Effect of wood cell wall composition on the rheological properties of wood particle/high density polyethylene composites

This study investigated the effect of wood cell wall composition on the rheological properties of wood particle/high density polyethylene (HDPE) blends. Four types of wood particle with different compositions were prepared: native wood flour (WF), hemicellulose-removed particle (HR), holocellulose (HC), and alpha-cellulose (alpha C). The particles were characterized in terms of functional groups, crystallinity, particle size, and morphology. Wood particle/HDPE composite formulations were melt-blended using a twin-screw extruder and the theological properties of the blends were characterized using a Haake microcompounder, torque rheometer, capillary rheometer, and rotational rheometer. Results show that removal of lignin and/or hemicelluloses changed the crystallinity and microstructure of cell walls. These changes in cell wall composition and morphology altered the melt torque, shear stress, viscosity, and storage and loss moduli. Specifically, the melts viscosity decreased as alpha C/HDPE > HR/HDPE > WF/HDPE > HC/HDPE. This demonstrates that the composition of cell walls substantially affect the rheological behavior of wood particle/HDPE composites. (C) 2014 Elsevier Ltd. All rights reserved.