Fig. 3: Mechanical properties of TPOU and CPOU fibers.

a Typical tensile stress-strain curves. b Comparison of their tensile strength and maximum elongation (error bars: standard deviations). c, d Cyclic tensile curves of c TPOU fiber and d CPOU fiber at 200% strain. There was no break between each consecutive cycle for the first 10 cycles. After being allowed the samples to relax for 1 h at room temperature, the 11th cyclic tensile test was performed. e Photographs of (i) original, (ii) 2.5 times stretched, and (iii) 1 min recovered (at room temperature) CPOU fiber.