writer：Rong Yang, Lv Ding, Weilong Chen, Xin Zhang, Jinchun Li
keywords：molecular-weight dependence，liquid crystalline polyester，β-Nucleating Agent，Isotactic Polypropylene
source：期刊
specific source：Industrial & Engineering Chemistry Research
Issue time：2018年
Unlike low-molecular-weight inorganic or organic nucleating agents (NAs), the physical properties, including phase transition and rheological behaviors, of polymeric NAs are greatly influenced by molecular weight. In this paper, the molecular-weight dependence of the β-nucleation behaviors of a polymeric NA (a main-chain liquid crystalline (LC) polyester, PBDPS) was studied in detail. The nucleation effect of PBDPS on isotactic polypropylene (iPP) shows a strong molecular-weight dependence. Lowmolecular-weight PBDPS tended to induce the formation of α-iPP, whereas high-molecular-weight PBDPS tended to induce β-iPP. Moreover, the relative content of β-iPP crystals (k_β) first increased and then decreased as the molecular weight of PBDPS increased, with the maximum value (86.1%) obtained when 2 wt % PBDPS21.2k was incorporated. Furthermore, the stiffness, toughness, and heat distortion temperature (HDT) of iPP were simultaneously improved by incorporating PBDPS.