Study of phenyl‐terminated hyperbranched polyester as a special β‐nucleating agent on the toughness of isotactic polypropylene

Abstract

The effect of phenyl‐terminated hyperbranched polyester (HBP‐Bz) with different generation (the first generation and the fourth generation) as a special β‐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 β nucleating activity of HBP‐Bz significantly depends on its concentration and molecular structure. The relative content of β‐crystal form (Kβ) increases with the increasing HBP‐Bz percentage reaches a maximum and then decreases as HBP‐Bz percentage further increases. The Kβ 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 π–π interaction between phenyl‐terminated groups and the helix chains of iPP crystallize on it, and therefore relatively good dispersibility, high β 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. © 2018 Society of Plastics Engineers

Modification of the Crystallization Behavior of Isotactic Polypropylene by Grafting Styrene Segments

“…8 As reported, the π−π conjugation from the adjacent phenyl rings helps stabilize the crystals and promote the crystallization. 39,40 In terms of melt grafting reaction, do the monomers without the phenyl groups have a similar effect of St to improve the crystallization of iPP? VCHX and 2-VB were grafted onto iPP whose molar dosages were the same as that of St for the preparation of PP-g-PS-3.…”

“…In the field of polymeric NAs, their structural characteristics reveals that they all have phenyl groups, which may act as a growth surface for the crystal and induce the helix chains of iPP chain to epitaxially crystallize on it . As reported, the π–π conjugation from the adjacent phenyl rings helps stabilize the crystals and promote the crystallization. , In terms of melt grafting reaction, do the monomers without the phenyl groups have a similar effect of St to improve the crystallization of iPP? VCHX and 2-VB were grafted onto iPP whose molar dosages were the same as that of St for the preparation of PP- g -PS-3.…”