Preparation and nucleation effects of nucleating agent hexahydrophthalic acid metal salts for isotactic polypropylene

A series of highly efficient nucleating agent hexahydrophthalic acid (HHPA) metal salts for isotactic polypropylene (iPP) were prepared from hexahydrophthalic anhydride and different metal compounds. Effects of HHPA metal salts on crystallization and melting behaviors of iPP had been investigated by means of wide-angle X-ray diffraction (WAXD), differential scanning calorimeter (DSC), and polarized optical microscopy (POM). At the same time, the moisture absorption test of HHPA metal salts was carried out. The results showed that sodium, calcium, lithium, magnesium, and barium salts of HHPA were highly efficient α-crystalline nucleating agents for iPP, aluminum salt of HHPA had limited positive effect on the formation of β crystalline form, zinc salt was a highly efficient β nucleating agent, and the relative content of β-crystals of iPP nucleated with 0.2 wt% of zinc salt of HHPA reached 0.864. In addition, HHPA metal salts had a lower moisture absorption than sodium benzoate, which was beneficial for preservation of these nucleating agents and corresponding articles.