The activation energy was calculated for the raw material
and for the as-spun membranes before and after
cross-linking with GA (Table 1). The values show that
dissolution and processing conditions does not affect the
thermal degradation of the material. It was previously reported
that the [25] thermal activation energy for gelatin is
between 175 and 275 kJ.mol1
, the difference to the present
investigation being attributed to the gelatin source, i.e.
animal or fish gelatin, and molecular weight. After crosslinking,
a decrease of Eact was observed in both transition
stages of the electrospun membranes (Table 1), which was
probably due to random scission of polymer chains [25]. GA
cross-linking of gelatin promotes water insoluble enzymes,
cross-linking being associated with more rigid molecules
with less ordered structures. Protein–protein interaction is,
therefore, apparently affected by chemical cross-linking,
and decreases the thermal stability of gelatin electrospun
membranes. During heating, the initially ordered structure
of the samples is gradually destroyed after breaking of
inter- and intra-molecular hydrogen bonds, which are
responsible for the maintenance of the polymeric chain
[25,27].