The use of structural materials throughout history
To understand better this, it is worth looking at the following figure, which illustrates the rate and importance of the use of structural materials throughout history. What kind of materials humanity used was highly dependent, among other things, on the availability, processability of raw materials, and the knowledge and technology available. It is no coincidence that archaeological ages were also determined by the material of which the everyday tools were made, so that the Stone, Copper, Bronze and Iron Age followed each other. Plastics have played an important role in these times as well, but in those times the importance of polymers of natural origin was bigger, whereas today artificial ones are prefered.
The conquest of plastics
Plastics have many advantages: they are light, inexpensive and easy to manufacture, so it is not surprising that in many industries (eg packaging, food, automotive) the use of plastics has increased exponentially in a relatively short period of time. In 2018, nearly 400 million tonnes of plastics were produced worldwide. Adding up the annual production of iron with its own 1500 million tonnes, this amount doesn’t seem so much, but it shouldn’t be overlooked where and in what form this quantity is. While the steel produced is mostly found in buildings, bridges, motor vehicles, ships and other smaller or larger structures, plastics typically have a different destiny. In fact, consumer society has settled into the convenient world of disposable plastics, producing one of the biggest environmental problems of our time: the unimaginable amount of plastic trash everywhere.
How did a friend become an enemy?
It is estimated that since the boom of plastic production, that is, since the 1950s, has accumulated around 5 billion tonnes of plastic waste. By way of illustration, the Romanian Parliament has an estimated mass of about 5 billion tonnes, but for its construction about 1 million cubic meters of marble and 700,000 tonnes of steel was used, so that the volume of the largest man-made structure is nowhere near the volume of man-made waste. In addition to the amount of waste, the health-damaging effects of plastics are increasingly being the focus of attention. Although plastics are popularly referred to as biocompatible (that is, well compatible with the body), they are also carcinogenic and inflammatory. During the decomposition of the plastics, the joints in it break and break up into small parts. The so-called microplastics get into the human body with water, air or food. These small particles are also more easily adhered to airborne dust or heavy metals, allowing them to enter the body in higher concentrations. The destruction of plastics is not an easy task either: the harmful substances emitted during the widely used incineration process further increase air pollution and have a negative impact on the environment.
Due to the above problems and the limitations of the applicability of plastics, the use of “good old” metals is coming back. In our series, we will detail areas where metals still play a significant role and are not expected to be replaced by plastics, as well as applications where metals are trying to replace plastics because of their environmental impact.