Lecture on the discipline Fundamentals of Materials Science “Natural Fibers”

Bast fibers

• Linen is one of the oldest textile fibers, but its use has declined since the invention of the cotton spinner.
• Ramie fibers are 10 to 15 cm long. The fibers are whiter and softer than flax. Ramie does not take dye well unless he is dry cleaned. Although natural ramie fiber is strong, it lacks durability, elasticity and elongation potential. Ramie fibers are resistant to mildew, insects and shrinkage. They are used for clothing, window treatments, rope, paper and table and bed linens.
• Hemp is similar to flax. The fibers range from 10 to 40 cm in length. Hemp has a low environmental impact: it does not require pesticides. It produces 250% more fiber than cotton and 600% more fiber than flax from the same amount of land. Hemp plants can be used to extract zinc and mercury contaminants from soil. Hemp is used for rope, clothing and paper. Addicts are willing to pay exorbitant prices for hemp clothing because it is associated with marijuana.
• Jute is one of the cheapest and one of the weakest cellulose fibers. Jute has low elasticity, elongation, sun resistance, mildew resistance and color fastness. It is used to make sugar and coffee bags, carpeting, ropes and wall coverings. Burlap is made from jute.

Leaf fibers

• Paina fiber is obtained from the leaves of the pineapple plant. They are used to make lightweight, clean, stiff fabrics for clothing, bags and table linens. Paina is also used to make mats.
• Abaca is a member of the banana tree family. The fibers are coarse and very long (up to half a meter). It is a strong, durable and flexible fiber used for ropes, floor mats, table linens, clothing and wicker furniture.

When to use stone or glass wool

Where to use glass wool:

• attic floor, floor of the 2nd floor of a private house made of timber (it has less weight and will not create a load);
• indoor walls (it is recommended to use material in the form of slabs, they are easier to install and hold more firmly);

Where is it better to choose basalt wool:

• roof slopes (material with a density of 100 - 120);
• in areas with high humidity (density should be at least 20, good resistance to moisture absorption);
• in small buildings with thin walls, for example, a change house or garage (density 150);
• in areas where it is necessary to prevent the spread of fire in the event of a fire (density 200 or special foil basalt wool).

It is important to know!

As it became clear, glass wool is inferior to stone wool in many characteristics. However, it also has a lower price, which for many is of key importance when choosing a material. Having carefully studied the comparative characteristics, everyone independently decides which type of heat insulator to choose.

Coverage Requirements

1. COATING REQUIREMENTS

1.1. The coating should be used for fire protection of structures used indoors with a non-aggressive environment and a relative air humidity of no more than 75%.

1.2. The materials for preparing the coating composition, as well as the technology for applying it to structures, must meet the requirements given in the mandatory annex.

1.3. The fire resistance limits of steel structures depending on the thickness of the coating layer are given in Table 1.

Table 1

1.4. The maximum deviation of the thickness of the applied coating layer from the design one in the direction of reduction should not exceed 5%.

1.5. The coating should not have cracks, peeling, or swelling.

1.6. The main physical and mechanical characteristics of the coating must correspond to those given in Table 2.

table 2

1.7. The coating consists of the following components: granulated mineral fiber, liquid glass and nepheline fire retardant.

1.8. The consumption of components per 1 m of coating, taking into account production losses, is given in Table 3.

Table 3

1.9. The coating component is granulated mineral fiber, manufactured in accordance with clause 2.2 of the mandatory annex to this standard, with a moisture content of no more than 2%.

1.10. The coating component is potassium liquid glass with a module of 2.6-2.8 according to normative and technical documentation approved in the prescribed manner, or sodium liquid glass with a module of 2.6-2.8 in accordance with GOST 13078-81.

1.11. The coating component is nepheline flame retardant in the form of a fine powder according to regulatory and technical documentation approved in the prescribed manner.

1.12. The coating components must be supplied: liquid glass - in metal barrels, mineral fiber and fire retardant - in plastic or paper bags, and stored in accordance with the requirements of regulatory and technical documentation approved in the prescribed manner.

