A Synergistic Effect of Multifunctional Magnesium Hydroxide@Layered Double Hydroxide Nanohybrid and an Organotin Polymer on the Poly(Vinyl Chloride) Properties

Poly(vinyl chloride) (PVC) is widely used for its versatility and cost‐effectiveness, but its inherent thermal instability requires advanced stabilization and flame‐retardant systems. Simultaneously enhancing thermal stability, flame retardancy, and mechanical performance remains challenging, as conventional additives often act through a single mechanism and suffer from poor PVC compatibility and limited synergy. Overcoming this, particularly through uniform dispersion and strong interfacial interaction between the organic and inorganic components, was a main challenge of this work. A hybrid formulation was developed to improve the thermal stability and fire performance of plasticized PVC by combining a pyridine‐based organotin polymer (PSn) with a multifunctional organo‐modified magnesium dihydroxide (MDH)@Zn‐Al layered double hydroxide (MLDH). Scanning electron microscope (SEM) showed improved dispersion with reduced aggregation in hybrid samples, while the absence of the LDH reflections in X‐ray diffraction (XRD) suggested uniform distribution within the PVC matrix. Thermal analysis revealed an enhancement in stability for the PSL5 sample (containing 2.5 wt.% PSn and 2.5 wt.% MLDH), where the onset degradation temperature increased from 165°C for neat PVC to 229°C, along with an increase in char residue from 10% to 21%. Thermal aging results further demonstrated a clear delay in discoloration compared to neat PVC. Flammability performance evaluation indicated that the total heat release (THR) decreased from 16.9 kJ g −1 (PVC) to 11 kJ g −1 (PSL5), while the limiting oxygen index (LOI) value increased from 26.8% to 28.7%, confirming relatively improved flame retardancy. Mechanical properties were also enhanced, with tensile strength increasing from 59.02 MPa (PVC) to 100.41 MPa (PSL5) and modulus from 2.68 to 4.98 GPa, while maintaining acceptable elongation.