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sided carbon tape. The samples were then dried at a room temperature ( ~ 26 °C) for 48 h to remove excess trapped moisture. After 48 h, the specimens were sputter coated with gold using Denton Vacuum Sputter Coater Desk V (Denton Vacuum, NJ, USA). The vacuum pressure was set at 0.05 tort for 60 sec of sputter coating with 50 Å thickness. A variable pressure SEM (Hitachi 3400 NII, Hitachi Technologies America, Inc., Pleasanton, CA, USA) was used to take pictures at various magnifications. Sample Following pressings, composite panel boards were conditioned at 25 °C and 50% relative humidity (RH) for 72 h. A table saw was employed to cut specimen boards in order to conduct three-point bending tests (EN 310:1993). Specimen board thickness was measured according to the EN 310:1993 test. Specimen board dimensions were 127 mm long, 50 mm wide, and | 3.5 to 5.5 mm thick, depending on the treatment. The specimen thickness dictated the free span length. Tests were performed on a universal testing machine [Instron Model 1122 (Instron Corp., Norwood, MA, USA)] using a crosshead speed of 5 mm/min. Densities of the composites were determined using the EN 323:1993 standard. Water absorbance (WA) and thickness swelling (TS) were conducted on 50 x 50 mm squares immersed in water for 24 h according to EN 317:1993 standards utilizing composite formulations of the various DDGS-PW dosages (EN 317:1993). Statistical Analysis Five specimens of each formulation were tested. The average values and standard errors were reported. The experimental data obtained were analyzed statistically by analysis of variance for statistical significance, and multiple comparisons of means were accomplished with Duncan’s Multiple Range Test (p d 0.05) (Statistix 9, Analytical Software, Tallahassee, FL, USA). surfaces and edges were examined. Flexural and Physical Tests Figure 1 a-d shows the FTIR spectra of ingredients DDGS and PW and composite panels 100DDGS (100% DDGS wt.) and 50DDGS-PW (50% DDGS:50% PW wt.). There was no difference in the absorption bands between the original DDGS and 100DDGS composite panel except for a peak region occurring at 625 cm -1 in the 100DDGS, which was absent in the DDGS ingredient spectra. The 600 to 700 cm -1 region is characteristic of P-S and P=S stretching (Pretsch HWDO 2000). That the region shows up in the 100DDGS suggests unfolding of the protein component so that a buried vibration could be observed. All spectra (Fig. 1a-d) showed characteristic H-bonding and -OH stretching absorption around 3300 to 3500 cm -1 and C-H asymmetric and symmetric stretching of methylene groups around 2800 to 3000 cm -1 (Pretsch HWDO . 2000 Nagieb HWDO . 2011; Hemsri HWDO . 2012; Deka HWDO . 2015; Li HWDO . 2016). This region’s band w as centered at 3384 cm -1 and is identified as -OH of carbohydrate overlapping the protein -NHs (Pretsch HWDO . 2000; Deka HWDO . 2015). A broad alkyl band occurs at 2921 cm -1 , which was RESULTS AND DISCUSSION FTIR Analysis
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Tisserat et al . (2018). “DDGS - PW fiberboards” B io R esources 13(2), 2678-2701.
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