Water absorption

If there is a possibility that the structure in which the insulation is embedded may come into contact with water, then the water absorption indicator is important, indicating how quickly the insulating layer will get wet. When wet, its properties deteriorate significantly, so when choosing insulation for entrance doors or filling walls in a bathhouse, you should give this priority attention.

The water absorption of glass wool is 1.7% by weight after 24 hours of direct contact with water. Basalt slabs have a value of 0.095%, making it twice as good in this category.

This is interesting: Corn fiber: biodegradable material, how it is produced, application

Fiber fillers

The base for this type of filler is long or short elementary fibers, both flexible and brittle. As a rule, fiber composites are obtained to impart special strength properties to a high-molecular compound. For this purpose, high-strength fibers made of glass, carbon (including carbon nanofibers or nanotubes), boron, polymer fibers, less often metal, carbides, nitrides, oxides and other inorganic compounds are used. Organic fibers of plant origin are also used, such as the previously mentioned cotton fiber.

Chopped short- and long-fiber and continuous fibers are used as fillers. In view of this, a fibrous composite may have properties similar to those of a dispersed material, or they may differ greatly from the latter and have distinctly reinforced or reinforced properties. When chopped fibers are used, the resulting materials can usually be easily processed using standard plastics processing methods such as extrusion and injection molding. When using long-fiber filler, such methods are not always available. The use of certain types of fibers can increase the mechanical properties of the finished composite by tens and hundreds compared to the original polymer.

Fig.1. Technical product made of glass fiber filled PA

The most popular fiber filler in the plastics processing industry is fiberglass. The industry produces many different brands of glass fibers, which differ in geometry, chemical composition and strength characteristics, but for the most part they are quite affordable. Fiberglass is used with almost all high-volume thermoplastic plastics, such as polyamide, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, etc. At the same time, glass fiber is also actively used to reinforce thermosetting polymers, for example, materials based on epoxy and phenol-formaldehyde resins, unsaturated polyesters, etc.

Thermoplastics are usually filled with up to 40% glass fiber, less often up to 70%. Thermosets are filled with glass fiber in quantities up to 80%. Fiberglass also has its drawbacks: its high fragility and the sizing coatings used in fiber production that reduce adhesion to the polymer matrix.

Mineral wool production technology

The starting materials for stone wool are limestone, diabase, basalt and dolomite, for slag wool - slag waste from blast furnace metallurgy, and glass wool is made from broken glass or from limestone, soda and sand. Despite the external similarity of, say, stone wool from different manufacturers, its characteristics will differ somewhat, since the exact combination of raw materials for each is entrusted to the calculation of the exact formula by technologists of production laboratories and keeping the results strictly secret.

It is necessary to create a recipe so that the resulting fiber has maximum quality properties: hydrophobicity and durability, chemical neutrality to metals and materials used in construction and finishing. Possessing these quality characteristics, mineral fiber must have the highest thermal insulation properties and resist any dynamic loads. There are two quality criteria applicable to mineral wool - the thickness of the fiber and its chemical composition. And if accurate information on the second criterion is not available to the general public, then the dependence of quality on the thickness of mineral wool fibers is as follows - the thinner the fiber, the higher the thermal insulation properties of mineral wool.

The production of mineral wool begins with the melting of raw materials; for this, the prepared mixture is loaded into cupola furnaces, bathtubs or shaft melting furnaces. The melting point is in the range of 1400-1500 degrees - maintaining accuracy when heating the initial mixture of components is extremely important, because the degree of viscosity of the melt determines the length and thickness of the resulting fibers, and therefore the dynamic and thermal insulation properties of the mineral wool itself.

At the next technological stage, the melt, brought to a given viscosity, enters centrifuges, inside of which rollers rotate at a speed of over 7000 rpm, tearing the molten mass into myriads of thin fibers. In the centrifuge chamber, the fibers are coated with binding components of synthetic origin - their role is usually phenol-formaldehyde resins. Then a powerful air stream throws the resulting fibers into a special chamber, where they settle, forming something like a carpet of given dimensions.

