THESIS - ROC CH ... - FINAL - resubmission.pdf - University of Guelph

Similar to Section 4.4.5, dominating areas of interest can be identified. The broad band
around 3000 to 3500 cm -1 is associated with free and bound water with O-H and N-H groups
(Guerrero and de la Caba 2010; Lodha and Netravali 2005). As discussed previously,
increasing RH broadens this region due to the increased hydrogen bonds formed binding water
to the films. Glycerol is strongly detected at frequencies of 1040 cm -1 (C-O linkage in C1 and C3
of glycerol), and 1117 cm -1 (stretching of C-O in C2) (Lodha and Netravali 2005). This large
presence of glycerol expectedly dwarfs any detectable C-O vibrations found from cellulose
(Alemdar and Sain 2008). The main absorption peaks of Amide I, Amide II, and Amide III can
be seen at 1630 cm -1 , 1540 cm -1 , and 1230 cm -1 (Lodha and Netravali 2005; Schmidt et al.
2005). These bands are associated with C=O stretching, N-H bending, and C-N stretching
respectively. Interaction between cellulose and SPI would affect the protein structure and could
be elucidated via these regions. Changes found within the Amide I and Amide II bands have
been strongly correlated to the secondary structure due to the absence of interference with
other vibrations (Barth 2007). Determining structural changes with the Amide III band is more
complicated due to side chain contributions (Barth 2007). However, predictions on secondary
structure have been previously made using the Amide III band (Cai and Singh 2004). Figure
6.10, Figure 6.11, and Figure 6.12 further analyzes the Amide I, II, III bands for evidence of
structural changes.
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