Material obtained by vulcanization of rubber. Rubber (rubber vulcanization product)

Rubber Rubber (from Latin resina "resin") is an elastic material obtained by vulcanization of rubber Rubbers Natural or synthetic elastomers characterized by elasticity, water resistance and electrical insulating properties, from which rubbers and ebonites are obtained by vulcanization

It is used for the manufacture of tires for various vehicles, seals, hoses, conveyor belts, medical, household and hygiene products, etc. by vulcanization method Obtained from natural or synthetic rubber by vulcanization method - mixing with a vulcanizing agent (usually with sulfur) followed by heating

The history of rubber begins with the discovery of the American continent. The indigenous population of Central and South America, collecting the milky sap of rubber trees (hevea), received rubber. Columbus also noticed that the heavy monolithic balls made of black elastic mass used in the games of the Indians bounce much better than the leather balls known to Europeans.

In addition to balls, rubber was used in everyday life: making dishes, sealing the bottoms of pie, creating waterproof "stockings", rubber was also used as glue: with it, the Indians glued feathers to the body for decoration. But Columbus's message about an unknown substance with unusual properties went unnoticed in Europe , although there is no doubt that the conquistadors and the first settlers of the New World widely used rubber

Europe really got acquainted with rubber in 1738, when the traveler S. Kodamine, who returned from America, presented samples of rubber to the French Academy of Sciences and demonstrated how to obtain it. For the first time, rubber did not receive practical use in Europe.

The first and only use for about 80 years was the manufacture of erasers for erasing pencil marks on paper. The narrowness of the use of rubber was due to the drying and hardening of rubber. He also invented a waterproof fabric obtained by impregnating a dense matter with a solution of rubber in kerosene. From this matter they began to make waterproof raincoats (received the common name "macintosh" by the name of the inventor of the fabric), galoshes, waterproof mail bags

In 1839, American inventor Charles Goodyear found a way to stabilize the elasticity of rubber by mixing crude rubber with sulfur and then heating it. This method is called vulcanization, and is probably the first industrial polymerization process. The product obtained as a result of vulcanization was called rubber. After the discovery of Goodyear, rubber became widely used in mechanical engineering as various seals and sleeves and in the emerging electrical industry, the industry of which was in dire need of a good insulating elastic material for the manufacture of cables.

The developing mechanical and electrical engineering, and later the automotive industry, consumed more and more rubber. This required more and more raw materials. Due to the increase in demand in South America, huge plantations of rubber plants began to emerge and rapidly develop, growing these plants in monoculture. Later, the center for growing rubber plants moved to Indonesia and Ceylon.

After rubber began to be widely used and natural sources of rubber could not cover the increased demand, it became clear that a replacement for the raw material base in the form of rubber plantations had to be found. The problem was aggravated by the fact that the plantations were monopoly owned by several countries (the main one was Great Britain), in addition, the raw materials were quite expensive due to the laboriousness of growing rubber plants and collecting rubber and high transportation costs. The search for alternative raw materials went in two ways: Search for rubber plants that could be cultivated in subtropical and temperate climates Production of synthetic rubbers from non-vegetable raw materials

The production of synthetic rubber began to develop intensively in the USSR, which became a pioneer in this field. This was due to an acute shortage of rubber for the intensively developing industry, the lack of effective natural rubber-bearing plants on the territory of the USSR, and the limitation of rubber supplies from abroad, as the ruling circles of some countries tried to interfere with the process of industrialization of the USSR. The problem of establishing large-scale industrial production of synthetic rubber was successfully solved, despite the skepticism of some foreign experts.

General purpose rubbers are used in those products in which the very nature of rubber is important and there are no special requirements for the finished product. Special purpose rubbers have a narrower scope and are used to give a rubber - technical product (tires, belts, shoe soles, etc.) e.) a given property, such as wear resistance, oil resistance, frost resistance, increased wet grip, etc.

The main properties of styrene butadiene are: high strength, tear resistance, elasticity and wear resistance This rubber is considered the best general purpose rubber due to its excellent properties of high abrasion resistance and high percentage of filling Used for most rubber products (including the manufacture of chewing gums)

The main advantages of butyl rubber are resistance to many aggressive media, including alkalis, hydrogen peroxide, some vegetable oils, and high dielectric properties. The most important area of ​​application of butyl rubber is the production of tires. In addition, butyl rubber is used in the production of various rubber products that are resistant to high temperatures and aggressive environments, rubberized fabrics.