From the deposition chamber, the fibers are fed to a lamellar or corrugating machine, where the carpet of fibers is given the desired shape and volume. Next, the mineral wool carpet is placed in a heat chamber - under the influence of high temperature, the organic binder undergoes polymerization, and the mineral wool itself acquires its final shape and volume. The final heat treatment takes place at strictly defined temperatures - it is at this stage that the strength properties of mineral wool are formed.

At the final stage, the polymerized mineral wool is cut into blocks of specified sizes and packaged.

Text

DESCRIPTION OF THE INVENTION FOR THE AUTHOR'S CERTIFICATE Union of Soviet and Socialist Republics 947112 (088.8) Date of publication of the description 30,07,82 FS, 10, Goberis, O, N. Nupman, B, V, Luzha; B,;B. Piktis, N. I, Pyatigorskaya, N, G. Samoilova, V, K, Yashni G. P. PROSKURinz All-Union Scientific Research Institute of Thermal Insulation 4 Yacin and Acoustic Building Materials and Products and Scientific Research Institute of Building Materials and Products (54) MINERLLS 1st FIBER GeOz Geo MO Sao MO KO Disadvantage 0.8 -120.1-4.00.5-1.08-204.5-210.1-55 of known compositions The invention relates to the production of thermal insulation materials, namely to compositions for the production of mineral fiber from silicate melt, The composition of glass for the production of mineral fiber is known.1, including, wt.%: 5 01 44.5-48.0 АСО3 7.0-10.0 Сао 17.0-32.0 М 00 2.0-4 .0Geo 0.3-1.1Ge aO 0.06-0.1 9Mt 0 6.0-1 9.0IO 0.5-1.5T 0 0.1-1.0Ga O 0.05-0.0 The closest to the proposed one is mineral fiber 21, including, wt.%: 50 27-61Ae 2 o, 8-23T 02 O; 30 there is a high melting point of the charge 1250-1400 C, as well as insufficiently high chemical resistance of the fiber obtained from it - acidity module (Mk) 1.6-2.38. In addition, mineral fiber is produced from the two most important components of the charge, which increases the cost of charge preparation departments , reduces the homogeneity of the melt and the quality of mineral wool products. The principle of the invention is to reduce the melting point, increase chemical resistance and reduce cost. The established chain of achievement is extinguished by the fact that the mineral fiber is 50, AE.O.G G, GL;m, 3 04711 CaO, MO, IO additionally contains PO with the following ratio of components, weight,% 2IOa 41.8 45.0AbkO 6.2-14.7T O 1.7-3.4RegOE 5.9-17.0GeO 13.2-14.4Mi O 0 .08-0.2CaO 4.3-7.8 OMR 8.5-13.11.1-2.8P O 0.3-2.1Specific mineral fiber compositions and their properties are given in the table. In order to obtain melts, they use sludge from bedrock ores, in particular the highly magnetic fraction of bedrock ore and the magnetic fraction of bedrock ore. The method of producing a melt for the production of silicate fibers is carried out as follows. They take one of the compositions, dry it in a drying drum to a moisture content of 3-5% and, using a piston or screw loader, feed it into the cooking zone of the Mchi bath. The use of waste from the enrichment of indigenous titanium ores will make it possible to obtain mineral fiber with increased chemical resistance. The reduced melting temperature of waste from the enrichment of indigenous titanium ores will ensure that technological melting processes are carried out at reduced temperatures in the working space of the furnace. This will reduce the specific heat consumption to produce 1 kg of melt, as well as increase the overhaul period of the melting units, since the corrosion of refractory materials decreases with a decrease in the temperature of the melt. The economic effect obtained when using the melt can be calculated by reducing fuel consumption by 15% and capital investments in the equipment of the charge preparation department. fermula Mineral fiber, including 10th, A 10 T 10, GeO, ReO, M&O, CaO, MO, IO, differing in that, with In order to reduce the melting point, increase chemical resistance and reduce cost, it additionally contains P 0 in the following ratio of components, wt.%: 1 O% 0 41.8-45.0 ABO 6.2-1 4.7 T, Oya

