Non-isothermal crystallization kinetics of polypropylene/layered double hydroxide composites

The crystalline behaviors of polymers have a large impact on their physical and mechanical properties, especially as reinforcing and toughening materials in the construction industry. This work investigates the crystallization behaviors of polypropylene (PP) composites with layered double hydroxide (LDH) by using differential scanning calorimeter and a polarizing optical microscope (POM), and analyzed the non-isothermal crystallization kinetics of PP composites by Avrami model and Mo's method. The results show that the entire process of non-isothermal crystallization is appropriate for Mo ' s method instead of Avrami model due to the offset of the curves in initial nucleation and secondary crystallization stages. The addition of LDH and modified LDH (SLDH) can increase the crystallinity (X-c) of PP despite decreasing the crystallization rate in the non-isothermal crystallization process. The migration activation energy ( increment E) indicates that LDH acts as a heterogeneous nucleating agent, which is consistent with POM results. The values of increment E and semi-crystallization time (t(1/2)) reveal that the nucleation capacity of PP/LDH is greater than that of PP/SLDH, but the crystallization rate of PP/LDH is slower than that of PP/SLDH, resulting in a decrease in X-c.

Automated summary

The study investigated the crystallization behaviors of PP composites with LDH and SLDH, showing that they affect the crystallinity and crystallization rate of PP. LDH acts as a heterogeneous nucleating agent, resulting in differences in nucleation capacity and crystallization rate compared to SLDH.