One of the numerous areas of application is coatings for outdoor sports and playgrounds. Ethylene-propylene rubber is suitable for the production of hoses, insulation, anti-slip profiles, bellows. These rubbers have two significant disadvantages. They cannot be mixed with other simple rubbers and are not resistant to oil.

[-CH2-CH=CH-CH2-]n - [-CH2-CH(CN)-]m Nitrile butadiene rubber - synthetic polymer, copolymerization product of butadiene with acrylonitrile very good resistance to oils and gasolines resistance to petroleum hydraulic fluids resistance to carbon solvents resistance to alkalis and solvents wide operating range: from -57°C to +120°C. poor resistance to ozone, sunlight and natural oxidizing agents poor resistance to oxidized solvents

Chloroprene rubber crystallizes under tension, due to which rubbers based on it have high strength. It is used for the production of rubber products: conveyor belts, belts, sleeves, hoses, diving suits, electrical insulating materials. They also manufacture sheaths of wires and cables, protective coatings. Adhesives and chloroprene latexes are of great industrial importance. Chloroprene rubber is an elastic light yellow mass.

Siloxane rubbers have a set of unique properties: increased thermal, frost and fire resistance, resistance to the accumulation of residual compression deformation, etc. They are used in very important areas of technology, and their relatively high cost pays off with a longer service life compared to rubbers based on hydrocarbon rubbers

Vulcanization is the process of heating rubbers thoroughly mixed with sulfur or sulfur-containing compounds, such as, for example, thiuram:

The mixture is heated at a temperature of 130 - 160 ° C. In this case, bonds of the type are formed between the rubber macromolecules:

and even polysulfide bonds:

if the mass fraction of sulfur in the mixture is large. The vulcanization process is shown below using the example of obtaining rubber from butadiene (divinyl) rubber. For the sake of simplicity, all cross-links are shown through a single sulfur atom. In fact, there may be disulfide bridges, and if ebonite is obtained, then bridges containing 8 sulfur atoms.

Rubber is an elastic material widely used for the manufacture of tires for automotive and tractor equipment and aircraft, for conveyor belts and escalator railings. And also for the manufacture of hoses, seals, suits for divers and chemical protection, boats, shoes.

To obtain rubber, the mass fraction of sulfur in a mixture with rubber should be in the range from 0.5 to 7%.

Ebonite is a material of dark brown or black color. A dielectric that lends itself well to all types of mechanical processing, is not hygroscopic, does not absorb gases, is resistant to acids and alkalis, swells in carbon disulfide (CS 2) and liquid hydrocarbons. At 70 - 80 ° C it softens. Above 200 ° C, it chars without melting. It is highly combustible, and therefore is increasingly being replaced by other materials.

To obtain ebonite, the mass fraction of sulfur in a mixture with rubber must be at least 15%, but can reach 34%.

Ebonite is used for the manufacture of electrical products, battery cans, containers for storing acids and alkalis.

