Bio-based plastics are made of renewable raw materials and serve as a replacement to traditional plastics derived from fossil raw materials. Scientists and technologists do not only adjust them to conventional production machinery, but also develop new applications for them. Therefore packaging, disposable tableware, or mulch films made of bio-based plastics, are now commercially available.
Depending on what the product will be utilised for, some bio-based plastics are guaranteed a long life, while others are easily biodegradable.
Bio-based plastics can be produced from many biogenic raw materials such as starch, sugar and cellulose.
Starch is widely available, inexpensive and for the development and production of bio-based plastics, the most interesting raw material. A high proportion of the produced starch is directly transformed (through continuous biotechnological processes) into glucose. Following this procedure, thermoplastic polyesters and polyurethanes are produced through biotechnological and / or chemical processes. By-products of the starch industry can also be used as raw materials for the fermentation processes.
Cellulose is contained in large quantities in most plants, and in addition to wood, is quantitatively the most important renewable resource currently available. Worldwide, about 1.3 billion tons per year will be "harvested" for technical applications. Even though the end product of wood pulp will mainly be used for the manufacture of paper and paperboard, it also has the potential for bio-based plastic production.
Cellulose esters, for example, are often used as polymer components for compounding with other bio-based polymers. In addition to this, the clear-sighted cellophane foil for packaging is also a cellulose product.
Sugar (sucrose) from beet or cane, is a disaccharide. Since sugar is technically variously applicable, the use of it as a renewable resource offers a new perspective for the production of bio-based plastics.
Numerous other natural resources such as
- Casein, a protein from skim milk,
- Chitin and chitosan from crab shells,
- Gelatin, a collagen protein from animal bone or skin,
- Vegetable oils and
- Proteins from cereals (wheat or corn)
can be utilised for the development and production of bio-based plastics. Epoxy resins from linseed oil, for example, are already qualitatively equal to the synthetic epoxides.
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