A.V. Makarevich

One of the recently emerging techniques of fibrous materials production, melt blowing, consists of forming fibers from substances heated above their melting (crystalline) or glass transition (glass-like) point with further blowing by gas flow. The sprayed fibrous mass is then cooled to solidification either in a gas flow or upon deposition on the forming substrate. Realized from polymers and then ceramics, the melt blowing technique has enriched materials science, engineering, and all commodity products by novel types of fibrous materials and products made from them with a unique combination of properties. The reasons for the popularity of melt blowing are the following. The shape stability and strength of melt-blown materials and products are controllable technological parameters that depend on the diameter and the intensity of the adhesive interaction between fibers and the number of contacts between them. The greater area of fiber surface in contrast to negligible clearances in between is the source of the uniqueness of melt-blown materials as systems whose properties are governed to a great degree by surface phenomena. Dielectric materials manufactured by melt blowing are subjected to the rigorous effects of heat, deformation, and friction during processing which is accompanied by natural electrical polarization of fibers. The fibers are transferred into an electret state (an electret is a dielectric that preserves its electrical polarization for a long time), which makes melt-blown materials the source of a permanent electrical field.

One of the key problems of failure-free operation of machinery is prevention of corrosion. The global scale of modern production makes this problem even more critical. At the beginning of the 21st century industrial contami- tion and the corrosion-active nature of the environment reached a level such that corrosive damage of materials became commensurate with their prod- tion volume and expenditure on anticorrosion protection of machines became comparable with investments in basic production. Anticorrosion techniques changed from being an auxiliary service to industrial enterprises into a dev- oping, scienti?cally intensive and generously ?nanced branch of production. Polymers occupy a very speci?c place amongst anticorrosion techniques. Polymers combine good chemical resistance with impermeability to di?- ent media and unusual deformation characteristics. The main principle of their application as anticorrosion means is the creation of a tight barrier that insulates metal machine parts or constructions from corrosion agents. The advantages of polymers allow the creation of such a barrier at minimal cost,providingprotectionoftheworkingmachinesfromcorrosion,combining their manufacture with preservation and decreasing the cost of anticorrosion. This is one of the main reasons why world production of polymer materials increased by almost 50% in the past decade.

One of the key problems of failure-free operation of machinery is prevention of corrosion. The global scale of modern production makes this problem even more critical. At the beginning of the 21st century industrial contami- tion and the corrosion-active nature of the environment reached a level such that corrosive damage of materials became commensurate with their prod- tion volume and expenditure on anticorrosion protection of machines became comparable with investments in basic production. Anticorrosion techniques changed from being an auxiliary service to industrial enterprises into a dev- oping, scienti?cally intensive and generously ?nanced branch of production. Polymers occupy a very speci?c place amongst anticorrosion techniques. Polymers combine good chemical resistance with impermeability to di?- ent media and unusual deformation characteristics. The main principle of their application as anticorrosion means is the creation of a tight barrier that insulates metal machine parts or constructions from corrosion agents. The advantages of polymers allow the creation of such a barrier at minimal cost,providingprotectionoftheworkingmachinesfromcorrosion,combining their manufacture with preservation and decreasing the cost of anticorrosion. This is one of the main reasons why world production of polymer materials increased by almost 50% in the past decade.

This book is devoted to a nontraditional class of materials which are manufactured by the melt-blowing process - i.e. by extrusion of polymer melt followed by fiber stretching with a gas stream. For the first time extensive data on classical and modern modifications of this technology are generalized and a review is given of extrusion head dies and subsidiary equipment. The text examines the structure and main properties of melt-blown materials as conditioned by peculiarities of overheated polymer melt spraying in an oxidizing medium. Information is given about filtering mechanisms and the main types of polymer fibrous filtering materials: electret, magnetic, adsorptional, bactericidic, and about carriers of microorganisms in biofilters. Social and ecological aspects of the application of melt-blown materials are analyzed.