Processing stability and radical scavenging efficiency of novel biobased stabilizers: Insights from long-term extrusion and DPPH assays
Katrin Markus, Tobias Kirschbaum, Elke Metzsch‐Zilligen, Rudolf Pfaendner
Abstract
• Simple synthesis route and preparation of biogenic phenolic stabilizers. • Stabilizers are subjected to extrusion under tougher conditions. • Comparison of extrusion experiments with radical efficency in DPPH assay to show a simple pre-test to estimate the performance. • Support of analytics by calculation of bond dissociation energies. • Elucidation of the stabilizer mechanism. This study investigates the effectiveness of phenolic antioxidants based on natural building blocks in stabilizing polypropylene by analyzing their structure-property relationships and mechanisms of action. Using the DPPH assay and extrusion experiments, we demonstrate that the antioxidant efficacy varies significantly among different phenolic structures. Di- and triphenols consistently outperform methoxy‑substituted ones due to lower steric hindrance and enhanced electron donation capabilities. Our findings also reveal that phenyl propionates are the most effective stabilizers, attributed to their ability to undergo dimolecular disproportionation, which allows for regeneration and the formation of additional stabilizing compounds. In contrast, benzoates and cinnamates exhibit lower radical efficiency due to higher bond dissociation energies and limited stabilization contribution. Overall, the presented results highlight the critical role of molecular structure in the performance of phenolic antioxidants, suggesting their potential for enhancing the stability of polymers in various applications within the plastics industry.