Scientific research results in pandemic conditions (COVID-19)
157
Boytemirov Otabek Eshmurodovich, Assistant teacher of Karshi University
of Engineering Economics
Shukurov Abror Sharipovich, The master student of Karshi University of
Engineering Economics, Neâmatov
Xusan Ibodullayevich, Karshi University of Engineering Economics
Qoâyboqarov Oybek Ergashevich, Karshi University of Engineering
Economics
STYRENE-BASED ORGANIC SUBSTANCES, CHEMISTRY OF POLYMERS AND
THEIR TECHNOLOGY
O. Boytemirov, A. Shukurov, O. Qoâyboqarov
Abstract: In this article, we discuss the properties of styrene, the organic
substances derived from it, and the chemistry and technology of polymers.
Keywords: Styrene, lipid, aerosol, pharynx, inhalation, polymer,
monomer, organic substances.
Physical properties: Styrene is a poison of general toxicity. It has
irritating, mutagenic and carcinogenic effects. It smells very bad. In case of
chronic intoxication, workers disrupt the metabolism of the central and
peripheral nervous systems, hematopoietic system, gastrointestinal tract,
nitrogen-protein, cholesterol and lipids, and reproductive diseases occur in
women. Styrene enters the div mainly through inhalation. If steam and
aerosol are sprayed on the mucous membranes of the nose, eyes and
pharynx, styrene causes irritation. Urinary metabolites benzene - mandelic
acid, phenylglyoxic acid, ginuric acid and benzoic acid are used as exposure
tests. Styrene is easily oxidized, halogens are added, polymerized (forms a
solid glass mass - polystyrene) and copolymerized with various monomers.
Polymerization continues at room temperature (sometimes as the
temperature rises), so styrene stabilizes antioxidants (e.g., ter-
butylpirocatecol, hydroquinone).
For example, halogenation reacts with bromine to form 1,2-
dibromethylbenzene with the vinyl group, not with benzene, unlike aniline.
Styrene is used almost exclusively for the production of polymers. Many
types of styrene-based polymers include polystyrene, polystyrene
(expanded polystyrene), styrene modified polyesters, ABS plastics
(acrylonitrile-butadiene-styrene)
and
SAN
(styrene-acrylonitrile).
Copolymerization reaction of butadiene and styrene in production and
forms styrene butadiene rubbers used in the manufacture of molded and
non-molded rubber products.Due to their radiation resistance, styrene-
butadiene rubbers are used in the production of gamma radiation resistant
rubbers. Styrene is easily oxidized, binds halogens, polymerizes (forms a
solid vitreous mass - polystyrene) and is copolymerized with various
monomers. Polymerization also occurs at room temperature (sometimes by
Scientific research results in pandemic conditions (COVID-19)
158
explosion), so it is stabilized with antioxidants (e.g., ter-butylpirocatecol,
hydroquinone) during storage. For example, halogenation occurs in the
reaction with bromine, unlike aniline, not along the benzene ring, but along
the vinyl group with the formation of 1,2-dibromethylbenzene. Styrene was
first isolated in 1831. But before World War II, styrene and its polymers
were not widely used in industry. Styrene was first obtained on an industrial
scale in 1930 in Germany. Styrene production began in the United States in
1933, but the polystyrene synthesized from it was of low quality and cheap.
Styrene was used only to produce polystyrene in powder form for injection
molding. The availability of large production facilities for the production of
monomeric styrene has encouraged the expansion of research on the use of
polystyrene in new industries, particularly in the production of consumer
goods. The development of research in the field of synthesis of polymers and
styrene copolymers has led to the creation of a large group of polymeric
materials with different properties. Ethylbenzene is a catalytic reforming
product in the C8 fraction of aromatic hydrocarbons, which can be separated
by distillation. However, this is an expensive method.
In practice, ethylbenzene is obtained by the classical exothermic
reaction by alkylation of benzene with ethylene in the liquid phase as a
catalyst for aluminum chloride: possible. Styrene can be obtained by
reaction of benzaldehyde with flax in the presence of boric acid or zinc
chloride at a temperature of 273-283 K and then decarboxylation by heating
in the presence of boric acid: Industrial polymers are used in packaging
materials, textiles, household items, building materials and others. Used as
polymers in fibers, films, coatings, foams and molded products. Polymers
have strength, hardness, impact strength, flexibility, elasticity, flexibility,
optical transparency, chemical resistance and more. These properties can be
modified initially using additives specific to polymers: plasticizers, fillers,
dyes, stabilizers. IN assigned to three groups can be polymeric materials
depending on these properties: elastomers, plastics, fibers. Elastomers
exhibit increasing re-deformation (elasticity), fibers - increasing stiffness,
plastic - strength and stiffness.Chain polymerization involves three main
stages: excitation, chain growth and fracture, and reaction continuation.
mechanisms through possible free radical, ionic or ionic coordination.
