Fig. 7.

Within the dynamic mechanical analysis (DMA), a sinusoidal stress σ (or strain ε) is applied over a frequency spectrum and the material's response strain ε (or stress σ) is recorded. Because of the viscoelastic properties of the material, the response lags behind the applied stress (strain) with a phase-lag angle δ. For detailed characterisation of the silk fibroin scaffold, the dynamic elastic or storage modulus E' in MPa (A 1), the loss factor tan(δ) (A 2) and the so-called loss modulus E″ in MPa, as a parameter for the amount of energy dissipated by the viscous mechanisms (A 3), were evaluated.