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Oxo-Additives for Polyolefin Degradation: Kinetics and Mechanism
Summary
This review examines how oxo-additives — metal salt compounds added to polyethylene and polypropylene to speed up oxidation — affect how fast these plastics break down in the environment. The research is directly relevant to microplastics because oxo-degradable plastics were marketed as an environmental solution but evidence suggests they may instead fragment into persistent microplastics rather than truly biodegrading, and this review helps clarify the conditions under which each outcome occurs.
This review considers the recent investigations in the scope of biodegradability of synthetic polymers, spanning polyethylene (PE), polypropylene (PP), and their corresponding composites, with a focus on the influence of oxo-additives (mostly transition metal salts). The types of oxo-additives and the mechanisms of oxidation acceleration are discussed. Furthermore, the influence of oxo-additives on both physicochemical and biological stages of degradation is evaluated (laboratory and field experiments with microorganisms/fungi action) with recent standards suggested for degradation estimation. Comparisons of the metal salts are given with respect to catalysis, as well as the synergetic influence of additives. The additives presented on the commercial market are also discussed.
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