Starch blend

from Wikipedia, the free encyclopedia

Starch blends are mixtures of thermoplastic starch (TPS) and plastics , which can be based either on petroleum or on renewable raw materials . These blends represent one of the largest proportions of bio-based plastics internationally and vary in their properties depending on their composition.

Composition and properties

Production of biopolymers based on starch

Thermoplastic starch (TPS) is usually only one of the components from which modern bioplastics based on starch are made due to its negative property of absorbing water. The second basic component of these plastic blends consists of water-repellent, biodegradable polymers such as polyester , polyester amides , polyurethanes or polyvinyl alcohol . A plastic blend is therefore composed of two phases, the continuous and hydrophobic (water-insoluble) polymer phase and the disperse and hydrophilic (water-soluble) starch phase. The starch-based material content can be between 25 and 70%.

During the melting process in the extruder , the starch phase and plastic phase combine to form a waterproof starch plastic. These findings formed the basis for the further development and the eventual breakthrough of starch plastics (EP 0596437, EP 0799335)

use

Starch blends and compounds are developed and produced individually for further use in the plastics processing industry, depending on the area of ​​application. As plastic granulates , they can be processed into foils, thermoformable flat foils, injection molded articles or coatings on the existing systems. Examples of this are carrier bags, yoghurt or drinking cups, plant pots, cutlery, diaper foils, coated paper and cardboard. Starch can also be thermoplastically modified by chemical changes such as conversion to starch esters or starch ethers with a high degree of substitution. However, because of the high costs involved, these methods have not yet caught on.

literature

  • Hans-Josef Endres, Andrea Siebert-Raths: Technical biopolymers. Hanser-Verlag, Munich 2009. ISBN 978-3-446-41683-3 .
  • Jürgen Lörcks: Bioplastics. Plants - raw materials, products. Fachagentur Nachwachsende Rohstoffe eV, Gülzow 2005 ( PDF download )