Synthesis and characterization of hydrotalcites: Potential thermal stabilizers for PVC

Abstract

Layered double hydroxides (LDH) are considered as a new emerging class of PVC stabilizers to replace toxic and environmentally hazardous class of heavy metals. A new series of Ca-Al-X (X=NO₃⁻, CO₃²⁻, Cl⁻, SO₄²⁻, PO₄³⁻) hydrotalcites have been prepared by hydrothermal process. The hydrotalcite particles are nanosized and have been characterized by EDX, XRD, FTIR and TGA techniques. A comparative study has been carried out to evaluate the effect of anions on PVC stabilization mechanism. A clear anionic effect is observed when they are subjected to HCl evolution studies. Color stability and UV-Vis spectroscopic studies of stabilized and unstabilized polymeric sheets support the long-term stability behavior of LDHs. A mechanistic approach indicates the role of adsorption process along with ion-exchange. \