2.4 Result and Discussion
31
0
1000
2000
3000
4000
5000
60
70
80
90
100
110
90
92
94
96
98
100
102
90
95
100
0
1000
2000
3000
4000
5000
Transmittance (%)
Wavelength (cm
-1 )
CS
3324
2939
1734
1650
1029
779
1195
Transmittance (%)
CR-CS
3330
2933
1728
1717
1433
1029
779
Transmittance (%)
G/CR-CS
3336
2932
1674
1603
1588
1373
1269
1174
1029
771
699
Fig. 2.3 FTIR pattern of CS, CR-CS and G/CR-CS
from alcohol and amine group [4, 26]. On comparing the FTIR spectrum of pure
chitosan (CS) with modified cross-linked chitosan (CR-CS), there was not much
difference in their spectrum. The major changes observed include a broadband shift
in peaks from (i) 3324–3330 cm
−1 , (ii) 2939–2933 cm
−1 , (iii) 1734–1728 cm
−1 and
(iv) 1650–1717 cm
−1 . The resultant shifts in peaks were attributed to the chemical
bonding of epichlorohydrin to pure chitosan structure. Hence, cross-linking did not
affect the structure of the modified chitosan but rather enhances some of its basic
functional groups.
However, the FTIR of modified grafted cross-linked chitosan (G/CR-CS) was
different from pure chitosan as shown in Fig. 2.3. The grafted cross-linked chitosan
(G/CR-CS) shows new sharp peaks at wavelengths 1174, 1269, 1373, 1588 and
1674 cm
−1 respectively. The peaks at wavelength 1174 cm
−1 corresponds to C–
O stretching vibrations while the peaks at 1269 and 1373 cm
−1 were attributed to
strong C–H stretching vibration. Also, while peak at 1674 cm
−1 was attributed to
vibrations of C=O from carbonyl group, that at 1588 cm
−1 represents N–H medium
bending vibration. Also increased intensity was observed to be exhibited by (G/CRCS) between wavelengths 1029–1674 cm
−1 . The increment in intensity provided
evidence of successful modification process. Hence, the presence of carbonyl (C=O)
31
0
1000
2000
3000
4000
5000
60
70
80
90
100
110
90
92
94
96
98
100
102
90
95
100
0
1000
2000
3000
4000
5000
Transmittance (%)
Wavelength (cm
-1 )
CS
3324
2939
1734
1650
1029
779
1195
Transmittance (%)
CR-CS
3330
2933
1728
1717
1433
1029
779
Transmittance (%)
G/CR-CS
3336
2932
1674
1603
1588
1373
1269
1174
1029
771
699
Fig. 2.3 FTIR pattern of CS, CR-CS and G/CR-CS
from alcohol and amine group [4, 26]. On comparing the FTIR spectrum of pure
chitosan (CS) with modified cross-linked chitosan (CR-CS), there was not much
difference in their spectrum. The major changes observed include a broadband shift
in peaks from (i) 3324–3330 cm
−1 , (ii) 2939–2933 cm
−1 , (iii) 1734–1728 cm
−1 and
(iv) 1650–1717 cm
−1 . The resultant shifts in peaks were attributed to the chemical
bonding of epichlorohydrin to pure chitosan structure. Hence, cross-linking did not
affect the structure of the modified chitosan but rather enhances some of its basic
functional groups.
However, the FTIR of modified grafted cross-linked chitosan (G/CR-CS) was
different from pure chitosan as shown in Fig. 2.3. The grafted cross-linked chitosan
(G/CR-CS) shows new sharp peaks at wavelengths 1174, 1269, 1373, 1588 and
1674 cm
−1 respectively. The peaks at wavelength 1174 cm
−1 corresponds to C–
O stretching vibrations while the peaks at 1269 and 1373 cm
−1 were attributed to
strong C–H stretching vibration. Also, while peak at 1674 cm
−1 was attributed to
vibrations of C=O from carbonyl group, that at 1588 cm
−1 represents N–H medium
bending vibration. Also increased intensity was observed to be exhibited by (G/CRCS) between wavelengths 1029–1674 cm
−1 . The increment in intensity provided
evidence of successful modification process. Hence, the presence of carbonyl (C=O)