2.3.2. Density
Prior to film properties determination, samples were conditioned
at 25 C and 58% relative humidity (RH) for 48 h. Films
thicknesses were measured (exactness of 0.001 mm) using
a Digimatic digital external micrometer (Mitutoyo Co., Japan) at ten
different points of the film. For determining film density, samples of
2 2 cm were maintained in a desiccator with phosphorus pentoxide
(0% RH) for 20 days and weighed. Thus, dry matter densities
were calculated by Eq. (1).where A is the film area (4 cm2), d the film thickness (cm), m the
film dry mass (g) and rS the dry matter density of the film (g/cm3)
(Larotonda et al., 2005). The film density was expressed as the
average of ten determinations.