Nucleation effect of adipic acid metal salts in isotactic polypropylene

A series of adipic acid metal salts as nucleating agents for isotactic polypropylene (iPP) were synthesized from adipic acid (Adi) and corresponding metal hydroxides or chlorides by neutralization or double decomposition reaction. The effect of different adipate on the crystallization and melting behavior of iPP were investigated by differential scanning calorimetry (DSC). The results indicated that after adding different metal salts of adipic acids, the crystallization peak temperature of nucleated iPP was increased by different degree. Adi, barium adipate (Adi-Ba), and zinc adipate (Adi-Zn) had higher nucleation efficiency. Notably, Adi-Zn and Adi-Ba were highly effective β-crystal nucleating agents; the others were α-crystal nucleating agents. In addition, the relative content of β-crystals in nucleated iPP was higher than 0.9 with the addition of Adi-Ba or Adi-Zn, especially when Adi-Zn was added at 0.05 mass% reached 0.9422, indicating that Adi-Ba and Adi-Zn are highly active and selective β-nucleating agents for iPP.