Incorporation of Alkali Lignin in Polyacrylonitrile: Phase Separation, Coagulation, and Cyclization Kinetics

Qian He; Pucha Zhou; Jian Hao; Chunxiang Lu; Yaodong Liu

doi:10.1021/acsomega.9b00478

Incorporation of Alkali Lignin in Polyacrylonitrile: Phase Separation, Coagulation, and Cyclization Kinetics

ACS Omega. 2019 Jul 1;4(7):11346-11353. doi: 10.1021/acsomega.9b00478. eCollection 2019 Jul 31.

Authors

Qian He^{1

2}, Pucha Zhou^{1

1}, Jian Hao^{1

2}, Chunxiang Lu^{1

1

3}, Yaodong Liu^{1

1

3}

Affiliations

¹ Key Laboratory of Carbon Materials and National Engineering Laboratory for Carbon Fiber Technology, Institute of Coal Chemistry, Chinese Academy of Sciences, 27 Taoyuan South Road, Taiyuan 030001, China.
² University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China.
³ Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

In this study, we systematically investigated the phase separation behaviors of polyacrylonitrile (PAN)/alkali lignin (AL)/dimethyl sulfoxide (DMSO) systems and found that the addition of AL causes phase separation and the systems form sea (PAN)/island (AL) types of structures. Interestingly, the AL-rich domains are very stable even after a long time of storage up to 15 days. Additionally, how the phase separation affected the solution rheology, the coagulation process and PAN cyclization were explored. The addition of AL in PAN/DMSO solutions changes the solution viscosity and gelation behaviors. Also, the existence of AL-rich domains accelerates the coagulation rate of the PAN solution in water. Because AL degrades at a lower temperature than PAN, it reduces the PAN cyclization temperature but leads to a higher cyclization activation energy, which could be caused by their different initiation mechanisms. These results would be useful to understand how the addition of AL affects the PAN solution structures, solution rheology, solution coagulation behaviors, and PAN stabilization reactions.