The TPS25/PLA sheets had higher tensile strength and
elastic modulus values than the TPS30/PLA sheets,
regardless of the coating procedure used (
Table 3
). As TPS is
the component in higher concentration in the blend, this
behavior is due to the greater amount of plasticizer in the
TPS30/PLA blend. According to the literature, the plasti-
cizing effect of glycerol on the amylose and amylopectin
chains reduces the tensile strength and rigidity of the
fi
lms
[17, 18, 19]
.
The cross-linked chitosan coating increased both the
tensile strength and the elastic modulus, and reduced the
elongation at break of the sheets when compared with the
control sheet. With the cross-linking of the coating, the
macromolecules are covalently linked, forming a three-
dimensional network and reducing the mobility of the
chains, which makes the sheets less
fl
exible and more
resistant. Kittur et al.
[20]
reported that cross-linked chi-
tosan
fi
lms showed an 18% reduction in elongation and 33%
increase in tensile strength when compared to non-cross-
linked
fi
lms