Study On Solid Conveying Process And Characteristics Of Single Shaft Eccentric Rotor Extruder

Polymer processing method have a vital influence on the performance and productivity of polymer material products.As a key stage of polymer plasticizing and conveying,solid conveying not only affects the shape,color and uniformity of polymer melt,but also directly determines the productivity and processing efficiency of plastic products.The polymer plasticizing and conveying method of eccentric rotor extruder(ERE)is dominated by elongation flow,which breaks the traditional plasticizing and conveying process with shear flow,and has the advantages of high conveying efficiency and good material adaptability.Based on the development of a new type of single shaft ERE,the solid conveying process and characteristics of the extruder are studied including solid conveying principle and parameterization of eccentric rotate plasticating and conveying unit(ERU),solid conveying experiment and methods of characterization,analysis and experimental verification of solid conveying capacity model,analysis of solid conveying morphology and characteristics of polyolefin,analysis of solid conveying characteristics of PP/Kaolin.The main tasks are as follows:First of all,this thesis analyzes the solid conveying principle of ERE and ERU,and divides ERU into closed positive displacement unit and unclosed exhaust unit,and parameterizes ERU including the rotor,stator,cavity and lays a theoretical foundation for experimental research.In addition,experimental content,experimental materials,experimental equipments and parameters,characterization methods are explained to prepare for the subsequent experimental research.Secondly,theoretical modeling and experimental verification are carried out for the polymer solid conveying capacity.According to the principle of positive displacement when the medium is compressed in a closed chamber,an accurate theoretical model of solid conveying capacity is established by introducing the return coefficient through experimental comparison.On this basis,the effects of material types,structural parameters and technological parameters on solid conveying capacity are experimentally studied.The results show that the solid conveying capacity increases with the increase of stator radius,lead of stator conveying section,rotor eccentricity and rotating speed,and decreases with the increase of clearance and return coefficient.And it is less affected by pressure and viscosity,and the conveying characteristic is hard.Then,by means of shock cooling,disassembling,taking photos and characterization,the morphology of bulk particles,aggregates and fusion are studied during solid conveying in the polyolefin system.Experimental results show that: ERU-1?3 are bulk particles,ERU-4?5 are compacted aggregates that begin to melt,and ERU-6?10 are fusion with a molten film.The fusion has obvious skin-core structure,showing different in microtopography,crystallization properties,condensed structure,thermal stability and rheological properties.With the periodic compression and release of materials by the ERE,the fused and unfused continuously cross permeate each other,and the skin and core layer constantly fuse with each other,finally forming a uniform melt.Finally,by means of shock cooling,disassembling,taking photos and characterization,analysis of solid conveying characteristics of PP/Kaolin are studied during solid conveying in the filling system.The effects of filling content on microtopography,crystallization properties,condensed structure,thermal stability and rheological properties are studied.The results show that PP/Kaolin not only has good dispersing and mixing effect,but also can maintain molecular weight,reduce degradation and induce the formation of new crystal under the action of periodic compression and release of material by ERE.