Depending on the reaction mechanism, free radical, ionic (cationic or
anionic) and ionic coordination polymerization. With stepwise
polymerization, monomers are formed as a result of the interaction of
functional groups with the construction of the polymer chain. The reaction
is carried out using a step-by-step mechanism (i.e., sequential, independent
motions) and the chain growth occurs slowly (unlike chain polymerization,
where chain growth occurs very rapidly ). Phased polymerization continues
through the formation of dimers, trimers, tetramers and others. Each of
Scientific research results in pandemic conditions (COVID-19)
159
these mediators can remove primary monomers with the same function
from the reaction zone and re-enter the reaction zone. Often, stepwise
polymerization is accompanied by the release of simple substances of low
molecular weight. Polymerization is a simple, low molecular weight
compound that is further complicated by high molecular weight. To do this,
each molecule of the source must be at least two molecules of the same or
different types of compounds, or in other words, source molecules, at least,
the functional capacity of the two-way bond depends on the number of
reaction groups (-OH, -COOH, -NH2, etc.), in which the presence or presence
is a double or triple bond. Depending on the performance of the resource,
the monomer is a linear, branched, or three-dimensional cross-linked
polymer. Separate the chain and step polymerization. In the case of
destruction according to the law of operation, the breakage of the
macromolecule chain occurs at any random place, accompanied by the
formation of low molecular weight parts, but the monomer is almost not
formed. It is not necessary if there are active centers in the polymer chain
when the law is violated. Decomposition of polymers can occur under the
influence of physical factors - heat, light, mechanical stress and chemicals -
oxygen, ozone, acids, alkalis. Thermal destruction continues under the
influence of temperature, both on the chain mechanism and according to the
law of chance. The rate of thermal decomposition determines the thermal
stability of the polymer and is determined by the strength of the bonds.
Thus, the bond strength for carbocaine polymers depends on the type of CC
substituents and their number. Increasing the number of ethylene -
propylene - isobutylene in series from left to right reduces the bond strength
in the main chain, and therefore the thermal stability of polypropylene is less
heat resistant than that of polyethylene and polyisobutylene. If there is an
atom, replace the hydrogen in ethylene with a phenyl group; polystyrene
polyethylene with relatively less thermal stability. All substitutions do not
necessarily reduce thermal stability. In some cases, the process of polymer
degradation is not associated with the destruction of the main chains and
side groups. Organic compounds, organic substances - substances
associated with hydrocarbons or their derivatives, ie almost all chemicals
containing carbon [1] is a class of chemical compounds that combine
compounds (except carbides, carbonic acid, carbonates, some carbon
oxides, etc.). Rhodanides, cyanides). Organic compounds are rare in the
earthâs crust, but are of great importance because all known life forms are
based on organic compounds.Such substances often enter the next life cycle,
such as soil organic matter (by the way, the annual production of the
biosphere is 380 billion tons) [2]. The main distillates of oil are the building
blocks of organic compounds [3]. Organic compounds, in addition to carbon
(C), are often hydrogen (H), oxygen (O), nitrogen (N), less - sulfur (S),
Scientific research results in pandemic conditions (COVID-19)
160
phosphorus (P), halogens (F, Cl, Br, I) includes , barium (B) and some metals
(separately or in various combinations) [4]. The main classes of organic
compounds of biological origin - proteins, lipids, carbohydrates, nucleic
acids, in addition to carbon, mainly hydrogen, nitrogen, oxygen, sulfur and
phosphorus there is. For this reason, âclassicâ organic compounds mainly
contain hydrogen, oxygen, nitrogen, and sulfur, but the elements that make
up organic compounds other than carbon can be almost any element. Carbon
compounds with other elements form a special class of organic compounds
- organoelement compounds. Compounds with the same composition and
molecular weight, but with different physicochemical properties. This
phenomenon is called isomerism. Polymers are a special type of substance
also known as high molecular weight compounds. Their structure usually
includes many small segments (compounds). These segments can be similar
to each other, then we talk about homopolymer. Polymers belong to
macromolecules - a class of substances composed of molecules of very large
size and mass. Polymers can be organic (polyethylene, polypropylene,
plexiglass, etc.) or inorganic (silicone); synthetic (polyvinyl chloride) or
natural (cellulose, starch) .There are currently several methods for
characterizing organic compounds: Crystallography (X-ray diffraction) is
the most accurate method, but a sufficiently high quality crystal is required
to obtain high accuracy.
Therefore, this method is not used very often. Elemental analysis is a
destructive method used to determine the composition of elements in a
molecule of a substance. Infrared spectroscopy (IR): mainly used to prove
the presence (or absence) of functional groups. Mass spectrometry: used to
determine the molecular weights of substances and how they are broken
down. NMR nuclear magnetic resonance spectroscopy. Ultraviolet
Spectroscopy (UV): Used to determine the level of bonding in a system.
References:
1.
Chemical Encyclopedia / Editorial Board: Knunyants I.L. et al. - M .:
Soviet Encyclopedia, 1995. - T. 4 (Half Three). - 639 b. - ISBN 5-82270-092-
4.
