“To imagine a world without plastic, we would have to jump back in time to the second half of the 1920s. It was a world where the home environment consisted of natural fabrics, wood, and metal; the kitchen was made of cast iron, the pipes of lead. It was a world without technical fabrics, where people skied with wooden boards on their feet and leather boots padded with wool.” 

“A world without plastic is possible, but it is a world now very far removed from our daily lives. It is possible to imagine living without the objects I have mentioned. It is more difficult to do so without consumer electronics, the infrastructure that requires these materials to produce and transport electricity, and without vehicles that are full of polymeric materials. In short, the mental exercise is feasible, but a return to the past is decidedly less so.”

From the words of Andrea Castrovinci, head of the SUPSI Polymer Engineering Laboratory, it is immediately clear how, over the decades, polymer materials have occupied an increasingly important place in our lives. This success stems from the countless properties of what we commonly call “plastics.”

"Before plastic became commonplace, the materials we used could be easily grouped into categories with specific properties. Think of metals, which we instinctively associate with characteristics such as electrical conductivity and malleability. Polymeric materials cover a very wide spectrum of characteristics, ranging from those typical of metals to those of ceramics, from natural fibers to wood. With polymeric materials, we can reproduce almost all of their properties and in many cases even surpass them: they can mimic natural fabrics; we can build load-bearing elements without resorting to cement or metals; they can mimic glass. Think of airplane windows or eyeglass lenses: what we call glass is actually transparent polymers."

These characteristics and the possibilities for use in a wide variety of fields are attributable to their unique molecular structure.

"The premise is that polymeric materials exist in nature: our skin and DNA are examples. The characteristic of these materials is the length of the molecules, composed of thousands, if not tens of thousands, of atoms attached to each other. We can imagine it as a string of pearls. By replacing a white bead with a black one, the macroscopic properties of the molecule change."

We commonly associate plastics with petroleum—a hydrocarbon—derived from fossil sources. From a chemical and historical point of view, where does this connection come from?

One of the most common plastics is polyethylene. Each macromolecule is composed of carbon atoms to which hydrogen atoms are attached. These two elements are abundant in fossil fuels. The above-mentioned string of pearls could be synthesized at a very low relative cost. However, it should be noted that the amount of oil used for the production of plastics is very low compared to other uses: it is estimated to be 4-8% of global consumption, a very low percentage compared to other uses of fossil fuels, including combustion."
 

Ball-and-stick model of part of the crystal structure of polyethylene. Source: Wikimedia Commons

This link with fossil fuels and, more generally, the issue of pollution linked to plastics is now the focus of public attention. However, this has not always been the case.

"Immediately after World War II, plastics were presented to the population as something extremely positive. They were because they made it possible to produce everyday objects quickly and cheaply. This perception was fueled by advertising. At the time, between 30 and 40 million tons of plastic were produced annually, and there was no perception of the end-of-life problem. For decades, we did not take this aspect into account. Only in recent years, first in the technical-scientific world, has this awareness spread to the general public. Today, we are aware of the problems associated with plastic pollution, but we forget all the positive functions of these materials, which are difficult to replace. Communication and information about plastic has been turned on its head and the negative aspects have become all-encompassing: most of the time, plastic is associated with the problem of pollution and dispersion in the environment, although polymeric materials, as we have seen, are not just that."

What options do we have to address the problem? 

"Technically, the energy contained in plastics can be recovered through incineration, but we know that CO2 is released in the process. There are technologies that allow us to reintroduce objects that have completed their first cycle of use into the value chain through collection and transformation. So we are turning a problem into something we can manage and that generates economic benefits. In a laboratory, you can do practically anything, but you always have to keep in mind that solutions must be scalable at an industrial level. This means finding a process that does not pollute too much, that is manageable in terms of solvent use, and that is part of an autonomous value chain. Solutions that depend on subsidies and public funding are not sustainable indefinitely."

What is happening in terms of the use of renewable sources?

"There are industrial companies that already synthesize plastic from renewable sources, and in general, efforts are being made to find production processes that are scalable and economically sustainable. In terms of bio-based materials, there is PLA, produced from plant sources. It represents a minimal percentage of the approximately 500 million tons of plastic produced each year, partly because its cost is higher than similar materials derived from fossil sources. In addition, it would be impossible to completely replace plastics with bio-based materials derived from corn or other sources. The Earth's agricultural surface area would not be sufficient to meet the demand."

What projects are you working on here at SUPSI in this area? 

"As a laboratory, we respond to requests from start-ups and companies looking to develop alternative solutions. We work on projects that make use of recycled or waste materials. My colleague, Dr. Anna Rita De Corso, is trying to synthesize a material from lignin, a by-product of the paper and timber industries. Another project uses waste algae from the cosmetics and pharmaceutical industries to make a polymer. Algae are an interesting source because they grow rapidly in bodies of water."

Xi is an example of a material made from recycled polypropylene and wood flour, sourced from woodworking waste. To find out more: “More eco-friendly toys in the future”

If it is true that research and industry are focusing on finding solutions to extend the life of objects made from polymeric materials, what can citizens do?

We can do our homework and recycle various polymeric materials, as we have been doing for decades with PET. We can separate food packaging, our sneakers, and technical fabrics, helping the system manage the end of life of these items. We can certainly reduce consumption, knowing that, as I said, going back to the past is impossible. We can simply manage plastic when we no longer need it. Our individual responsibility is to deliver it to the value chain that exists downstream."

The Institute of Mechanical  Engineering and Materials Technology at SUPSI (MEMTi), together with Greenchemicals and Krauss Maffei, is organizing a series of conferences - the Polymer Additives Academy - dedicated to professionals working in the polymers and additives sector to examine case studies, learn about the latest industry news, and explore current issues, from regulatory changes to bio-based materials, from photovoltaics to fire safety, and recycling.