Kinetic Analysis of PVC Composites Modified With Different Types of Layered Double Hydroxides

This study investigates the impact of layered double hydroxides (LDHs) intercalated with various ions on the thermal degradation and stability of polyvinyl chloride (PVC). Three types of LDHs—carbonate LDHs (C-LDHs), diphenyl phosphate LDHs (P-LDHs), and sarcosine LDHs (N-LDHs)—were synthesized using co-precipitation and hydrothermal methods. Thermogravimetric analysis (TGA) revealed that C-LDHs significantly enhanced the thermal stability of PVC, increasing the activation energy during early degradation phases by up to 25% compared to pure PVC. N-LDHs also improved stability, particularly at higher temperatures, with activation energy rising by 18% in the later stages. P-LDHs, however, showed the least stabilization effect, with a 10% lower activation energy compared to pure PVC. The degradation process of PVC in the presence of LDHs was analyzed using model-free methods, which revealed the complex multistep nature of PVC degradation. Reaction mechanisms were predicted using the generalized master plot method, identifying distinct stages of thermal degradation. Overall, C-LDHs were found to be the most effective at retarding PVC thermal degradation, suggesting their potential as advanced eco-friendly stabilizers. The use of model-free methods and reaction mechanism analysis offers new insights into the design of more efficient thermal stabilizers for polymers.