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Single high-performance fibers (Kevlar® K129, Twaron® 2040, Technora® T200, Dyneema® SK76, Zylon® AS, Vectran® HT, and S-glass) are subject to lateral cutting action by an industrial blade. Due to the inherent variability of such testing, 40–60 replicate experiments were performed for each fiber type, at each of three different loading orientations, and the data were fit with a generalized extreme value distribution to summarize likelihood of failure under each condition. The results show that when organic fibers are cut at an angle that introduces shear loads, cut resistance drops by 60–90% compared to normal-incidence cut loading. This trend is driven by the highly oriented and fibrillar nature of organic fibers, in contrast to the isotropic S-glass fibers which show comparatively little change in cut resistance with blade orientation. Overall, the Vectran fibers provide the best resistance to normal loading, while the S-glass fibers are most resistant to non-normal loading. Micrographs show that, for organic fibers, shear loads lead to more localized failure compared to normally loaded fibers. [ABSTRACT FROM AUTHOR]

Conformal atomic layer deposition (ALD) of Al2O3 and TiO2 thin films on Kevlar®, poly(p-phenylene terephthalamide) (PPTA) fibers at 50 and 100 °C affects the fiber cut resistance. Systematic studies of ALD coatings between 10 to 400 A thick formed at 50 and 100 °C revealed excellent conformality, and trends in cutting performance depended on materials and process details. Å 50 Å/50 Å TiO2/Al2O3 bilayer formed at 50 °C increased cut resistance of PPTA by 30% compared to untreated fiber materials. In situ infrared analysis shows that trimethylaluminum (TMA) Al2O3 precursor reacts sub-surface with PPTA and tends to degraded mechanical performance. The TiCl4 TiO2 precursor reacts to form a barrier that limits TMA/PPTA interactions, allowing a harder Al2O3 layer to form on top of TiO2. The thin ALD coatings do not substantially affect durability, flexibility, or weight of the PPTA, making ALD a potentially viable means to enhance the protective properties of Kevlar and other polymer fiber systems. [ABSTRACT FROM AUTHOR]