Hollow particles were prepared by the treatment of styrene-metbacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position （in aqueous phase or at the interface of O/W） and stirr...Hollow particles were prepared by the treatment of styrene-metbacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position （in aqueous phase or at the interface of O/W） and stirring speed （90, 110 and 240 r/min） on the formation of hollow particles were investigated. It is found that the soft stirring in aqueous phase at 90 r/min leads to the formation of monohollow particles, while the violent stirring at the interface of O/W and 240 r/min gives non-hollow products. In contrast, the weak stirring in aqueous phase at 110 r/min results in sterically heterogeneous dispersion of methacrylic acid-rich regions within the original particles, and hence the formation of multihollow particles. Further investigation indicates that the change of stirring efficiency provides a way to tune the diffusion behavior of monomer styrene, and therefore influences the distribution of methacrylic acid units in the original particles as well as the morphology of the treated particles.展开更多
A new electromagnetic stirring technique that is driven by hydrodynamic forces was presented. This technique offers the following advantages. First,the stirrer can be immersed in the liquid metal,thereby significantly...A new electromagnetic stirring technique that is driven by hydrodynamic forces was presented. This technique offers the following advantages. First,the stirrer can be immersed in the liquid metal,thereby significantly increasing the penetration depth of the electromagnetic forces and significantly improving the stirring efficiency; thus,this technique is particularly suitable for large-scale liquid metal. Second,under certain conditions,this technique can overcome difficulties that are encountered with traditional stirrers,such as accessing regions that are difficult to reach in working spaces with complex or narrow shapes. This stirrer also has a simpler structure than a traditional stirrer; thus,the design can be easily modified,and no external power supply is required. An experimental prototype was also presented for controlling the fluid flow rate,thereby controlling the electromagnetic force and velocity field of the driven liquid metal. The velocity distribution in a liquid Ga In Sn alloy under fluid-driven electromagnetic stirring was quantitatively measured using ultrasonic Doppler velocimetry（ UDV）. The primary results show that a remarkable velocity field has been achieved and that fluid-driven electromagnetic stirring is an effective means of stirring liquid metal. Finally,the potential applications of this technique in industry,along with key challenges,were discussed.展开更多
基金Project supported by China Scholarship CouncilProject(09JJ3100) supported by Hunan Provincial Natural Science Foundation of China
文摘Hollow particles were prepared by the treatment of styrene-metbacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position （in aqueous phase or at the interface of O/W） and stirring speed （90, 110 and 240 r/min） on the formation of hollow particles were investigated. It is found that the soft stirring in aqueous phase at 90 r/min leads to the formation of monohollow particles, while the violent stirring at the interface of O/W and 240 r/min gives non-hollow products. In contrast, the weak stirring in aqueous phase at 110 r/min results in sterically heterogeneous dispersion of methacrylic acid-rich regions within the original particles, and hence the formation of multihollow particles. Further investigation indicates that the change of stirring efficiency provides a way to tune the diffusion behavior of monomer styrene, and therefore influences the distribution of methacrylic acid units in the original particles as well as the morphology of the treated particles.
基金Item Sponsored by the Program of "One Hundred Talented People"of the Chinese Academy of Sciences(111800M105)Chinese Academy Sciences Funding(04078400)
文摘A new electromagnetic stirring technique that is driven by hydrodynamic forces was presented. This technique offers the following advantages. First,the stirrer can be immersed in the liquid metal,thereby significantly increasing the penetration depth of the electromagnetic forces and significantly improving the stirring efficiency; thus,this technique is particularly suitable for large-scale liquid metal. Second,under certain conditions,this technique can overcome difficulties that are encountered with traditional stirrers,such as accessing regions that are difficult to reach in working spaces with complex or narrow shapes. This stirrer also has a simpler structure than a traditional stirrer; thus,the design can be easily modified,and no external power supply is required. An experimental prototype was also presented for controlling the fluid flow rate,thereby controlling the electromagnetic force and velocity field of the driven liquid metal. The velocity distribution in a liquid Ga In Sn alloy under fluid-driven electromagnetic stirring was quantitatively measured using ultrasonic Doppler velocimetry（ UDV）. The primary results show that a remarkable velocity field has been achieved and that fluid-driven electromagnetic stirring is an effective means of stirring liquid metal. Finally,the potential applications of this technique in industry,along with key challenges,were discussed.
