## 3 Results and Discussion
### Comparison of Properties with Commercial-Bleached Eucalyptus Pulp Handsheets  
The analyzed physical-mechanical and structural properties of paper (grammage, thickness, density, apparent volume, and air permeability) have a significant impact on its quality and suitability for different applications. For this reason, it is relevant to understand paper properties in order to find suitable opportunities for innovation. Below, we present the relationship between the properties of papers made from different parts of the selected Invasive Exotic Species, in comparison to those of paper made from commercial Eucalyptus pulp. As is well-known, a higher grammage is generally associated with thicker and more durable paper, which is important for applications requiring strength and durability. However, excessively high grammage can make the paper stiff and challenging to fold, which may be undesirable for certain applications like printing. Moreover, thicker paper generally has a higher printing capacity and a better appearance, which is crucial for high-quality printing applications and influences paper stiffness and strength. Furthermore, a higher specific density is usually linked to more compact and durable paper, and, on the other side, a higher specific volume typically indicates that the paper is more porous and less dense. Both properties can influence ink absorption in printing applications and the tactile feel of the paper. The Eucalyptus properties (performed test results can be observed in Table 5) of high pulp yield, high wood density, excellent fiber quality, and good handsheet properties make this species one of the most important hardwood species used in the paper industry [44]. In Galicia, Spain, it is possible to find broad areas destined to grow Eucalyptus monocultures, whose final objective is use within the paper and wood industries. In recent years, commercial pulps have been undergoing changes in their composition, despite Eucalyptus remaining one of the most commonly used species as a source of cellulose in Europe. Despite the proven properties of wood-derived cellulose, other studies [45] propose cellulose extracted from non-wood species as a raw material for the production of commercial paper, yielding different properties through its use. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Properties** & **Test A** & **Test B** & **Test C** \\ \hline Drainability (\({}^{\circ}\)SR) & 27.50 & 43.00 & 18.00 \\ \hline Grammage (g/m\({}^{2}\)) & 53.22 & 56.70 & 49.79 \\ \hline Thickness (\(\mu\)m) & 132.00 & 102.00 & 140.00 \\ \hline Specific density (g/cm\({}^{3}\)) & 0.40 & 0.56 & 0.36 \\ \hline Specific volume (cm\({}^{3}\)/g) & 3.48 & 1.79 & 2.81 \\ \hline Air resistance-Gurley 300 cm\({}^{3}\) (s) & 1.65 & 13.15 & \textless{}1 \\ \hline Air Permeability (\(\mu\)m/(Pa-s)) & 8200.00 & 1028.00 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Commercial fiber made handsheets mechanical properties. Test A is PFI the time of 60 s; Test B is the PFI time of 120 s; and Test C is the PFI time of 30 s.  
This is the case with _Tradescantia fluminensis_, which, unlike the commercial pulp used in this study, provides higher Schopper degrees and consequently lower air permeability (and higher Gurley times) with shorter refining times (with a refining time of 30 s, we obtained 65 \({}^{\circ}\)SR and 262.3 s of air passage resistance, whereas, with the commercial pulp used, we obtained 18 \({}^{\circ}\)SR and Gurley times of less than 1 s). This, as shown in Figure 21, can also be observed in the test sheets made from _Phylotacca americana_ leaves and _Arundo donax_ leaves, concluding that leaf matter demonstrates great potential in relation to air permeability and air resistance properties for shorter refining periods. It is relevant to highlight that unbleached pulps delignified from crafted and less-contaminated processes allow us to obtain competitive properties, obtaining values, on occasion, similar to those obtained from bleached commercial fibers.