Materials / Recycling PETplanet Insider Vol. 25 No. 12/24 www.petpla.net 25 ity of the recyclate used (if reported: type and quantity of impurities) and, if applicable, its ageing condition. On the other hand, the currently known information on modes of action and mechanisms of ageing on recyclates (e.g. hydrolysis, thermo-oxidative degradation, etc.) and their influencing factors will be compiled; finally, the reported correlations to physicochemical parameters (type and amount of contained additives, chain lengths and end groups), the reported models for describing (and, if possible, predicting) the aging behaviour will be considered. The focus of this research (e.g., class and type of polymer, (un)reinforced, etc.) will be agreed upon and jointly determined among the participants. Together with the project participants, the influencing factors from the input recyclates on the mechanical properties and ageing behaviour are weighted. Taking into account individual requirement profiles, exemplary and representative formulations are produced at Fraunhofer LBF using selected recyclates and defined additives. The recyclates used are first characterised in detail regarding the molecular parameters relevant for processing and application properties. The focus is on the chemical composition (in terms of polymer content and impurities), the additives and the molecular weight distribution. Rheological properties of the compounds produced are determined and their mechanical behaviour (tensile-elongation tests, Charpy notched impact strength if necessary) is evaluated. Furnance ageing (tensile-elongation behaviour at a defined temperature as a function of time, at approx. 6 ageing times) is carried out to evaluate the ageing properties. Within the scope of the project, several compounding and injection moulding campaigns (max. total of 60 variations, divided into several campaigns) will be carried out in order to further reduce the multitude of influencing parameters and to be able to understand the underlying dependencies better and better. The detailed planning and selection of the experiments will be done in close coordination with the participants and in consideration of the respective input. After each campaign, selected material analytical investigations are carried out for better understanding of the underlying modes of action and dependencies more closely, also at the molecular level. Various thermal (e.g. TGA, DSC), microscopic (e.g. SEM, IR and Raman microscopy), spectroscopic and chromatographic methods (e.g. NMR, GPC, HPLC) are used here. Based on these findings, structure-property relationships will be derived with the intended goal of better understanding dependencies of mechanical and rheological properties as well as long-term properties (e.g. ageing behaviour) when using PCR of selected engineering thermoplastics. Furthermore, these findings should serve for an estimation or prediction of similar compositions. www.lbf.fraunhofer.de/en/ research-projects/material-and-longtime-properties-recyclates.html
RkJQdWJsaXNoZXIy NTY0MjI=