Preparation Of Modified Polypropylene For Automobile

Polypropylene(PP)has been widely used in automotive interior and exterior parts,such as bumpers,dashboards,etc.,which makes it most perspective and considerable-demanded material in the automotive industry.In order to study the effect of processes on the product performance and production of the automotive-use-exclusive PP material,the critical processes including pretreatment,mixing process,feeding technology,screw combination,extrusion process(including temperature,rotational speed,output)have been investigated.The influence pattern has been found,the mechanism analyzed,and yield/energy consumption/properties stability compared to work out a more efficient and controllable process,to optimize the plant batch production.The effect of coupling agents of different varieties and proportions on the activation effect has been studied by measuring and comparing the activation degree and precipitation volume.It is concluded that the addition of 2% coupling agents to the calcium carbonate system would result in the optimum surface modification effect,whereas,the addition of 1.6% coupling agents to 1250-grade talc system lead to the best comprehensive performance.The effect of mixing time and mixing speed on premix evenness has been studied.It is found that the best mixing effect is achieved with high speed mixing for 90 seconds,or with low speed mixing for 1.5 minutes.The effects of different feeding processes on mechanical properties,output,energy consumption and quality stability of the products have been studied through the design of high speed mixing,main feeding,side feeding and partial side feeding processes.The best quality is achieved when all materials are fed through high speed premixing,however,the efficiency is lowest and energy consumption is high.The efficiency and energy consumption achieve the optimum when 5% and 15% of the materials are fed through the main feeding and side feeding,respectively.The effect of screw combination on the material properties,specific energy consumption and quality stability have been investigated by adjusting the number and thickness of the threaded block in the plasticizing zone and mixing zone,and whether or not to add the tooth-shaped plate.It is found that the comprehensive energy consumption and quality is better with weak-plasticizing and strong-shearing-screw when the premixing feeding process is used,however,the combination of output,energy consumption and quality is better with screw combination of thick-plasticizing,thick-kneading block,tooth-shaped plate and thin-kneading block,when the side feeding process is used.The interaction among the extrusion temperature,rotational speed and yield has been studied by 3 factor-3level orthodoxy DOE experiment to determine the optimum extrusion process.SEM was utilized to analyze the formation mechanism.The impact strength and the breaking elongation reach the optimum value at 30 KJ/m2 and 55.9%,when the temperature is 204.8?,the screw speed 519.5rpm,and feeding speed 656kg/h.And SEM shows the material is homogeneous,and the interface is compatible.Production control chart has been prepared to study the process capability.The result shows that the product performance is well in line with technical requirements,and quality is stable and reliable.