Material Development in the Twin-screw Extruder for the Mechanical Recycling of the Bioplastic PHB(V)

• Applicant: Professor Dr.-Ing. Christian Bonten
• Subject Area: Polymeric and Biogenic Materials and Derived Composites ; Biomaterials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 496235143

Biodegradable plastics can make an important contribution to reducing the input of plastics into the environment. However, the number of applications in which this material property provides a meaningful benefit is limited. In contrast, the recyclability of new bioplastics is all the more important in order to fully exploit their potential over several cycles of use.The biopolymer polyhydroxybutyrate (PHB) and its copolymer polyhydroxybutyrate-co-hydroxyvalerate (PHBV) can be produced entirely from renewable raw materials and are biodegradable even in seawater; they are considered sleeping giants. However, with slow crystallization and low viscosity, the processing technology here faces major challenges. During melt processing, polymer chain degradation occurs after just a few minutes, resulting in a high loss of viscosity. Mechanical recycling via remelting of the bioplastic is therefore hardly conceivable at present.In order to make PHB(V) accessible to further processing methods such as film blowing or extrusion, the material properties are to be improved within the scope of this research project by reactive compounding in a twin-screw extruder with suitable modifiers. In particular, the aim is to achieve a consistently high viscosity over time, which should enable these bioplastics to be recycled.

• DFG Programme: Research Grants