Paper mill sludge (PMS) is a waste material from pulping. In this article it was used to replace part of a wood fiber (WF) filler to reinforce high‐density polyethylene (HDPE). The properties of the PMS/WF/HDPE composites were investigated. When half of WF was replaced with PMS, the bending strength and modulus of WF/HDPE composites decreased by 16.08% and 29.91%, respectively, but their impact strength increased by 11.31%. Dynamic mechanical analysis demonstrated that with PMS addition, the storage modulus decreased and the loss tangent increased. Although the flexural properties of the PMS/WF/HDPE composites decreased compared to WF/HDPE composite, they still had satisfactorily high strengths. The 30:30:36 PMS/WF/HDPE composite presented bending and impact strengths of 61.00 MPa and 12.11 kJ m−2, respectively. The 50:20:26 PMS/WF/HDPE composite presented bending and impact strengths of 55.02 MPa and 10.37 kJ m−2, respectively. Rheological test proved that substituting part of WF with PMS would not affectmanufacture processing. This study indicated that paper mill sludge could be used in wood plastic composites, which would reduce pollution from paper manufacturing. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

In this article, wood-plastic composites(WPCs) were manufactured with wood flour(80～120mesh、40～80mesh、20～40mesh、10～20mesh) combing with high density polyethylene(HDPE). Effects of the size of wood flour on mechanical properies and density of composites were investigated. Results showed that particle size of wood flour had an important effect on properitiesof WPCs. Change of mesh number had a outstanding effect on flexural modulus, tensile modulus and impact strength, howere, little effect on flexural strength and tensile strength. When mesh number of wood flour changed from 80～120mesh to 10～20mesh,flexural modulus and tensile modulus were respectively enhanced by 42.4% and 28.4%, respectively, and impact strength was decreased by 35.5%.Size of wood flour basically had no effect on density of composite within 10～120mesh. The use of wood flour or fiber as fillers and reinforcements in thermoplastics has been gaining acceptance in commodity plastics applications in the past few years. WPCs are currently experiencing a dramatic increase in use. Most of them are used to produce window/door profiles,decking,railing,ang siding. Wood thermoplastic composites are manufactured by dispering wood fiber or wood flour(WF) into molten plastics to form composite materials by processing techniques such as extrusion,themoforming, and compression or injection molding[1]. WPCs have such advantages[2]：(1)With wood as filler can improve heat resistance and strength of plastic, and wood has a low cost, comparing with inorganic filler, wood has a low density. Wood as strengthen material has a great potential in improving tensile strength and flexural modulus[3]；(2) For composite of same volume, composites with wood as filler have a little abrasion for equipment and can be regenerated；(3)They have a low water absorption and low hygroscopic property, They are not in need of protective waterproof paint, at the same time, composite can be dyed and painted for them own needs；(4)They are superior to wood in resistantnce to crack、leaf mold and termite aspects, composites are the same biodegradation as wood；(5)They can be processed or connected like wood；（6）They can be processed into a lots of complicated shape product by means of extrusion or molding and so on, meanwhile, they have high-efficiency raw material conversion and itself recycle utilization[4]. While there are many sucesses to report in WPCs, there are still some issues that need to be addressed before this technology will reach its full potential. This technology involves two different types of materials: one hygroscopic(biomass) and one hydrophobic(plastic), so there are issues of phase separation and compatibilization[5]. In this paper, Effects of the size of wood powder on mechanical properties of WPCs were studied.

In this paper, instead of glass fiber, a bio-fiber (piemarker fiber) was used to reinforce unsaturated polyester (UP). UP resin was reinforced with piemarker fiber (PF) in a mold under hot pressing. The mechanical properties of the result composites were tested and hot pressing procedure was optimized. The optimum hot pressing technology was obtained. When hot pressing temperature was 90°C and mat was hot pressed for 1.5h. The mechanical properties of the composites indicated that: the optimum mass ratio of piemarker fiber to UP was 30:70, at which the flexural strength of the composite was 48.77MPa, the tensile strength was 29.082MPa, and the impact strength was 9.89KJ/m2.