Abstract: As a type of novel high-efficient nucleating agent for polypropylene (PP), a series of hexahydrophthalic acid (HHPA) metal salts was prepared by hexahydrophthalic anhydride and different metal salts. Chemical structure of the resultant products was characterized by fourier transform infrared spectroscopy (FTIR), and their effect on the crystallization and melting behaviors of PP was analyzed by differential scanning calorimetry (DSC). The moisture absorption of HHPA metal salts was also evaluated. The results indicated that HHPA metal salts could act as a highly efficient α-crystal nucleating agent for PP, and the peak crystallization temperature of nucleated PP was improved significantly when 0.3wt % of HHPA metal salt was incorporated into PP. It was also found that the sodium salt of HHPA (HHPA-Na) had the best nucleating effect, and the peak crystallization temperature of nucleated PP increased by 12.1 ℃ compared with pure PP. In addition, the HHPA metal salts exhibited a low hygroscopicity, which is advantageous for preservation of this nucleating agent and the relevant molded parts.

Key words: hexahydrophthalic acid metal salt, nucleating agent, polypropylene