Topic or topic section	Page
Alkadienes - definition and classification
Alkadienes with cumulated double bonds
Allen, his physical properties
Electronic structure of allene
Spatial structure of allene
Chemical properties of allene. Water connection. Keto-enol tautomerism
Attachment of other polar molecules to the allene
Isolated alkadienes. Reactions of addition of non-polar and polar molecules to them.
Ionic hydrogenation of unsymmetrical isolated alkadienes. Kursanov-Parnes reaction. Selectivity in this reaction
Conjugated Alkadienes. Divinyl. Its electronic structure.
Spatial structure of divinyl.
Attachment of non-polar (H 2, Cl 2, Br 2 and I 2) and polar molecules to conjugated dienes at positions 1 - 4 and 1 - 2. Selectivity in this reaction
Reaction of divinyl with hydrogen
Reaction of isoprene with bromine
Dependence of the number of products of the addition reaction of nonpolar molecules on the presence or absence of symmetry in the structure of conjugated dienes
Dependence of the number of products of the addition reaction of polar molecules on the structure of conjugated dienes
The reaction of divinyl with hydrogen chloride
Reaction of isoprene with water
Polymerization of conjugated alkadienes
Obtaining nonstereoregular butadiene rubber
Obtaining stereoregular isoprene rubber
Ziegler-Natta catalysts
Method for producing chloroprene, its polymerization and vulcanization
Vulcanization of chloroprene rubber
Properties And Applications Of Chloroprene Rubber
Methods for obtaining 1,3-butadiene
Physical properties of 1,3-butadiene
The method of obtaining divinyl from ethyl alcohol according to S.V. Lebedev
Two-stage method for obtaining divinyl by dehydrogenation of ethanol and dehydration of a mixture of ethanol and ethanal
Method for producing divinyl from butane-butylene fraction of associated oil gases
Methods for obtaining isoprene
"Dioxane" method for obtaining isoprene from 2-methylpropene and two moles of methanal
Method for isoprene production by dehydrogenation of 2-methylbutane
Method for producing isoprene according to Favorsky from acetone and acetylene by hydrogenation of 2-methyl-3-butyn-2-ol obtained at the first stage
Physical and chemical properties of isoprene
Reaction of isoprene with maleic anhydride - Diels-Alder reaction
Vulcanization of rubbers - obtaining rubber and ebonite
Application of rubber
Performance properties of ebonite and its application
Content

Rubber is used in the production of car tires and rubber products

Rubber products in industry (manufacturing).

To obtain rubberized fabrics, they take linen or paper fabric and rubber glue, which is a rubber mixture dissolved in gasoline or benzene. The glue is carefully and evenly smeared and pressed into the fabric; after drying and evaporation of the solvent, a rubberized fabric is obtained. For the manufacture of gasket material capable of withstanding high temperatures, paronite is used, which is a rubber mixture into which asbestos fiber is introduced. This mixture is mixed with gasoline, passed through rollers and cured into sheets with a thickness of 0.2 to 6 mm. To obtain rubber tubes, rubber is passed through a syringe machine, where a highly heated (up to 100-110 °) mixture is forced through a head of the required diameter. As a result, a tube is obtained, which is subjected to vulcanization. The manufacture of durite sleeves is as follows: strips are cut out of calendered rubber and placed on a metal core, in which the outer diameter is equal to the inner diameter of the sleeve. The edges of the strips are lubricated with rubber glue and rolled with a roller, then one or more layers of fabric are applied and smeared with rubber glue, and a layer of rubber is applied on top. After that, the assembled sleeve is subjected to vulcanization. Automotive chambers are made from rubber pipes, extruded or glued along the chamber. There are two ways of making chambers: shaped and mandrel. The mandrel chambers are vulcanized on metal or curved mandrels. These chambers have one or two transverse joints. After docking, the chambers at the junction are subjected to vulcanization. In the mold method, the chambers are vulcanized in individual vulcanizers equipped with an automatic temperature controller. To avoid gluing the walls, talc is introduced into the chamber. Automobile tires are assembled on special machines from several layers of a special fabric (cord) coated with a rubber layer. Fabric frame, i.e. tire skeleton, carefully rolled, and the edges of the fabric layers are wrapped. Outside, the frame is covered in the running part with a thick layer of rubber, called a tread, and a thinner layer of carving is applied to the sidewalls. The tire thus prepared is subjected to vulcanization.

Storage of rubber products.

When storing rubber, the following conditions must be observed:

1. Air temperature should not be below 5° and not exceed 15°; humidity 40-60%.

2. Lack of daylight, for which windows should be covered with yellow or red paint that does not transmit ultraviolet rays.

3. Rubber products must lie on wooden racks, which must be located at a distance of at least 1 m from heating devices.

4. Rubber products should be wrapped with paper or cloth and packed in boxes; sleeves must be stretched, but not left in hanks. Tires cannot be stacked; they are recommended to be placed on the tread part in a row on the racks.

Sources: 1. Dzevulsky V.M. Technology of metals and wood. - M.: State publishing house of agricultural literature. 1995.S.438-440.

