Review on preparation and applications of electro-blown spun micro-nano inorganic fibers
Significance With the development of sophisticated technologies,novel materials are required for compatibility,lightweight,high strength and temperature resistance.Combined with the large length-to-diameter ratio and high specific surface area of one-dimensional materials,micro-nano inorganic fibers with size effect show great potential for many applications.However,there are some problems including insufficient fineness,poor controllability and continuity in the current methods of preparing micro-nano fibers,such as stretching method,chemical vapor deposition and phase separation.Moreover,the most mature and widely used electrospinning technology has some problems,such as low production efficiency and strict restrictions on spinning solution with high viscosity,which hinder the large-scale industrialization of high-performance inorganic fibers.Recently,electro-blown spinning,based on the coupling effect between electric field force and ejection force of the air stream,has demionstrated capability of contributing to the high yield and high quality of micro-nano fibers.Meanwhile,the airflow can assist in starting,stabilizing,and completing the rotation process of jet.Compared with traditional electrospinning and solution blow spinning technologies,inorganic fibers prepared by electro-blown spinning are characterized by higher yield(dozens to hundreds of times more than electrospinning),small diameter(nanometer and submicron scale)and uniformity.Progress In order to promote the electro-blown spinning technology and provide theoretical and practical basis for preparing inorganic fiber,this paper reviews the basic researches,including the principle and advanced equipment.The core components are composed of feeding device,spinning die,high-voltage power supply,gas control system and receiving device.For large-scale production,there are many novel designs for spinning die,such as disc multi-nozzle,multi-branch/tip equipment,solution channel surrounded by internal/external double-layer air flow.The influencing factors of fabricating inorganic fibers by this technology are analyzed in detail in terms of the properties of spinning solution,the geometric characteristics of spinneret,the properties of air flow,the spinning voltage and the tip-collector distance,especially the controllable process of industrialization.Moreover,taking Al2 O3 fiber as an example,the electro-blown spinning technology is compared with solution-blown spinning and conventional electrospinning technology from fiber morphology,pore size of membrane and production efficiency.The advantages and drawbacks of electro-blown spinning technology are discussed and clarified.In addition,the applications of electro-blown spinning inorganic fibers are presented,which concentrates on the fields of dye adsorption and degradation,biomedicine,energy,catalysis and industrial manufacturing.Conclusion and Prospect It has been demonstrated that the superimposed airflow and electrostatic effect,with a double drafting force makes the electro-blown spinning technology achieve certain breakthroughs in the pursuit of both high yield and high quality of micro-nano inorganic fibers.The technology is suitable for preparing a wide range of ceramic materials and carbon fibers,especially for high-concentration solutions or gels.However,there are still some problems such as insufficient understanding of the jet motion under the dual control of airflow and voltage,poor toughness of produced inorganic fibers and mostly short fibers,and the lack of large-scale electro-blown spinning equipment.Therefore,efforts need to be made in the following aspects in the future.1)It is crucial to improve the quality of inorganic fiber while ensuring the yield.The laws of jet motion and synergistic control methods under the dual control of airflow/voltage need to be clarified through the establishment of mathematical models and simulation.2)It is necessary to diversify the structure/function of inorganic fibers.The first is to develop macro/micro special structure inorganic fibers,while the second is to play the advantages of electro-blown spinning technology easily combined with functional materials.3)It is also necessary to strengthen the development and application of the porous and lightweight inorganic fibers and the ultrafine inorganic yarn.
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