Polymers and materials, household items, equipment made from them are an important part of industry and human life as a whole. Natural resources, unfortunately, have been greatly depleted during their use. Therefore, people had to learn how to synthesize artificial materials that have a number of important technical characteristics. One of these is polypropylene. The chemical formula of this compound, the features of its properties and the structure of the molecule will be considered during the article.
Polymers - General Description
This class of compounds includes those that have a very high molecular weight. After all, polymers are complex organic compounds consisting of repeatedly repeating monomeric units, which can be from several tens to hundreds, thousands and millions.
Among all polymers, the following groups can be distinguished:
- Natural origin - proteins, nucleic acids, ATP molecules and so on.
- Artificial - those that are based on natural, but have been chemically modified in order to improve technical characteristics. For example, artificial rubbers.
- Synthetic - those that are created only through chemical reactions, synthesis in the laboratory and industrial plants. Synthetic fabrics and fibers, polyethylenes, synthetic rubbers, polyvinyl chloride, polypropylene and others can serve as examples.
All designated polymer groups are an important industrial raw material for the production and production of various equipment, household items, dishes, toys, furniture and other things.
Representatives of the most important synthetic polymers
The chemical formula of one of the most important representatives of synthetic polymers is written as (-CH 2 -CH 2 -) n . This is polyethylene. Areas of its use are known. These are household needs (household film), and industrial, and food industry (packaging material). However, although it is the most common, it is by no means the only representative that is extremely important for humans. You can also name polymers such as:
- polyvinyl chloride;
- polypropylene;
- polyisobutylene;
- polystyrene;
- teflon;
- polyvinyl acetate and others.
It is in the construction business, as well as for the manufacture of dishes, such a material as polypropylene plays an important role. Therefore, we will further consider precisely its features from a chemical point of view.
Polypropylene Formula
From the point of view of the science of chemistry, the composition of a given substance can be expressed by different types of formulas. The first option is a molecular form of recording. In this case, the polypropylene formula looks like this: (C 3 H 6 ) n . The last n means the degree of polymerization, that is, the number of structural starting units in the macrochain.
Such a record allows us to conclude about the qualitative and quantitative composition of the molecule. Polypropene consists of carbon and hydrogen atoms, and their number in the monomer unit is 3/6, respectively, and in the general chain depends on the exponent n. If we talk about the structure of the compound itself, about the order of the bonds of atoms in the molecule, then another kind of recording of the substance is necessary.
Polypropylene: structural formula
The type of record, which shows the order of the atoms in a molecule, is called the structural formula. For the substance we are considering, it will have the following form: (-CH 2 -CH-CH 3 -) n . Obviously, the generally accepted valency of atoms in organic chemistry persists in this case as well. The formula of polypropylene or polypropene shows which monomer unit underlies the compound. It is formed from unsaturated hydrocarbon (alkene) propene or propylene. Its empirical formula: C 3 H 8 .
Starting Monomer
The monomer formula for producing polypropylene is as follows: (—CH 2 —CH — CH 3 -). If this fragment is repeated several hundred times, then we will get a whole macromolecule of a synthetic polymer, which is the material under consideration. In addition, we have already pointed out that in general the usual alkene, propene, should be considered the starting material for the polymerization reaction. He is the monomer of polypropylene. The structural formula will be written as CH 3 —CH = CH 2 . When a double bond is broken during the polymerization, the desired fragment is formed. The same monomer unit, which, repeating itself, forms a polymer macromolecule.
Physical and chemical properties
The formula of polypropylene (-CH 2 -CH-CH 3 -) n allows us to judge its physical and chemical characteristics. We list the main ones.
- Physical properties of this polymer: density 0.91 g / cm 3 , solid, abrasion resistant, not subject to corrosion. The color is white, opaque. The smell is absent. In water, organic solvents at ordinary temperatures, insoluble. When the indicator is above 100 0 C it dissolves in hydrocarbon compounds. It begins to soften after 140 0 , at 170 0 it melts. It has heat and frost resistance.
- Chemical properties. From the point of view of activity, polypropene can be attributed to practically inert substances. It is able to interact only with especially strong oxidizing agents: fuming nitric, chlorosulfonic acids, oleum, active halogens (fluorine, chlorine). It does not interact with water at all, even at elevated temperatures. It reacts with oxygen only when irradiated with ultraviolet light; the process is accompanied by polymer destruction. In organic solvents swells and dissolves with increasing temperature.
The indicated properties can be attributed to the technical characteristics of the material itself, which is used in industry. However, not all polypropylene is the same. There are special stabilizing additives with the help of which various varieties of the polymer under consideration are created.
Material Specifications
Several basic properties that polypropylene possesses can be identified. Its characteristics are as follows:
- When heated, it is able to melt, previously softened.
- It does not have conductive properties.
- Shockproof, durable for wear.
- Resistant to abrasion.
- Ages when exposed to the sun and oxygen, but the process is quite slow.
- Like a polymer, it has a small molecular weight.
- It has white color, is translucent, has no taste or smell.
- When burned, it does not emit harmful substances, emits a light floral aroma.
- It is flexible, durable, resistant to various kinds of pollution.
- It has heat and frost resistance.
All the indicated properties of polypropylene as a material make it possible to use it for various needs. It is easy to use, convenient to care for and use in the practical activities of any sector of the national economy.
In total, three main varieties of this material can be distinguished:
- attactic;
- syndiotactic;
- isotactic.
The main difference in them is the spatial structure of the molecule. Specifically, the location of methyl groups in the chain. Also, stabilizing additives, the number of monomer units in the macrostructure influence the technical characteristics.
This material is produced either in the form of crystalline granular structures, or in the form of fibers, sheets.
Areas of use
Polypropylene material is used for the production of various films, packaging containers, food containers. It is from it that ordinary plastic cups and other items of disposable tableware are made. This material is used for the manufacture of durable, resistant to chemical agents polypropylene plumbing pipes.
It is also used to create soundproof materials. Adhesive tape is also one of the varieties of polypropylene.
Attactic material is used for the manufacture of:
- mastic;
- adhesives;
- putty;
- sticky tapes;
- road surfaces and stuff.
A large number of polypropylene sheets, fibers are spent on the manufacture of toys, stationery, household and household items.