Study On Preparation And Mechanical Properties Of Short Carbon Fiber Reinforced Polyethylene Composites

With the development of high performance thermoplastic resins and thermoplasticcomposite molding technology continues to mature, and thermoplastic composite materialshave become the field of composite materials research and development of the most strikingpoint. On this article，in order to shorten preparation cycle ane reduced production costs, usechopped carbon fiber as reinforcement, the polyethylene resin as matrix. The carbon fiberreinforced thermoplastic composites were prepared by the way of screw injection moldingmethod. The effect of carbon fiber content, the surface treatment of carbon fiber onmechanical properties were investigated by measuring the density, hardness, tensile andfatigue. The failure mechanism of tensile fracture, fatigue fracture failure mechanism and themechanism of carbon fiber reinforced were analyzed. The results show that:(1) With the increase of carbon fiber content, the density and the hardness of compositesincrease gradually. When the carbon fiber content is less than3.365%, the hardness ofcomposites is increased near-linearly. when the Carbon fiber content is more than3.365%, thehardness of composites is increase.sharply. When the carbon fiber content is4.021%, theVickers hardness of the composite increased by more than35.489%that of purepolyethylente.(2) The tensile strength and the elastic modulus of added carbon fiber composites arebetter than that of pure polyethylene. And with the increase of carbon fiber content, the tensilestrength and the tensile modulus of carbon fiber-reinforced polyethylene composites increasedgradually. When the carbon-fiber quality score is4.021%, the tensile strength and the elasticmodulus increased by18.421%,208.024%than that of pure polyethylene.(3) When carbon fiber content is Equal, the tensile strength and the elastic modulus of airoxidation-treated carbon fiber-reinforced polyethylene composite are improved than that ofthe untreated. When the carbon fiber content is0.411%, the elastic modulus of airoxidation-treated carbon fiber-reinforced polyethylene composite is36.192%more than thatof the untreated. When the carbon fiber content is3.986%, the tensile strength of airoxidation-treated carbon fiber-reinforced polyethylene composite is4.719%more than that ofthe untreated.(4) With the increase of carbon fiber content, the fatigue cycle and the fatigue limit ofcarbon fiber-reinforced polyethylene resin composite is increases. The fatigue limit graduallyincreased from2.870MPa in the pure polyethylene to8.990MPa in4.021percent carbon fiberreinforce composites. In all, The fatigue limit gradually increased by213.240%, the rate ofincrease is gradually reduced. With the reduction of the external alternating loads, the fatiguecycle is rise, the S-N curve was similar though the carbon fiber content is different. (5) In term of the tensile fracture surface of untreated carbon fiber reinforcedpolyethylene resin composites, the force drawing phenomenonp of Polyethylene resinmatrix will be seen. The tensile fracture of the treated has only a small amount of carbon fiberare pull out and a largenumber of adhesion of polyethylene resin in the carbon fiber surface,carbon fiber is firmly adhered to polyethylene resin matrix and they are not separated eachother. Little carbon fiber was pulled out to form hole, part of the carbon fibers are beingpulled off from the roots. In the polyethylene resin matrix, carbon fiber although only oneoutcrop, but it still did not separate from polyethylene resin matrix. In term of fatigue fracture,the length of the carbon fiber exposed in air oxidation-treated carbon fiber-reinforcedpolyethylene composite much longer than the untreated. With the increase of carbon fibercontent, the crazing of fatigue fracture surface reduce gradually, dimple morphology is moreand more thick.