One of the key challenges in the field of material engineering is the development of lightweight materials with improved mechanical and functional properties.
Due to high strength-to-weight ratio and high temperature, fire and media resistance high-performance or high-temperature (HT) thermoplastic polymers have a great potential for the use in challenging lightweight applications, e.g., aerospace and medical technology, or tooling industries. The unique material properties of HT thermoplastics combined with the advantages of additive manufacturing enable completely new applications with complex design considerations and/or lower manufacturing costs and lead times.
However, additive manufacturing of HT thermoplastic polymers via the known appropriate techniques, specialy  fused filament fabrication (FFF), encounters significant challenges associated with inherent polymer properties such as high processing temperature and, in the case of semicrystalline polymers, crystallization behaviour. This makes HT materials highly sensitive to changes in processing conditions and consequently the final performance.
In this contribution, we present the effect of printing parameters on the performance of HT polymer parts fabricated via FFF. We discuss the development of interlayer strength based on the theory of inter-diffusion of polymer chains across the interface as well as crystallization phenomenae. The aim is to provide comparative information on process-structure-property relationships and explore the potential use and limits of both, amorph and simicrystalline polymers in the FFF process.