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The effects of fiber length and fiber loading on the mechanical properties of wood-plastic (polypropylene) composites

The results show that increases in fiber length and fiber loading significantly increased (P < 0.05) the mechanical properties of the WPCs (MOE and tensile modulus). The behavior of the composites against MOR and impact strength varied according to fiber length and loading level. In general, the tensile strength was observed to be the same. | Research Article Turk J Agric For 34 (2010) 191-196 © TÜBİTAK doi:10.3906/tar-0903-16 The effects of fiber length and fiber loading on the mechanical properties of wood-plastic (polypropylene) composites Farshid BASIJI1, Vahidreza SAFDARI1,*, Amir NOURBAKHSH2, Srikanth PILLA3 1Department of Agriculture and Natural Resources, Islamic Azad University, Karaj Branch, Karaj, IRAN 2Research Institute of Forests and Rangelands (RIFR), Wood and Forest Products Research Department, Tehran, IRAN 3Department of Civil & Environmental Engineering, Stanford University, CA, USA Received: 11.03.2009 Abstract: This study examined the effects of wood pulp fiber length (short, medium, and long), and fiber loading (27%, 37%, 47%, and 0% [non-reinforced PP]) with 3% maleic anhydride-grafted polypropylene on the mechanical properties of wood-plastic composites (WPCs). Polypropylene and fibers were compounded into pellets using a counter-rotating twin-screw extruder and test specimens were prepared by injection molding. The results show that increases in fiber length and fiber loading significantly increased (P 2) 0 (control) a : Maleic anhydride grafted polypropylene for all reinforced samples was permanent (3%). 192 F. BASIJI, V. SAFDARI , A. NOURBAKHSH, S. PILLA 20. Fibers that passed through mesh size 14, but not mesh size 20, were designated as long (≥2 mm) and fibers that passed through mesh size 20 were designated as medium (1-2 mm). Due to the lack of short fibers, some long and medium fibers were chopped using a laboratory electrical rotary mill to obtain short fibers (<1 mm). The ratio of fiber length to width (aspect ratio) of the fibers was determined. All the fibers were dried on aluminum foil in a temperature-controlled room for 48 h, and then were defibrillated in a large sealed plastic flask using an air pump. Further drying of the defibrillated fibers was performed in a kiln to reduce the moisture level to <6%. Composite preparation The components of each .