Quantification of the Modulus of Elasticity and Dynamic Properties of Sylgard for Various Mixing Ratios, 2003-2006

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  • Bryn A. Martin
  • Tom Kotsakos
  • Justin Stevens
  • Sebastien Nicolaon
  • Steven Cespedes


Sylgard Elastomer is used to construct phantom models of human tissue. The mechanical properties of Sylgard 184 are tested over a range of mixing ratios of Sylgard 184. Young’s modulus is determined from the tests and compared to the moduli of human tissue. Although more data is needed to validate the preliminary results, Sylgard’s mechanical properties at the range of ratios tested correlate with properties measured on human tissue. However, Sylgard 184 is a linearly elastic material while human tissue is not. Simulation of human tissue using Sylgard should only be in ranges where a linear relationship can be approximated.


The following mixing ratios were created: 10:1, 15:1, 20:1, 25:1, 30:1, and 35:1. The ratio is of base to curing agent by mass. A convenient amount of Sylgard 184 base is poured into a container and it is weighed on a mass balance. While the container remains on the mass balance, the curing agent is added very slowly until the desired mixture mass ratio is achieved. The mixture is stirred for five minutes with a stirring rod. The mixture is then degassed several times to remove the air bubbles. Once the mixture is free of air bubbles, the mixture goes into the mold. Cylindrical samples are chosen. Five samples of each mixing ratio are created. The molds are oversized drinking straws (~23 cm lenght by 0.635 cm diameter). A pump sucks the mixture up through the straw. The mixture moves up the straw slowly; sufficient time is available to stop the pumping when the straw is filled.

Sylgard 184 base and hardener
Drawing mixture into plastic straws
Straws after curing
Testing apparatus (old-fashioned, lol)


Young's modulus Vs. Ratio Sylgard 184, Dow Corning