Plastics are an integral and important part of the global economy, and their production has increased from 15 million tonnes in the 1960s to 311 million tonnes in 2014 over the last 50 years. This figure is projected to triple by 2050, when plastic production may account for 20% of the world’s annual oil consumption. At the same time, the dynamic rise in production and the growing scale of application of plastic products have resulted in an increase in their mismanagement and, consequently, in the negative impact on the environment. There is without a doubt a clear need to design plastics to be used in the circular economy and recycled on a larger scale than today.
One of the solutions on which the attention of scientists from all over the world is focused are “bioplastics”. This is a fairly general term, which can cover both biological-based (plant-based) materials as well as readily biodegradable materials. Knowledge of the differences between these concepts is essential for consumer awareness and for the development of clearer product labelling, as pointed out by the European Environment Agency, which incidentally estimates that only about 1% of plastic-derived products on the world market can be considered compostable or biodegradable.
Bioplastic keeps up… appearances
Biodegradable or compostable plastics can be produced from both bio-based raw materials (e.g. maize, sugar cane) and fossil raw materials (petroleum). Natural polymers modified under laboratory conditions (e.g. cellulose, lignin) and synthetic polymers are considered biodegradable, and they can both be derived from natural polymers by being “redesigned”, i.e. changed in terms of basic physical and chemical properties, without much difficulty. However, the mere modification of natural polymers does not make them biodegradable to the same or comparable extent as natural ones. Very often, in the case of biodegradable or compostable plastics, the degradation process is only possible under specific industrial conditions or in professional composting plants. In addition, the rate of biodegradation depends on the running conditions of this process, i.e. temperature, duration, presence of microorganisms, availability of nutrients, oxygen and moisture. Consequently, this issue requires a number of studies ranging from the production of a new material to the study of the full cycle of biodegradability in order to assess whether it is more beneficial than popular plastics. Microplastic is particularly problematic in terms of biodegradability, the negative effect of which is the subject of many debates and very unfavourable reports. Moreover, bioplastics resulting from modifications of natural polymers do not automatically become less toxic and safe for living organisms. Numerous studies have shown that they can contain a number of chemical substances that pose a risk and can be toxic to living organisms just as much as classic plastics by disrupting the rhythm of the body’s activity.
The increment of patented bioplastics compared to classic plastics has been invariably constant and comparable since the early 1980s. Currently, the most extensive group are chemically modified biopolymers, i.e. modified cellulose, polysaccharides, starch and others. Bio-PE, Bio-PET, Bio-PA are polymers wherein a significant percentage (e.g. 30%) consists of plant material. Contrary to what might be expected, these materials are not biodegradable. However, the use of plant raw material makes the production of this substance less dependent on crude oil. As a result, the production process is characterized by reduced CO2 emissions, which translates into a less negative impact on the environment. However, bioplastics have a negative impact on the environment, in aspects such as eutrophication of soils and waters, increased emissions of suspended particulates no larger than 10 µm in the air, use of cultivated land for their production or additional water demand.
Do we have a leader yet?
An interesting alternative solution to the above may be a material called PEF – a plastic based on starch. Currently, the production of this material requires 70% less energy, as well as leads to the production of only 1/3 of CO2 compared to traditional PET plastics. Moreover, the advantages of this material go even further. It is more durable, which consequently means a much smaller amount of raw material needed to produce a given object, e.g. a bottle, of the same strength. In addition, the material has improved properties regarding the migration of oxygen and carbon dioxide through its barrier, which means that the beverage in the bottle can remain fresh for longer. Furthermore, it is fully recyclable. All of this makes PEF an object of considerable interest. No wonder that Avantium and their technology quickly became a leader in this segment, arousing curiosity and appetite of companies such as Coca-Cola, Danone or Carlsberg. Will this type of material eliminate PET from the market? Time will tell, but all signs point to this very likely scenario.
Strength often lies in flexibility
Another very interesting concept of a new type of polymer worth paying attention to is the vitrimer. Vitrimers are characterized in that the polymer network within them is not permanent, so under appropriate conditions (e.g. elevated temperature), it undergoes continuous reorganization. Chemical bonds in this type of material can be said to be in a kind of “dynamic equilibrium”, while maintaining the properties of cross-linked materials, such as stiffness, shape stability and chemical resistance. Under appropriate conditions, this material is both durable and flexible; the vitrimer is also able to regenerate in the event of damage. Another important advantage is that it allows easy and complete recycling, because it can be processed into any form at elevated temperature without losing the properties of the original material. Durable packaging, e.g. phone cases, the automobile industry and transportation are just a few of the possible areas of its application, all thanks to Ludwik Leibler, a Frenchman of Polish origin. Are we nearing the end of cracking, readily discardable plastics?
The market of plastic waste management is a market full of challenges, as well as significant opportunities. Everything points to a very interesting future of this submarket. Undoubtedly, packaging remains a large target sector for the plastics market. However, no matter what the future holds, it is worth limiting the amount of plastic in your environment – you can reduce it by making thoughtful purchases and thus lowering the amount of consumed unnecessary waste.
Author: Maciej Stodulski, PhD