Study on crystallization structure and thermal behavior of iPP induced by a new liquid crystal nucleator

Abstract

In this study, a new liquid crystal polymer, named as smectic liquid crystal polymer (LCPs-P), was synthesized by reacting diosgenyl 4-(10-undecen-1-yloyloxy) benzoate with polymethylhydrosiloxane using chloroplatinic acid as a catalyst. The mesomorphic properties of the LCPs-P were characterized with polarizing optical microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis, and X-ray diffraction (XRD). Then, the influence of the LCPs-P as a new nucleator on the crystallization structures, thermal properties, and kinetic properties of isotactic polypropylene (iPP) was investigated by XRD and DSC. The experimental results indicated that the LCPs-P exhibited fan-shaped texture of a smectic A phase between 55°C and 318°C. The content of the β-crystal ( K β) of the iPP blends mainly depended on the LCPs-P content and the crystallization temperature. By optimally combining the LCPs-P content with the crystallization temperature, a high K β could be obtained. When the content of the LCPs-P was 0.9 wt%, the maximum K β could reach 51% after isothermal crystallization for 1 h at 130°C. Moreover, the addition of the LCPs-P could increase the crystallization temperature and shorten the crystallization time of the iPP blends.