Volume 57, Issue 11 pp. 651-661
Full Paper

Phase transitions of the rapid-compression-induced mesomorphic isotactic polypropylene under high-pressure annealing

Xiaobo Fu

Xiaobo Fu

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Wenxia Jia

Wenxia Jia

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Xiaoting Li

Xiaoting Li

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Yaming Wang

Yaming Wang

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Zhen Wang

Zhen Wang

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Chuntai Liu

Chuntai Liu

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Changyu Shen

Changyu Shen

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

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Chunguang Shao

Corresponding Author

Chunguang Shao

National Engineering Research Center for Advanced Polymer Processing Technology, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China

Correspondence to: C. Shao (E-mail: [email protected])Search for more papers by this author
First published: 23 March 2019
Citations: 13

ABSTRACT

The mesomorphic isotactic polypropylene was prepared by rapid compression instead of the common method of temperature quenching, and their phase transition under high pressure was investigated in depth by combining wide-angle X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry techniques. It was found that annealing under pressure can promote the further arrangement of chain segments of the mesophase toward the crossed state in the orthorhombic γ-phase, and the long period of the mesophase slightly decreased from 8.2 to 7.2 nm. The kinetics of this meso-γ transition strongly depends on pressure. As annealing pressure increased, the mobility of molecular segments was reduced, and then the onset and finishing time of phase transition were both delayed significantly. A critical annealing pressure was found between 1.6 and 1.75 GPa, which determines whether the phase transition occurs or not. When pressure reaches 1.75 GPa, mesophase did not transform at all within 120 min. Based on the results, a reasonable mechanism was proposed to show the crystallization process of mesophase under high-pressure annealing. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 651–661

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