2.5.4. Optical Properties

The color and transparency of the films were evaluated using a Technidyne Color Touch 2 spectrophotometer (New Albany, IN, USA). Measurements were performed on at least three random positions of the films using the D65 illuminant and 10◦ observer. Color coordinates L\* (lightness), a\* (redness; ±red-green) and b\* (yellowness; ±yellow-blue) were obtained. The transparency of the films was calculated according to the equation defined in ISO 2289 [21].
