Influences of Hyperbranched Polyester Modification on the Crystallization Kinetics of Isotactic Polypropylene/Graphene Oxide Composites

• Published in: Polymers Vol. 11; no. 3; p. 433
• Main Authors: Hao, Zengheng, Li, Lu, Yang, Bo, Sheng, Xingyue, Liao, Xia, He, Leilei, Liu, Pan
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 06.03.2019; MDPI
• Subjects: Crystal growth; Crystallization; crystallization kinetics; Fourier transforms; Graphene; graphene oxide; hyperbranched polyester; Infrared spectra; isotactic polypropylene; Isotacticity; Kinetics; Mechanical properties; Nucleation; nucleation and crystal growth; Optical microscopy; Photoelectrons; Polyesters; Polymer matrix composites; Polymers; Polypropylene; Thermogravimetric analysis; Transmission electron microscopy; X ray photoelectron spectroscopy; Beijing China; United States > US; China; graphene oxide; hyperbranched polyester; isotactic polypropylene; crystallization kinetics; nucleation and crystal growth
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym11030433

In this study, the hyperbranched polyester grafted graphene oxide (GO-H202) was synthesized, and the isotactic polypropylene/graphene oxide (iPP/GO) composites were prepared. Results of X-ray photoelectron spectra (XPS), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) revealed the successful synthesis of GO-H202, while thermogravimetric analysis (TGA) indicated that the weight ratio of grafting was about 35 wt %. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were carried out to investigate the role of GO and GO-H202 on the crystallization kinetics of the composites. Results suggested that the addition of GO enhanced the nucleation rate and crystallizability of the composites, while GO-H202 exhibited a higher crystallization acceleration effect compared to neat GO; results of isothermal crystallization kinetics and self-nucleation isothermal crystallization kinetics showed that both the overall crystallization rate and crystal growth rate increase after the addition of GO and GO-H202, and the crystallization acceleration of GO-H202 became evidently stronger compared to GO. Moreover, the variation trends of Avrami exponent with the isothermal crystallization temperature changed significantly after the addition of GO or GO-H202, which might imply that the addition of GO and GO-H202 lead to different crystallization dimensionalities during the isothermal crystallization of the composites. The related mechanism was also discussed.