4 minute read
HOW TO GARANTEE THE QUALITY OF BIOPLASTICS?
RESEARCHER IN FOCUS
Plastic made from biodegradable raw materials like sugar beet, maize, and wheat. Is this the panacea that could eliminate conventional plastics from petroleum chemicals once and for all? Ineke Velghe, PhD student at KU Leuven-Brugge, does not see it going that fast just yet. First, a sustainable solution must be found for the degradation of the material during processing. Moreover, bioplastics will mainly be used for specific applications.
Ineke studied Industrial Design at the University of Antwerp. In 2018, she moved to KU Leuven-Brugge to pursue further studies in plastics processing. The reason is not far off. “As a product developer, you are constantly working with materials. Gradually, I became so fascinated by materials science and plastics that I wanted to learn more about them. The master’s programme at KU LeuvenBrugge appealed to me the most, even though it meant two years of additional study.”
We are now five years on and Ineke is still at the Bruges campus. She is attached to Professor Frederik Desplentere’s research group ProPolis (Processing of Polymers and Innovative Material Systems), a division of the umbrella ‘New Materials Group’.
Packaging
Within the vast field of plastics processing, Ineke conducts research into sustainable plastic applications. As a case study, she chose PLA or polylactic acid, a thermoplastic polymer made from lactic acid.
“PLA is gaining popularity because of its image as a bio-based and biodegradable alternative to conventional plastic,” explains Ineke. “In fact, it is already widely used to package food or for implants in surgery. Furthermore, it is also the most widely used filament type for 3D printing. You can make detailed prints in all the colours of the rainbow with it.”
According to Ineke, PLA or other biodegradable plastics will never be able to completely replace conventional plastics. “Both materials will continue to co-exist in the future, each with its own applications. For example, in agriculture or fisheries where the material may inevitably end up in nature, bioplastics are most appropriate.”
Degradation
As is often the case, not all that glitters is gold. So, PLA also presents a downside. “The problem is situated in the manufacturing process, more specifically in injection molding and extrusion”, explains Ineke. “The polymer chains fall apart into smaller pieces which leads to the degradation of the material. This manifests itself in a change of the mechanical, thermal, and rheological properties, affecting stretch, stiffness, meltability, fluidity and colour. This, of course, does not benefit producers. Their aim is precisely a consistently high quality of their product. Consequently, they want to be able to estimate exactly how much degradation will occur during processing and its impact on the final product.”
Estimating the degradation process has been guess work to date. It comes down to trial and error by each producer and a high degree of uncertainty remains. Therefore, Ineke set out to develop a quantitative model that can predict the extent of degradation. To do so, she uses fundamental parameters such as shear stress, melting temperature and moisture content that do not depend on the processing equipment used. “In my research, processing is done by single-screw extrusion using molecular weight as an indicator of degradation,” says Ineke.
Transition
For bioplastics producers, the future looks promising. The results of Ineke’s research will allow them to predict the expected degradation during the processing process and minimise its effects. In doing so, the Bruges researcher kills two birds with one stone. It makes bioplastics even more attractive to companies and it also means a big boost for the transition to biodegradable materials in a circular economy.
Ineke’s research mandate at ProPolis in Bruges expires in 2025. There is a real chance that she will pick up the thread of product development after that. Enriched with so much material knowledge and research experience, a promising future as an industrial designer awaits her.
Yves Persoons
