Effect of annealing treatment on impact toughness and crystallization behaviors of polypropylene/ethylene vinyl acetate copolymer/layered double hydroxide composites

Abstract This research endeavors to explore the potential of annealing treatment as a viable strategy to optimize the utilization of polypropylene (PP) composites, while preserving their exceptional properties. By incorporating ethylene vinyl acetate (EVA) copolymer and layered double hydroxide (LDH) into PP, this work meticulously analyzes the changes in crystallization behaviors and impact properties under varying annealing conditions. Impact strength is systematically assessed by a digital pendulum impact tester, whereas the crystalline structure is analyzed through polarized light optical microscopy (POM), differential scanning calorimetry (DSC), and x‐ray diffraction (XRD). The notch impact test exhibits a gradual increase in impact strength from 100 to 130°C, followed by a decline at 140°C. The XRD and DSC results elucidate subtle β‐crystal diffraction peaks for PP/EVA and PP/EVA/LDH composites, attributed to the transformative effect of EVA and LDH on PP crystals. POM analysis further unveils a reduction in spherical crystal size and gradual blurring of grain boundaries during the annealing process. Highlights PP/EVA/LDH composites are effectively regulated by changing the annealing treatment conditions. The crystallization behaviors and crystal structure of PP are induced due to synergistic effect of EVA and LDH under annealing treatment. The toughness of PP is enhanced significantly by synergistic effect of EVA and LDH under annealing treatment.