Viscoelastic Properties of Elastomers for Small Joint Replacements

Abstract

In the first part of this paper, the E' (storage modulus) and E' (loss modulus) values of six cylindrical specimens of Silastic® Q7-4780 medical grade silicone (suitable as a 90 day implant material), immersed in containers with physiological saline solution at 37°C, were measured using dynamic mechanical analysis. The results were compared with previous published data of a medical grade silicone, suitable as a 29 day implant material. The moduli of Q7-4780 were frequency-dependent as expected and were not significantly different from the shorter-term implant material. In the second part of this paper, the E' and E' values of Elast-Eon™ 3, a polyurethane with poly(dimethylsiloxane) (PDMS) and poly(hexamethylamine oxide) (PHMO) segments, were measured before and after accelerated aging in an oven at 70°C for 38 days. The moduli of six cylindrical specimens of Nagor® medium hardness medical grade silicone were also investigated using the same aging conditions. The results showed, that both the E' and E' of the Elast-Eon™3 were affected by accelerated aging. However the properties of Nagor® silicone were not affected.