Elaboration and Characterization of Composite Materials Reinforced by Papaya Trunk Fibers (Carica papaya) and Particles of the Hulls of the Kernels of the Winged Fruits (Canarium schweinfurthii) with Polyester Matrix

In this work we determine the physical and mechanical properties of local composites reinforced with papaya trunk fibers (FTP) on one hand and particles of the hulls of the kernels of the garlic (PCNFA) in the other hand. The samples are produced according to BSI 2782 standards; by combining fibers and untreated to polyester matrix following the contact molding method. We notice that the long fibers of papaya trunks improve the tensile/compression characteristics of composites by 45.44% compared to pure polyester; while the short fibers improve the flexural strength of composites by 62.30% compared to pure polyester. Furthermore, adding fibers decreases the density of the final composite material and the rate of water absorption increases with the size of the fibers. As regards composite materials with particle reinforcement from the cores of the winged fruits, the particle size (fine ≤ 800 μm and large ≤ 1.6 mm) has no influence on the Young’s modulus and on the rate of water absorption. On the other hand, fine particles improve the flexural strength of composite materials by 53.08% compared to pure polyester; fine particles increase the density by 19% compared to the density of pure polyester. How to cite this paper: Parfait, Z.E., Marcel, N.P., Didine, N.E., Wiryikfu, N.C., Fabien, B.E., Valery, N.A.C. and Ateba, A. (2020) Elaboration and Characterization of Composite Materials Reinforced by Papaya Trunk Fibers (Carica papaya) and Particles of the Hulls of the Kernels of the Winged Fruits (Canarium schweinfurthii) with Polyester Matrix. Journal of Minerals and Materials Characterization and Engineering, 8, 341-352. https://doi.org/10.4236/jmmce.2020.85021 Received: July 9, 2020 Accepted: August 2, 2020 Published: August 5, 2020 Z. E. Parfait et al. DOI: 10.4236/jmmce.2020.85021 342 J. Minerals and Materials Characterization and Engineering


Introduction
The need of new materials is a permanent concern in many industrial sectors. Environmental protection being a global concern, the integrating new ecological materials is a necessity. Currently synthetic fibers are largely dominant in the industrial sector. However, their use raises many problems due to the emission of harmful compounds and a high production energy [1]. Papaya and aiele are widespread crops in sub-Saharan Africa country because of their fruit [2] [3] [4]. As the current recycling of synthetic fiber composites has offered no ecological solution, the use of natural reinforced composites seems/proves to be an alternative for environmental protection [5]. As a result, natural components are a growing contribution to the development of composite materials. The choice of fibers in the composite depends on their sensitivities and their mechanical, thermal and physical properties. Among the fibers used, mention may be made of: Pineapple, abaca, sisal agave, alfa, hemp, kenaf, agave sisal fibers and fibers of textile palm [6] [7] [8] [9]. The study on the unsaturated polyester/doum palm fiber composite shows that the nature, morphology, arrangement and type of the fibers play a major role in the absorption phenomena of the composite. The behavior of the composite with a fiber content exceeding 10% goes from a linear behavior with fragile rupture to an almost linear behavior with a progressive rupture of the fibers which limits the progression of cracks within the composite [7] [8]. In composite materials with particle reinforcement in general, the interface has good properties [6].
The present work aims to valorize the waste of local agriculture through the exploitation of fibers (papaya trunks) and stones (the winged fruits).

Process for Obtaining Short and Long Fibers from Papaya
The fibers of the papaya tree trunks are obtained in a long process as shown in We used the male papaya trees after the second flowering. The papaya tree trunks were cut into 40 cm long pieces, then cut longitudinally. The elements thus acquired were soaked in water without additive for a period of one month as shown in Figure 2. The extraction of our papaya trunk fibers is done by retting as shown in Figures 2(c) and Figure 3 [10].
The folds thus obtained were immersed in hot water (70˚C) mixed with a molar concentration sodium hydroxide for two days then we extract the fibers.

