We explain what plastic is, the types that exist and the various uses of this polymer. In addition, its history and its properties.
What is plastic?
Plastic is the generic and common name given to a series of substances molecular structure and similar physicochemical characteristics, whose fundamental characteristic is to have elasticity Y flexibility during an interval of temperatures, thus allowing its molding and adaptation to various shapes. This name comes from his eminent plasticity, that is to say, its facility to acquire certain forms.
Most plastics are, specifically, synthetic materials and petroleum derivatives, obtained through polymerization processes, that is, processes of synthesis of long chains of atoms of carbon, which give rise to an organic substance that is malleable when hot and resistant to cold. There are also plastics that are not derived from petroleum, such as plastics derived from starch, cellulose and certain bacteria.
This material is extremely versatile thanks to its lightness, pleasant touch and resistance to both biological and environmental degradation (except for prolonged exposure to UV rays in some cases).
These properties are difficult to achieve with other materials, and make plastic both a blessing and a problem, since while being the most useful and effective synthetic material in human history, it is also the main source of pollution solid of planet (trash). Fortunately, plastic is recyclable, although its production is much cheaper and easier than its reuse.
When subjected to direct heat, most plastics release gases rich in dioxins and furans, carcinogenic hydrocarbons and compounds capable of suffocating living beings, in addition to causing tremendous atmospheric damage.
Types of plastic
There are various ways of classifying plastics, such as:
- According to the origin of the monomers that compose it.
- Natural The monomers come from natural substances such as rubber, cellulose and casein (protein present in milk). For example: cellophane and rubber.
- Artificial. Monomers come from synthetic substances, mainly derived from Petroleum. For example: polyethylene.
- According to its reaction to heat.
- Thermoplastics. When heated they acquire a liquid consistency and when cooled they acquire a vitreous state (similar to glass). This type of plastic can be heated and molded, and then it can be reheated several times and change its shape back. For example, him polyethylene and rubber.
- Thermostable. When heated, they are molded and cooled to take a certain shape, then it is impossible to reheat them to melt them again. That is why they are said to be rigid or thermodide. For example: Bakelite and polyesters.
- Elastomers Also called "rubbers", they are polymers with high elasticity. If a force deforming, have a high capacity to recover their original shape when said force is removed. For example: neoprene.
- According to its molecular structure.
- Amorphous. Their molecules are disorganized and do not tend to form any structure ordered, which is why they leave large spaces between their particles for the light, thus achieving transparent plastics. For example: atactic polystyrene.
- Crystallizable. They tend to form rigid crystals resistant to deformation. Depending on the cooling rate of a polymer its crystallinity can be increased or decreased. If it is cooled fast it decreases its crystallinity, and if it is cooled slowly, its crystallinity increases. In the case of amorphous plastics, they will not have any level of crystallinity, no matter how fast they cool. For example: polypropylene is a crystallizable plastic.
- Semi-crystallizable. They have intermediate characteristics between amorphous and crystallizable, since they have disordered areas and other ordered ones. The passage of light through them will depend on their thickness. For example: low poly density.
Uses of plastic
The applications of plastic are virtually endless: from spare parts for electronic, electrical and industrial devices, such as insulators, protectors, covers, shock absorbers, etc., to components of the construction sector such as pipes, waterproofing, insulation, glass, etc.
Another very common use of plastic is in the manufacture of tools, toys, packaging, furniture, containers, dividers, fasteners and, above all, bags.
History of plastic
The invention of plastic revolutionized human industry forever. It was initially developed at the end of the 19th century as a substitute for ivory to create billiard balls, by the American John Weasley Hyatt, who was able to synthesize a celluloid by dissolving vegetable cellulose in camphor and ethanol.
Years later, in 1909, Leo Hendrik Baekeland made a polymer from phenol and formaldehyde, which was the first synthetic plastic in history, still known as “bakelite”.
This is considered as the beginning of the "era of plastic" that had its peak in the twentieth century, when the exploration of plastic resins began and their subsequent application to practically all fields of the industry.
Ten years later, in 1919, the macromolecular composition of plastic was discovered thanks to the studies of the German Hermann Staudinger.
Plastic properties
Plastics are sets of organic macromolecules, generally of synthetic origin, mostly waterproof, resistant, diamagnetic and good acoustic, electrical and thermal insulators, although they are not very resistant to temperatures very high in their entirety.
In addition, they are not very dense, cheap to manufacture, easy to work and mold. Once they have cooled down to a certain shape, they are resistant to corrosion and many chemical elements, except organic solvents (such as thinner, diluent whose name comes from English).
For the rest, most plastics are not biodegradable, although they are currently experimenting in that direction, nor are they easy to Recycle, which makes them an important source of contamination that persists in the weather.