3.2. FTIR analysis
FTIR spectra were also recorded for IGT/PVA composite at different
percentages of NC. The characteristic band at 3442 cm−1 was
detected for the stretching frequency of OH groups as shown in
Fig. 4. Asymmetric and symmetric stretching vibrations for methylene
groups appeared at around 2930 and 2856 cm−1. A significant
band at 1747 cm−1 is attributed to C O group stretching vibrations.
The strong peak at 1495 cm−1 is ascribed to characteristic
asymmetrical stretch of COO− group. The characteristic asymmetrical
stretch of COO–group is caused to appear as bands at
1441 and 1367 cm−1. The spectra showed bands at 11,420 and
1280 cm−1; 1243 and 1100 cm−1 for the stretching vibrations of
C O of the polyols, ether and alcohol groups. The strong peak at
1243 cm−1 is attributed to stretching vibrations of C O groups
(Fig. 4c). The bands around 2925 and 2854 cm−1 1 are assigned to
asymmetric and the symmetric stretching to CH2 group, respectively.
Two peaks at 1737 and 1434 cm−1 can be observed for to
CO stretching vibrations: OH and CH bending respectively. The
absorption peaks at 525 and 450 cm−1 are assigned to Si O Al and
Si O Si bonds for tetrahedral bending modes. The intense peak at
around 1028 cm−1 indicates the Si O stretching frequencies. Three
bending vibrations were considered at 915 cm−1 (Al· · ·Al· · ·OH),
747 cm −1 (Al· · ·Fe· · ·OH) and 736 cm−1 (Al· · ·Mg· · ·OH) due to associated
hydroxyl group of bentonite with Al+3 cation. In the spectra
of PVA/IGT/nanopowder blend nanofibre, the absorption peak at
1617 cm−1 is assigned to asymmetrical stretch of COO− group
which appeared at 1594 cm−1 for IGT and shifted to 1618 cm
for IGT/PVA nanofibre, suggesting that most of the carboxylic acid
groups were associated with intramolecular hydrogen bonding.