Evaluation of the synergistic effect of layered double hydroxides with micro- and nano-CaCO3 on the thermal stability of polyvinyl chloride composites

Abstract

Synergistic stabilizing effect of layered double hydroxides (LDHs) with micro- as well as nano-sized calcium carbonate (CaCO3) on thermal stability of polyvinyl chloride (PVC) was studied and evaluated. Nano-sized CaCO3 was prepared in the laboratory by matrix-mediated growth and controlled (in situ deposition) technique. Crystal size of nano-CaCO3 was estimated by studying x-ray diffraction pattern. The PVC composites were prepared using Brabender Plastograph instrument. Various formulations were prepared by taking fixed amount of LDH and varying the concentration of micro-/nano-sized CaCO3. PVC sheets of 1 mm thickness were prepared on compression molding machine. Thermal stability in terms of thermal degradation was studied by thermogravimetric analyzer. Surface morphology and mechanical property were studied using scanning electron microscopy and universal tensile machine. Increase in the onset temperature of the PVC sheets was considered as imparting a better thermal stability to PVC. Better synergistic effect on the stabilization of PVC was observed in case of LDH with nano-sized CaCO3 and compared with micro-sized CaCO3.