There plastic it is a synthetic or semi-synthetic material that is easily malleable and therefore capable of being shaped to acquire the most disparate shapes. The first plastics were produced in the nineteenth century, but large-scale diffusion occurred in the following century, especially after the end of the Second World War. At the basis of the plastic boom were new scientific discoveries, including those made by the Italian chemist Giulio Natta in the 1950s, which allowed more materials to be produced efficient and economical. Plastic has thus become a constant presence in our daily lives and an important element of modernization of society. Global production today is more than two hundred times higher than it was in the 1950s, but, along with numerous advantagesis also worrying environmental problems.
What is plastic
Plastic is a man-made material. Its main characteristic lies in the fact that it is shaped by the effect of heat or pressure, but when it cools maintains the desired shape. Plastic is made up of polymersi.e. macromolecules, and is “built” through the use of hydrocarbons: oil, natural gas, coal.
However, there is not just one type of plastic. In contrast, plastics can be divided based on numerous parameters. The most important subdivision concerns the reaction to heat, for which two macro categories are distinguished:
- Thermoplastics, which can be reshaped and recycled. This type of material is used for food packaging, bottles, most household objects and many other applications.
- Thermosetting plastics, which undergo permanent changes when in contact with heat and cannot therefore be remodeled or recycled. This includes materials used for sockets, switches, some parts of aircraft and hulls, tanks, pot handles and other objects.
How and when was plastic born?
Although humans have been able to shape natural substances since the dawn of time, “modern” plastic was only born in the nineteenth century. The first matter of this type is generally considered to be the parkesinaa semi-synthetic substance produced by the English chemist Alexander Parkes between 1861 and 1862. More important was an 1870 invention, the celluloidpatented by the American John W. Wyatt. Conceived to make billiard balls, celluloid found many other uses: it was used to make combs, dishes and, above all, photographic film.
Thanks to the new material, cinema was born at the end of the century. Celluloid, however, had the defect of being easily flammable and over the years it was replaced by other synthetic materials.
Plastic in the twentieth century
The twentieth century was the “century of plastic”, both for the discoveries of new materials and for the exponential increase in production. In 1907 a Belgian chemist, Leo Baekeland, synthesized the first thermosetting material, known as bakelite, which for several decades was the most used plastic. In the following years, polyvinyl chloride (PVC), which however only spread on a large scale after the Second World War, and the cellophane, which, being transparent and waterproof, is ideal for food packaging. In the 1930s, with the arrival and production of nylonthe era of synthetic fibers also began.
Gradually, plastic entered the homes of citizens of the Western world, albeit to an extent not comparable to that of today.
The Second World War
After the Second World War, plastic experienced a real boom. From a scientific point of view, the most important discoveries were those of the German chemist Karl Zieglerwho perfected the production of the polyethylene (PET), and Italian Giulio Nattainventor, the following year, of polypropylene (marketed under the name moplen). These new materials quickly became the most widespread plastics in the world.
Global production of plastics, which in 1950 was just over two million tons, began to grow rapidly, transforming people’s daily lives. As time passed, plastic was used to produce an ever-increasing number of objects. In the 1970s, for example, the first ones were created PET bottles, very widespread today. In 2000, global plastic production exceeded 200 million tons per year: almost 100 times that of fifty years earlier.
The most recent innovation is the development of bioplastics, which include two large groups:
- the plastics created from natural elements”that is, of organic origin.
- plastics biodegradablethat is, which can be “degraded” by the action of microorganisms.
Are considered bioplastics also subjects that have both characteristics. Their diffusion, without prejudice to some precedents, occurred mainly in the 2000swhen a new sensitivity to environmental problems developed.
However, i Production costs of bioplastics are high and limit its diffusion: today only around 1% of the plastic materials produced globally belong to the “bio” type. Furthermore, their impact on the environment is the subject of debate and it is not certain that they are less polluting than “normal” plastic.
Plastic production has contributed to improve and make our lives more comfortable. Plastic is light, cheap, versatile and allows us to have large-scale access to goods that, if produced with other materials, would have been prohibitively expensive. However, plastic creates serious pollution problemsespecially because it remains in the environment and often ends up in the sea.
Plastic recycling, moreover, is still not widespread. According to the OECD, global production reached i in 2019 460 million tonsbut only 9% is recycled, while 19% is incinerated, 50% disposed of in “regular” landfills and 22% disposed of irregularly.