Study On The Powdered Rubber With Composite Styrene-butadiene Latex From High And Low Temperature Synthesis

Based on the styrene-butadiene latex process produced by high-temperature and low-temperature test,the subject achieved a pilot scale-up production at Chambroad Chemical Industry Research Institute.The modified latex was tested with modified emulsified asphalt and road test pavement.In order to expand the application field of high-performance styrene-butadiene latex,the process of powder preparation was explored and applied to the modification of matrix asphalt.The two processes of latex grafting and coacervation were compared to determine the optimal preparation process of powdered styrene-butadiene rubber.The pilot scale-up process of styrene-butadiene latex in high-temperature and low-temperature preparation process was studied.It was found that the exothermic heat in the early stage was huge,and the polymerization kettle temperature fluctuated between 5.9 ? and 34.4 ?,and the process was unstable.The heat transfer process in the pilot test was studied by exploring the temperature control curves under different refrigeration measures.It is found that the use of-15 ? refrigerant liquid,dual-refrigerator switching refrigeration and jacketed refrigeration can control the wide range fluctuation of the kettle temperature in the low-temperature polymerization stage,and solve the heat transfer problem.The pilot test of the styrene-butadiene latex modified emulsified asphalt was carried out.The results show that the test section has good stability and the performance meets the relevant indicators of the Ministry of Communications.In the powder preparation of styrene-butadiene latex,styrene-butadiene latex produced by high-low temperature polymerization process was used as raw material,and styrene and acrylonitrile were used as grafting monomers.The styrene-butadiene latex was powdered by latex grafting.In the latex grafting test,the grafting rate of 55 ? was increased by 4.75% using the activator EDTA iron sodium salt and sodium hydrogen sulfite.1.5% emulsifier dosage and 1.3% electrolyte dosage give latex the highest grafting rate and grafting efficiency.However,the low-temperature performance loss of the powdered styrene-butadiene rubber modified asphalt prepared by the latex grafting method is severe,and the ductility at 5 ? is less than 10 cm,it's not suitable for modified asphalt.In view of the shortage of latex grafting process,the grafting monomer was abandoned,and the styrene-butadiene latex was directly powdered by coacervation.Through the investigation of the influence of flocculant,flocculation temperature,release agent and coagulant on the coagulant process,the optimal powder styrene-butadiene rubber production process was finally determined.The formula and conditions are as follows: the release agent is a compounding agent such as sodium stearate,sodium oleate and silicone oil.The flocculant is selected from a sodium chloride solution with a mass fraction of 15%,and the coagulant is selected to have a mass fraction of 15% magnesium sulfate.The solution had a flocculation temperature of 55 ?.The powdered styrene-butadiene rubber prepared by coacervation method was tested on modified asphalt.The results showed that when the addition amount was 2%,the softening point of modified asphalt was 54.8 ?,which was 7.2 ? higher than that of matrix asphalt;the 5 ? ductility is increased from 10 cm to 100 cm.Powdered styrene-butadiene rubber improves both high and low temperature properties of asphalt,it's the best powder styrene-butadiene rubber preparation process.