Structure–Property Relationships in Recycled <scp>HDPE</scp> Composites: Role of Nanofiller/Antioxidant Treatment on Mechanical, Rheological, and Diffusion Properties

ABSTRACT This study addresses the significant economic and environmental challenges associated with plastic waste by investigating the recyclability of high‐density polyethylene (HDPE) for packaging applications. Departing from prior research focused predominantly on mechanical and rheological performance, this work provides a distinctive investigation into structure–property relationships by examining the influence of a nanofiller on an antioxidant diffusion behavior in recycled HDPE over successive cycles. This approach reveals critical interactions for designing sustainable recycled materials. To evaluate the potential for food packaging reuse, the diffusion of the common HDPE stabilizer Irganox 1076 (Ir‐76; SML = 6 mg kg −1 ) was analyzed in films of both recycled and nanofiller‐filled recycled HDPE. Diffusion studies were conducted using the Roe method, where a multilayer film stack—comprising a central layer containing Ir‐76 sandwiched between unloaded layers—was annealed to allow additive diffusion. The concentration of Ir‐76 in each subsequently separated layer was quantified using FTIR spectroscopy, enabling the determination of diffusion coefficients ( D ). Results demonstrate that adding 3 wt% Cloisite 15A to virgin or recycled HDPE reduces the stabilizer's diffusion rate by up to 66%, while simultaneously enhancing mechanical properties. This combination of reduced additive diffusion and improved performance enhances the material's attractiveness for the plastic packaging sector, whether based on virgin or recycled feedstock.