<p>The crystallization kinetics of poly(ε-caprolactone) (PCL) and chlorinated polyethylene (CPE) binary blends were investigated, focusing on the effects of varying CPE content and chlorine concentration. Differential scanning calorimetry (DSC) and polarized optical microscopy were used to study the non-isothermal and isothermal crystallization kinetics. The results show that addition of CPE significantly influenced the crystallization behavior of PCL, and the extent of this effect was strongly dependent on the chlorine content of the CPE. Blends with a higher chlorine content (48%) in CPE exhibited enhanced interactions and higher miscibility with PCL, whereas the lower chlorine content (25%) indicated the immiscible nature of the blends. The interaction energy density calculations supported the presence of stronger PCL-CPE interactions at higher chlorine concentrations. Owing to the higher miscibility, increasing the CPE content in the PCL/CPE blend decreased the relative crystallinity, lowered the melting peak, reduced the crystal growth rate, and slowed the overall crystallization process. These effects were more pronounced at higher chlorine levels, whereas lower chlorine levels were not significantly affected by the immiscible nature of the blend. The blend composition and crystallization temperature influenced the crystallization kinetics and melting behavior. Higher CPE concentrations resulted in less perfect and heterogeneous crystalline structures. These findings contribute to a better understanding of the crystallization kinetics of PCL/CPE blends and provide valuable insights for specific applications.</p> Graphical abstract <p>Crystallization kinetics of poly(ε-caprolactone) and chlorinated polyethylene binary blends</p> <p></p>