A highly active and selective beta-nucleating agent for isotactic polypropylene and crystallization behavior of beta-nucleated isotactic polypropylene under rapid cooling

摘要

Zinc adipate (Adi-Zn) was observed to be a highly active and selective beta-nucleating agent for isotactic polypropylene (iPP). The effects of Adi-Zn on the mechanical properties and the beta-crystals content of nucleated iPP were investigated. The impact strength of iPP nucleated with 0.2 wt % Adi-Zn was 1.8 times higher than that of neat iPP. In addition, wide-angle X-ray diffraction analysis indicated that the content of beta-crystals in nucleated iPP (k(beta) value) reached 0.973 with 0.1 wt % Adi-Zn, indicating that Adi-Zn is a highly active and selective beta-nucleating agent for iPP. Furthermore, fast scanning chip calorimetry (FSC) studies using cooling rates from 60 to 13,800 degrees C min(-1) revealed that the formation of beta-crystals significantly depended on the cooling rates. At cooling rates below 3000 degrees C min(-1), only beta-crystals existed. However, at cooling rates above 6000 degrees C min(-1), beta-crystals failed to form. Moreover, a lower critical crystallization temperature that corresponded to the generation of beta-crystals was investigated using cooling-induced crystallization, and the results are in good agreement with those of a previous study. (C) 2016 Wiley Periodicals, Inc.