Understanding the multiple characteristics of microplastics generated from polypropylene bottles

Polypropylene (PP) is widely used for food and beverage storage, yet its propensity to release microplastics (MPs) and nanoplastics (NPs) under routine use conditions remains poorly understood. Here, we investigate MP/NP release from PP infant feeding bottles and water bottles under controlled thermal and mechanical stresses. Using Raman spectroscopy, FE-SEM, high-resolution TEM, and AFM, we identified particles down to ∼ 60 nm, extending the detectable size range beyond most previous studies. Release rates correlated strongly with temperature and frequency of use, ranging from 3.9 × 10 6 to 10.3 × 10 6 L -1 for baby bottles and 5.3 × 10 6 to 9.1 × 10 6 L -1 for water bottles respectively. Particles were predominantly flake-like and irregular, with crystalline–amorphous transitions and multilayer breakdown observed. Baby bottles released more MPs under thermal stress, whereas surface and mechanical stresses predominated in water bottles. These results provide new mechanistic insights into PP degradation pathways and highlight the importance of advanced, multi-modal analytical approaches for future evaluation of nanoscale plastic release.