Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus

Wang, Bing; Fancey, Kevin S.

Abstract

The viscoelastic behavior of semi-crystalline polyamide 6,6 fiber is exploited in viscoelastically prestressed polymeric matrix composites. To understand better the underlying prestress mechanisms, strain–time performance of the fiber material is investigated in this work, under high creep stress values (330–665 MPa). A latch-based Weibull model enables prediction of the “true” elastic modulus through instantaneous deformation from the creep-recovery data, giving 4.6 ± 0.4 GPa. The fiber shows approximate linear viscoelastic characteristics, so that the time–stress superposition principle (TSSP) can be implemented, with a linear relationship between the stress shift factor and applied stress. The resulting master creep curve enables creep behavior at 330 MPa to be predicted over a large timescale, thus creep at 590 MPa for 24 h would be equivalent to a 330 MPa creep stress for ∼5200 years. Similarly, the TSSP is applied to the resulting recovery data, to obtain a master recovery curve. This is equivalent to load removal in the master creep curve, in which the yarns would have been subjected to 330 MPa creep stress for ∼4.56 × 107 h. Since our work involves high stress values, the findings may be of interest to those involved with long-term load-bearing applications using polyamide materials.

Citation

Wang, B., & Fancey, K. S. (2017). Application of time–stress superposition to viscoelastic behavior of polyamide 6,6 fiber and its “true” elastic modulus. Journal of Applied Polymer Science, 134(24), Article 44971. https://doi.org/10.1002/app.44971

• Acceptance Date: Jan 16, 2017
• Online Publication Date: Feb 20, 2017
• Publication Date: Jun 20, 2017
• Deposit Date: Mar 8, 2017
• Publicly Available Date: Feb 20, 2018
• Journal: Journal of applied polymer science
• Print ISSN: 0021-8995
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 134
• Issue: 24
• Article Number: 44971
• DOI: https://doi.org/10.1002/app.44971
• Keywords: Applications; Fibres; Polyamides; Thermoplastics; Viscosity and viscoelasticity
• Public URL: https://hull-repository.worktribe.com/output/449181
• Publisher URL: http://onlinelibrary.wiley.com/wol1/doi/10.1002/app.44971/abstract
• Additional Information: Authors' accepted manuscript of article published in: Journal of applied polymer science, 2017, v.134, issue 24.
• Contract Date: Feb 20, 2018