The interviewer is Professor Hans-Josef Endres, Director of the IKK Institute of Plastics and Circular Economy, Leibniz University, Hannover-Ina Witkert.
Professor Hans-Josef Endres
Q: The image of plastic is not good. Can bioplastics help change people’s attitudes?
A: Prof. Hans-Josef Endres: Bioplastics have an impact on the image of plastics because of their advantages in raw materials and disposal. The bad image of plastics is not only because they are related to petrochemistry, but also because of their longevity. From the product point of view, this is an advantage, but in terms of waste and random disposal, it is seen as a disadvantage. In fact, the situation of bioplastics is not much better. On the contrary: In the public, the negative image of petroleum-based plastics is often transferred to bioplastics. Although they have the advantages of compostability and recyclability, consumers cannot distinguish between them.
Q: Will bio-based plastics be criticized for consuming food resources?
A: Professor Endres: This criticism is too general. The greenhouse effect also consumes land, and the energy sector also uses renewable raw materials. In addition, when we talk about the raw materials of bio-based plastics, we are not only referring to those materials that are the basis for food, but also cotton, rubber or linoleum, and more and more agricultural waste. But let's put it aside for now. If you use bio-based materials to make 350 million tons of plastic every year, you will need about 5% of the usable area.
Q: There are bio-based plastics and biodegradable plastics. Which is better?
A: Professor Endres: It depends on their application. Biobased only describes the source of the raw materials used to produce the polymer. When microorganisms can metabolize polymer structures in biological processes, plastics are biodegradable and completely independent of the source of raw materials. For example, you can also use crude oil to make biodegradable plastics and renewable raw materials to make durable plastics. The first plastics that people made were all bio-based, because we didn't have crude oil at the time.
Q: If bio-based plastics are not biodegradable, why are they produced?
A: Professor Endres: People may also ask, if bio-based plastics can be produced in a petrochemical way, why should bio-based plastics be produced? The advantage is that CO2 is reduced. Every plastic material is disposed of at the end of its useful life-by burning, or in the case of many bioplastics, by composting.
Bio-based plastics are climate neutral because every plant absorbs as much CO2 during its life cycle as it emits when it burns or decomposes.In addition, the demand for plastics is rising. Soon, we will no longer need 5% or even 10% of crude oil reserves to produce plastics. For this reason, the mineral oil industry can more easily get rid of the plastic industry as a customer, and vice versa; currently plastics still need petrochemical raw materials.
Q: What is the current research focus of bioplastics?
A: Professor Endres: A major research area is the development of so-called drop-ins. These are bio-based plastics with the same structure as their petrochemical counterparts. For example, polyethylene or PET made from bioethanol. Technically, they provide the same properties as traditional plastics, but ecologically they are better because they are bio-based, which means renewable.
Q: In its plastics strategy, the EU focuses on recycling. Is this a problem with bioplastics?
A: Professor Endres: Bioplastics can also be separated in waste streams, recycled and made into new products. If they are composted or even burned, it still recycles carbon naturally through photosynthesis. When we recycle petrochemical plastics, carbon is technically recycled. Drop-ins can also be easily recycled with their petrochemical counterparts.
In addition, we also have new types of bioplastics, such as PLA. PLA must--just like any other plastic material--be separated from the waste stream.This means that recyclability depends on the amount of materials available. PLA is easy to identify in the waste stream; it can be recycled, but due to the small quantity, it is not worth including a special classification stage for the PLA at this time. For example, the recycling of PET has developed along with the increase in the amount of PET.
Q: Research in the field of biocomposite materials is also ongoing. Compared with other composite materials, what are their advantages?
A: Professor Endres: The case of carbon fiber illustrates the dilemma of composite materials. CFK has been optimized for many years, but the researchers did not consider the end of the life cycle. Carbon fiber material has very good performance characteristics, but it is difficult to handle. In addition, the production of carbon fiber is very energy intensive. Cars made of CFK components are significantly lighter and therefore consume less fuel or energy. However, the car needs to travel 150,000 kilometers to obtain CO2, which causes its output to be offset. In the case of CFK, environmental pollution is transferred to the fiber production stage and its unresolved disposal stage. This is where the advantage of biocomposites lies. They are also suitable for the production of lightweight materials. But here, we have a material component with a source of bio-based raw materials. At the same time, natural fibers can burn more easily and CO2 is neutralized. At the end of its life cycle, the situation is much better than carbon fiber.
Q: What do you think of the German circular economy in the international context?
A: Professor Endres: Several countries are moving in the same direction. For example, Canada is also increasingly inclined to a circular economy and hopes to reduce a large number of approved packaging plastics. But there, the waste disposal logistics system has not been properly established. In some Asian countries, the awareness of circular economy is also increasing.
However, in the United States, most plastic waste is dumped. Some European countries, including Germany, have played a pioneering role in the field of plastic packaging recycling. Germany introduced dual systems more than 20 years ago. Germany has a technological advantage in this field, but it has not really taken advantage of it so far. Until now, with the increase in political and public pressure, the industry has only become active.