1.7-3.4 7 947112 8inventions EO 5.9 17.OPeO 1 3.2-14.4MiO ( ),08-0.2CaO 4.3-7.83 R 8.5-13.11, 1-2.80.3-2.1 Sources of information taken into account during the examination1. Copyright certificate USSRMo 581104, class, C 03 C 13/00, 1976.2

Author's certificate USSRMo 649670, class, C 03 C 13/00, 1977. Compiled by I, Ilyinykh Editor V, Petrash Techred T, fanta Proofreader E. Roshko Order 5515/35 Circulation 508 Subscribed VNIIPI of the USSR State Committee for Inventions and Discoveries 113035, Moscow, Zh, Raushskaya nab., 4/5 branch of PPP “Patent”, Uzhgorod, st., Proektnaya, 4

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Story

The history of fibers is the history of humanity, from primitive existence to modern post-industrial society. Without clothing, home interior, without technical textiles, everyday life, culture, sports, science, technology, and medicine are unthinkable. But all types of textiles do not exist without fibers, which at the same time are only raw materials, but without which it is impossible to produce all types of textiles and other fiber-containing materials.

It is interesting to note that many thousands of years ago, from the end of the Paleolithic era (~ 10-12 thousand years BC) until the end of the 18th century, man used exclusively natural (plant and animal origin) fibers . And only the first industrial revolution (2nd technological structure - mid-19th century) and, of course, advances in science and, above all, chemistry and chemical technologies gave rise to the first generation of chemical fibers (cellulose hydrate - copper-ammonia and viscose). From that moment until the present time, the production of chemical fibers has developed extremely quickly in terms of quantity (overtaken the production of natural fibers in 100 years) and in a number of positions in terms of quality (significant improvement in consumer properties). The history of fibers is briefly presented in Table 1, from which it follows that the history of chemical fibers has gone through three stages, and the last one has not yet ended and the third, young generation of chemical fibers is going through its formation stage. A SMALL TERMINOLOGICAL DEVICE

There are discrepancies in Russian (formerly Soviet) and international terms. According to Soviet and Russian terminology, fibers are divided into natural (plant, animal) and chemical (artificial and synthetic).

Let’s ask ourselves the question “doesn’t everything that surrounds us consist of chemical elements and substances?” And therefore they are chemical and, therefore, natural fibers are also chemical. The remarkable Soviet scientists who proposed this term “chemical” were, first of all, chemist-technologists and put into this term the meaning that they are not produced by nature (biochemistry), but are produced by humans using chemical technologies. Chemical technology is placed in first place and dominates in this term.

International terminology denotes all artificial and synthetic fibers (polymers) in contrast to natural - not made by hands, as made by human hands (man-made) - manmade fibers. This definition is more correct from my point of view. With the development of polymer chemistry and fiber production technologies, terminology in this area also develops, becomes more precise, and becomes more complex. Terms such as polymer and non-polymer fibers, organic, inorganic, nano-sized fibers, fibers filled with nanoparticles obtained using genetic engineering, etc. are used.

Bringing terminology into line with advances in third-generation fiber production will continue; This needs to be monitored by both fiber producers and consumers in order to understand each other.

Basalt superfine and thin staple fibers. Areas of use.

Due to the low cost of production, materials made from thin basalt staple fibers are widely used.

Industrial civil engineering - thermal insulation of enclosing structures, floors, roofs, facade insulation of buildings. Fire protection systems for buildings, metal structures. Thermal insulation of steam pipelines and heating mains. Thermal insulation in industry - furnaces and thermal equipment.

Due to the low cost of production, materials made from thin basalt staple fibers are widely used.

Application of basalt superfine fiber and BSTV materials

Energy – nuclear, thermal power plants, turbines, heating plants, steam boilers, heating mains; heat and sound insulation of thermal equipment.

Fireproof materials for fire protection systems: firewalls, protection of critical metal structures, fire doors, cable penetrations, etc.

