Journal of Textile Research ›› 2019, Vol. 40 ›› Issue (11): 9-12.doi: 10.13475/j.fzxb.20181102705

• Fiber Materials • Previous Articles     Next Articles

Influence of heat treatment on structure and properties of thermotropic liquid crystalline polyarylate fiber

YANG Fan1,2, LIU Junhua1,2, BIAN Angting1,2, WANG Yanping1,2(), QIAN Qiyuan3, NI Jianhua2, XIA Yumin1,2, HE Yong1,4, WANG Yimin1,2   

  1. 1. State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620, China
    2. College of Material Science and Engineering, Donghua University, Shanghai 201620, China
    3. Wuxi Jintong High Performance Fiber Co., Ltd., Wuxi, Jiangsu 214161, China
    4. Innovation Center for Textile Science and Technology, Donghua University, Shanghai 201620, China
  • Received:2018-11-12 Revised:2019-08-16 Online:2019-11-15 Published:2019-11-26
  • Contact: WANG Yanping E-mail:wyp@dhu.edu.cn

Abstract:

In view of the unstable structure and low strength of thermotropic liquid crystalline polyarylate (TLCPAR) as-spun fiber, the heat treatment was carried out to increase the molecular weight and therefore improve the strength of the fiber. The TLCPAR as-spun fiber with relaxed state was treated under the conditions of different heat treatment temperatures and time in nitrogen gas flow. The wide angle X-ray diffraction was adopted to analyze the crystallinity, crystalline size and orientation and the mechanical properties were tested by yarn strength tester. The results show that after heat treatment, the crystalline size of the (110) and (211) planes of the TLCPAR fiber has a significant increase. After being subjected to the heat treatment of 230 ℃ for 48 h, the crystallinity of the fiber increases by 37.1%, and the crystalline orientation decreases only 2%. It is shown that the molecular chains are stacked more orderly and closely after heat treatment. The change in structure of TLCPAR fiber results in an increase of 86.8% in strength and 20.9% in elastic modulus.

Key words: polyarylate fiber, thermotropic liquid crystalline polyarylate, heat treatment, crystallinity, mechanical property

CLC Number: 

  • TQ342.724

Fig.1

Two-dimensional WAXD diagrams of TLCPAR fiber before (a) and after (b) heat treatment"

Fig.2

One-dimensional WAXD curves of TLCPAR fiber before and after heat treatment"

Fig.3

Changes of crystalline size of TLCPAR fiber with heat treatment temperature"

Fig.4

Changes of crystallinity of TLCPAR fiber with heat treatment temperature"

Tab.1

Crystalline orientation of TLCPAR fiber under differentt heat treatment temperature"

时间/h 取向度/%
180 ℃ 200 ℃ 205 ℃ 210 ℃ 215 ℃ 220 ℃ 225 ℃ 230 ℃
6 91 91 91 91 91 90 91 91
12 91 91 91 90 91 90 90 90
24 91 90 91 91 91 90 90 90
36 90 91 90 90 90 90 89 89
48 91 90 90 90 90 89 90 89

Fig.5

Changes of strength of TLCPAR fiber with heat treatment temperature"

Fig.6

Changes of elastic modulus of TLCPAR fiber with heat treatment time"

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