Bioplastics as an Alternative
Since the 1980s bioplastics have been increasingly discussed and produced as an alternative to conventional plastics. Whereas for a long time the focus was on the ecological aspect of biodegradability, today economic arguments play an important role. With the increasing price of oil biologically based plastics are becoming more and more interesting to the plastic industry.
However, biodegradable and bio-based do not mean the same. Although in both cases we speak, somewhat imprecisely, about bioplastics, the terms actually describe two very different characteristics that can be combined with each other but can also occur individually.
A plastic is biodegradable when it can be broken down into the elements water, carbon dioxide, methane and biomass. The biodegradability does not have to do with the particular raw material on which a plastic is based but rather with the structure of the material. There are also petroleum-based plastics that are biodegradable.
In Europe biodegradability is certified with the seedling. A product bearing the seedling logo meets the requirements of the European standard for biodegradable plastics (EN 13432). To achieve this, the maximum mass remaining after three months of composting is 10%. However, this guideline applies to industrial composting plants. On domestic compost heaps a considerably longer degrading time can be expected.
A plastic is bio-based if it is made from a sustainable (vegetable) raw material. Bio-based plastics can be manufactured from starch, cellulose, sugar, vegetable oils, lignin and proteins, for example. These basic substances can be derived from maize, wood, sugar or potatoes.
Bio-based plastics are regarded critically. The criticism is much the same as that applied to bio-fuels: «full tanks – empty plates» – as the area on which to cultivate crops for food production is reduced. Similarly, the question whether bio-based plastics are in fact more ecological than those based on mineral oil is hotly debated. If one looks at the entire life cycle of such a plastic – from planting to watering, harvesting, production and transport – biological plastics do not necessarily score better.
«Bio» as a Marketing Strategy
It should also be remembered that today many producers change over to “bio” because ecological sustainability is a good selling point. But the products do not always provide what they promise. For instance a PLA water bottle (made of polymerized lactic acid) can, in practice, hardly be composted – and if, by mistake, it ends up the PET collection it can dirty the material cycle there. In addition bioplastic tends to convey the wrong message – that we can continue to consume thoughtlessly.
Consequently, the real usefulness of bioplastics is debated. In countries where there is hardly any waste management and a large amount of plastic enters the seas they can represent an alternative. Using them in the area of agriculture can also make sense. But it is important always to ensure that, wherever possible bioplastics are made out of left-over vegetable products that do not serve as food for human beings.