The tensile (stress/strain) was measured in a universal testing
machine, Model WDW e 300E Time Group Inc. using the method
described in ASTM D1708-10, which is suitable for determining
the tensile properties of plastics or the traction of films with
thicknesses ranging from 0.0025 mm to 2.5 mm. The initial grip
separation was set to 22 mm and traction speed to 12.5 mm/min,
with 150 kgf load cell. Five samples were analysed in each test
and all testing occurred at room temperature (approximately
25 C). The thickness of the individual films was measured with a
Mitutoyo® manual micrometer, with divisions of 0.01 mm, at five
random points on each sample, which were determined to have a
mean value of 0.08 ± 0.04 mm for the TTI, 0.10 ± 0.04 mm for
chitosan films and 0.07 ± 0.03 mm for PVA films. Prior to testing,
the samples were placed in an environment with 50 ± 5%
relative humidity and a temperature of 23 ± 2 C for a period of
40 h.