Fig. 5shows the typical stressestrain curves obtained for all the
films after one andfive storage weeks under controlled conditions
(53% RH and 25
C), where the different mechanical behaviour of
the matrices and the effect of ageing can be observed. Although
starchfilms exhibited the typical mechanical behaviour of a brittle
material, without plastic deformation and with very low extensibility at break, the great resistance to break of PVA is highlighted.
Elastic modulus (EM), tensile strength at break (TS) and percentage of elongation at break (E, %) are the parameters used to
describe the mechanical behaviour offilms.Table 4shows the mean