Modelling of silk-reinforced PDMS properties for soft tissue engineering applications.

Background: Polydimethylsiloxane (PDMS) is widely used in biomedical research and technology, but its mechanical properties should be tuned according to the desired product specifications. Mixing ratio of base polymer to curing agent or additives enables its mechanical properties to be manipulated and fit to mechanical properties of biological tissues.

Objective: In this paper, we analysed the effect of mechanical load on silk-reinforced PDMS depending on silk concentration.

Methods: We prepared cylinder-type PDMS samples with different silk concentrations and performed cyclic uniaxial compression tests with a fixed magnitude of applied strain. Next, we analysed the mechanical charascteristics of PDMS using computational modelling.

Results: The stress-strain data within the large-strain region of different PDMS cylinders without silk and with 1%, 5% and 10% silk concentrations was fitted to non-linear second order Mooney-Rivlin, and third-order Ogden models. The results show the equivalence of both models for investigated strain region of PDMS. On the other hand, PDMS cylinders with 10% silk concentration allowed the successful fitting of experimental data just for the second-order Mooney-Rivlin model, while all numerical probes to find an appropriate fitting parameters for third-order Ogden models were unsuccessful.

Conclusions: The second-order Mooney-Rivlin model is preferable for analysing the properties of silk-reinforced PDMS over the entire measurement range.