Transport–Kinetics Framework for Thermal Stabilization of Biodegradable Polymer Nanocomposites

ABSTRACT Biodegradable polymers such as polylactic acid (PLA), polycaprolactone (PCL), and polyhydroxybutyrate (PHB) offer sustainable alternatives to conventional petroleum‐based plastics, but limited thermal stability can constrain processing and service performance. This work presents a transport–kinetics framework that couples thermo‐oxidative degradation kinetics with oxygen‐transport resistance to compare stabilization by nanoscale fillers. Montmorillonite (MMT), cellulose nanocrystals (CNCs), and multi‐walled carbon nanotubes (CNTs) were evaluated as representative layered, bio‐based, and high‐aspect‐ratio architectures. At the highest investigated nanofiller loadings, the degradation‐onset temperature increased by 26.7°C for PLA/MMT, 35.2°C for PCL/CNT, and 21.1°C for PHB/CNC relative to the corresponding neat matrices. The apparent activation energy increased by approximately 25%, 30%, and 20%, respectively. A dimensionless stabilization parameter, Ψ = ( E a / E a ,0) ( D 0 / D eff ), combines the kinetic and transport contributions. The maximum Ψ values were 1.92 for PLA/MMT, 2.60 for PCL/CNT, and 1.54 for PHB/CNC, compared with 1.13 for PLA/microclay and 1.00 for each neat‐polymer baseline. The framework therefore provides a transparent comparative metric when both activation energy and effective oxygen diffusivity are measured, while treating morphology‐based explanations as mechanistic interpretation rather than direct evidence in the absence of microscopy.