Abstract:

A new type of wood_plastic composite (NF-WPC) was prepared by one-step extrusion of needle-shaped wood-fiber and high density polyethylene (HDPE) using a twin-screw/single-screw extruder system. Orthogonal experiment was adopted to statistically analyze the influence of the dimension of the needle-shaped aspen wood fiber, the percentage of the fiber, the percentage of coupling agent maleic anhydride grated polyethylene (MAPE) and the percentage of the lubricant paraffin on the mechanical properties of NF-WPC, and was compared with wood-flour/HDPE composite prepared by the same process. The results showed that the influence of the percentage of the needle-shaped fiber on the impact strength of NF-WPC was significant, while much more significant on the bending and tensile properties. The percentage of MAPE influenced significantly to the tensile strength and toughness of NF-WPC. In the conditions of this paper the dimension of wood fiber and the percentage of lubricant paraffin had a minor influence on the mechanical properties of NF-WPC. The optimized formula was that fiber length was 3～4 mm, ratio of length to diameter was 8～11, fiber percentage was 60%, MAPE percentage was 4%, paraffin percentage was 0.3%. The mechanical properties of the NF-WPC prepared according to the optimized formula were as follows: flexural strength 58.7 Mpa, flexural modulus 3.0 Gpa, tensile strength 39.6 Mpa, tensile modulus 4.0 Gpa and impact strength 12.7 kJ·m^-2 respectively. Compared to the wood-flour/HDPE composite prepared by the same process, the mechanical properties of the NF_WPC prepared according to the optimized formula were better except the impact strength which was a little lower.

Key words: wood-fiber, polyethylene, wood plastic composites, orthogonal experiment