Influences of molecular structure on the isothermal crystallization behavior and mechanical properties of β-nucleated isotactic polypropylene

ABSTRACT

To investigate the influence of molecular structure of isotactic polypropylene (iPP) on the crystallization behavior and mechanical properties of its β-nucleated product, in this study, four iPP samples were selected. Results of molecular structure characterizations revealed that the molecular weight of the iPP resins are close, while the average isotacticities and the isotacticity distributions of the samples are quite different from each other. Isothermal crystallization kinetics study suggested that due to their different average isotacticities and isotacticity distributions, the crystallinity difference of the four samples is as high as 5.3%, and the crystallinity of β-crystal difference is as high as 7.2%. Generally, the higher the average isotacticity of the iPP and the wider its distribution are, the stronger the β-crystallization ability of the sample is. Moreover, the mechanical measurement revealed that high average isotacticity and the wide isotacticity distribution of the iPP resulted in the strong the β-crystallization ability and thus better the toughness.

Graphical abstract

KEYWORDS:

• Isotactic polypropylene
• β-nucleating agent
• molecular structure
• isothermal crystallization kinetics
• mechanical properties

Additional information

Funding

This work was supported by the The National Natural Science Foundation of China [51503134,51702282]; the Fundamental Research Funds for the Central Universities; State Key Laboratory of Polymer Materials Engineering [SKLPME 2017-3-02].

Notes on contributors

Weijiao Jiang

Miss Weijiao Jiang, majored in polymer materials and engineering, is currently a post graduate student in State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University (Chengdu 610065, China).

Xiuduo Song

Dr. Xiuduo Song, majored in composite materials, is a senior engineer at Key Laboratory of Combustion and Explosion Technology, Xi’ an Modern Chemistry Research Institute (Xi’ an 710065, China).

Rui Zhou

Mr. Rui Zhou, majored in composite materials, is a senior engineer at Key Laboratory of Combustion and Explosion Technology, Xi’ an Modern Chemistry Research Institute (Xi’ an 710065, China).

Zongkai Wu

Mr. Zongkai Wu, majored in composite materials, is a senior engineer at Key Laboratory of Combustion and Explosion Technology, Xi’ an Modern Chemistry Research Institute (Xi’ an 710065, China).

Bo Hu

Mr. Bo Hu, majored in materials science and engineering, is a senior engineer at Dongfang Electric Machinery Co., Ltd (Deyang 618000, China).

Yue Zhang

Dr. Yue Zhang, majored in materials science and engineering, is a senior engineer at Dongfang Electric Machinery Co., Ltd (Deyang 618000, China).

Zhiming Liang

Mr. Zhiming Liang, majored in materials science and engineering, is currently working at Dongfang Electric Machinery Co., Ltd (Deyang 618000, China).

Zhengfang Chen

Miss Zhengfang Chen, majored in polymer materials and engineering, is currently a post graduate student in State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University (Chengdu 610065, China).

Jian Kang

Dr. Jian Kang, majored in polymer materials and engineering, is currently a associated professor in State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University (Chengdu 610065, China).

Ming Xiang

Professor Ming Xiang, majored in polymer materials and engineering, is currently working at State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University (Chengdu 610065, China).