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resolved in the 2 nd derivative spectrum into four bands: strong 2958 cm -1 (-CH 3 asymmetrical stretching), very strong 2927 cm -1 (-CH 2 asymmetrical stretching), 2876 cm -1 (-CH 3 symmetrical stretching), and very strong 2858 cm -1 (-CH 2 symmetrical stretching) (Pretsch HWDO . 2000; Deka HWDO . 2015). A residual ester or lignocellulosic carbonyl and protein bands occur at 1738 cm -1 (-C=O, medium carbonyl band either from lignin or uronic esters), and 1656 cm -1 (N-C=O, amide I). The 1543 and 1517 cm -1 (H-N- CO) bands are the protein amide IIs (Pretsch HWDO . 2000; Deka HWDO . 2015). Bands 1470 cm -1 and 1372 cm -1 are identified as CH 2 and CH 3 deformations, respectively, and are commonly known as the alkyl deformation region of the spectrum (Pretsch HWDO . 2000). Other prominent bands are located at 1117 cm -1 (O-C=O), 1081 cm -1 (-CHO-), 1050 cm -1 (-CH 2 O-), and 994 cm -1 (unknown).
Fig. 1. FTIR spectra of ingredients (a) DDGS and (c) PW and bio-composites (b) 100DDGS and (d) 50DDGS-PW Figure 1b 100DDGS spectrum is similar to Fig. 1a of the DDGS ingredient. As previously noted, a strong band occurs at 625 cm -1 representing P-S and P=S stretching of protein. This band was inconspicuous in the spectrum of the folded DDGS protein (Fig. 1a) but now obvious in the unfolded matrix (Fig. 1b). Figure 1c is the spectrum of PW. Like in many carbohydrates a broad and strong symmetric absorption band is observed at 3420 cm -1 for the (H bonding and -OH stretching) with a moderate intensity alkyl band occurring at 2925 cm -1 (Pretsch HWDO . 2000; Li HWDO . 2016). The broad band at 2925 cm -1 is resolved into a sharp 2969 cm -1 (-
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Tisserat et al . (2018). “DDGS - PW fiberboards” B io R esources 13(2), 2678-2701.
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