Aging-Induced Additive Release and Degradation Mechanisms in Recycled Polyvinyl Chloride: Coupling Experimental and Molecular Dynamics Insights

Abstract

Abstract The global accumulation of plastic waste has driven the widespread adoption of recycling strategies for sustainable resource management. However, uncertainties in recycled material quality and the release of plastic additives remain critical challenges for environmental safety. To elucidate chemical release behavior and polymer degradation mechanisms of commonly recycled plastics under aging conditions, polyvinyl chloride (PVC) was selected as a representative recycled plastic model and evaluated under accelerated aging with varying recycled contents and representative additives. We found that increasing recycled content intensified oxidation of PVC, reduced molecular weight by 45%, and decreased thermal stability after 60 days of aging. Additive loss increased with aging duration and recycled content, with antioxidant AO-1076 showing the highest depletion. Molecular dynamics (MD) simulations showed that blending recycled PVC weakens additive–polymer binding and increases additive diffusivity. These findings highlight the necessity of raw material quality control and risk assessment for recycled plastic products.