2.6.1. Structural Properties

The structures produced were characterized in terms of basis weight (ISO 12625- 6), thickness and bulk (ISO 12525-3). The basis weight was obtained by the quotient between the average mass of each structure and the respective area (0.02138 m<sup>2</sup> ). The thickness was obtained using a Frank-PTI micrometer. The bulk was obtained by the quotient between the thickness and the basis weight of the structures. Additionally, the porosity (apparent theoretical porosity) of the structure was also calculated according to the following equation:

$$Porosity\left(\%\right) = 100 \times \left(1 - \frac{\rho\_{structures}}{\rho\_{cellulose}}\right) \tag{1}$$

where *ρcellulose* was the density of the cellulose (1.5 g/cm<sup>3</sup> ) [12] and *ρstructure* was the apparent density of the structures (g/cm<sup>3</sup> ).
