Preparation And Properties Study Of Drag Reducing Polymer Microcapsule

Drag reducing polymer microencapsulation are drag reducing polymer particles on the surface of which there is a layer material by physical, chemical or mechanical methods . The aim of microencapsulation is that avoiding the adhesion of particles and producing particles which can be stably stored in room temperature or when the particles are scattered as slurry. The drag reducing polymer microencapsulation belongs to the domain of Gel chemistry, and it involves the surface characters of particles, the surface interaction between particle and liquid; and the same time, microencapsulating needs the theory guidance of high molecular chemistry and physics and so on; In addition, with the industrial application of drag reducing polymer microencapsulation, technological process must be designed and it must be optimized flowed by the theory of chemical engineering. Because of the importance of drag reducing agent (DRA) in oil transportation industry and the problems in producing, storage and transportation of DRA, it is imperative that enforcing surface modification of drag reducing polymer particles.This study at first analyzed the swelling and dissolution theory of polymer, the stability theory of scattering system and introduced briefly methods and theories of microencapsulation.It analyzed the surface characters and chemical structure of drag reducing polymer particles; It pointed out the porous characters and molecular structure of long chain with multiple branched chains, this was the main reason that caused the adhesion of drag reducing polymer particles; It analyzed the importance of solubility parameters of drag reducing polymer and dispersant in producing microcapsule system; And it analyzed the wall materials and methods of drag reducing polymer microencapsulation.Drag reducing polymer microcapsules were produced successfully by melt scattering and condensing method, with polyethylene wax as wall material and mixed solvent of butanol and ethylene glycol monomethyl ether as dispersant. In the process of microencapsulation, the stirring speed must be from fast to slow, ensuring homogeneous dispersion and avoiding rupture of microcapsules. The thickness of microcapsules produced by this method was thicker than others, and the diameter scattering of it was uniform. But the operating condition of this method was so strict, and it could not be used for industry application easily.Drag reducing polymer microcapsules were produced by in situ polymerization method, with urea and formaldehyde as wall material monomers and water as dispersant. In this method, urea and formaldehyde might be prepared into prepolymer firstly, then the prepolymer was added into scattering system (two-step method), and they could also be added directly into scattering system (one-step method). The stirring speed was the key control parameter in this method. If the stirring speed was very slow, the core material and the wall material could not be mixed uniformly, and if it was very high, the shell layer might be damaged. The operation of one-step method was convenient, and it might be used for industry application.One-step method was used for industrial scaling-up, and the elementary industry product of drag reducing polymer microcapsules was obtained. The quality of this product met the design requirements. industrial scaling-up further explained the importance of stirring speed in process of drag reducing polymer microencapsulation.Drag reducing polymer microcapsules were produced by in situ polymerization method, with styrene as wall material monomers, potassium persulfate, ferric sulfite, sodium bisulfite as initiators and water as dispersant. In the process of microencapsulation, the stirring speed must be so slow that styrene can be absorbed on the surface of drag reducing polymer particles.Drag reducing polymer microencapsulation by spray drying method with xanthan gum and alcohol gum as wall materials was studied primarily. Because of big diameter of drag reducing polymer particles and small diameter of drying chamber, most of particles were adhesived on the wall of drying chamber, and only small part of microcapsules were obtained. But the characters of obtained microcapsules were stable, and met the design requirements.All microcapsules produced by different method were tested with scanning electron microscope (SEM), particle size analyzer, infrared (IR) absorption analyzer, x-ray diffraction analyzer (XRD), and simultaneous thermal analyzer, and met the design requirements. The microcapsules production could be stored for long time. The microcapsules produced by urea-formaldehyde polymerizing method were prepared into alcohol-based and water-based slurries. The slurries were contrasted with slurry which was prepared with drag reducing polymer particles that were not coated, and the themo-stability of the former are better than that of the latter.