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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.

Inhaltsverzeichnis

Frontmatter

1. Introduction (Historical Review)

Abstract
Melt blowing belongs, without doubt, to a newly developed industrial technique, though its onset dates back to the early 1950s. By that time, the world industry of chemical fibers already had at its disposal such highly productive and high-speed technologies as fiber formation from solutions and melts followed by linear extension [1, 2]. During the Cold War the U.S. administration showed an interest in producing of microfibrous polymer adsorbents intended for capturing radioactive particles in upper atmospheric layers which were signs of nuclear weapon tests intensively carried out in the U.S.S.R. during those years.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

2. Melt Blowing Techniques

Abstract
The melt blowing technique presents the unique possibility of varying the structure and properties of fibrous materials across a wide range, which attracts plastics manufacturers and designers. This variation might be realized at any stage of material molding, beginning with extrusion till cohesive bonding of cooled fibers on a substrate.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

3. Equipment

Abstract
Equipment for melt blowing resembles facilities for coating more than machines for plastics processing, though it includes such traditional units as extruders fitted with high precision spray heads which are manufactured by special methods comparable to jeweler’s art. That is why experiments connected with modification of precision elements of spray heads, receiving units, and other special equipment are highly expensive. So, the developers of melt blowing equipment highly rate the experience accumulated by them and this is, probably, the main reason why there is a scarcity of publications reflecting melt blowing problems in the scientific literature. Every design described in this chapter is based on know-how without which highly productive and reliable operation of equipment is improbable.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

4. Structure of Melt-Blown Polymer Fibrous Materials (PFM)

Abstract
The Method of melt blowing differs essentially from traditional methods of plastics processing. It proceeds at the boundary of oxidizing destruction of polymers when their technological properties are specified by low viscosity of the polymer mass in a viscous-flow state. This brings about active oxidation of the fiber surface layer, and intensified adhesive interaction between fibers and solid modifiers. The indicated phenomena. together with adsorptive interaction of fibers with modifiers in a liquid or gaseous state, condition the specific structure of melt-blown materials. They are characterized by the fiber diameter, the density of cohesive bonds hetween fibers. the porosity of the fibrous mass, the modifier concentration, etc. The structural parameters are determined by the technological regimes of material manufacture.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

5. Specific Properties of Melt-Blown PFM

Abstract
The specific structure of melt-blown materials conditions their unusual service characteristics. which are determined by porosity. the large specific area of PFM, and the high physicochemical activity of the fiber surface layer. Such activity is caused by the specifics of the melt blowing process when fibers are formed from the polynmer melt at the boundary of thermal-oxidation destruction. Melt blowing leads to the generation of a spontaneons polarizing charge. which imparts unexpected properties to PFM. Some of them are considered in this chapter.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

6. Fibrous Materials in Filtration Systems

Abstract
One of the most positive trends in melt blowing technology is the production of fibrous materials for filtering systems. Filtration is the motion of liquids or gases through a porous medium. Liquid or gaseous media are separated from contaminants during filtration. In the process of filtration suspensions or aerosols are separated by porous screens letting liquid or gas pass but keeping solid particles back. Filtration is performed by filters whose major part is the filtering element (FE), which is a porous screen made of a filtering material (FM). A diversity of filtration conditions exist (various sihes and types of contaminants, volumes of media being filtered and velocity of filtration, degree of cleaning, and so on) which determine the use of a wide range of FM, including paper metal meshes, synthetic and natural fabric and fibers, porous plastics, and powder materials. Melt-blown polymer materials occupy their own merited place within the combinations of synthetic FM and are efficiently used in the techniques of purifying technological and working media, as well as industrial wastes.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

7. Electret Filtering PFM

Abstract
Cleaning of air and gas from suspended solid and liquid particles is of paramount importance in medicine, biochemistry, dectronics, the atomic power industry and many other fields. The most simple, reliable and economical way of cleaning gaseous media of highly dispersed aerosol is using filters with a fibrous FE. The search for highly efficient purification systems able to remove submicron particles from air has led to the development of electret filters consisting of a FE with charged polymer fibers [1-4].
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

8. Magnetic Filtering PFM

Abstract
The V.A. Belyi Metal-Polymer Research Institute of NASB (MPRI) has elaborated a new class of filtering materials — magnetic PFM [1-8]. The technological base for manufacturing such materials is the melt blowing technique involving the following procedures: extrusion of a polymer melt filled by ferrite (barium or strontium) powder, fiber extension by gas flow, and fiber treatment in a magnetic field. The polymer melt is extruded through spinneret holes whose diameter far exceeds that of the filler particle. The thermal regime of spraying provides for cohesive bonding of the fibers on the forming substrate. The material is also textured during spraying. The final stage of magnetic PFM or finished FE manufacture is filler particle magnetizing in a permanent or pulse magnetic field.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

9. Adsorptive and Microbicidal PFM

Abstract
Adsorptive PFM are designed for combined deep filtration of industrial sewage where fine suspensions of solid particles, emulsified petroleum products, dissolved heavy metal salts, organic toxicants, and detergents are present simultaneously in significant variations in pH and waste composition.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

10. PFM as Carriers of Microorganisms

Abstract
A present trend in industrial technologies is the growing role of catalytic biotechnological systems, in particular, systems for biologically cleaning air and water by employing of biologically active polymer materials (BAPM). The functional mechanisms of these materials (where a high molecular weight matrix is the carrier of live cells of microorganisms, plants, animals, or men) are governed by the metabolism of immobilized cell cultures under given conditions. The rapid widening of the BAPM range in recent decades can be attributed to the strengthening of the biotechnology sectors in a number of the vital domains of economy, including fine organic synthesis, the pharmacentical and food industries, medicine, agriculture, and industrial ecology [1].
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

11. Other Applications of PFM

Abstract
The service characteristics of melt-blown materials depend strong on the high specific area and nonequilibrium state of the fiber surface layer that has rather high surface energy. The physicochemical activity of this class of materials in various technological, working and natural media has defined their optimum fields of application in industry, medicine, construction, and other important spheres. New means of efficiently cleaning running water and foodstuffs, as well as technological media, wastes, and industrial waste gases are extensively explored now. Disposable melt-blown hygienic and engineering products, novel grades of textile decorative fabric, leatherette, carpeting, and other household articles have become of paramount importance for the modern generation. Melt-blown materials have already occupied a significant place in civil construction successfully solving problems in heat, sound, and waterproofing of buildings and various structures. Today’s advances and prospects in medical technique development are also improhable without fihrous materials. A powerful global packaging industry that has expanded during the last half century employs melt-blown products widely, too. A diagram presented in Fig. 11.1 shows the potentialities of melt-blown materials and visualizes the main trends in their use. Following, some characteristics of the group of materials mentioned in the diagram are given.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

12. Ecological and Social Problems

Abstract
By now, the volume of consumption of melt-blown materials has reached a critical point in response to the perceptible influence of those products on society and the state of the environment.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

13. Conclusion

Abstract
Little known so far to a customer at large melt-blowing technique is now seriously and for long holding its place among a totality of production technologies being the base of modern inciwitry. Recently elaborated numerous melt-blown materials and articles have speeded up the development of a number of major fields of human activities (industry, construction, engineering ecology, etc.) and are rightfully associated with the contemporary level of civilization.
L. S. Pinchuk, V. A. Goldade, A. V. Makarevich, V. N. Kestelman

Backmatter

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