**3.2 Mechanical characterization of composite materials**

Different formulations were carried out with incorporation rates of the cocoa pod powder from 0 to 50%. The following properties, flexural strength, tensile

**Figure 2.** *Infrared of raw cocoa shell powder.*


#### **Table 5.**

*IR spectrum of cocoa shell powder: the characteristic infrared vibration bands, relating to CCP.*


*Mechanical Properties and Chemical Stability of Bathroom Wall Composites Manufactured… DOI: http://dx.doi.org/10.5772/intechopen.102457*

#### **Table 6.**

*Mechanical properties of composite.*

strength, impact strength, and water absorption, have been used to define the properties of composites. As shown in **Table 6**, the mechanical properties of composites are given.

### *3.2.1 Tensile strength*

The tensile strength was studied as a function of the rate of incorporation of the cocoa powder into the PET. As shown in **Table 6**, that the tensile strength of the composite increases with the amount of load introduced 10–30% and is equivalent to a value of 55.8–60.3 MPa, respectively, but when the level of 30% powder is reached, this value drops from 60.3 to 43.9 MPa. Observation of the table indicates that the greatest value of the tensile strength is reached after adding 30% of powder. This high value of the resistance results in a reinforcement of the PET, which has become more rigid and can withstand large loads. The small size and their particle size distribution in the composite allow good adhesion and contribute to the densification of the composite. Beyond 30% of the powder content, the resistance to decrease that would lead to believe that the PET matrix was not sufficient to cross and homogeneously fluidize the surface of the composite creating pores, which would contribute to the low resistance to traction.

#### *3.2.2 Flexural property*

Analysis of the table reveals that the flexural strength increases with the addition of the powder. The incorporation rate of 10 to 30% made it possible to go from a value of 10.5 to 19.50 (MPa). This could be explained by the fact that an increase in the loading rate would lead to the presence of a high rate of loading on a cross section of the composite and therefore increasing the flexural strength. We also note that beyond 30% of the incorporation rate, there is a decrease in the value of the flexural strength. This drop could be explained by poor dispersion of the powder in the matrix and this observation is confirmed by the tensile strength where we see similar results.

#### *3.2.3 Impact strength*

**Table 6** presents the values of the Charpy impact resistance (CIS) of nonnotched samples of PET composites with a proportion of cocoa shell powder varying from 10 to 50%.

For a load rate below 30%, there is an increase in the CIS, which reaches its highest value 10.3 (MPa) at 30% CCP. Beyond 30% the CIS decreases, because the addition of more powder creates regions of stress concentrations that require comparatively less energy to initiate a crack; this reduction could also be explained by the fact of the low resistance of the interface between the powder and the matrix. During impact, most of the energy absorbed is used to increase the distance between the load and the die.


#### **Table 7.**

*Weight loss of specimen in nitric acid and sodium hydroxide solutions (g).*
