2.5.2. Swelling Ability

Film swelling was determined by following the method proposed by Banerjee et al. [16]. A film (30 mm × 30 mm) was dried at 100 ◦C for 2 h and immersed in distilled water at room temperature for 24 h. The WUR and area swelling ratio (ASR) of the film were calculated by the weight difference of the film before and after water absorption.

#### 2.5.3. Water Vapor Permeability

The films were cut into pieces with size of 4 cm × 4 cm. The water vapor permeability of the film was measured following the method provided by Shima Jafarzadeh [17]. The water vapor transmission rate (WVTR) was measured from the slopes (linear) of the steadystate portion of weight loss of the cup versus time curve. Further, the WVP of the films was measured as follows:

$$\text{WVP} = \text{WVTR} \times \frac{\text{D}}{\text{AP}} \tag{1}$$

where D is the thickness of the film and Δp is the partial water vapor pressure difference over the two sides of the film.
