| The widespread use of plastic and rubber has brought a convenient life to everyone,However,as the amount of use is large,the recycling is difficult,and the pollution and other problems are exposed,people are paying more and more attention to the treatment of such products.The treatment of waste plastics and rubber has become an important issue of environmental protection in the world.Traditional treatment methods such as incineration and landfill can only add environmental pollution.The best way to deal with it is to recycle waste plastic and rubber products and use them as resources.Among them,the sleeper composite materials,which uses waste plastic,waste tires and other solid waste as raw materials,is continuously extruded after plasticization and mixing,which can not only solve the "white pollution" and "black pollution",but also effectively makes up for the current shortage of wooden sleepers and concrete sleepers.The rapid development of my country's railways has attracted worldwide attention.However,while the trains are rapidly updated,higher requirements are also placed on railway sleepers.The wooden sleepers and concrete sleepers currently used in our country are gradually unable to meet the requirements,but the sleeper composite materials has long life,good elasticity,vibration reduction and noise reduction,light weight,suitable for complex environments,and a wide range of applications.For example,urban rail and heavy-duty railway dedicated lines are suitable for working conditions with different speeds,axle loads,and gauges.(1)The thesis uses recycled plastic(HDPE),recycled rubber,glass fiber and mica as raw materials,The mica is treated with a silane coupling agent,then the components are blended and extruded in a certain proportion,and the particles are injected into standard samples for characterization and testing,and the mechanical properties,physical properties,and melt flow of the samples are evaluated Speed and microstructure,explore the best formula and process.The results show that the performance is the best under the ratio of 39.5% recycled high-density polyethylene(HDPE);20% PP;37.5% glass fiber(GF)and 3% compatibilizer.Among them,the mechanical properties,flame retardant properties,and electrical properties all meet the standards of the Ministry of Housing and Urban-Rural Development.(2)In order to further reduce the cost of sleeper composite materials,recycled rubber powder was added on the basis of the best formula,and a pilot-level granulation trial production was carried out in Liyang Jinwei Company,using an underwater cutting process.Explore the changes in mechanical properties and electrical properties after adding recycled rubber powder.The results show that: after adding rubber,the mechanical properties of the composite material samples decrease,but the electrical properties,flame retardancy,and hardness basically meet the standards of the Ministry of Housing and Urban-Rural Development.After summarizing,an improvement plan for rubber-plastic co-extrusion is proposed.(3)The assembly line design for the molding and production of large-scale sleeper composite materials is proposed,and two process routes are mainly designed: the first is the homogeneous co-extrusion method,which has a higher level of automation and continuous production.The second is the hot extrusion and cold pressing method,which improves the extrusion speed,production efficiency and output compared to the traditional cold top method.The thesis deepened the research on the formula and production process of recycled rubber-plastic sleeper composite materials,and designed a more reasonable molding plan for large-scale extrusion parts. |
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