Preparation And Application Explorationof Polyacrylamide Superabsorbentmicrospheres

Super Absorbent Resin(SAR)is an emerging functional polymer material that can absorb tens or hundreds of times its own weight in water and swell to a larger size.Super Absorbent Resin also has the ability to retain water for a certain period of time after absorbing water.Highly absorbent resins are composed of synthetic and natural high absorbent resins,and synthetic high absorbent resins are the hot spot of research at present.The water absorption capacity of highly absorbent resins has a great relationship with resin morphology,crosslinker dosage,initiator dosage,etc.,which directly affects the practical application of highly absorbent resins.Due to its large specific surface area and small size,spherical highly absorbent resin has important application value in many applications such as agriculture,medical industry,and petrochemical industry.The spherical shape of highly absorbent resins is more likely to be uniform in particle size than the lumpy shape of highly absorbent resins,allowing them to be used in more demanding and complex applications.Polyacrylamide microspheres are the most commonly used highly absorbent resin microspheres in tertiary oil recovery,and can be used as dissection agents,blocking agents,thickening agents and other oilfield chemical additives.However,due to the process problems and annual industrialization difficulties,polyacrylamide microspheres are often of uneven particle size,which may lead to incomplete blocking and uneven profile adjustment in the actual oil recovery process.In order to solve the above problems of current polyacrylamide microspheres,this thesis aims to prepare a polyacrylamide spherical high absorbent resin with uniform and controllable particle size,and to study the polyacrylamide spherical high absorbent resins prepared by different methods and their applications,as follows:(1)Polyacrylamide microspheres with a particle size distribution of about 40 μm were prepared by reversed-phase suspension polymerization using acrylamide as the monomer,ammonium persulfate as the initiator,N’N methylenebisacrylamide as the cross-linker,and emulsifier Span20 and Span80 in a certain ratio.The product was characterized by infrared spectroscopy,scanning electron microscopy,particle size distribution,thermal weight loss analysis,and swelling and water retention cycle test.The polyacrylamide obtained has a water absorption multiplier of 1700%,can retain water for 6 h at room temperature,and can be recycled five times with a water absorption multiplier of 900%.It was also tested in a simulated oil recovery process to explore its practical application ability,and the sealing rate was 91% with excellent sealing effect.(2)Monodisperse polyacrylamide microspheres with particle size distribution around 7μm were prepared by reverse-phase suspension polymerization with acrylamide as monomer,ammonium persulfate as initiator,Span20 and Span80 compounding emulsifier,and N’N methylenebisacrylamide as crosslinker after SPG membrane emulsification.The method of SPG membrane emulsification can assist in the formation of emulsions to make monomer droplets uniformly dispersed.The polyacrylamide microspheres were characterized by infrared spectroscopy,particle size distribution detection,thermal weight loss analysis,scanning electron microscopy,and swelling and water retention cycling tests,and the polyacrylamide microspheres obtained had a water absorption multiplicity of1400%,could retain water for 4 h at room temperature,and could be recycled three times with a water absorption multiplicity of 700%.It was also tested in the simulated oil recovery process to explore its practical application ability,and the sealing rate was 94%,with good sealing effect.(3)Water-soluble polyacrylamide microspheres with controllable particle size of 200nm-1 μm were prepared by dispersion polymerization using acrylamide as monomer,azo diisobutyronitrile(AIBN)as initiator and polyvinylpyrrolidone-K30(PVP-K30)as dispersant.The morphology and thermal stability of the microspheres were characterized by infrared spectroscopy,scanning electron microscopy analysis,and thermal weight loss analysis.The emulsion was thickened by simulated emulsion(cyclohexane:deionized water ratio = 10:3,emulsifier type Span20,emulsifier dosage 2.75 wt% of the oil phase mass),and the stabilization time of the emulsion was improved,so that the emulsion which should be delaminated at 12 h was delaminated only at 26 h.The emulsion stabilization time was improved by 116.67%,which reflected its practical value.