Özet
The evolution of crystalline domain orientation vs. mechanical properties of aramid fibers under mechanical loading was investigated for initial crystalline domain orientations between 16.7° and 9.7°. The latter resulted in a broad range of longitudinal moduli between 66 GPa and 119 GPa but tensile strengths in the narrow range of 3.5–4.0 GPa. Mechanical conditioning up to 90% of the fiber tensile strength increased the initial modulus converging to 100 GPa which corresponds to a stable crystalline domain orientation of 11.6°, while the unloading modulus at stresses near the tensile strength converged to ∼165 GPa which approaches the theoretical modulus of 220 GPa. On the contrary, the tensile strength remained unchanged with increasing crystalline domain orientation, and was shown to be independent of the fiber gauge length, thus implying that failure is not due to flaws obeying weakest link statistics. Instead, short gauge length tests (200 μm) showed failure initiation at the fiber skin followed by crack propagation at the skin-core interface, resulting in extrusion of the fiber core, which points to the skin-core interface as an important factor limiting the tensile strength of this class of fibers.
Orijinal dil | İngilizce |
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Sayfa (başlangıç-bitiş) | 96-106 |
Sayfa sayısı | 11 |
Dergi | Polymer |
Hacim | 140 |
DOI'lar | |
Yayın durumu | Yayınlandı - 28 Mar 2018 |
Harici olarak yayınlandı | Evet |
Bibliyografik not
Publisher Copyright:© 2018 Elsevier Ltd
Finansman
This research was supported by the United States Army under contract number W91CRB-16-C-0011 . University of Illinois authors wish to thank Dr. Mauro Sardela of Frederick Seitz Materials Research Laboratory for the valuable discussions on the XRD measurements.
Finansörler | Finansör numarası |
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U.S. Army | W91CRB-16-C-0011 |