12.10.2020 – invited experts spoke about the respective bioplastics
At the start of the project, invited experts, entrepreneurs and scientists presented the different bioplastics with which we intended to work on during the semester. Subsequent to this online conference, the students chose a bioplastic for which they were to develop circulating applications.
Protein based bioplastic
Dr. Matthias Jacob is a research associate at the Institute of Pharmacy at the Martin Luther University in Halle. He explained to us the composition of proteins and their fields of application. Proteins are the building blocks of life and are built up and broken down by enzymes. Through the chemical cross-linking of their amino acid chains, proteins can be used as binders, in foamed form or as films. They are completely degradable and edible.
Polylactic Acid (PLA)
Dr. Stefan Kabasci from the Fraunhofer Institute UMSICHT presented the bio-based thermoplastic PLA (polylactic acid). As the name suggests, it is polymerized from lactic acid, which can be produced from corn, tapioca or sugar. The plastic is compostable in industrial facilities. In other environments, however, it is rather resistant, even to chemicals. Among other uses, it finds application as a self-dissolving medical material. PLA can be recycled, but there is a loss of quality due to melting. The basis for recycling would be sorting and collecting the material in recycling plants, but this hardly takes place at present due to low quantities.
Chitosan – bioplastic made from chitin
Dr. Jonas Fink is co-founder of the insect protein producer MadeByMade. In his presentation, he talked about the advantages of insect breeding and use compared to conventional agriculture (space-saving, resource-saving, high nutritional values).
Food waste serves as food for the insects, which is decomposed within a few hours (in comparison: microorganisms need several weeks on average). The species madebymade uses is the black soldier fly, as it does not transmit diseases and has no stinging organ.
However, after extracting the valuable proteins from the maggots, the chitin remains a so far unused by-product. Chitin can be turned into the biopolymer chitosan, which is suitable for various areas of application. It is often used as a reinforcing additive or adhesive in other bioplastics, and is popular in medicine because of its antimicrobial properties.
Bacterially produced bioplastic – PHB
Gundula Peschel spoke about polyhydroxybutyric acid, or PHB in short.
PHB is a biodegradable material with similar properties to PP produced by certain bacteria, especially Ralstonia eutropha, from sugars. The biosynthesis by microorganisms consists of three steps catalysed by three enzymes.
According to Gundela Peschel, PHB is also exciting from a material technology point of view, as it is odourless, dyeable, relatively heat-resistant and inelastic.
Today, PHB is already commercially available, mostly in flake form. One problem is the still high costs in production, as the production scale is quite low.
Bernhard Schipper from the company ScobyTec in Leipzig presented us their development of a leather substitute from bacterial cellulose, which is a natural biopolymer. The motivation for targeting at leather substitutes is the better carbon and water footprint of bacterial cellulose in comparison to leather and the increasing demand for leather as a material in itself. Additionally, bacterial cellulose differs from plant cellulose: the bacterial cellulose is free of lignin and hemicellulose and its finer fibres in a grown network change the physical material properties.
PA-flax-composite in the form of unidirectional tapes
Sandra Richter from the Fraunhofer IMWS in Halle (Saale) presented a semi-finished product at the conference that is a composite of flax and polyamide PA10.10. The composite is in tape form, the fibres are unidirectionally aligned, which is why the tape is also called a UD tape. Flax is a possible alternative to composites with carbon fibres and glass fibres and can compete with the mechanical properties. PA10.10 is produced from renewable resources. Yet, it is not biodegradable.
|Protein based bioplastic:||Prof. Dr. Markus Pietzsch|
Dr. Matthias Jacob
|Polylactic Acid (PLA):||Dr. Stephan Kabasci|
|Chitosan:||Dr. Jonas Finck|
|PHB:||Dr. Gundela Peschel|
|Bacterial cellulose:||Bernhard Schipper|
|PA-flax-composite:||Dr. Sandra Richter|