## 3 Results
### Influence of Treatments on Crystallinity and Thermal Analysis of Curaua Fibers  
All treatments resulted in fibers rich in holocellulose with different lignin compositions and soluble components. In addition to the morphologic and chemical analysis of the curaua fibers, X-ray diffraction investigated the effect of the applied treatments on crystallinity. The measured curves are shown in Figure 2, with their respective Ic calculated following Equation (4). Figure 1: SEM micrographs with 500 times magnification: curaua fibers (**A**,**B**); curaua fibers treated with hot water (**C**); curaua fibers treated with hot water and mercerized (**D**); curaua fibers treated with hypochlorite (**E**); curaua fibers treated with hypochlorite and mercerized (**F**). Independent of the applied treatment, three peaks were found in the X-ray diffraction analyses (Figure 2): one broad peak between 15 and 16.5 (20), a second at 23 (20), and the third at 35 (20). These peaks correspond to the crystallographic planes (001), (002), and (040) [39]. The applied treatments affected the intensity of the recorded signals. Whereas the untreated fibers show the lowest intensity, the peak height increased for all applied treatments. In general, it can be observed that the more severe treatments changed the morphology of the curaua fibers. Also, the strongest signal was captured for the sodium hypochlorite treated and mrererization fibers. Furthermore, the mrerererization process led to an amplified formation of a plateau between 15 and 16.5 (20). Whereas the other treatments led to a broad and rounded peak with the maximum at 16 (20), the diffractogram of the mrerereized fibers shows two connected peaks at 15 and 16.5 (20). Based on these results, the crystallinity index was calculated. As explained elsewhere, the only crystalline component of the curaua fibers is alpha-cellulose. Considering this, the crystallinity index shows that the highest amount of alpha-cellulose is present in the fibers treated with sodium hypochlorite and mrerereized. This means that all applied treatments preferentially remove amorphous components from the fibers. Therefore, it can be deduced that the external layers of the curaua fibers, which were modified or removed by the treatments, are mainly amorphous. The thermal behavior of the curaua fibers in TGA and its derivative are shown in Figure 3. At up to 200 \({}^{\circ}\)C, all fibers showed a loss of weight. This occurred due to the elimination of moisture present in the lignocellulosic material. According to the TGA image, the untreated curaua fiber showed thermal stability up to 250 \({}^{\circ}\)C. The thermal stability in lignocellulosic compounds is based on the content of lignin, hemicellulose, and cellulose that these compounds present. Cellulose is the most crystalline part of the material, presenting a difficult degradation due to its highly organized structure. This component provides thermal stability to the fiber [40]. The higher the content of crystalline structures, the greater the thermal stability of the sample. Therefore, the higher the levels of hemicellulose and lignin, the lower the thermal stability of the sample [40,41]. Figure 2: X-ray diffraction: curaua fibers and the different types of treatment. After the curaua fiber was treated with sodium hypochlorite, its thermal stability at around 60 \({}^{\circ}\)C was reduced. Hypochlorite broke the lignin structure but reacted with cellulose and hemicellulose, exposing the fibrils more. The DTG curves showed that the two samples of mercerized fibers, washed with water and hypochlorite, showed two degradation peaks, one peak of weight loss below 150 \({}^{\circ}\)C and the other with peak temperature at 350 and 330 \({}^{\circ}\)C, respectively. This last weight loss is related to the degradation of the cellulose present in both samples [42]. The untreated fibers were washed with water, and sodium hypochlorite showed three peaks.