Study On The Extrusion Of UHMWPE Fiber Precursor By Single Screw Extruder

The development of UHMWPE fiber began in 1970 s.UHMWPE fiber has many excellent properties,such as light quality,soft,high modulus,high strength,long flexure life,low conductivity,water resistance,impact resistance,strong acid and alkali resistance,low temperature resistance,chemical corrosion resistance,solvent resistance and ultraviolet resistance,so the application field is very wide.However,with the increase of molecular weight,the melt viscosity of polyethylene increases sharply,so the conventional method is very difficult to spinning.Due to foreign technology monopoly and late development in China,The output of UHMWPE fiber,the quality of products and the cost of consumption are different from foreign countries.The high-end UHMWPE fiber needs to be imported.The quality of the raw silk determines the properties of the fiber.Therefore,it is of great significance to study the preparation technology of UHMWPE fibril precursor.Through the theoretical analysis,computer design,POLYFLOW simulation and experiment,a new method of continuous extrusion of UHMWPE fiber precursor with single screw is developed.This method does not need the process of dissolution,extraction and drying in gel spinning,and overcomes the disadvantage of continuous extrusion in solid extrusion.The details are as follows:Based on the analysis of material forming principle and special forming rule of UHMWPE,It is clear that UHMWPE is extrudable and only when the maximum extrusion pressure is greater than the rated pressure of the head and the material is fully melted,It can be extruded normally.Moreover,because the forming process of UHMWPE is mainly a heat conduction process,based on the Fourier formula and the law of conservation of energy,the differential equation of heat conduction is established.Based on the theory of solid transport,the stress of the feed compression section,the solid plug section,the spiral gradient section and the forming section are studied and analyzed.The pressure trend diagram is obtained.The results show that the feed compression and the solid plug section contribute the most to the extrusion pressure.The best thread angle,the best groove depth and the best groove width are obtained through thegraphic method and reference documents.The best thread angle,the best groove depth H and the best groove width are obtained through the graphic method and reference documents.Three dimensional modeling of core components of SJ-45 extruder is completed by UG.In order to explore the improved design of the barrel and screw,it is sufficient to melt the material when it reaches the head.The POLYFLOW simulation software is used to simulate the melting process of UHMWPE in the extruding process,and the temperature field,velocity field,pressure field and shear rate field in the process of material melting are obtained.The research shows that when the heating length is 200 mm and the temperature is 200 degrees,the material can be fully fused.In order to find out whether the single screw extruder can provide enough pressure and simulate the correctness of the single screw extruder,the single screw extruded UHMWPE fiber precursor was successfully realized by experiment,the process parameters of continuous extrusion of UHMWPE fiber precursor were explored.There is little difference between the fruit and the extrusion parameters.