Thermally Induced Reorganization in LCP Fibers: Molecular Origin of Mechanical Strength
The ordering of liquid crystalline polymer fiber during heat treatment is of great interest for many commercial reasons. This is because, by convention, fiber property can be greatly improved by heat-treatment at below the melting temperature and often such processing conditions are also very complex. There are many variations of such treatments, in terms of temperature, exposure time and whether the fibers are under tension or not. The state-of-the-art technology will be to optimize the desired property without significantly enhancing the undesired properties. The types of heat treatment are highly correlated to the understanding of the mechanism of improving the properties at the molecular level and the microstructures. Using WAXS and synchrotron SAXS techniques, the structure and morphology of our commercial LCP (liquid crystalline polymer), a co-polymer of CO (Vectran) and its variant polymer fiber COTHBP are being examined. Both fibers have the typical liquid crystalline polymer structure, ie, highly ordered across the fiber axis and aperiodic sequencing along the fiber axis. Physical testing has revealed a three fold increase in strength in both fibers, however, the modulus is observed to increase significantly in COTBP and not so much CO. This paper reports on the changes and the differences on the structural and morphological behavior for both the as-spun and heat-treated LCP fibers. We have also use thermal analysis technique to provide a guide to the heat-treatment cycle. We propose an 'organized kinks' model to describe the differences between the two polymer fibers. Future publication will focus on the in-situ behavior at elevated temperatures and under heat-treatment.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 985477
- Report Number(s):
- UCRL-CONF-232815; TRN: US1006148
- Resource Relation:
- Journal Volume: 93; Journal Issue: 1; Conference: Presented at: 2007 NATAS Conference, East Lansing, MI, United States, Aug 26 - Aug 29, 2007
- Country of Publication:
- United States
- Language:
- English
Similar Records
Liquid crystal polymer/polyethylene (LCP/PE) in-situ composite thin film: Effect of counter-rotating die on film structure and properties
Blends of thermotropic LCP having alkoxy side-groups with PBT: Comparison of their tensile properties with main-chain LCP blends (II)