We explain what polymer is, their classification, properties and characteristics. In addition, natural and synthetic polymers.
What is a polymer?
In chemistry , polymers are a type of macromolecules consisting of chains of simpler units , called monomers, linked together by covalent bonds (Van der Waals forces, hydrogen bonds or hydrophobic interactions). Its name, in fact, comes from the Greek polys (“many”) and groupers (“segment”).
They are generally organic molecules of enormous importance both in the natural and in the industrial world of the human being . These include the DNA in our cells or the starch of the plants, even the nylon and most plastics .
At the end of the 19th century and the beginning of the 20th century, how to manipulate them was discovered . This revolutionized the handling of materials by humanity forever.
If they are classified according to their origin , the polymers can be:
- N atural polymers . Its origin is biological.
- Inthetic s polymers . They are created entirely by the human being.
- Emitynthetic s polymers . They are created by transformation of natural polymers.
If they are classified according to their composition , we can distinguish between:
- Polymers or organics , which have a main chainof carbon atoms .
- Polymers or vinyl organics , similar to organic ones, but with carbon-carbon double bonds. They include polyolefins, styrenics, halogenated vinyl and acrylics.
- Polymers or non-vinyl organics have oxygen and / or nitrogen atoms in their main chain, in addition to carbons. They include polyesters, polyamides and polyurethanes.
- Norgan and polymers , based on other elements such as sulfur (polysulfides) or silicon (silicone).
Natural polymers exist as such in nature , as biomolecules and compounds that make up the body of living beings . The emergence of natural polymers in the world represented an important point in the biochemical complexity of life .
These include the vast majority of proteins , nucleic acids, polysaccharides (complex sugars, such as plant cellulose and fungal chitin ), rubber or vegetable rubber, and a huge etcetera.
The first synthetic polymer was created in 1907: bakelite , durable and inexpensive material. Its great industrial success was largely due to its simple and economical manufacturing, using phenol and formaldehyde. Much progress has been made since then in obtaining new and more powerful materials of organic origin, particularly in the petrochemical industry.
The polymers can be created in the laboratory by joining specific monomers in a chain , using organic or inorganic inputs, under controlled conditions of temperature , pressure and presence of catalysts. This generates a chain or step reaction that results in the generation of the compound .
Properties and characteristics of polymers
In general, polymers are bad electrical conductors , so they are often used as insulators in the electrical industry, for example, plastic as a cable wrap. However, there are conductive polymers, created in 1974, whose applications are still being studied.
Temperature, on the other hand, is an important factor in the behavior of polymers. At low temperatures they become hard, fragile , similar to glass, while at normal temperatures they tend to elasticity . If the temperature rises towards its melting point , they begin to lose their shape and decompose.
Examples of polymers
Some of the best known and most important human polymers are:
- Polyvinylchloride . Also known as PVC and of general formula (C 2 H 3 Cl) n , it is obtained from the polymerization of vinyl chloride units. It is the derivative of the most versatile plastic known and used for all types of packaging, footwear, coatings, flexible and even pipes.
- Polystyrene . Known as PS, it is obtained from styrene monomers, being able to obtain very diverse results: more or less transparent, more or less brittle, or even very dense and waterproof variants. It was first synthesized in Germany in 1930 and since then about 10.6 million tons are produced annually in the world.
- Polymethylmethacrylate . Abbreviated with the acronym PMMA, it is a typical engineering plastic, and is one of the most competitive in terms of its industrial applications, being extremely transparent and resistant.
- Polypropylene . Referred to as acronym PP, it is a thermoplastic polymer, partially crystalline and made from propylene or propene. It is used in food packaging, tissues, laboratory equipment and transparent films or films to coat.
- Polyurethane . This polymer is obtained by combining hydroxyl bases and diisocyanates, and they can be thermoplastic or thermostable. They are frequently used in the footwear, paint, synthetic textile fibers, packaging, preservatives or machine and vehicle components industry.