests like tensile strength and hardness properties. The signal-to-noise ratios were successfully accomplished to identify optimal process parameters for improving the individual responses. The ANOVA and interaction was additional supports to enhance the mechanical properties. The scanning electron microscope was used to examine the fracture surfaces at the tensile fracture specimens with optimal conditions. Moreover, the maximum mechanical characteristics were attained by the increasing of nanocarbon fiber in the processed polymer matrix composites.

1. Introduction

To improve unique characteristics like chemical stability, maximum thermal conductivity, withstand breakdown potency, and better insulation properties which depend on the various applications of packaging-based materials and enhanced electronics-based applications, utilization of nano-based filler materials on the various resins agents was done to produce the polymer nanocomposites. In most of the applications, polymer-based nanocomposites contain better thermal conductivity under the maintenance of 0.5 W/m·k which is less than the limits [15].

Maximum utilization of various applications like aerospace, automotive, and biomedical are related to different fields. The nanoreinforcement into the polymer composites fabrication improves the mechanical attributes. In current applications of composite-related production, thermal conductivity is the most important factor for enhancing the adhesion properties among the base material and nanoreinforcement particles. The addition of nano-based carbon reinforcements enhances the properties of adhesion between the matrix material and nanostrengthening particles [67]. The fabricated polymer composites normally contain the special characteristics like simple processing with less cost, less density, better resistance to chemicals, and less thermal conductivity which are related to maximum engineering-based applications, especially in materials. The above-recommended solutions are fulfilled by fiber-based reinforced polymers composites due to the high class of prospective matter that affords the capability to produce the appropriate design of innovative ideas in the trending industries to solve the above-mentioned issues [810].

Normally, the fiber-based reinforced polymers had better strength when reinforced into the appropriate reinforcing nanofillers which are embedded in the different polymer-based matrixes. The polymer composite by matrix materials are active in bonding components that support transfer the loading into the fibers for withstand the protecting materials [1114]. The fabrication of eco life composites are utilized by natural fibers materials like hemp, banana, kenaf, jute, sisal, etc., and the synthetic-based materials are carbon fiber, glass, and Kevlar fiber, etc. Next side of the polymer matrixes, thermos setting, and thermoplastic materials defined by the polymerization process and solving agents are epoxies, vinyl ester, and polyesters which are based on the thermosetting matrixes. These composites achieved the cross-linking mechanism through the polymerization or condensation process. Compared with thermoplastic, thermosetting matrixes have better adhesive properties, excellent mechanical characteristics, and fine impregnation characteristics. The thermosetting processes are estimated by various heat conditions but not under the circumstances of liquefying process; however, it is possible in reheating or solvents. In thermoplastic types, polypropylene, polyvinyl chloride, and polyurethanes are more costly to fabricate and also affect the environment [1518].

The enhanced mechanical properties are achieved in the fiber-based polymer matrix composites which are based on the polymer matrix and fiber materials. These composites are mostly utilized to establish the duration of the applications, for example, materials structure [1921]. The fiber-based polymer matrix composites are used in different engineering applications like construction sites, the navy, building sections, aerospace, and automotive. The hybridization enhances the properties of the polymer composites according to previous researchers. Engineering applications are widely developed by hybrid-based polymer composites, but monofiber polymer composites are more complicated to meet the outstanding performance in some special cases [22].

By the influence of nanofiller materials, for composing the fiber-based polymer composites that exhibit the better potential strength is possible by the nitride elements. These nitride elements possess the enhanced mechanical, electrical, and thermal properties when compared with other than nitride based filler materials. Few examples of filler materials are carbon nitride, titanium nitride, silicon nitride, aluminumnitride, titanium nitride, and zirconium nitride and these nitride-based filler elements are normally favored in the fabrication of polymer-based composites to exhibit better wear-resistant and elastic properties, corrosion resistance, magnetic properties, and other electrical attributes [23].

