*3.2.1. Mechanical properties*

The influence of bagasse fiber addition on the PP flexural and impact properties was evaluated. **Table 1** presents the values of the flexural modulus, flexural strength, and impact strength of the materials. Biocomposites showed different mechanical properties, indicating that the treatments affect the fiber-matrix interaction.

The results show that bagasse fiber incorporation induces a significant improvement of flexural properties of PP. For PP-bagasse and PP-Bag+NaOH biocomposite flexural modulus (FM) increased 60 and 42%, respectively. On the same way, flexural strength (FS) reached improvements of 20 and 8% compared to neat PP. For PP-Bag+NaOH+Silane, FM was enhanced 16%, respectively, in comparison with PP. However, the FS value was not significantly different (p ≥ 0.05). Similar results were reported by Cerqueira et al. [34] when they studied the morphology and mechanical properties of PP-bagasse biocomposites. The authors reported that biocomposites present higher FM and FS values in comparison with neat PP and suggested a good interaction under the compressive stresses developed in part of the transverse section of the biocomposite specimens during bending.

On the other hand, the impact tests did not show significant differences between the PP matrix and the biocomposites PP bagasse and PP-Bag+NaOH. However, for PP-Bag+NaOH+Silane an


Different letters (a–d) in the same column indicate significant differences (p < 0.05). \*Mean of five replications ± standard deviation.

**Table 1.** Flexural and impact properties of PP and PP-bagasse biocomposites.

increase of 40% was observed. This result shows that silanization increases the capacity of PP to absorb energy. This phenomenon can be explained by a possible energy absorption promoted by fracture mechanisms, which involve detachment, slippage, and fragmentation of the fiber. These mechanisms do not occur in neat PP and PP biocomposites without silanization.
