Molecular-Weight Dependence of Nucleation Effect of a Liquid Crystalline Polyester β-Nucleating Agent for Isotactic Polypropylene

Molecular-Weight Dependence of Nucleation Effect of a Liquid Crystalline Polyester β-Nucleating Agent for Isotactic Polypropylene
来源：李锦春教授个人网站 2021-01-25

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.
[来源：中国聚合物网]