The assessment of the extent of degradation of polymer molecules during processing via conventional (e.g., extrusion and injection molding) and emerging (e.g., additive manufacturing; AM) techniques is important for both the final polymer material performance with respect to technical specifications and the material circularity. In this contribution, the most relevant (thermal, thermo-mechanical, thermal-oxidative, hydrolysis) degradation mechanisms of polymer materials during processing are discussed, addressing conventional extrusion-based manufacturing, including mechanical recycling, and AM. An overview is given of the most important experimental characterization techniques, and it is explained how these can be connected with modeling tools. Case studies are incorporated, dealing with polyesters, styrene-based materials, and polyolefins, as well as the typical AM polymers. Guidelines are formulated in view of a better molecular scale driven degradation control.

A design of PET mechanical recycling at the industrial scale requires the inspection of the relevance of pre-treatment steps, degradation reactions and repair potential, accounting for the impact of contamination ( e.g. NIAS) and regulations.

To verify if PET mechanical recycling is feasible, we need to acknowledge chemical and material property variations. This review highlights the relevance of the connectivity of these variations as a function of the number of recycling cycles.

Synthesis, structure and systematic study of the redox and spectroscopic properties of [{Mo₆X₈}(aromatic sulfonate)₆]²⁻.

Photophysical properties of Mo ₆ cluster-doped silica particles.