Synthesis And Properties Investigation Of Micron-sized Polystyrene/Polyacrylamide Core-shell Microspheres

At present,the exploitation of oil fields in China has entered the middle and late stage,and the oil saturation of near oil wells has decreased sharply after many plugging times.Therefore,most oil fields in China is using profile control and water shutoff technology to stabilize oil and control water and improve oil production rate.At this stage,the most widely used oil field profile control plugging agent is polyacrylamide,but the compressive and shear strength of polyacrylamide saturated with water can't meet the actual production demand because of its good water absorption.Therefore,the core-shell polyacrylamide micron microsphere supported by polystyrene was designed to meet the needs of profile control and water plugging in oil field.Firstly,polystyrene microspheres were synthesized through dispersion polymerization method in a certain proportion of ethanol/water using 2,2'-Azobis(2-methylpropionitrile)as an initiator and polyvinylpyrrolidone and hydroxyapatite as dispersants.Effects of reaction temperature,dispersion medium,initiator,dispersant,monomer on the particle size and distribution PS microspheres were investigated.Among them,the polymerization temperature had a great influence on the efficiency of initiator and the solubility of dispersing medium.Moreover,the monomer concentration and the polarity of dispersing medium were the key to the preparation of large particle size PS microspheres,which mainly affected the nucleation period polymer critical chain length.The concentration of initiator affected the polymerization rate and time.However,the success of styrene polymerization mainly depended on the synergistic action of PVP and HAP.As a consequence,the polystyrene microspheres were prepared under the optimal condition in 90.28% yield.Their average particle size and polydispersity index was respectively about 8 ?m and 1.0958.Secondly,in order to synthesize polystyrene/polyacrylamide microspheres in the same system,the dispersion polymerization of acrylamide was explored.Herein,the effects of various factors on the dispersion polymerization of acrylamide(AM)were investigated in an alcohol/water dispersion system,and the optimal polymerization conditions for synthesizing PAM microspheres were determined.Under these conditions,PAM can be stabilized into spheres,and the polymerization yield can reach 90.64%.The obtained polymer microspheres were characterized by FT-IR,SEM,and TGA test analysis.Lastly,on the basis of the above research,PS/PAM core-shell polymer microspheres(the average particle size was around 21.45?m)were synthesized by dispersion polymerization.The effects of dispersion medium,shell monomer dosage and addition time,crosslinking agent,dispersant and co-stabilizer on the polymerization reaction were investigated,and the optimum polymerization conditions were determined.Further,the thermal stability,water absorption rate,salt tolerance and plugging properties of PS/PAM core-shell microspheres were measured.The results showed that the obtained microspheres possessed high thermostability and salt tolerance,and the water absorption rate was up to 1.8125.It provides a new choice for oil field exploitation of the type of profile control plugging agent,and lays a theoretical and experimental foundation for the industrial production and application of core-shell polymer microspheres.