## 4 Discussion  
The chemical treatments of curaua fibers in hot water and the mercerization process did not significantly affect the lignin content. The most significant changes were found after sodium hypochlorite treatment. Sodium hypochlorite treatments reduced the lignin content by about 60%. [PERSON] et al. [23] demonstrated that the easy-to-access lignin parts are soluble in alkaline solutions. Therefore, the alkaline potential of sodium hypochlorite solution is seen as the reason for removing the lignin. The changes in ash and humidity are insignificant and do not follow a coherent pattern. The amount of lignin remained stable regardless of whether a post-treatment (mercerization) was carried out. The SEM images in Figure 1E and F show this alteration. The individual fibers completely detached as a result of these procedures. Not only do the individual fibers appear to have detached, but thin tissues and tiny filaments may also be seen projecting from them. According to this literature [61], chemical treatments can promote the structural reorganization of fibers, resulting in dimensional stability, removing impurities and amorphous components, and exposing more crystalline areas. The TGA/DTG results agree with the found chemical analysis. The curaua fibers treated with hot water did not show any changes in fiber structure that would alter their thermal behavior, but those treated with sodium hypochlorite showed peaks of weight loss, indicating the evaporation of moisture and the degradation of hemicellulose and cellulose. In a study conducted by [PERSON] et al. [62], this loss is attributed to the degradation of lignin, which is related to breaking ether and carbon-carbon bonds. Therefore, the disappearance of this peak with the fiber treatments indicated that the mercerization treatments and the sequence of treatments removed a large part of the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Samples** & **T\({}_{\textbf{m}}\)** (\({}^{\circ}\)**C)** & **\(\Delta\)H\({}_{\textbf{m}}\) (J/g)** & **X\({}_{\textbf{c}}\) (\%)** \\ \hline PLA matrix & 159.2 & 24.6 & 13.3 \\ CF 10 wt\%/PLA & 159.4 & 24.0 & 15.1 \\ CF 20 wt\%/PLA & 159.4 & 28.9 & 20.3 \\ CWM 10 wt\%/PLA & 159.8 & 26.6 & 18.0 \\ CWM 20 wt\%/PLA & 160.1 & 36.7 & 27.1 \\ CHM 10 wt\%/PLA & 160.0 & 24.8 & 15.6 \\ CHM 20 wt\%/PLA & 161.2 & 29.3 & 19.8 \\ \hline PHB matrix & 174.7 & 45.1 & 30.9 \\ CF 10 wt\%/ PHB & 174.7 & 39.1 & 29.7 \\ CF 20 wt\%/ PHB & 174.4 & 34.8 & 29.8 \\ CWM 10 wt\%/PHB & 174.6 & 41.6 & 31.6 \\ CWM 20 wt\%/PHB & 175.1 & 38.2 & 32.7 \\ CHM 10 wt\%/PHB & 175.2 & 42.8 & 32.5 \\ CHM 20 wt\%/PHB & 174.9 & 38.7 & 33.2 \\ \hline \hline \end{tabular}  
* CF: untreated curaua fibers; CWM: curaua treated with hot water and mercerized; CHM: curaua treated with hypochlorite and mercerized.  
\end{table} 
Table 3: DSC data of PLA, PHB and PLA, and PHB composites. amorphous constituents. Thus, their thermal behavior was affected, their thermal stability was lower, and their thermal degradation temperatures were also lower. According to this study [63], jute fiber treated with hot water followed by chemical treatment was able to progressively remove hemicellulose and reduce the lignin content present in the fiber. In addition, it showed an increase in interfacial shear strength and flexural properties of jute/epoxy composites. Tensile and flexural testing examined the impact of the matrix, filler content, and fiber treatments on the mechanical characteristics of thermoplastic composites reinforced with curaua. Some groups of PLA composites reinforced with curaua showed a reduction in tensile and flexural strength compared to the tensile strength of the unfilled PLA matrix. By contrasting the PHB polymer without filler with the PHB composites, it was determined that adding 10% curaua fibers to the PHB matrix did not significantly increase its resistance to tensile or flexural stress. Unlike the PLA composites, filling with cleaned and mercerized fibers did not increase the PHB matrix's strength.