2.3.7. Mechanical Tests

Dumbbell-shaped specimens were die-cut from the electrospun films and conditioned to ambient conditions, i.e., 25 ◦C and 50% RH, for 24 h prior to tensile testing. Tests were carried out at room temperature in a universal mechanical testing machine AGS-X 500N from Shimadzu Corp. (Kyoto, Japan) in accordance with ASTM D638 (Type IV) standard. This was equipped with a 1-kN load cell and the cross-head speed was set at 10 mm/min. A minimum of six specimens was measured for each sample and the average results with standard deviation were reported.

#### 2.3.8. Water Vapor Permeability

The water vapor permeability (WVP) of the samples was determined, in triplicate, using the gravimetric method ASTM E96-95. To this end, 5 mL of distilled water was placed inside a Payne permeability cup (Ø = 3.5 cm) from Elcometer Sprl (Hermalle-sous-Argenteau, Belgium) to expose the film to 100% RH on one side. The liquid was not in contact with the film. Once the films were secured with silicon rings, they were placed within a desiccator at 0% RH cabinet at 25 ◦C. The dryness of the cabinet was held constant using dried silica gel. Cups with aluminum films were used as control samples to estimate solvent loss through the sealing. The cups were weighted periodically using an analytical balance with a ±0.0001 g accuracy. Water vapor permeation was calculated from the steady-state permeation slopes obtained from the regression analysis of weight loss data vs. time, and the weight loss was calculated as the total loss minus the loss through the sealing.
