A. I. Sidorina and T. V. DruzhininaUDC 677.494.027.622The influence of the type of solvent and silver ions on the structural and rheological properties of polyacrylonitrile (PAN) solutions and the feasibility of their conversion into nanofibres by spinneretless electrospinning are studied.Ultrathin and nanosized materials, including fibres, are of great interest because of creation, based on them, of a special class of functional and active materials for filtration, sorption, and medical purposes [1-3]. One of the simplest methods of production of ultrathin nanosized fibres is forming polymer fibres in electrostatic field, which is what is called electrospinning (electroforming) process.Of late, ultrathin and nano-diameter fibres, just as the electrospinning process itself, are associated with ultramodern materials, At the same time, fibres of this type are being produced since long in the form of nonwoven materials, which are used widely as filters for trapping aerosols [4]. However, in spite of this fact and a large number of publications in this domain [5][6][7], many aspects of the theory of polymer fibre electrospinning processes require further studies because of marked broadening of the range of polymers of various structures used for processing into ultrathin fibres as well as of appearance of capillaryless electrospinning techniques.The high ability of polyacrylonirile (PAN) to undergo carbonization predetermines the potential for use of its electrospinning products as precursors of carbon-reinforced fibre nanomaterial and production of fibre nanocomposites with silver particles, which provides the possibility of creating high-efficiency filter materials with antibacterial properties.In this work, we studied the influence of polymer concentration, solvent type, and silver ion content on the structural and rheological properties PAN spinning solutions and their fibre-forming ability in capillaryless electrospinning. The solutions were treated on Nanospider TM NS LAB 200S equipment. Use in electrospinning of less concentrated solutions than solutions used in classical spinning methods provided the possibility of varying polymer concentration in the solution in the 7-12% range [8].In this work, we used commercial copolymer of acrylonitrile, methyl methacrylate, and itaconic acid having a molecular mass of 45000. The solvents used for producing spinning solutions were dimethyl formamide (DMF − a traditional PAN solvent), dimethyl acetamide (DMA − widely used as a solvent in production of para-aramide fibre), and nontoxic dimethyl sulfoxide (DMSO), use of which is important in what is called the "dry" electrospinning technique.The PAN solutions were prepared at 80°C. The viscosity of the solutions was determined by a Rheotest-2.1 rotary viscometer (German firm MLW). The measurements were made in a cylinder−cylinder cell at shear stress σ in the 2.8-560 Pa range and shear rate γ & of 1.5-656/sec -1 . The viscosity was determined at 20°C, which corresponds to the conditions suitable for work on Nanospider TM N...
