Papers by Keyword: Polymer Microsphere

Abstract: Hypercrosslinked polymer microspheres with high specific surface areas were prepared successfully by exposing reactive, gel-type polymer precursors to a Friedel-Crafts catalyst. The lightly crosslinked gel-type polymer precursors were synthesised by non-aqueous dispersion (NAD) polymerisation in microsphere form, and were used subsequently in hypercrosslinking reactions. Extensive microporosity was generated in the products, leading to remarkably high inner specific surface areas of up to ~1,500 m²/g. SEM and BET spectroscopy were used to monitor the course of the hypercrosslinking reactions.

Abstract: The metallization of polymer microsphere has attracted attention in recent years due to its wide range of technological applications. In this study, chemical etching with concentrated sulfuric acid and potassium dichromate bichrome (K₂Cr₂O₇) was used to prepare acrylic resin microspheres’ surfaces for high polymer/metal adhesion. Meanwhile, the influence of etching time and temperature on the surface morphology of electroless nickel plated acrylic resin microsphere was investigated. The optimal etching process conditions were identified in this test as follows: etching temperature of 70°C and etching time of 60 ~ 90min. Specular reflection FTIR and scanning electron microscopy was employed to observe the morphology of the nickel plated films and the Ni/polymer interfacial structures. As the results shown, the effect of etching process conditions on the coating thickness and the surface topography of the film was obviously.

Abstract: In this paper, the law of hydration expansion of polymer microsphere and the plugging rate of polymer microsphere under condition of different influencing factors such as hydration time, mass concentration, and permeability are studied. The applicable conditions are optimized as following: The optimum hydration time, mass concentration, and formation permeability through laboratory experiment is 5 days 3000 mg/L~4000 mg/L, permeability under 4 um² respectively. Finally, oil displacement experiment is carried out under laboratory conditions. The results show that the enhancement in oil recovery obtained in core flow experiment is about 7 %, which suggests that it has a wide application prospects in tertiary oil recovery.

Abstract: The magnetic polymer microspheres were synthesized by copolymerization of styrene with a water-soluble polyurethane macromonomer in the presence of Fe₃O₄ in ethanol/water medium. The structure of copolymer was determined by FTIR spectroscopy. The morphology and the average size of magnetic microspheres were characterized by transmission electron microscopy. The magnetic properties were recorded with a vibrating sample magnetometer. The results show that the magnetic microspheres had an average particle size of 500nm. The magnetic microspheres have super paramagnetic, enhanced hydrophilicity and the characteristics of simple and rapid magnetic separation. The magnetic susceptibility was 3.898×10^-5emu/(Oe·g) and the saturation magnetization was 41.122 emu/g.

Abstract: Polymer microsphere is a deep profile control agent which has been developed in recent years. Microsphere’s excellently elastic property makes it possible to be injected, or to penetrate deep into formation, and plug high permeable layers. Many laboratory investigations have been carried out on polymer microspheres by researchers, and field tests also have been done in some oilfields. The laboratory and field test results show that polymer microspheres can plug pore throats effectively, decrease permeability of high permeable channels, thus force injected water to change it’s direction and enhance water-flood sweep efficiency. In this paper, based on the mechanisms of profile modifying and plugging of polymer microsphere, Streamline models have been build abstractly to simulate the profile controlling progress of polymer microspheres, observe the transformation of streamline field, and analyze its impact on the pressure of water injection wells and performance of oil wells. In the end, the mechanisms of profile modifying and plugging of polymer microspheres have been interpreted based on the streamline field.

Abstract: This paper demonstrates that silica nanoparticles were modified by the four silane coupling agents (KH-151, KH-550, KH-560, KH-570) firstly, then polystyrene/silica (PS/SiO₂) composite microsphere with PS core and silica nanoparticles shell were prepared by Pickering emulsion polymerization. The characterization of optical microscope (OM), scanning electron microscope (SEM), and thermogravimetic analysis ( TGA) illustrates that these microsphere are composed of PS and silica nanoparticles. Silica nanoparticles modified by the different silane coupling agents could form the stable PS/SiO₂ microsphere over 70 °C, while the unmodified silica nanoparticles are difficult to form stable PS/SiO₂ microspheres at the same temperature. The PS/KH-151-SiO₂ microsphere exhibits the least average particle size, while the PS/KH-570-SiO₂ microsphere produces the largest. Both SEM and TGA confirm that microsphere surface exists solid nanoparticles.