Characterisation and modelling of the microstructure-property relationship of self-reinforced polymers with regard to fatigue and damage behaviour by using PET

• Applicants: Dr.-Ing. Wilfried Liebig; Professorin Dr.-Ing. Anna Trauth
• Subject Area: Polymeric and Biogenic Materials and Derived Composites
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566752939

Common composites are known for their high density-specific stiffness and strength. These advantageous properties have led to classic composites gaining acceptance over conventional metals in many applications. However, the use of these composites brings with it a disposal problem owing to the difficulty in separating the fibre from the matrix. In contrast, there are self-reinforced polymers; fully polymeric recyclable thermoplastic composites in which fibre and matrix originate from one polymer or the same polymer family. The similar chemical structure not only leads to excellent interfacial adhesion between fibre and matrix, but also affects damage initiation and damage propagation under mechanical loading.Although self-reinforced polymers were developed as early as 1975 and have been commercially available for years, apart from a large number of quasi-static material characteristics, there are practically no systematic studies available that can describe and predict the degradation behaviour of self-reinforced polymers under cyclic mechanical loading. This is critical, as mechanical fatigue is considered the most common failure behaviour in composite materials. In order to ensure a safe and reliable design of self-reinforced polymer structural components and thus increase the market penetration of recyclable composites, it is therefore necessary to be able to describe and predict the damage and fatigue behaviour of self-reinforced polymers under cyclic mechanical loading.The research project therefore aims to systematically investigate the damage and fatigue behaviour of self-reinforced PET. For this purpose, in addition quasi-static investigations, the degradation behaviour under the influence of stress amplitude, fibre volume content, temperature and frequency will be comprehensively characterised and analysed under uniaxial tensile loading. In addition, a model for predicting and estimating the lifetime of self-reinforced polymers is being developed. This enables the efficient design of structural components based on self-reinforced polymers and thus allows their large-scale use.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Frank Henning