Study On Modeling Technology Of Plasticization Transport Of Polymer Under Volume Elongational Flow

Conventional polymer processing methods using screw processing equipment were based on shear flow fields.The current processing methods generally have both of the characteristics of high energy consumption and poor adaptability to materials.Related studies have shown that the material were melted and mixed more efficiently under the elongational flow compared with that under the shear flow.Professor Jin-ping Qu from South China University of Technology has designed an eccentric rotor extruder based on a elongational flow field.The equipment can achieve high-efficiency on plasticization and melt blending of polymer materials.This paper was based on the theory of elongational flow.The eccentric rotor plasticizing model equipment was designed based on the eccentric rotor extruder.The successful development of the equipment is conducive to exploring the plasticized transport process of different materials in the eccentric rotor extruder,which will promote the serial production process of the eccentric rotor extruder.The difference between the processing method using eccentric rotor based on the elongational flow field and the traditional processing method using screw equipment based on the shear flow field were discussed in this paper.What's more,it also briefly described the application and research of the polymer processing equipment based on the elongational flow.The structure and working principle of the eccentric rotor plasticizing test equipment were introduced.The parametric equation of the eccentric rotor was established,and the mathematical relationship between the force and the pressure of the rotor was established,too.On this basis,the plasticization experiment was carried out on the equipment with low density polyethylene(LDPE),and the plasticization process of the material was observed expediently.In addition,in order to investigate the plasticization mode and the dispersion of the heterogeneous blends in the equipment,low density polyethylene/polystyrene(LDPE/PS)incompatible blends after different plasticizing units were tested.In the paper,the micro-morphology of the material was characterized by scanning electron microscope(SEM).The crystallization properties of the material were tested by differential scanning calorimetry(DSC).The dynamic mechanical properties of the material were tested by dynamic rheological measurements(DRM).The experiment showed that:(1)The incompatible blends were uniformly dispersed after suffering a small number of volume compression-release effects with short thermal history.(2)When the material has passed through 15 plasticizing units,the dispersed particles were dispersed in the critical dispersion size.The dispersed phase was first oriented in the extrusion direction to form a fiber morphology having a large aspect ratio.The fibers were gradually elongated and broken,which eventually form dispersed small particles.(3)Compared with the sample that directly extrudes the elastic modulus,loss modulus and viscosity of the materials increased after passing through a plurality of plasticizing units.After the material reaches the critical dispersion size,the dispersed phase particles cannot be further refined with the increase of the plasticizing unit,and the interface bonding between LDPE and PS was deteriorated.Based on the analysis of experimental results and previous studies,a polymer melt plasticized transport and melt mixing of incompatible blends in a elongational flow due to volume compression-release effects was proposed.The research results of this paper provided an important theoretical experimental basis and equipment basis for the application of the elongational flow in the polymerization processing industry,which will improved design and application of the eccentric rotor extruder.