2.4. Scanning electron microscope (SEM)
The morphology of the packaging materials, antifungally active
and control, were visualized using a scanning electron microscope
(Joel-5410), operating at a vacuum pressure of 1 10
4
Pa, with a
voltage of 10 kV with 0.5 0.5 cm. Samples were coated with gold
prior to analysis in order to increase electrical conductivity.
2.5. Dif ferential scanning calorimeter (DSC)
The thermal characterization of the packaging (active and con-trol) was performed by DSC (Mettler Toledo, DSC-822e) under non-isothermal conditions. Samples weighing 10.0 mg were heated
from 0 to 30 0
Cat10
C/min followed by cooling to 0
C at the
same rate, then heated again to 30 0
C to obtain the melting point
in the second heating and the crystallization point in the cooling
stage. The calculation of the relative percentage of crystallinity ( X
c
)
was based on a two-phase (crystallineeamorphous) peak area
method:
Xc
¼ðDH m D Hc
Þ =D H
f
(1)
where DH c
is the enthalpy released during cold crystallization; DHm
is the enthalpy of fusion; and DH f
is the enthalpy of fusion of 10 0%
crystalline PET taken to be equal to 120 J/g ( Todorov & Viana, 20 07).