**1. Introduction**

These days several shortcomings have been observed with respect to the utilization of synthetic fiber-reinforced polymers, hence empowering the drive for more utilization of plant fiber composite in structural designs. The primary weaknesses of synthetic fiber-reinforced polymers which includes issue in afterlife disposal and non-biodegradability are completely settled by utilizing plant fibers in polymer reinforcements. Reinforced composites are prime choice for light weight structural designs and automotive body parts assembly.

Extensive literature on recent advancements in reinforced composites and its reliability are reported in classical reports of Dehmous et al. [1], Okafor et al. [2],

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*Composite and Nanocomposite Materials - From Knowledge to Industrial Applications*

[9] Blaber J, Adair B, Antoniou A. Ncorr: Open-source 2D digital image correlation matlab software.

2015;**55**(6):1105-1122. DOI: 10.1007/

[10] Hecht F. New development in Freefem++. Journal of Numerical Mathematics. 2012;**20**(3-4):251-266. DOI: 10.1515/jnum-2012-0013

Experimental Mechanics.

s11340-015-0009-1

**References**

[1] Sevenois R, Koussios S. Analytic methods for stress analysis of twodimensional flat anisotropic plates with notches: An overview. Applied Mechanics Reviews. 2014;**66**(6):060802.

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[2] Gürdal Z, Hafta RT, Hajela P. Design and optimization of laminated composite materials. 1st ed. New York:

[3] Akour SN, Nayfeh JF, Nicholson DW. Defense hole design for a shear dominant loaded plate. International Journal of Applied Mechanics. 2010;**2**(02):381-398. DOI: 10.1142/S1758825110000548

[4] Erickson PE, Riley WF. Minimizing stress concentrations around circular holes in uniaxially loaded plates. Experimental Mechanics. 1978;**18**(3): 97-100. DOI: 10.1007/BF02325003

[5] Durelli AJ, Brown K, Yee P. Optimization of geometric discontinuities in stress fields. Experimental Mechanics.

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[6] Jain N. The reduction of stress concentration in a uni-axially loaded infinite width rectangular isotropic/ orthotropic plate with central circular hole by coaxial auxiliary holes. International Islamic University Malaysia Engineering Journal. 2012;**12**(6):141-150. DOI: 10.31436/

[7] ASTM Committee. Standard test method for tensile properties of polymer matrix composite materials. ASTM D3039/D M; 3039; 2008

[8] ASTM Committee. Standard test method for in-plane shear response of polymer matrix composite materials by tensile test of a ±45 laminate. ASTM D

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iiumej.v12i6.228

Xie and Wang [3], Beaumont et al. [4], Pei et al. [5], Bittrich et al. [6], Prasad et al. [7], Wang et al. [8]. The hygrothermal efficiencies has been reported by Foulc et al. [9], Shettar et al. [10]. In addition, the utilization of reinforced composites predicates the reuse of domestic and agricultural residues. For example, vehicles made with fiber-reinforced composites are lighter and run on smaller engines which produce fewer emissions to the environment. Most items produced using natural fiber composites is a win-win for manufacturers. Most composite material ventures can utilize their genius green item data to build deals because customers comprehend the ecological dangers of synthetic assembling.

biomass. Exceptional nontoxicity and biodegradable properties of biopolymers boosts their applications in composites formulation, hardware and restorative gadgets. Fuse of nano-sized support in the biopolymers to improve the properties

*Strength Analysis and Variation of Elastic Properties in Plantain Fiber/Polyester Composites…*

Though thermosets and thermoplastics sound similar, they have very different properties and applications [11]. Thermosets typically changes from fluid to solid state after curing chemical reaction initiated by addition of a catalyst, cross-linker, and curing agent. In the course of the chemical reaction, the material solidifies as a result of cross-linking and formation of longer molecular networks. Subsequently, any further exposure to high heat will cause the material to degrade unlike thermoplastic parts that melts and softens whenever exposed to elevated temperature, thermoset simply become set in their physical and mechanical properties after an initial treatment and therefore are no longer affected by additional heat exposure. Again, thermoplastics are dissolvable plastics. At temperature above liquefying point, the thermoplastic condenses. The thermoplastic sets once again into solid state when the temperature is reduced and the handling temperature dips under its melting point. This inherent characteristic of thermoplastics enables its softening when heated above its melting point and re-forming as the temperature decreases below the melting point. Most of the times, the expenses of materials for creating thermoset are lower when contrasted with thermoplastic. Also thermoset is regularly simple for wetting the reinforcements and shaping last composites items. Thermoplastics will in general be harder than thermosets and require no refrigeration as uncured thermosets as often as possible do, and can be more effectively be reused and fixed. Elastomers are typically thermosets (requiring vulcanization). Obviously literature has indicated several approximate relationships between some reinforced composites elastic constants and the homogenized modules of elasticity [12–14]. Also recent research have reported the possibility of measuring variation elastic constants of materials using ultrasonic methods [15–18]. However, scanty research is available on strength analysis and variation of elastic properties in plantain fiber/polyester composites, a gap that the present study seeks to fill.

