3.3.3. Mechanical Properties

The ultimate tensile strength σUTS of the starch-glycerol films was 4.1 ± 2.1 MPa, Young's modulus *E* was 0.7 ± 0.4 MPa and the fracture strain ε<sup>f</sup> was 23.7% ± 13.9%. The mechanical properties were changed by adding CNC and SNP, however, all measured values of nanocomposites lie within the 95% confidence interval of the values of starch-glycerol films (Figure 7). Although all samples were prepared with high diligence, the notch sensitivity of the organic composites caused the high uncertainties of the measured mechanical properties.

**Figure 7.** Mechanical properties of CNC and SNP nanocomposites. (**a**) The ultimate tensile strength, (**b**) Young's modulus, and (**c**) the elongation at break.
