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PEER-REVIEWED ARTICLE
EXPERIMENTAL Materials
DDGS were obtained as the commercial animal corn feed pellet product (Archers Daniel Midland Co., Decatur, IL, USA). Prolia TM (200/90) (PRO) containing 54% protein and 5% moisture was provided by Cargill Inc., Cedar Rapids, IA, USA and used as provided. 3DXORZQLD HORQJDWD wood material was obtained from 36-month-old trees grown in Fort Valley, GA. PW shavings were milled successively through 4-, 2-, and then 1-mm screens with a Thomas-Wiley mill grinder (Model 4, Thomas Scientific, Swedesboro, NJ, USA). Particles were then sized through a Ro-Tap Tm Shaker (Model RX-29, Tyler, Mentor OH, USA) that employed 203 mm diameter stainless steel screen/sieves. The sieve/screens employed were #12, #30, #40, #80, #140, and #200 US Standards (Newark Wire Cloth Company, Clifton, NJ, USA). The shaker was operated for 60 min intervals at 278 rpm to obtain particle separation. Two PW mixtures composed of 50% ≤ 600 μm particle selection, obtained from particles passing through the #30 mesh sieve, and a 600 to 1700 μm particle selection, obtained from particles passing through the #12 mesh sieve and collected on the #30 mesh sieve, were used throughout this study. PW contained 6% moisture. DDGS were ground in a Wiley mill as described. DDGS were defatted with hexane as the solvent using a Soxhlet extractor to obtain a DDGS containing 30% crude protein and 5% moisture. DDGS were ball ground into a flour (< 425 P m particles) using a laboratory bench top ball mill (Model 801CVM, U.S. Stoneware, East Palestine, OH, USA) to obtain fine powder. DDGS was ground in Alumina mill jars containing Burundum cylindrical grinding media pellets (13 mm diam, | 7.3 g wt.) (U.S. Stoneware) at a speed of 50 rpm for 60 h. DDGS flour was sieved through a #80 mesh to be obtained as d 250 μm particles. Preparations To test the influence of mold temperature on DDGS-PW composites, a composite composed of 80 g of DDGS was mixed with 40 g of < 600 P m PW particles and 40 g of 600 to 1700 P m PW particles. DDGS and PW were mixed in a zip-lock bag and given 15 min of circular agitation using a 0.074 m 3 compact dryer (Model MCSDRY1S, Magic Chef, Chicago, IL, USA). An aluminum mold (outer dimensions: 15.2 cm width u 30.5 cm length u 5 cm depth and mold cavity: 12.7 cm width u 28 cm length u 5 cm depth) was employed. The mold interior was sprayed thoroughly with mold release (Paintable Dry Spray with Teflon, No. T212-A, IMS, Chagrin Falls, OH, USA). Pressings were conducted using manual hydraulic presses (Model 4126, Carver Press Inc., Wabash, IN, USA). The mold was then transferred to a preheated Carver press at 150, 170, 180, 185, or 190 °C. Initially, molds were given 2.8 MPa pressure for 4 min, and then pressure was released in order to remove internal air build-up within the composite. Then, molds were pressed to 4.2 MPa for 4 min and pressure was released again. Finally, molds were pressed to 5.6 MPa for an additional 4 min. Total heating/compression time was ~12 min. Mold composites were then held at 5.6 MPa pressure while the heating was terminated, and cooling process of the press platens commenced ( YLD cold water). The mold was removed from the Carver press when the mold surface reached 27 °C. The influence of PW particle size on the mechanical properties of DDGS-PW composites was determined by testing particles obtained from sieve/screens as previously described. Composites composed of 80 g of DDGS were mixed with 80 g of < 1700, <
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Tisserat et al . (2018). “DDGS - PW fiberboards” B io R esources 13(2), 2678-2701.
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