2.5.3. Transparency

The light transmission of the PHBV films was determined in specimens of 50 × 30 mm<sup>2</sup> by quantifying the absorption of light at wavelengths between 200 and 700 nm, using an ultraviolet–visible (UV–Vis) spectrophotometer VIS3000 from Dinko Instruments (Barcelona, Spain). The transparency value (*T*) of the films was calculated using Equation (1) [1], whereas their opacity value (*O*) was determined using Equation (2) [40]:

$$T = \frac{A\_{600}}{L} \tag{1}$$

$$O = A\_{500}L$$

where *A*500 and *A*600 are the absorbance values at 500 and 600 nm, respectively, and *L* is the film thickness (mm).