Process for Obtaining Particles from the Seeds of the Garlic
The cores obtained are illustrated by Figure 4.
The kernels of the pili fruit are crushed in order to extract the fines. The empty cores are grounded and sieved with 800 μm and 1.60 mm sieves ( Figure 5) to obtain the corresponding particles ( Figure 6) [10] [11].
The particle sizes obtained are as follows ≤ 800 µm (fine particles) and ≤1.60 mm (large particles) as shown in Figure 6.

Implementation of Samples
The samples with reinforced rate of 30% are used because it the composite exhibits poor characteristics [12]. Table 1 gives the dimensions and the proportions of the elements used the polyester resin is mixed with 1% hardener [11].

Preparation of Test Pieces/Samples
The test pieces shaped according to standard BSI 2782 are parallelepipedic block of 150 × 10 × 10 (mm). The main steps in shaping our test pieces are given in Figure 7.
The samples obtained and classified by type of reinforcement are shown in Figure 8.

The Density
To determine the density of our composite material, we calculate the apparent density for each of the samples using Equation (1).
with: a ρ : apparent density; r P : mass of reinforcement; r v : the reinforcement volume.
For each formulation, the experimental density of the composite is obtained by averaging Equation (2) for each test piece [13].    Figure 9. Apparent density as a function of reinforcement type. Figure 10. Experimental density as a function of reinforcement type.

The Rate of Water Absorption
The amounts of water absorbed by our composite materials reinforced with papaya trunk fibers and particles of the seeds of the garlic shown by Figure 12 are determined by Equation (4).
% 100 The water absorption curves of the various composites reinforced with papaya trunk fibers (long and short) and particles of the seeds of the winged fruit (large and fine) are similar to room temperature, the one given by Fick's law of diffusion in a binary medium [14]. The following observations are made:  For composites with particle reinforcement of the kernels of garlic, the particle size does not influence the rate of water infiltration.  In the case of composites with a reinforcement of trunk fibers from papaya trees, the longer the fibers, the less water the material takes up.  Composites with short fiber reinforcement take more water than composites with particles of garlic kernels which absorb more than those with long fiber reinforcement.

Mechanical Characterization
The mechanical properties are obtained from the three-point compression and bending tests of different composite samples.

Compression Test
The comparative study of the average values of the Young's moduli obtained during the compression test helped us to plot the histogram of Figure 13.
From Figure 13 we see that:  The Young's modulus of long fiber reinforced composites is greater than that of short fibers.  The length of the fibers influences the mechanical behavior of the composites, composites with long fiber reinforcements have better behavior in the elastic range compared to those with short fiber reinforcement.  The Young's modulus of fine particle reinforcement composites is greater than that of medium black fruit core particles. The mechanical characteristics of composites with reinforcement of black fruit kernel particles fluctuate with the particle size distribution (of the interstices in the material).  Reducing the particle size of the particles improves their behavior in the elastic range.

Bending Test
The three points bending test is carried out using a CBR press (CONTROLS T1004) and Equation (6) and Equation (7)   The results are presented in Table 3.
The comparative study of flexural elasticity modules (FEM) and flexural resistance modules (FRM) of fiber and particle reinforced composites is given in Figure 14 and Figure 15 respectively [11] [19] [20].
These histograms reveal that: • The elastic modulus of flexion does not vary with the size or the type of reinforcement because the difference between the different values of modules is minimal; • The multidirectional nature of composites with short fiber reinforcement gives it a modulus of flexural strength significantly higher than the composites one with long fiber reinforcement (report 1.27); • The resistance modulus of composites with fine particle reinforcement (≤800 µm) is 2.27 times higher than the composites with medium particle reinforcement (≥1.6 mm). This difference may be caused by the particle size and the presence of a gap in large-particle composites which is not completely homogenized with the resin.

Conclusions
The aim of this paper was to determine some physical and mechanical properties     The addition of fibers decreases the density of the final composite material and the rate of water absorption increases with the length of the fibers.  The particle size (fine particles ≤ 800 µm and large particles ≥ 1.6 mm) of composite materials reinforced with the cores of winged fruits has no influence on the Young's Modulus and therefore no effect on the mechanical behaviour (regarding tension and compression)  The size (fineness) of the particles of the kernels of the fruit of the wing improves the bending resistance of the composite materials and increases have a density of 19% relative to the density of the polyester.  The rate of water absorption is not influenced by the size of the particles.