Tailoring Multi‐Cation LDHs With Cyanurate Intercalation: A Synergistic Approach Toward Eco‐Friendly PVC Thermal Stabilization

To address the thermal instability of polyvinyl chloride (PVC) and the environmental risks of conventional stabilizers, cyanurate‐intercalated layered double hydroxides (LDHs), including MgAl‐LDH (MA), La‐doped MgAl‐LDH (MAL), and Ca/La‐doped MgAl‐LDH (CMAL), were synthesized. Comprehensive XRD, FTIR, TGA, and SEM characterization confirmed the structural integrity of the samples. These LDHs were incorporated into PVC to fabricate composite materials, whose thermal stabilization efficiency was systematically evaluated through accelerated aging, Congo red, and dynamic thermal stability tests. Thermogravimetric analysis revealed that CMAL/PVC exhibited the highest initial decomposition temperature (281°C), surpassing MA/PVC (270°C), MAL/PVC (274°C), and neat PVC (256°C). Consistent enhancements were observed in color retention and HCl scavenging capacity, which correlated with increased thermal degradation resistance. Mechanistic studies demonstrated that cyanuric acid‐modified LDHs effectively suppressed autocatalytic HCl elimination and conjugated polyene formation during the thermal aging process at 180°C and the HCl absorption experiment. The multimetal synergy in CMAL enhanced Cl − coordination and acid neutralization, thereby inhibiting PVC degradation cascades. This work provides fundamental insights into designing eco‐friendly LDH‐based thermal stabilizers for high‐performance PVC applications, demonstrating significant potential for sustainable polymer engineering.