Elaborating more realistic model microplastics by simulating polypropylene's environmental ageing
Margaux Glais, Thierry Falher, Elise Deniau, Christophe Chassenieux, Fabienne Lagarde
Abstract
In this work, we propose a new protocol for producing model microplastics from an industrial polymer and compare it to a conventional method, cryomilling. Polypropylene industrial pellets were chosen due to their widespread production and frequent presence in the environment, making them a notable source of microplastics. Both protocols start with aging under Ultra-Violet light of the pellets but differ in the subsequent mechanical stress applied—strong vs. soft—to break down the photodegraded pellets into microplastics. All generated particles were fully characterized in terms of size, shape, oxidation rate, and stability in aqueous media. Microplastics produced via cryomilling exhibited significant size and oxidation heterogeneity and tended to aggregate in water. Although the new protocol involving soft mechanical stress required a longer preparation time, it simulated more accurately the environmental degradation of raw plastic. This method successfully produced oxidized microplastics with a controlled size distribution centered around 50 µm which remained stable in water without stabilizers. • Model microplastics were generated by mimicking environmental degradation of macroplastics into secondary microplastics. • This new protocol allows to prepare secondary MPs from all types of industrial plastics with control of their composition. • Models of secondary microplastics exhibit good homogeneity in size and oxidation rate. • Model of secondary microplastics prepared with this procedure are stable into water without any stabilizer.