Production of ceramics, porcelain, building materials - thermal insulation of furnaces and equipment for the production of ceramic and porcelain products (dishes, vases, sanitary ware, etc.), furnaces for the production of bricks, ceramic tiles.

Mechanical engineering – thermal insulation of thermal equipment, heating and hardening furnaces, heating mains.

Aviation industry - heat and sound insulating mats covered with waterproofing fabric for heat and sound insulation of engines and fuselage. The Soyuz spacecraft used BSTV. The materials have confirmed their high quality.

Shipbuilding – thermal insulation boards on an inorganic binder for heat and sound insulation of ship installations, equipment, ship hulls, bulkheads.

Cryogenic technology and equipment – ​​insulation materials for the production of liquefied gases, liquid oxygen, etc.

Metallurgy – materials for thermal insulation of various types of technological furnaces and thermal equipment, regenerators, recuperators, pipelines, communications.

Chemical and petrochemical industry - thermal insulation of thermal equipment, heating furnaces, drying chambers, steam boilers, steam pipelines, heating mains; non-flammable, fire-resistant materials for fire protection of equipment and facilities.

Production of building materials and structures - insulated panels for prefabricated houses and structures, floors; suspended ceilings, fire bulkheads, firewalls, fire-resistant doors, building plastics.

Filters. BSTV is widely used for the production of filter materials and products, fine filters for air and liquid media, and high-temperature filters. BSTV produced at temperatures of 1400 – 1500°C is an ideal material for hydroponics when growing bacterial cultures, plant seedlings, etc.

Household appliances – thermal insulation of gas and electric stoves, ovens, electric ovens.

See also: Technologies and equipment for the production of super-thin basalt fiberTechnological equipment for the production of thermal insulation boards

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Introduction

Currently, the most developed countries are moving into the 6th technological order, and developing countries are catching up behind them. This way of life (post-industrial society) is based on new, breakthrough technologies and, above all, nano-, bio-, info-, cognitive-, and social technologies. This new paradigm for the development of civilization affects all areas of human practice and affects all technologies of previous orders. The latter do not disappear, but are significantly modified and modernized. But, most importantly, a qualitative change is the emergence of new technologies, their transition to a commercial level, the introduction of products of these technologies and modified traditional technologies into the everyday life of a civilized person (medicine, transport of all types, construction, clothing, home interiors and accessories, sports, army , means of communication, etc.).

Krichevsky G.E. – Professor, Doctor of Technical Sciences, Honored Worker of the Russian Federation, UNESCO expert, academician of RIA and MIA, Laureate of the MSR State Prize, member of the Nanotechnological Society of Russia. about the author

This tectonic, technological shift did not bypass the field of fiber production, without which not only the production of textiles of all types, but many technical products of traditional and non-traditional applications (composites, medical implants, displays, etc.) is not possible.

Scope of application

To make mineral wool, melted glass, blast furnace slag, and volcanic rocks are used. Using a centrifuge, fibers are obtained from the melt, which are mixed with a binder of synthetic origin. From the resulting mass, mineral wool slabs are formed, which vary in size, density and hardness.

Thermal insulation boards made of mineral fibers are used for heat and sound insulation

:

• floors;
• pitched and flat roofs;
• roofs made of three-layer panels;
• floors;
• ceilings;
• partitions;
• three-layer lightweight walls made of block materials (mineral wool is placed in the middle of the structure);
• frame walls;
• facades (when insulated under plaster and as part of ventilated curtain facades).

An example of a wall pie using mineral wool

Price list

Insulation of ventilation façade with cladding

Characteristics of woven fillers for polymer composite materials

A characteristic parameter for describing woven materials is its density, which characterizes the number of threads per unit width (along the warp) or length (along the weft) of the fabric. Fabric density characterizes the frequency of threads in the fabric. The further the threads are located from one another, the less density, i.e. the fabric is thinner. The closer the threads are to one another, the greater the density, i.e., the denser the fabric.

The thickness of the fabric depends on the thickness of the threads or on the number of yarn from which it is made, and on its structure. The thickness ranges from tenths of a millimeter to several millimeters.