Links

• N. Korzinov. The battle for rubber

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See what "Rubber (rubber vulcanization product)" is in other dictionaries:

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A synthetic or natural substance that has the properties of elasticity, electrical insulation characteristics and water resistance is called rubber. Vulcanization of such a substance by carrying out reactions involving certain chemical elements or under the influence of ionizing radiation leads to the formation of rubber.

How did rubber come about?

The chronicle of the appearance of rubber in the countries of rubber Europe began when Columbus in 1493 brought outlandish treasures from the new continent. Among them was an amazingly bouncy ball that the local natives made from milky juice. The Indians called this juice “cauchu” (from “kau” - tree, “chu” - tears, cry) and used it in ritual ceremonies. The name stuck at the Spanish royal court. However, in Europe, the existence of unusual material was forgotten until the 18th century.

General interest in rubber arose only after the French navigator C. Condamine in 1738 presented scientists from the Paris Academy of Sciences with a certain elastic material, samples of products from it, its description and extraction methods. Sh. Condamine brought these things from an expedition to South America. There, the natives made various household items from the resin of special trees. This material is called "rubber", from lat. resina - "resin". It was from that time that the search for ways to use this substance began.

What is rubber?

However, there is little in common between the name resina and the concept under which we perceive this material today. After all, tree resin is just a raw material for rubber.

Vulcanization of rubber makes it possible to significantly improve its quality, make it more elastic, strong and durable. It is this process that makes it possible to obtain many varieties of rubber for technical, technological and domestic purposes.

The value of rubber

Today, the most massive received in the production of rubber. Modern industry produces various types for automobile, aviation, bicycle tires. It is used in the manufacture of all kinds of seals for detachable elements in hydraulic, pneumatic and vacuum devices.

The product obtained in the process of vulcanization of rubber with sulfur and other chemical elements is used for electrical insulation, in the production of medical and laboratory instruments and devices. In addition, various rubbers are used to make heavy-duty, anti-corrosion coatings for boilers and pipes, various types of adhesives and thin-walled high-strength small products. The synthesis of artificial rubber made it possible to create some types of solid rocket fuel, where this material plays the role of fuel.

What is rubber vulcanization and what does it do?

The technological process of vulcanization involves the mixing of rubber, sulfur and other substances in the required proportions. They are heat treated. When rubber is heated with a sulfur agent, the molecules of this substance are bonded to each other by sulfur bonds. Some of their groups form a single three-dimensional spatial grid.

The composition of rubber includes a large amount of hydrocarbon polyisoprene (C5H8) n, proteins, amino acids, fatty acids, salts of some metals and other impurities.

In a molecule of natural rubber, up to 40 thousand elementary units can be present, it does not dissolve in water, but it breaks down perfectly. However, if the rubber is able to almost completely dissolve in gasoline, then the rubber will only swell in it.

Vulcanization of this material helps to reduce the plastic properties of rubber, optimizes the degree of its swelling and solubility in direct contact with organic solvents.

The rubber vulcanization process provides the resulting material with more durable properties. Rubber made using this technology is able to maintain elasticity over a wide temperature range. At the same time, violations of the technological process in the form of an increase in the addition of sulfur lead to the appearance of hardness of the material and the loss of elastic abilities. The result is a completely different substance, which is called ebonite. Before the advent of modern ebonite, it was considered one of the best insulating materials.

Alternative Methods

Nevertheless, science, as you know, does not stand still. Today, other vulcanizing agents are known, but sulfur still remains the highest priority. To accelerate the vulcanization of rubber, 2-mercaptobenzthiazole and some of its derivatives are used. As an alternative technique, ionizing radiation is carried out using certain organic peroxides.

Usually, in any type of vulcanization, a mixture of rubber and various additives is used as the feedstock, giving the rubber the required properties or improving its quality. The addition of fillers such as carbon black and chalk helps to reduce the cost of the resulting material.

As a result of the technological process, the rubber vulcanization product acquires high strength and good elasticity. That is why various types of natural and synthetic rubbers are used as raw materials for the manufacture of rubber.

Prospects for further development

Thanks to the development of synthetic rubber production technologies, rubber production is no longer completely dependent on natural material. However, modern technology has not displaced the potential of a natural resource. To date, the share of consumption of natural rubber for industrial purposes is about 30%.

