Influence of Metal β-Diketonate Addition on Thermal Stability and Cytotoxicity in Calcium-Zinc Stabilized PVC/MgAl-Layered Double Hydroxide Composite
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Despite its widespread dominance in the construction sector, polyvinyl chloride (PVC) requires robust thermal stabilization to suppress dehydrochlorination during high-temperature processing. The liberated hydrogen chloride (HCl) gas acts as an autocatalyst, precipitating structural degradation and severe discoloration. Conventional stabilization strategies, however, are severely constrained by the toxicity of lead-based additives and the prohibitive costs of organotin compounds, driving a critical demand for eco-friendly alternatives. Among various co-stabilizers, β-diketones are widely deployed to sustain the initial color of PVC. Nonetheless, their specific reaction mechanisms can accelerate long-term degradation unless coupled with an effective HCl scavenger. Specifically, these compounds mitigate degradation either by capturing acetylacetone to displace allylic chlorine or by chelating ZnCl₂, thereby enhancing both initial color retention and long-term thermal endurance. To address these challenges, this study develops an eco-friendly complex stabilizer to replace traditional heavy-metal-based thermal stabilizers containing toxic elements such as cadmium, barium, lead, and chromium. The objective is to achieve at least 90% of the performance of conventional lead stabilizers regarding thermal stability, dechlorination efficiency, and lead-leaching resistance. While maintaining a fixed ratio of a non-toxic calcium-zinc (Ca-Zn) stabilizer, methyltin mercaptide (MTM), and MgAl-layered double hydroxide (MgAl-LDH), the concentrations of metal β-diketonates-specifically aluminum acetylacetonate and zirconium acetylacetonate-were systematically varied. The optimal formulation balancing thermal resistance and non-toxicity was established through discoloration testing of the fabricated PVC/LDH composites and cytotoxicity evaluations via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays.
Keywords: Polyvinyl chloride, stabilizer, composite, thermal stability, cytotoxicity
This research was conducted with funding from the Environmental Technology Development Project of the Korea Environmental Industry & Technology Institute(KEITI). (No. RS-2025-02223750)