The physical and mechanical properties of fabric are characterized by breaking stress and elongation. The breaking load and tensile strength are determined by both the warp and the weft. Elongation is an increase in the length of a sample when a tensile load is applied to it. Typically, elongation is expressed as a percentage of the original length of the specimen.

Determination of the mechanical characteristics of fibrous fillers (threads, tows, fabrics) is carried out according to GOST 6943.10–79

Unbalanced woven fillers

Twill and satin weave fabrics are unbalanced in the weave pattern, since on one surface of the panel (front side), for example, in the direction of the warp, straight warp threads predominate, on the opposite surface (wrong side) in the same direction - transverse weft threads. If a fabric of such a structure is impregnated with a binder and a single-layer plate is pressed from it, then after cooling and removal from under the press plates it will bend, since the front and back sides of the plate have different thermoelastic properties.

Fabrics of any weave made from highly twisted threads are characterized by unbalanced twist. The torques embedded in each thread cause the fabric to curl and cause the thin-walled plates made from materials filled with such fabrics to lose flatness.

Deformation characteristics of woven fillers

Woven fillers are elastic porous materials. During molding, the filler is subjected to deformation, and the thickness of the package and its porosity change, and elastic deformations and corresponding stresses accumulate in the fibers. Therefore, to obtain products of certain sizes and monolithic material with a given ratio of components, it is necessary to know about the deformation properties of the filler.

The main deformation characteristic of woven fillers is effective stiffness, which depends on the type of fibers used to make fabrics and the order of their organization. The effective stiffness is determined by tension of the fillers in the direction of the warp or weft, as well as by compression perpendicular to the plane of the filler. Most often, the stiffness value is determined using an experimental pressure-thickness graph. From this deformation curve, it is possible to determine the change in the porosity of the material with increasing pressure.

Impregnation ability of woven fillers

The most important feature of sheet and bulk fillers, primarily fabrics, is the pronounced dependence of their ability to be impregnated and wetted by liquid compositions on texture and direction in the plane (along the weft or warp).

Cuvette for determining the wettability of fabric fillers

Figure 2: Cuvette for determining filler wettability:

1 – cuvette; 2 – filler strips; 3 – binder; 4 – cuvette cover; 5 – sealing gasket;

The ability to wet is characterized by the maximum height of liquid rising through the filler and the time to reach the maximum height.

What's better?

And so glass wool and mineral wool, what exactly is the difference? At this point we will analyze their pros and cons. You can’t understand much just by looking at it externally. The only difference is that the mineral wool product is voluminous and has a darker color. Of course, this will not help in choosing. There are no winners when it comes to thermal conductivity comparisons. Thermal conductivity level coefficient:

• glass wool – 0.041-0.043 W/mK;
• mineral wool – 0.030-0.052 W/mK.

In this indicator, the difference between glass wool and mineral wool is not big, so there is no winner here.

Comparison of heat resistance characteristics:

• heat resistance properties of mineral wool – 600-700 °C;
• glass wool – 450 °C.

Glass wool

When it comes to elasticity and strength, glass wool is the leader here. Mineral wool has a fiber length of 2-10 microns, while glass wool fibers have a fiber length of 3-15 microns. Fiber length:

• glass wool – 15-60mm;
• mineral wool – 16 mm.

It is thanks to these criteria that glass wool snatches an advantage from its opponent.

Glass wool has the ability to absorb moisture, which is why it shrinks, unlike mineral wool. During the entire period of operation, mineral wool does not lose its original shape. And in this, of course, mineral wool turns out to be the best.

The price category is on the side of glass wool, because mineral wool is more expensive:

• 1 sq. m of glass wool – 800 – 900 rubles;
• 1 sq. m of mineral wool - about 1200 rubles.

This is all justified by the fact that the materials for its production are more expensive, as is the product itself. So before choosing insulation, you should wisely calculate your budget in order to make the right choice.

When insulating horizontal and unloaded areas (for example, as insulation of attics), I use exclusively glass wool, because mineral wool does not provide the necessary continuous coverage of the area. In this case, the advantage is on the side of glass wool.

