Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Performance of UV weathered HDPE composites containing hull fiber from DDGS and corn grain Pankaj Pandey a, ⁎ , Sreekala G. Bajwa a , Dilpreet S. Bajwa b , Karl Englund c a Department of Agricultural & Biosystems Engineering, North Dakota State University, Fargo, ND, USA b Department of Mechanical Engineering, North Dakota State University, Fargo, ND, USA c Composite Materials & Engineering Center, Washington State University, Pullman, WA, USA ARTICLE INFO Keywords: DDGS Corn Hull fiber UV weathering Composites HDPE ABSTRACT The availability of distiller’s dried grain with solubles (DDGS), the main co-product of corn ethanol production, exceeds its demand as feedstuff. A physical separation process named elusieve can separate the hull fiber from DDGS or corn flour to obtain DDGS with enhanced protein and oil content, or corn flour with higher starch content. This study was performed to investigate the potential of using the hull fiber separated with elusieve process on DDGS or corn flour as fillers in high density polyethylene (HDPE) composites at the commercial scale. Additionally, the degradation effects of UV accelerated weathering on this material were investigated. Commercial scale composite samples were made with six combinations of oak fiber, corn hull fiber and DDGS fiber, with the fiber loading maintained at 50%, and then the samples were subjected to UV accelerated weathering for 2000 h. The unexposed DDGS samples showed better resistance to moisture absorption (less than 5%) than the corn filler samples (18%). The specific gravity for all the filler composites was more than one for both unexposed and UV weathered composites. The DDGS fiber also showed higher flexural properties in oak25/ DDGS25 than other filler composites. For all samples, the accelerated weathering resulted in a lightening during the first 1000 h of exposure, followed by a darkening at 2000 h of UV exposure. Overall, UV weathering resulted in a chain scission of the HDPE polymer increasing the crystallinity of the polymer in the weathered filler composites. 1. Introduction Over the last few decades,natural fiber polymer composites have gained markets in building, landscaping and automobile applications because of their durability, low density, easy processing, high specific strength and stiffness, all at a low cost (Faruk et al., 2014; Pickering et al., 2016). These composites are generally considered for non- structural components for indoor applications as well as outdoor pro- ducts such as fencing, decking, and pavements (Soccalingame et al., 2016; Stark et al., 2004). In addition, agricultural residues and cellu- losic byproduct streams have been investigated as alternate fiber fillers in polymer composites (Georgopoulos et al., 2005; Nyambo et al., 2010). However, there is very limited research on the long-term per- formance of these polymer composites with agricultural byproduct as fillers under weathering agents such as UV light and moisture (Bajwa et al., 2015; Rahman et al., 2011). The external factors such as UV light, heat, moisture, and humidity together affect the integrity of the fiber-matrix structures in a composite causing photodegradation. The weathering of natural fibers results in the degradation of lignin into water soluble products such as carboxylic acids, quinone, and hydroperoxy radicals (Li and Ragaukas, 2000). The polyolefins degrade due to the presence of chromophores such as cat- alyst residues, carbonyl groups, hydroperoxide group, and double bonds formed during the polymer manufacturing (Stark and Mueller, 2008). The degradation by carbonyl groups cause the most noticeable photodegradation through either of two reactions called as Norrish I or Norrish II reactions (Jabarin and Lofgren, 1994). These two reactions have unique mechanisms: Norrish I reaction generates free radicals which ultimately results into either cross linking between chains or chain scission whereas Norrish II leads to the formation of carbonyl and terminal vinyl groups with chain scission (Jabarin and Lofgren, 1994). Distiller’s dried grains with solubles (DDGS) is the main co-product of corn ethanol from the dry grind process. It is the unfermented por- tion of the corn grain remaining in the concentrated form after the starch is utilized. The expansion of corn ethanol industries in the US resulted in the dramatic increase in the production of DDGS from 9 million tons in 2005 to 40 million tons in 2015 (Dinneen, 2016). Cur- rently, DDGS is mainly used as a feed supplement for livestock and http://dx.doi.org/10.1016/j.indcrop.2017.06.050 Received 9 February 2017; Received in revised form 11 June 2017; Accepted 19 June 2017 ⁎ Corresponding author. E-mail address: Pankaj.Pandey@ndsu.edu (P. Pandey). Industrial Crops & Products xxx (xxxx) xxx–xxx 0926-6690/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Pandey, P., Industrial Crops & Products (2017), http://dx.doi.org/10.1016/j.indcrop.2017.06.050