Effect of fiber gripping method on the single fiber tensile test: II. Comparison of fiber gripping materials and loading rates

Single poly(p-phenylene terephthalamide) (PPTA) fiber tensile tests were carried out under quasi-static and high strain rate loading conditions using poly(methyl methacrylate) and rubber grips to investigate effects of grip materials and loading rates on fiber tensile properties. Differences in ultimate tensile strengths, failure strains, and moduli of PPTA fibers obtained by two different grip materials were insignificant. On the other hand, the fiber tensile properties showed significantly rate-dependent behaviors, which were graphically confirmed by kernel density plots as a non-parametric statistical analysis. Strength models considering three aspects (stochastic, fracture mechanics, and polymer chain domain behaviors) were also shown to link the loading rate effect in relation to fracture mechanisms.