**2. Background to plantain cultivation and utilization as reinforcement**

An expanded enthusiasm for the utilization of agricultural wastes in development of reinforced composites has been on the increase. Natural fibers extracted from bio wastes offer a few points of interest over woody biomass, since they are accessible in huge amounts as leftovers and agricultural wastes [19, 20]. The plantain pseudo stem (PPS) and empty fruit bunch (EFB) strands presented in this chapter are agricultural by-products that are biodegradable and locally available from renewable agricultural sources with potentials to contribute to reduction in environmental pollution when utilized in large scale as polymeric reinforcements. Plantain fruit is one of the staples in Nigeria and it is mainly cultivated in the tropics and ethnic enclaves [21]. It is evaluated that 70 million individuals in West and Central Africa derive most of their nourishment and vitality requirements from plantain fruit plant [22, 23]. Plantain fruit has a fare potential in the light of its huge

cultivation and consumption in Nigeria and many other African countries.

Akinyemi et al. [24] reported that plantain plant is the third most important plant grown after cassava and yam in Nigeria; collaborating, Kaine and Okoje [25] showed that plantain production is a very profitable enterprise as every ₦1 naira invested in plantain production yields a return on investment of about ₦12.60 kobo. In a study about economics of plantain production Kainga et al. [26] found that the

**in polymer composites**

**183**

contributes to the upgrade functional applications of the matrix.

*DOI: http://dx.doi.org/10.5772/intechopen.90890*

Due to scarcely available information regarding some new material response to structural discontinuity, superior properties of those composites are seriously compromised by the utilization of bizarrely enormous factor of safety in design. Accordingly, the quick fate of composite materials as a class of innovative materials may depend more on clear assessment of its performance in various structural design scenario. All inclusive acknowledgment of composites as eco-friendly materials will therefore depend especially on the certainty of the designer and client about the variation of its elastic properties. In a typical fiber-reinforced composites, the polymer matrix serves as a binder and deforming most times for stress distribution purposes. There are different options in the choice of matrix/fibers and the general composition of reinforced composites is shown in **Figure 1**. The figure identified the three major categories of polymers to include biopolymers, thermoplastics and thermosets. Biopolymers are chain like atoms created by organic

**Figure 1.** *Composition of reinforced composites.*

### *Strength Analysis and Variation of Elastic Properties in Plantain Fiber/Polyester Composites… DOI: http://dx.doi.org/10.5772/intechopen.90890*

biomass. Exceptional nontoxicity and biodegradable properties of biopolymers boosts their applications in composites formulation, hardware and restorative gadgets. Fuse of nano-sized support in the biopolymers to improve the properties contributes to the upgrade functional applications of the matrix.

Though thermosets and thermoplastics sound similar, they have very different properties and applications [11]. Thermosets typically changes from fluid to solid state after curing chemical reaction initiated by addition of a catalyst, cross-linker, and curing agent. In the course of the chemical reaction, the material solidifies as a result of cross-linking and formation of longer molecular networks. Subsequently, any further exposure to high heat will cause the material to degrade unlike thermoplastic parts that melts and softens whenever exposed to elevated temperature, thermoset simply become set in their physical and mechanical properties after an initial treatment and therefore are no longer affected by additional heat exposure.

Again, thermoplastics are dissolvable plastics. At temperature above liquefying point, the thermoplastic condenses. The thermoplastic sets once again into solid state when the temperature is reduced and the handling temperature dips under its melting point. This inherent characteristic of thermoplastics enables its softening when heated above its melting point and re-forming as the temperature decreases below the melting point. Most of the times, the expenses of materials for creating thermoset are lower when contrasted with thermoplastic. Also thermoset is regularly simple for wetting the reinforcements and shaping last composites items. Thermoplastics will in general be harder than thermosets and require no refrigeration as uncured thermosets as often as possible do, and can be more effectively be reused and fixed. Elastomers are typically thermosets (requiring vulcanization).

Obviously literature has indicated several approximate relationships between some reinforced composites elastic constants and the homogenized modules of elasticity [12–14]. Also recent research have reported the possibility of measuring variation elastic constants of materials using ultrasonic methods [15–18]. However, scanty research is available on strength analysis and variation of elastic properties in plantain fiber/polyester composites, a gap that the present study seeks to fill.