The major important aspect of composite is nanofillers and these nanofilleris are available in the form of fiber, fragment, whiskers, and sheet. Now the nanofillers are a promising method to develop the mechanical properties of the natural fiber-based reinforced polymer composites. Nanofillers produce better properties than base materials due to this composite occupy the smaller region by the larges surfaces [24]. More researchers developed the composites by assured nanomaterials to improve the mechanical attributes and also develop the material properties by the way of electrical, optical, heat resistance, and magnetic characteristics. There two steps single or multiple are involved in composition of the nanocomposites and nanoparticles having a size of 100 nm. The pure epoxy-based resins to produce the composites by the addition of nanofillers have desired characteristics were not achieved due to agglomerated presentation. But the evenly dispersed agglomerated particles achieve the desired properties. The multistep process achieves the better nanocomposites without modifying the melting temperature and processing factors. Figure 1 shows the experimental procedures [25]. From the in depth of literature, nitride-based nano-based fillers are utilized to a great extent to compose better mechanical properties in the presence of polymer-based nanocomposites. Most of the studies are done on various fiber materials and other ceramic-based reinforcements but there is less work that is concentrated on the material of carbon fiber and E glass fiber. Similarly, less work has been done in finding the optimal processing parameter by the S/N ratios. Therefore, in this research, nanobased carbon fiber was selected as nanofillers, and the support of E glass fibers was taken to compose polymer matrix composites by the compression molding process. Then the prepared composites were accounted for measuring the performance of mechanical characteristics with the Taguchi technique.

2. Material and Methods

In this paper, nanobased fillers of carbon fiber and E glass fibers were used to produce the polymer-based nanocomposites having the sizes of each fibers is 70 nm scale for carbon. Owing to this, carbon fiber possess superior density and mechanical properties and are low in cost and simple to purchase. In the various manufacturing and logistical applications, these nanocarbon fillers were broadly used and also used in the automotive, aerospace, and other defense-related applications. And the epoxy resin was selected as the binding material between the base on nanocarbon fillers and the E glass fibers [26].

Initially, the E glass fiber and the nano-based carbon fibers were purchased from the local suppliers having densities 2.05 and 2.60 g/cm3, respectively. The selected epoxy resins had viscosity 10,000 cPS, and the appropriate hardener was the most important factor for merging these nanofillers. By this way, hardener 951 HY was the epoxy material having the cPS range of 17,000. Then these hardeners and epoxy resins were mixed in a ratio of 10 : 1 into the mechanical agitator. Before that, the nanocarbon and E glass fibers were taken as the percentage at different weights, respectively. Before starting the process, the required molding steel plate having the dimensions 300 mm × 280 mm × 6 mm basins was used to produce the polymer composites.

After selecting the materials, base E glass fiber was placed as the primary material in the steel plate with above-mentioned dimensions. Initially, the film is punched with holes was protected on the E glass prepared mat on the steel plate for the desired film-made material. Then the wax was coated on the placed E glass mat for getting quick settling for the curing process. Next, the epoxy resin was concerned for coating over the E glass mat, and subsequently, the first layer of the mat was completed. Then the completed mat was applied by the epoxy to cover the carbon fiber and finally, the second layer was also generated. This process was repeated for three times to make the three layers with 4 mm thickness of specimens. Lastly, the compression molding technique was initiated to produce the successfull components maintaining 150 bar of pressure at a sustained period of 2 hr, and these conditions promoted the final materials having the enhanced surface finishes and desired dimensions. These procedures were followed as per the completion of the stacking process. There are three different weight concentrations E glass fiber (40%, 45%, and 50%), nanocarbon fiber (10%, 15%, and 20%), and epoxy concentrations (30%, 40%, and 50%), respectively were designed by the Taguchi method (Tables 1 and 2).

There was some important factors that were need to fix the cross-linking mechanism to attain better outcomes in the final cured composites part. Therefore, after the removing the laminated form from the mold, the processed composites were approached for hot air process maintaining the oven temperature at 60°C for 2 hr and then cooling process was accomplished for 24 hr at room temperature. The prepared composites were employed to conduct the tensile test under the ASTM D3039 standards with the support of universal testing machine maintaining 100 kN load. After the tensile tests, the hardness test was conducted on the process polymer matrix composites as per the specimen standards of ASTM D785. Different volume fractions of various nanofillers and epoxy resins were designed by the Taguchi method [27].

