Preparation And Properties Of Carbon Fiber Reinforced Wood Fiber/HDPE Composites

As an environmentally friendly materials,wood-plastic composites(WPC) have been widely used in architectural, automotive, furniture, and other fields.But WPC has low mechanical strength,this limit it can only be applied in place of low mechanical strength requirements.Therefore, improving the mechanical strength of WPC has become increasingly important.In this paper,carbon fiber was added in the WPC as reinforcing fiber, the effects of the content of carbon fiber, carbon fiber surface treatment methods, combinations between carbon cloth and WPC panel,and different preparation process on the properties of the composites were studied.(1) Short carbon fibers(SCF) and continuous long carbon fiber(LCF) were added to the WPC to enhance the properties of WF/HDPE composite.The effects of the carbon fiber content on the mechanical properties of the hybrid composites were studied. The results showed that when the amount of short carbon fiber was 10%, the tensile strength of the composite was the highest increase by 31.2%; when the amount of short fibers was 6%, the flexural strength and impact strength reached the maximum, were increased by 22.1% and 24.4%. When the amount of continuous long carbon fibers was 4%, the tensile strength of the composite was highest, improved by 185%; When the amount of long carbon fiber was 5%, the flexural strength and impact strength reached maximum, were increased by 78% and 352%.(2) Carbon fiber was treated by gas, liquid and gas-liquid dual-phase to further improve the the mechanical properties of CFRP. The results showed that the treatment of the carbon fiber was helpful to improve the mechanical propertiesand creep performance of WF/HDPE composite.The best method was gas-treatment,the tensile strength increased by 34.5%, the flexural strength increased by 23%, the impact strength increased by 54.7%.(3) By controlling the thickness of the skin and core WPC board, the carbon cloth was added at different positions of WPC, for the 7mm-thickness laminate,four combinations were designed ,respectively. The first one was called "313", which means that the laminate board was consist of lmm-thickness core-WPC board and 3mm-thickness skin-board, the carbon cloth was molded on the surface of core-WPC. The second one was called "232",its core-WPC was 3mm-thickness and skin WPC was 2mm-thickness.The third one was called "151", which was consist of lmm-thickness skin-WPC and 5mm-thickness core-WPC. The last one was called "070",carbon cloth was placed on the upper and lower surface of the 7mm-thickness WPC board.lt was found that the bending strength of "070" structure was the highest, improved by 148%; For the tensile strength and impact strength, "232" structure was preferable, increased by 328% and 645%.Twenty-four hours’creep test showed that the closer carbon cloth from the surface, the better the creep resistance capability, the "070 " structure’s creep performance was the best.(4) This research used different molding processes to get carbon fiber reinforced wood-plastic composite materials,short carbon fiber reinforced WPC’s molding process (SCF/WPC molding), short carbon fiber reinforced WPC extrusion process (SCF/WPC extrusion) and continuous long carbon fiber reinforced WPC’s molding process (LCF/WPC molding).The mechanical properties results of three different kinds of preparation methods of wood-plastic composites showed that LCF/WPC molding process was the best, followed by the SCF/WPC extrusion process, and SCF/WPC molding process was the worst. Dynamic mechanical thermal performance analysis showed that the order of three processes’Tg was LCF/WPC molding> SCF/WPC extrusion> SCF/WPC molding, LCF/WPC molding process’s heat resistance performance was the best. Creep properties test results at room temperature showed that SCF/WPC extrusion process’s strain was minimal, followed by LCF/WPC molding, the SCF/WPC molding process’s strain was maximum.(5) Carbon cloth was molded on the surface of WPC. The effect of the carbon fiber surface sizing agent on the mechanical properties of the hybrid composites was studied. The results showed that the sizing agent on the surface of carbon fiber was benefit for bonding with WF/HDPE composite.