Study Of Phenyl-Terminated Hyperbranched Polyester As A Special Beta-Nucleating Agent On The Toughness Of Isotactic Polypropylene

The effect of phenyl-terminated hyperbranched polyester (HBP-Bz) with different generation (the first generation and the fourth generation) as a special beta-nucleating agent on the toughness of isotactic polypropylene (iPP) was investigated by dynamic rheological measurements, scanning electron microscopy, differential scanning calorimetry, wide-angle X-ray diffraction, polarized optical microscopy, and mechanical properties measurements. The results show that the beta nucleating activity of HBP-Bz significantly depends on its concentration and molecular structure. The relative content of beta-crystal form (K-beta) increases with the increasing HBP-Bz percentage reaches a maximum and then decreases as HBP-Bz percentage further increases. The K-beta values of iPP/HBP-G1-1% and iPP/HBP-G4-1% blends are 26.52% and 20.80%, respectively. When compared with HBP-G4, HBP-G1 has incompact molecular structure, facilitating the pi-pi interaction between phenyl-terminated groups and the helix chains of iPP crystallize on it, and therefore relatively good dispersibility, high beta nucleating activity and excellent toughening effect are obtained. The impact strength of iPP was dramatically improved, especially with addition of 1 wt% HBP-G1. POLYM. ENG. SCI., 59:E133-E143, 2019. (c) 2018 Society of Plastics Engineers