3. Results and Discussion

3.1. Mechanical Characteristics of E Glass/Nanocarbon Fiber/Epoxy Composites

As per the ASTM specifications of tensile and hardness, all the experiment specimens were prepared. The investigational outcomes like tensile and hardness was extracted from the polymer-based composites. Table 3 shows the polymer outcomes of tensile and hardness values. As shown in Table 3, all the output responses with L9 basis results were improved by the addition of nanocarbon filler materials into the E glass fibers by the epoxy-based nanopolymer composites. Especially, the specimen 5 had the maximum tensile strength at the attained parameters of 45 wt% of E glass fiber, 15 wt% of nanocarbon fiber, and 50% of epoxy. The increasing content of nanocarbon fiber and addition of sufficient quantity with 50% epoxy waere the major influencing factors to enhance the tensile strength. Subsequently, the hardness attained maximum effects on the processed polymer matrix composites. The corresponding parameters were 50 wt% of E glass fiber, 20 wt% of nanocarbon fiber, and 40% of epoxy. It is revealed that the maximum content of nanocarbon fiber had a significant role in superior hardness of the polymer matrix composites samples. Figures 2 and 3 shows the individual response analysis of tensile strength and hardness properties on the processed-nanopolymer composites.

As shown in Figure 3, the pie chart analysis of hardness experiments clearly indicated that sample 9 attained the maximum hardness when compared with other sets of polymer composites which were fabricated by E glass fiber, nanocarbon fiber, and epoxy resins. The proper setting which belongs to compression molding factors also has majorly important aspects for enhancing the mechanical characteristics.

3.2. S/N Ratio Analysis on Tensile and Hardness on the Polymer Matrix Composites

Even though the individual responses of polymer matrix composites were concentrated, some individual optimization was definitely influenced to enhance the mechanical characteristics by the upgraded level. Therefore, in this section, signal-to-noise (S/N) ratios were generated for both the individual responses of tensile strength and hardness properties, respectively. As per the instructions of Taguchi and DOE, the S/N ratio was utilized to produce the individual optimization by the supports of ANOVA and interaction plots. Table 4 exhibits the S/N ratios for tensile strength and hardness outcomes. As shown in Table 4, detailed S/N ratios were determined successfully and analyzed by ANOVA. It is understood that the S/N ratio values were attained to maximum as mentioned in the earlier section for individual responses. Now this parameter was validated with interaction plots and ANOVA. Therefore, the linear model regression analysis was implemented to identify the individual responses. Larger the better option was utilized for identifying the individual contribution level. Similarly, the hardness was also attained to the maximum of S/N ratio values as per the larger the better option.

The ANOVA analysis further validated the individual input polymer parameters by the support of P and F values. From these values, the percentage contribution was analyzed properly and the contributed percentage was highly attained with the increase of nanocarbon fibers. The overall contribution was 14.8% of E glass fiber, 55.0 of nanocarbon fiber, and 30.1% of epoxy. The ANOVA for polymer composites input factors with their tensile outcomes performances are exhibited in Table 5. The overall model of R2 values is 92%.

Table 6 shows the response for S/N ratios of tensile outcomes. As shown in Table 6, each and every rank system was analyzed properly by the influencing of delta order. It is revealed that the maximum rank was accumulated in input factors of E glass fiber that contains the first rank contains the highest point by following the next factors nanocarbon and epoxy occupies the 2 and 3, respectively. Similarly, the interaction graph shows the optimal input factors for polymer composites, shown in Figure 4, which reveals that the optimal polymer input parameters were attained at the range of 45 wt% of E glass fiber, 15 wt% of nanocarbon fiber, and 50 wt% of epoxy.

The ANOVA investigation further confirmed the independent input polymer parameters by the support of P and F significant values. The ANOVA table of hardness and its polymer matrix input factors are displayed in Table 7. As shown in Table 7, the contributed percentage was accomplished by the increasing of nanocarbon fibers. The overall contribution was of 46% of E glass fiber, 17% of nanocarbon fiber, and 36.5% of epoxy. The overall model of R2 values is 71.45%.

Table 8 exhibits the response for S/N ratios of hardness. As shown in Table 8, each and every rank order combination was measured properly by the influence of delta order. It is understood that the highest rank occurred in the input factors of E glass fiber that contains the first rank; the factors epoxy and nanocarbon attained the ranks 2 and 3, respectively. Similarly, the interaction graph shows the optimal input factors for polymer composites hardness and which are shown in Figure 5. As shown in Figure 5, it was concluded that the optimal polymer input parameters were conquered at the range of 50 wt% of E glass fiber, 20 wt% of nanocarbon fiber, and 40 wt% of epoxy. The main effect plot confirms that the presence of nanocarbon fiber and maximum concentration E glass fiber improves the mechanical properties and the S/N ratio which was confirmed by the appearance of rank method as shown in Table 8.

