Comparison of chromatographic, spectroscopic, thermal, and mechanical measurement techniques for polyethylene recyclate characterization

Description

In this study, three commercially available polyethylene post-consumer recyclates (rPE-1, rPE-2, and rPE-3) produced from packaging waste streams are characterized in terms of stabilization and flow properties and compared to a virgin pipe grade PE-HD of the PE100-RC class. Two methods were used for stabilization characterization, high pressure liquid chromatography with ultraviolet detection (HPLC-UV) and oxidation induction temperature (TOX) measurement. For characterization of flow properties melt flow rate measurements (MFR) were performed. Furthermore, tensile tests of injection-molded specimens and molar mass measurement via gel permeation chromatography with infrared detection (GPC-IR) were conducted and correlated with the flow properties. The three recyclates show significant differences in stabilization to the virgin PE100-RC. While the stabilizer contents (active and unconsumed Irganox 1010 and Irgafos 168) of the recyclates range from 0.01 ppm to 0.08 ppm, PE100-RC contains in total 0.20 ppm of these stabilizers. TOX measurements show a similar trend with the recyclates ranging from 228 °C to 242 °C, while PE100-RC delivers values of up to 261 °C. The characterization of flow properties showed a wide range of properties for the recyclates and substantiate the differences between packaging and pipe PE-HD. The MFRs of the recyclates range between 0.8 g/10 min and 2.5 g/10 min, while the PE100-RC showed a much lower MFR of 0.23 g/10 min. The strain-at-break values of the recyclates range between 35 % and 120 %, while PE100-RC already broke at 21 % strain. Finally, the mass average molar masses (Mw) of the recylates range between 142,000 and 168,000 g/mol, while PE100-RC shows a higher Mw of 188,000 g/mol.

Period	02 Sept 2021
Event title	Polymer Meeting 14
Event type	Conference
Location	AustriaShow on map