Supplementary Material

Figure S1. (a) Sample deformation of hard-elastic iPP film at 25 {degree sign}C, 1s-1 tracked by CCD camera, and (b) comparison between εcorrect and ε. s⁻¹. Figure S2. Nominal stress - Hencky strain curves for repeated tensile tests at different strain rates: (a) 250 s-1; (b) 100 s-1; (c) 10 s-1; (d) 1 s-1; (e) 0.1 s-1; (f) 0.01 s-1; (g) 0.005 s-1. Figure S3. Nominal stress - Hencky strain curves for repeated tensile tests at different temperatures: (a) 0 {degree sign}C; (b) 25 {degree sign}C; (c) 100 {degree sign}C; (d) 150 {degree sign}C