3.3. Contour Investigations on Tensile Strength with Various Input Polymer Composites

Figure 6(a)6(c) shows various input polymer matrix composites on the attained tensile strength. Figure 6(a) exhibits the E glass and nanocarbon fibers of the obtained tensile strength on the polymer matrix composites. As shown in Figure 6(a), it was implicit that the increasing of carbon nanofiber and E glass fibers improves the ductile strength. Figure 6(b) displays different concentrations of nanocarbon fiber and epoxy of the accomplished tensile strength on the processed polymer matrix composites. It is understood that the medium of nanocarbon fiber with low concentration of epoxy produced a better tensile strength. Figure 6(c) shows a different weight percentage of epoxy and E glass fiber on the attained tensile strength of polymer matrix composites. As shown in Figure 6(c), it was revealed that the low content of epoxy and maximum weight percentage of E glass fiber improves the mechanical strength. The maximum concentration of the E glass and nanocarbon fibers improves the interfacial strength and results in developing the grain boundaries to reduce the crack during the processing and tensile test.

3.4. Contour Investigations on Hardness Properties with Various Input Polymer Composites

Figure 7(a)7(c) shows the various input polymer matrix composites on the produced hardness. Figure 7(a) exhibits the E glass and nanocarbon fibers of the obtained hardness properties on the processed polymer matrix composites. As shown in Figure 7(a), it was implied that the increasing of carbon nanofiber and E glass fibers improves the hardness strength. Figure 7(b) displays the various percentages of nanocarbon fiber and epoxy of the obtained hardness properties on the fabricated polymer matrix composites. It is unstated that the maximum nanocarbon fibers with less concentration of epoxy produced better hardness properties. Figure 7(c) shows different weight percentage of epoxy and E glass fiber on the attained hardness strength of polymer matrix composites. As shown in Figure 7(c), it was exposed that the moderate content of epoxy and maximum quantity fraction of E glass fiber improve the hardness strength. From the detailed analysis of contour investigations on the processed polymer composites mechanical characteristics of both the responses were attained. The overall enhanced properties based on the polymer matrix composites were produced effectively by the influence of various working input factors like E glass fiber, nanocarbon fibers, and epoxy resins. The major influencing factor was nanocarbon fibers by increasing the addition from 15% to 20%, less epoxy from 30% to 40%, and E glass fiber 40%–45%, respectively. The processed polymer matrix composites produced better interfacial bonding properties by the influence of nanocarbon fibers.

3.5. Microstructure of Fractured Polymer Matrix Composites at Optimal Condition

Figure 8 shows the fractured region on the polymer matrix composites at the optimal process parameters. That the optimal processing input factors were 45 wt% of E glass fiber, 15 wt% of nanocarbon fiber, and 50 wt% of epoxy. During the ductile fracture, the maximum load was taken between the interfaces of E glass fiber and nanocarbon fiber. This attained structure exposed better interfacial properties which were revealed from the tensile values. The corrected epoxy resins also produces the maximum attained load which migrated from the tensile experiments. Similarly, the maximum hardness was accumulated in these same optimal parameters with slight variation in the epoxy resin concentration [28].

4. Conclusion

From the research result by overall experiment, the modified nanocomposites were achieved effectively by different concentration of input factors like E glass fiber, nanocarbon fibers, and epoxy. During the process, the final mat-finish polymer matrix composites were fabricated under the compression molding process. The maximum concentration of the nanocarbon fiber was the major reason to enhance the mechanical properties. Taguchi was also integrated to generate the individual significant responses by the influence of S/N ratios with linear regression model. The ANOVA composes the maximum utilization of contributed percentage for both mechanical outcomes. The attained optimal parameters with tensile properties were 45 wt% of E glass fiber, 15 wt% of nanocarbon fiber, and 50 wt% of epoxy. Similarly, the hardness achievements are 50 wt% of E glass fiber, 20 wt% of nanocarbon fiber, and 40 wt% of epoxy. The SEM examination successfully revealed the fracture surfaces between the epoxy and the fillers of nanocarbon and E glass fibers.

Data Availability

The data used to support the findings of this study are included within this article.

Conflicts of Interest

The authors declare that they have no conflicts of interest.