The unique qualities of a natural resource make rubber irreplaceable. It is necessary in the production of large-sized rubber products, for example, in the manufacture of tires for special equipment. The most famous tire manufacturers in the world use mixtures of natural and synthetic rubbers in their technologies. That is why the largest percentage of the use of natural raw materials falls on the tire sector of the industry.

The main ways to obtain rubber in nature:

1) rubber is obtained from the milky juice of some plants, mainly Hevea, whose birthplace is Brazil;

2) incisions are made on Hevea trees to obtain rubber;

3) milky juice, which is released from the incisions and is a colloidal solution of rubber, is collected;

4) after that, it undergoes coagulation by the action of an electrolyte (acid solution) or by heating;

5) rubber is released as a result of coagulation.

The main properties of rubber:

1) the most important property of rubber is its elasticity.

Elasticity- this is the property of experiencing significant elastic deformations with a relatively small acting force, for example, stretching, compressing, and then restoring its previous shape after the termination of the force;

2) a valuable property of rubber for practical use is also impermeability to water and gases.

In Europe, rubber products (galoshes, waterproof clothing) began to spread from the beginning of the 19th century. The famous scientist Goodyear discovered rubber vulcanization process- turning it into rubber by heating with sulfur, which made it possible to obtain durable and elastic rubber.

3) rubber has even better elasticity, in this no other material can compare with it; it is stronger than rubber and more resistant to temperature changes.

In terms of its importance in the national economy, rubber is on a par with steel, oil, and coal.

Composition and structure of natural rubber: a) qualitative analysis shows that rubber consists of two elements - carbon and hydrogen, i.e. belongs to the class of hydrocarbons; b) its quantitative analysis leads to the simplest formula C 5 H 8; c) the determination of the molecular weight shows that it reaches several hundred thousand (150,000–500,000); d) rubber is a natural polymer; e) its molecular formula is (C 5 H 8) n; f) rubber macromolecules are formed by isoprene molecules; g) rubber molecules, although they have a linear structure, are not elongated in a line, but are repeatedly bent, as if folded into balls; h) when the rubber is stretched, such molecules straighten out, the rubber sample becomes longer from this.

Characteristic features of rubber vulcanization:

1) natural and synthetic rubbers are used mainly in the form of rubber, since it has a much higher strength, elasticity and a number of other valuable properties. To obtain rubber, rubber is vulcanized;

2) from a mixture of rubber with sulfur, fillers (soot is an especially important filler) and other substances, the desired products are molded and heated.

26. Aromatic hydrocarbons (arenes)

Characteristic features of aromatic hydrocarbons:

1)aromatic hydrocarbons (arenes) are hydrocarbons whose molecules contain one or more benzene rings, for example:

a) benzene;

b) naphthalene;

c) anthracene;

2) the simplest representative of aromatic hydrocarbons is benzene, its formula is C 6 H 6;

3) the structural formula of the benzene nucleus with alternating three double and three single bonds was proposed as early as 1865;

4) known aromatic hydrocarbons with multiple bonds in the side chains, such as styrene, as well as polynuclear, which contain several benzene nuclei (naphthalene).

Methods for obtaining and using aromatic hydrocarbons:

1) aromatic hydrocarbons are contained in coal tar obtained by coking coal;

2) another important source of their production is the oil of some fields, for example Maikop;

3) to meet the huge demand for aromatic hydrocarbons, they are also obtained by catalytic aromatization of acyclic petroleum hydrocarbons.

This problem was successfully solved by N.D. Zelinsky and his students B.A. Kazansky and A.F. Plate, who converted many saturated hydrocarbons into aromatic ones.

So, from C 7 H 16 heptane, when heated in the presence of a catalyst, toluene is obtained;

4) aromatic hydrocarbons and their derivatives are widely used to obtain plastics, synthetic dyes, drugs and explosives, synthetic rubbers, detergents;

5) benzene and all compounds that contain a benzene nucleus are called aromatic, since the first studied representatives of this series were fragrant substances or compounds isolated from natural aromatic substances;

6) now this series also includes numerous compounds that do not have a pleasant smell, but have a complex of chemical properties called aromatic properties;

7) many other aromatic polynitro compounds (containing three or more nitro groups - NO 2) are also used as explosives.