Effects of MG(Oh)2 and MWCNTs on the Thermal Degradation Kinetics of LLDPE in Nitrogen: Part B—Non-Isothermal Tests

Abstract

[Abstract] A major challenge in polymer composite research is accurately predicting thermal degradation behavior under different heating conditions while effectively distinguishing primary polymer decomposition from filler-related mass loss. This study introduces a novel approach by employing a logistic derivative function fitting method, which allows for the clear separation of magnesium hydroxide (MH) dehydration from the main degradation of linear low-density polyethylene (LLDPE). Understanding the thermal stability of LLDPE composites is crucial for enhancing fire safety and long-term durability in industrial applications. This study investigates the effect of MH and multi-walled carbon nanotubes (MWCNTs) on the thermal degradation of LLDPE under a nitrogen atmosphere, using non-isothermal thermogravimetric analysis (TGA). Pure LLDPE (PE), LLDPE/MH (mPE), and LLDPE/MH/MWCNTs (mcPE) composites were tested at four heating rates (5, 10, 15, and 20 K min–1). The degradation kinetics were analyzed using ASTM E698 and Ozawa–Flynn–Wall classical methods, alongside a logistic-based model that enhances the accuracy of degradation predictions. The results revealed that while the main degradation process of LLDPE remains largely unchanged, secondary degradation reactions were effectively suppressed by the fillers. Additionally, the logistic model allowed for accurate estimation of degradation behavior at untested heating rates. This methodology provides a powerful tool for optimizing polymer composite formulations, particularly in cable insulation and fire-retardant coatings, where enhanced thermal stability is essential for safety and material longevity.