When working with glass wool, it is possible to cladding uneven surfaces and can be used for cladding different shapes and configurations of structures. After all, it is very soft and elastic. When working with mineral wool, it will be more difficult to achieve the same result. After all, it has a higher density.

Other types of fillers

Other types of additives under consideration for polymers are used less frequently. Woven fillers consist mainly of glass, cotton and carbon fabrics. They are used for the production of high-strength plastics with anisotropic properties. Woven fillers are most often combined with thermosetting polymers. The binder for such plastics can be epoxy oligomers, unsaturated polyesters, but it can also be polyamide. The amount of filler in such a composite reaches 40-85%.

Rice. 2. Decorative laminate

Non-woven fillers are also used, which cannot be classified as fibrous or dispersed. These include various meshes, cardboard, paper, felt mats, etc. As a rule, these materials are impregnated with binder solutions (most often thermosets). The resulting composite is then dried to evaporate the solvent and processed into finished products by cold pressing. This is how laminates are produced. The method was popular in the 20th century, but in recent years has lost ground to higher-yield plastics processing technologies such as extrusion.

Transportation

When choosing a thermal insulation material, it is worth taking into account such an obligatory factor as transportation. There is a big difference between mineral wool and glass wool. Glass wool will be more convenient during transportation, because it is lighter, the rolls are compressed into more convenient rolls or equally convenient slabs, which will make unloading easier. During transportation, it does not lose its qualities and shape, because it is more resistant to vibrations. And transportation of mineral wool will be less convenient due to larger rolls and greater weight, which will complicate loading and unloading of the material. If you are not careful when loading, unloading and transporting, there is a possibility of damaging the mineral wool. Or there is simply the possibility that the mineral wool will lose its shape during transportation.

Glass wool

VEV based on linear polymers

The first group of VEVs are based on linear (1D dimensional) polymers and the simplest of them, polyethylene.

For materials made from linear polymers, back in 1930, Staudinger proposed an ideal model of a supramolecular structure that provides a high modulus of elasticity along the main chains (11000 kg/mm2) and only 45 kg/mm2 between macromolecules bound by van der Waals forces.

Figure 3. Ideal physical structure of a linear polymer according to Staudinger.

As you can see (Fig. 3), the strength of the structure is determined by the elongation and high orientation of the chains of macromolecules along the fiber axis.

The technology (state of the spinning solution and melt, drawing conditions) for the production of fibers must be designed in such a way that folds of macromolecules do not form. Fiber-forming polymers, with a certain chemical structure of macromolecules, already in solution form elongated, oriented structures combined into blocks (liquid crystals). When fibers are formed from such a state, reinforced by a high degree of elongation, a structure close to ideal according to Staudinger is formed (Fig. 3). This technology was first implemented by DuPont (USA) in the production of Kevlar fibers based on polyparaaramid and polyphenylene terephthalamide. In these high-strength fibers, the aromatic rings are linked by amide groups

The presence of cycles in the chain provides elasticity, and amide groups form intermolecular hydrogen bonds, which are responsible for tensile strength.

Using a similar technology (liquid crystalline state in solution, high degree of elongation during molding, VEVs are produced from various polymers by different companies, in different countries under different trade names: Technora (Taijin, Japan), Vectran (Gelanese, USA), Tverlana, Terlon (USSR, Russia), Mogelan-HSt and others.

References:

• G.E. Krichevsky. Nano-, bio-, chemical technologies and the production of a new generation of fibers, textiles and clothing. M., publishing house "Izvestia", 2011, 528 p.
• High Performance Fibers. Hearle J. W. S. (ed.). Woodhead Publishing Ltd, 2010, p.329.

Military textiles. Edited by E Wilusz, US Army Natick Soldier Center, USA. Woodhead Publishing Series in Textiles. 2008, 362 rub.

• PCI Fibers. Fiber Economics in an Ever Changing World Outlook Conference. www.usifi.com/…look_2011pdf

Abbreviation for fiber names