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24 March 2022

Curiosity about plastics

A short guide to discover the curiosities, characteristics and properties of plastics

Plastic is an extremely versatile, durable and innovative material and is now used in many different industries. The terms comes from the Greek "plastikos", meaning "suitable for moulding".

One of the main characteristics of plastics is their malleability, i.e. their ability to take and maintain any shape. The first experiments to create plastics derived from petroleum date bake to the 1920s, but it was from the 1930s with the invention of plexiglass, followed by PVC and polyurethane , that plastics began to become more and more popular for use in the home, becoming the protagonist of everyday life.

You will have heard a lot about this material. But do you really know all its properties and advantages? Let's find out how it was created, how it is produced, its main characteristics and some interesting facts about its use. 

History of plastics: how did it come about?

Plastics are considered a relatively recent and modern material, but they have a long history. In the 19th century, Englishman Alexander Parkens, while studying cellulose nitrate, patented the first semi-synthetic plastic, which he called Parkesine (also know as Xylonite), and which was initially used to make handles and boxes.

The real spread of the new material began a few years later, when the American Hyatt brothers discovered the celluloid formula for the production of billiard balls. At the time, the material could not be processed using high-temperature moulding techniques because it was highly flammable. The problem was only solved with the development of cellulose acetate, which was flame retardant and could therefore be used in various sectors such as aviation and film.

The history of plastics was marked by other important milestones in the following years, such as the discovery of PVC and cellophane production processes, but it was in the 1920s and 1930s that a truly modern plastics industry was created with the introduction of new processing and moulding techniques:

  • in 1933, polyethylene was invented;
  • in 1938, nylon (polyamide), a synthetic fibre used mainly in textiles, was invented;
  • in 1941 polyethylene terephthalate (PET) was patented, used mainly for the production of artificial textile fibres, and, latet, for food packaging;
  • in 1954, Giulio Natta invented isotactic polypropylene, which in the following years was increasingly used for the production of household items.

The 1960s saw the definitive affirmation of plastics as indispensable and increasingly common materials in everyday life. Thanks to the development of so-called "technopolymers", such as polymethylpentene, which is perfectly trasparent and resistant to sterilisation, or polyimides, thermosetting resins that are unalterable even at high temperatures, plastics also found applications in the medical, automotive, mechanical and household appliance industries.

How is plastic produced?

Plastics are produced from compounds of carbon and hydrogen, called monomers, which in turn are derived from fossil fuels such as oil or methane. The monomers are joined together through special chemical processes to form polymers of different lenghts. This produces synthetic resins, to which other elements are added, suc as dyes and other substances that serve to give the plastics the desired characteristics. The materials obtained are then transformed into granules and powders, ready to be processed and transformed into plastic objects of various types.

Characteristics and properties of plastics

Plastics is a particularly durable material with a long life cycle: it is not biodegradable, does not melt and is resistant to weathering. Solid and light at room temperature, it is an excellent electrical, thermal and acoustic insulator. Depending on its composition, each plastic material can have specific characteristics and properties. In general we distinguish beetween:

  • thermoplastics, such as polyethylene (PE), polypropylene (PP), PET and PVC, which can be easily melted, softened and shaped several times and have very good resistance to acids, but not to solvents;
  • thermosetting plastics that can be processed at high temperatures but, once formed and hardened, cannot be moulded. These plastics, including polyurethane, are resistant to solvents but not to acids.

Among the properties of plastics are their excellent resistance to stress, which can be even higher in the case of special plastics, ther extreme ductility and malleability, as well as the high level of hygiene ensured, which makes them particularly suitable for packaging of food products.

Plastic recycling and environmental sustainability

Although plastic is not biodegradable, it can be properly disposed of, recycled through various processes and then reused to produce new plastic products, or fed into waste-to-energy plants to produce heat or electricity. The problems with plastics do not so much arise from their production as from poor disposal practices, which lead to their dispersion or accumulation in the environment. This is why it is essential to engage in separate waste collection and to correctly separate waste according to the material it is made of. A small gesture, however, can be important in reducing environmental impact and helping to preserve marine and terrestrial ecosystems.

Some interesting facts you (perhaps) don't yet know about plastics

Thanks to its extraordinary versatility, plastics can be used in the most diverse sectors and areas of use, but there are some interesting facts about this material you may not yet know:

  1. Fleece fabric has the same origin as plastic bottles: this syntethic textile is made from a fibre derived from polyester and is obtained by a special mechanical process. The recycling process of PET (polyethylene terephthalate) bottles makes it possible to produce fleece clothing and sweatshirts. Once shredded, the recycled plastic material is fed into washing tanks, milled, dried and reprocessed into a bulky, soft synthetic fibre, ready to be woven.
  2. In Scotland there is a bridge made entirely of recycled plastic bottles: the structure, built in just two weeks using 50 tonnes of PET plastic waste, is about 30 metres long and allows pedestrians and vehicles to pass underneath. Recycled and 100% recyclable, the bridge is a perfect example in the world of a structure of this size built with recycled plastic.
  3. In Beijing, it is possible to pay for underground tickets by recycling plastic: thanks to special machines located in the various stations, passangers can travel for free simply by putting empty bottles and containers in the bins, thus helping to preserve the environment and increase plastic recycling.
  4. Cellophane is biodegradable: unlike polypropylene sheets, cellophane is produced from viscose, a water-soluble cellulose derivative, and is biodegradable after 90 days in cantact with the soil.
  5. Researchers have created plastic polymers that are able to regenerate themselves spontaneously, flexible and fully recyclable, these polymers may have enormous potential for large-scale development for use in multiple applications, as well as significant ecological advantages over non-recyclable plastics.
  6. According to the 2020 Sustainability Report of Corepla (the National Consortium for the collection, recycling and recovery of plastic packaging), in 2020 in Italy, 1,820,270 tonnes (95%) were recovered. 47% of plastic packaging was sent for recycling, while 48% was used to produce energy. Thanks to recycling, 458,00 tonnes of virgin raw material and 9,472 Gwh of primary energy were saved and 906,000 tonnes of CO2 eq. emissions were saved, with considerable healyh and environmental benefits.
  7. According to the Corepla report, in 2020 the urban separate collection of plastic packaging waste (i.e. that delivered by end consumers and collected by the municipalities) reached 1,433,203 tonnes, an increase of 4% compared to the previous years. The quantity collected in relation to the number of inhabitants served also increased (23.7 kg per inhabitant). The collection consists of 90.6% plastic packaging and the remaining 9.4% foreign and neutral fracions contained in single-material collection. The recovery of more than one million tonnes of plastic packaging waste avoided 34 million cubic metres of waste going to landfill.

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