28. Jul 2020
Rompa Group, a plastics processor with operations at sites on three continents, recently drafted a whitepaper on sustainability. Rompa uses recycled plastics in its production processes and is currently conducting tests with bioplastics for several major customers – a good reason to include a chapter on bioplastics in its whitepaper.
Rompa first talks about the growing popularity of these materials, despite the fact that their price tend to be higher and supply is insufficient to meet demand. At the moment, bioplastics make up circa 1% of the total plastic market, but this percentage is expected to grow quickly.
The paper then goes back to the very basics, to ensure readers understand what bioplastics are. The paper explains that, in general, a distinction is drawn between four types of plastics:
1) Biobased and non-biodegradable, so-called “drop-in” (bio-PE and bio-PET)
2) Biobased and (naturally or industrially) biodegradable (PLA, PHA, PBS and corn starch blends)
3) Fossil-based and non-biodegradable (ABS, PC, PS, ASA, PB)
4) Fossil-based and (industrially) biodegradable (PBAT, PCL)
The first two are bioplastics that share the same characteristics as regular plastic, except for the fact that the basic molecules come from natural resources such as starch from potatoes and corn, sugar, cellulose, lactic acid or proteins.
“The major benefits of biobased plastics are that they reduce our dependence on fossil resources and, contrary to fossil-based plastics, are climate-neutral,” according to the whitepaper.
Rompa goes on to explain that some bioplastics are naturally compostable; in water, outside air, soil or a combination thereof. Then there are bioplastics that are degradable, but not in nature.
“Whatever type you use, reuse and recycling are viable options for bioplastics as well. In fact, this is actively encouraged by various government institutions.”
The third category is the category that most plastics belong to - fossil-based and non-biodegradable. The fourth category consists of plastics made from oil, but with specific characteristics that make them biodegradable. At the moment, this type of plastic is made from virgin resources. In the future, the goal is to use residual materials and waste streams for its production as well.
Bioplastics have various pros – they are made from non-depletable, renewable resources and are carbon neutral - as well as cons. An often heard argument, for example, is that they use arable land on which food crops could otherwise be cultivated. It has been calculated that currently, circa 0.02% of the world’s agricultural land is used to cultivate the feedstocks used for bioplastics. Other much cited disadvantages:
• Some are made from edible feedstocks, giving rise to controversy;
• Bioplastics are generally more expensive than fossil plastics;
• Even biodegradable plastic does not simply disappear. The rate at which plastic is broken down depends on the type of material and the environment. Some bioplastics can be broken down entirely in a matter of months, but in the meantime, they continue to pose a risk to wildlife.
Currently, biobased and biodegradable plastics are mainly used for e.g. (food) packaging materials, disposable cups and cutlery, shopping bags and in the agricultural sector. The best application for a type of plastic depends on its characteristics. For example, a biobased PLA that is easily permeable to water vapour is not suited for the production of water bottles. On the other hand, it offers unique benefits when used for a “breathing” packaging for fruit and vegetables.
How close are we to a future with biobased plastics?
According to this whitepaper, if a sufficient amount of biobased plastic were available, 85-90% of all fossil-based plastic could easily be replaced by biobased plastic. Obviously we are nowhere near that yet.
According to researcher Christiaan Bolck from Wageningen Food & Biobased Research, we would need circa 5% of the world’s total annual biomass harvest to fully transition to biobased plastics. “As you can see, we have a long way to go,” the paper’s authors conclude.