Natural Rubber Compounding Process And Correlation With Rheological And Extrusion Behavior

The study focused on the NR and NR/CB compound,investigated the effect of mixing process on the molecular weight and distribution of NR by means of Mooney viscometer,gel chromatograph,rotational rheometer ARES,investigated the effect of mixing process on mixing process on rheological properties of carbon black filled natural rubber by means of rubber processing analyzer RPA,capillary rheometer,rubber extruder and so on.The results showed that the molecular weight of the unfilled NR compound decreases and the molecular weight distribution narrows with mixing rotor speed increased,the binder content increases,the Mooney viscosity,filler network degree,extrusion swell ratio decrease,extrusion stability increases,the binder content in NR/CB compound rubber increases,extrusion swell ratio decreased,extrusion stability increased of the compound.So increasing the rotor speed can improve the process rheology.When the initial mixing temperature Ti is lower than 70°C,the molecular weight slightly increased,the molecular weight distribution broadened slightly,and the Mooney viscosity remained essentially unchanged of the unfilled NR and the bonding content,Mooney viscosity,the degree of filler network,extrusion swell ratio decreased slightly of NR/CB compound with the rise of Ti,when the Ti is higher than 70°C,the above indicators show opposite changes of the unfilled NR and no significant changes in performance indicators of NR/CB compound.The molecular weight reduced and molecular weight distribution narrowed of NR after mixing for 2 minutes,it's molecular weight and its distribution are basically constant with the extension of mixing time.The binder content increased and the Mooney viscosity,extrusion swell ratio and other properties are all reduced,and the extrusion stability is improved,but no significant change in the above properties after mixing for 8 minutes of NR/CB compound.Based on the experimental data of the mixing process,the relationship between the shear rheological property?RPA?and the extrusion rheological property?capillary?between the shear viscosity?₍?6? and the extrusion rate?was established:?_?61?=6?+b.And by changing the type of carbon black,the relationship between the shear viscosity?RPA?and the extrusion rheological properties?extruder?between the shear viscosity and the extrusion rate was established:?_?62?=8?^?+n;and obtained the functional relationship between RPA storage modulus and extruder outlet stress:E=?^??+q.