Study On CPVC And PVC Plasticizing And Melting Mechanism Of Two-twin Eccentric Rotor

Chlorinated polyvinyl chloride(CPVC)is an important modified product of polyvinyl chloride(PVC).After the chlorination reaction increases the chlorine content,it has obtained better mechanical properties and higher Vicar softening temperature,which can be applied to high temperature and high pressure in particular fields such as liquid transportation.Thus,it is an engineering plastic with broad application prospects.However,the processing characteristics of CPVC,such as high melt viscosity and shear heat sensitivity,make the processing window of CPVC narrow in screw-type processing equipment,and the processing is complicated.The new polymer molding processing equipment based on continuous volume extensional rheology has changed the processing principle dominated by the shear flow field in the traditional screw processing equipment.As a result,it has short thermal history,low energy consumption,good dispersion and mixing effect,and material adaptability.Comprehensive and other characteristics in the field of multi-phase multi-component polymer alloys,fiberreinforced polymer-based composites,biomass composites,and other material forming processing fields have a wide range of research and applications.In this paper,the volume stretch deformation plasticizing transport technology is i nnovatively applied to the extrusion processing of CPVC and PVC.Through the self-d eveloped integral and combined biaxial eccentric rotor extruders,the mathematical and physical model of the plasticizing unit of biaxial eccentric rotor extruder is established, and the energy index of stretch deformation is defined.Furthermore,the gelation pro cess of CPVC and PVC in a continuous volumetric tensile flow field was studied.By analyzing the relationship between the temperature,rotation speed,the crucial paramet ers of the eccentric rotor and the degree of gelation and the submicron phase state of materials,the gelation mechanism of CPVC and PVC in the continuous volumetric ten sile flow field and the minimum flow unit in each melting and plasticizing area were revealed.The results show that the biaxial eccentric rotor extruder has the characteristics of positive displacement conveying and can make full use of the friction heat and plastic heat dissipation of CPVC and PVC resin in the drawing flow field.As a result,the melt plasticization of CPVC and PVC can be realized at a lower processing temperature,and its unit consumption is only70% of that of the traditional conical twin-screw extruder.In this paper,through the segmented experiment of the combined biaxial eccentric rotor extruder,it is found that CPVC particles are compacted in the solid conveying section and deform along the flow direction under the action of tensile deformation.Some of the particle films break and release the coated primary particles and primary particle aggregates.The pomegranate-like multi-layer structure is rapidly deconstructed under the action of the tensile flow field in the melting section,and the primary particle flow unit is wholly formed.Under the synergistic effect of heat and conduction,the primary particles begin to fuse.After the effect of the exhaust section and homogenization section,the ordered CPVC molecular chains relax and entangle with each other to form an ordered three-dimensional network.Comparative analysis of the mechanical properties of PVCU pipes prepared by twin eccentric rotor extruder and traditional screw extruder.It is found that the tensile and impact properties of PVC-U pipes prepared by a continuous volume extension flow field are better than those of traditional screw extruders.The machine prepared the pipe.The generated three-dimensional network with secondary crystallites as cross-linking points is more regular and orderly,benefiting from the induced orientation effect of volumetric extensional flow.Compared with the PVC-U pipe prepared by the screw shear flow field,it is stretched.The tensile strength of the PVC-U pipe prepared by the flow field increased by 19.5%,the elongation at break increased by 200%,and the impact strength increased by 39.1%.Based on theoretical calculations and experimental results,it is shown that the biaxial eccentric rotor extruder dominated by continuous volumetric extension flow field has significant advantages in processing and forming CPVC and PVC materials and can achieve CPVC and PVC processing at a lower processing temperature.Furthermore,rapid gelation,while increasing the degree of gelation and forming a more ordered three-dimensional network structure,which can significantly improve the mechanical properties of CPVC and PVC materials.Thus,the research results of this paper provide a new and efficient plasticizing and molding processing method for the field of CPVC and PVC molding processing and provide crucial theoretical support and production guidance for the industrial application of this technology.