2.3.6. Water Solubility

The films solubility was determined according to the methodology proposed by Colla et al. [42] with slight modifications. Films were cut with sizes of 2 × 3 cm2, which were dried to constant weight at 105 ◦C during 2.5 h. Each sample was placed in a beaker with 80 mL of distilled water. The samples were kept under gentle stirring (≈ 60 rpm) in a Corning plate (Model PC-620D, New York, NY, USA) at room temperature (23 ± 3 ◦C) within 24 h. Liquid together with the film was then filtered with filter paper (Whatman No. 1, pre-dried at 105 ◦C to constant weight). Filter papers with film residues were dried again at 105 ◦C to constant weight to obtain the dry matter. The solubility was recorded as the percentage of dry material of the solubilized film (%*S*) for 24 h and was determined using the following equation:

$$\text{Solubility}(\% \text{S}) = \frac{W\_i - W\_f}{W\_i} \times 100\tag{4}$$

where, *Wi* is the weight of the dry film and *Wf* is the weight of the dry sample after immersion in water.

### 2.3.7. Water Vapor Permeability (WVP)

WVP was determined according to ASTM E-9680 [43] method, known as the cup method or test cell. The films were cut into circles and placed on cells containing approximately 12 g of dry silica gel (desiccant) to generate a relative humidity close to 0%. Subsequently, the cells were placed in a desiccator containing a saturated NaCl solution to generate a 75% RH at room temperature (25 ± 2 ◦C) solution. Weight variation of the cells over time was recorded, for which the cells every 60 min for at least 7 h were weighed. The recorded data were fit to a linear regression model and the transmission rate (TR) was calculated from the slope (g s−1) obtained from the straight line and the effective permeation area (0.0031 m2), while the WVP (g Pa−<sup>1</sup> s−<sup>1</sup> m<sup>−</sup>1) was determined according to the equation:

$$TR = \left(\frac{\Delta w}{\Delta t}\right)\frac{1}{A} \tag{5}$$

$$WVP = \frac{(TR)(c)}{\Delta P} \tag{6}$$

where Δ*w* is the weight change in the cell (g) at the time Δ*t* (s), *A* is the exposed area of the film in the cell (m2), *e* is the film thickness (m) and Δ*P* is the gradient of the partial pressure of water vapor (Pa) in the desiccator and inside the cell.

#### 2.3.8. Mechanical Properties

Determinations were performed according to the methodology described by Mali et al. [44]. Ten strips (60 × 10 mm2) were cut for each formulation; the thickness was measured at 10 random spots along each strip using a micrometer (Mitutoyo, Kobe, Japan). The films were subjected to a tensile stress in a TAXT-Plus texturometer (Stable Micro Systems, Surrey, UK) with a 30 kg load cell, following the guidelines of ASTM-882-95a [45]. Tensile tests were performed at a strain rate of 20 mm min−<sup>1</sup> and a distance between the clamping pincers 4 cm. The tensile strength (TS) in MPa, the elongation at break (%*E*) in % were recorded and the elasticity modulus (EM) in MPa was determined.

#### 2.3.9. X-ray Diffraction

The diffractograms of the films were obtained by means of an X-ray diffractometer (Panalytical Xpert PRO, Almelo, OV, The Netherlands) with Ni-filtered CuKα radiation at a voltage of 40 kV and a current of 30 mA (λ = 0.154 nm), equipped with an X´Celerator detector. The diffractograms were collected within the scanning angle 2θ from 5◦ to 40◦ with a scanning speed of 1◦ min−1. The crystallinity of the films was calculated with the following equation:

$$\text{Cristillinity } (\%) = \frac{A\_{\text{c}}}{A\_{\text{c}} + A\_{\text{d}}} \times 100\tag{7}$$

where, *Ac* is the area of the crystalline region and *Aa* is the area of the amorphous region.
