Study On The Dynamic Vulcanization Mechanism,Structure And Performance Of TPV Thermoplastic Elastomer Via Continuous Volume Elongation Deformation

EPDM/PP thermoplastic elastomer,with its merits like good insulation,impact resistance,elastic properties,easy machining and recyclability,has been widely used in many fields,such as automotive parts,wires and cables and building materials.At present,screw extruders are generally used to prepare TPV elastomers.The screw plasticating and conveying equipments based on shear rheology are generally adopted in polymer processing,in which materiels are dominated by shear stress.Therefore,there are some ubiquity disadvantages of the current methods of polymer materials processing,such as long thermo-mechanical,high energy consumption,weak dispersion and mixing,and dependence on material properties.The eccentric rotor extrusion equipment based on elongational rheology makes the materials subject to continuous volume elongation deformation during the plasticizing and conveying process,which improves the dispersion and mixing effect of the polymer composites and improves the microstructure and macroscopic performance of TPV elastomer.So this paper provides new methods and equipment for the preparation of high-performance TPV systemsIn this paper,an eccentric rotor extruder was used to prepare EPDM/PP thermoplastic elastomers.Comparing the samples obtained by pre-compacted EPDM(two-step method)and direct cross-linking processing(one-step method),we found that the TPV elastomers obtained through the pre-compacting process has significantly improved various mechanical properties,and explored the processing parameters of the best comprehensive performance.We found that when the EPDM/PP ratio was 60/40,the processing temperature was at 190? and processing rotation speeds of 60rpm and 90rpm,TPV materials showed the best comprehensive mechanical properties.Meanwhile,the two-step method greatly improved the tensile and elastic properties of the samples prepared by the one-step method,which were increased by 9.4%and 11.9%respectively.Under the premise of the same optimal ratio and process parameters,we compared the samples prepared by the eccentric rotor extruder based on elongational rheology and the twin screw extruder based on shear rheology.The structure and performance of EPDM/PP systems under the action of volume elongational flow were characterized and analyzed by means of micro-morphology,dynamic mechanical testing,and crystallization performance testing.The research showed that,compared with the processed samples by the twin-screw,the processed samples by the eccentric rotor based on continuous volume elongational rheology had smaller rubber particles,more uniform dispersion,higher cross-link density,smaller PP crystallinity,better compatibility,strong mutual penetration of two-phase molecular chains and other characteristics,Therefore,the processed samples by the eccentric rotor ultimately demonstrated better mechanical performanceBased on theoretical analysis and experimental results,it is shown that continuous volume elongation deformation-controlled eccentric rotor extruder has significant advantages in preparing EPDM/PP elastomers,which will solve the long-term problems of EPDM/PP processed by traditional twin-screw extrusion.In conclusion,this research provides a new and efficient processing method for EPDM/PP elastomer preparation,and provides theoretical and experimental basis for the promotion and application of this technology.