Role of CaCO3 in Retarding UV- and Thermally Induced Degradation of PVC Compounds

This study provides an in-depth investigation of the influence of calcium carbonate (CaCO3) filler on the mechanical performance and aging resistance of polyvinyl chloride (PVC)-based composites. PVC/CaCO3 composites containing 2.5, 5, and 7.5 wt% of CaCO3 were subjected to accelerated aging under combined ultraviolet (UV) irradiation and thermal stress for up to 1248 h. The key mechanical properties of specimens —tensile strength and elongation at break—were measured before and after aging. Changes in surface morphology, coloration, hydrophobicity, and chemical composition were characterized using scanning electron microscopy (SEM-EDS), X-ray spectroscopy, atomic force microscopy (AFM), contact angle measurements, and carbonyl index calculation to quantify relationships between the structural and physical properties of the specimens and aging conditions. The results reveal a significant correlation between filler content and the mechanical behavior of aged specimens, highlighting the potential of CaCO3 reinforcement not only to improve the retention of mechanical properties but also to increase the service life of PVC-based insulation compounds.