Effect Of The Mixing Process On Structure And Properties Of Carbon Black-Filled Natural Rubber Compounds

As an important equipment in rubber processing,mixing process have an significant effect on the mix processing performance and product quality.In this paper,the influence of processing parameters on the Mooney viscosity,mixing compounds,property of vulcanized NR was studied.Processing parameters include rotor speed, mixing time,the pressure of the top bolt,initial temperature and cooling water temperature.The results showed that:(1)When accelerated the rotor speed,speed of eating powder accelerated;the maximum torque droped;the discharging temperature and energy consumption increased;Mooney viscosity firstly increased slightly,then declined rapidly;the dispersion of carbon black increased and then decreased;levels were not high;Payne effect decreased and then increased;crosslinking density of vulcanizated rubber decreased slightly;Payne effect of vulcanized NR weakened.Comprehensive comparison, vulcanizated NR under 77r/min had best performance.(2)With the extension of mixing time, the maximum torque rotor had little change,the discharging temperature and energy consumption increased;Mooney viscosity declined;rubber vulcanization torque decreased and had little difference between cure rates;crosslinking density of vulcanizated NR had little change;the dispersion of carbon black increased.Comprehensive comparison, when carbon black mixing time was 5min,vulcanizated NR had best performance.(3)When increased pressure on the top bolt,the discharging temperature increased; Mooney viscosity first increased and then decreased;it had little effect on the curing characteristics;carbon black dispersion in rubber compound firstly increased and decrease;when the pressure is 0.6MPa, the grade of carbon black dispersion was higher; elastic modulus of vulcanized rubber under low deformation increased and decreasd;crosslinking density of vulcanizated NR had little change.Comprehensive comparison, when the pressure is 0.8MPa, vulcanizated NR had best performance.(4)When the cooling water temperature rised, the discharging temperature increased; Mooney viscosity first increased and then decreased;rubber vulcanization torque decreased and had little change between cure rates;proper cooling water temperature is conducive to the dispersion of carbon black in rubber compound,at about 50℃the carbon black dispersion is better.Comprehensive comparison, when the cooling water temperature is about 50℃,vulcanizated NR had best performance.(5)When the initial temperature increased,it is conducive to eating powder and dispersion of carbon black;the discharging temperature increased,but less than the increased rate of initial temperature;when the initial temperature is 60℃,energy consumption is biggest;Mooney viscosity first increased and then decreased;t90 slightly shorter; scorch time changed little;cure rate increased;crosslinking density of vulcanizated NR decreased.Comprehensive comparison,when the initial temperature is 60℃, vulcanizated NR had best performance.In this paper, experimental results showed that mixing process had a significant impact on the structure and properties of compouds filled with carbon black.Select the appropriate conditions had great significance on improving the mixing quality,product performance,productivity and reducing energy consumption.