## 3 Results and Discussion
### Water Uptake Properties
Despite this visual difference, it is worthy to note the scale. For the short-term graph, some specimens do not follow the expected behavior (e.g., BioEP/CFF 10 wt%), but the changes in the water absorption are very low, of about 0.2-0.3 wt%, which could be even included in the measurement error. In addition, this initial stage (24 h), is very sensitive to the surface, i.e., the presence of particles not fully embedded and directly exposed to water, which could cause these slight changes. The stationary water absorption after 90 days, represents the actual water uptake behavior as all these initial phenomena disappear, and this agrees with the expected behavior in terms of particle size and loading. Table 4 shows the values of the saturation by weight (\(W_{\text{s}}\)), as well as the diffusion coefficient (\(D\)) and the corrected diffusion coefficient (\(D_{\text{c}}\)) of BioEP resin and the obtained BioEP/FF composites. The diffusion coefficient is one of the most important parameters of the [PERSON]'s model, which is related to the initial diffusion of water molecules into the matrix surface by entering through external micro-voids towards the internal structure of the composites [81]. As can be seen, the BioEP resin is characterized by a \(W_{\text{s}}\) of 2.2 wt%, a \(D\) of \(0.72\times 10^{-9}\) cm\({}^{2}\) s\({}^{-1}\). and a \(D_{\text{c}}\) of \(0.36\times 10^{-9}\) cm\({}^{2}\) s\({}^{-1}\). After the incorporation of the highly hydrophilic lignocellulosic residue, it is observed, as expected, that \(D\) and \(D_{\text{c}}\) increase as the CFF and FFF content does, following the behavior shown by other composites reinforced with natural \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Code** & \(W_{\text{s}}\) **(wt\%)** & \(D\times 10^{-9}\) **(cm\({}^{2}\) s\({}^{-1}\))** & \(D_{\text{c}}\times 10^{-9}\) **(cm\({}^{2}\) s\({}^{-1}\))** \\ \hline BioEP & 2.2 \(\pm\) 0.0 & 0.72 \(\pm\) 0.90 & 0.36 \(\pm\) 0.42 \\ BioEP\_10 CFF & 4.9 \(\pm\) 0.1 & 1.51 \(\pm\) 0.40 & 4.99 \(\pm\) 2.03 \\ BioEP\_20 CFF & 7.5 \(\pm\) 0.1 & 2.07 \(\pm\) 0.06 & 6.84 \(\pm\) 2.9 \\ BioEP\_30 CFF & 8.4 \(\pm\) 0.2 & 3.35 \(\pm\) 0.10 & 11.1 \(\pm\) 2.5 \\ BioEP\_40 CFF & 12.7 \(\pm\) 0.1 & 4.27 \(\pm\) 0.05 & 14.2 \(\pm\) 0.9 \\ BioEP\_10 FFFF & 4.6 \(\pm\) 0.1 & 1.38 \(\pm\) 0.01 & 4.56 \(\pm\) 0.2 \\ BioEP\_20 FFFF & 6.5 \(\pm\) 0.1 & 2.23 \(\pm\) 0.05 & 7.37 \(\pm\) 0.6 \\ BioEP\_30 FFFF & 7.7 \(\pm\) 0.1 & 2.39 \(\pm\) 0.04 & 7.9 \(\pm\) 0.8 \\ BioEP\_40 FFFF & 12.4 \(\pm\) 0.1 & 3.39 \(\pm\) 0.05 & 11.2 \(\pm\) 0.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Values of water saturation (\(W_{\text{s}}\)), diffusion coefficient (\(D\)) and the corrected diffusion coefficient (\(D_{\text{c}}\)) for BioEP resin and BioEP composites reinforced with different CFF and FFF content. Figure 7: Evolution of water absorption over time of BioEP resin and BioEP composites filled with CFF (10 and 40 wt%) and FFF (10 and 40 wt%): **(a)** water absorption during the first 24 h; **(b)** water absorption during a period of 12 weeks. fillers [18; 82; 83]. Therefore, it can be concluded that the increase in the amount of lignocellulosic filler increases the ability of water molecules to enter through the composite. Comparing both composites (with CFF and FFF), it can be seen how CFF-filled materials tend to have a higher diffusion coefficient than FFF-filled composites, mainly due to the larger particle size and the more significant presence of voids in the internal structure of the composite due to the lack of matrix-filler interaction [84].