Elastic and viscous properties of Silly Putty

We consider in this paper the elastic and viscous properties of Silly Putty and confirm the well known fact that the properties depend on the rate at which the material is deformed. Rapid deformations were studied by dropping masses onto one end of a Silly Putty cylinder, and slow deformations were studied by compressing the cylinder in a materials testing machine. The results were compared with a simple engineering model of viscoelastic materials to estimate the stiffness and the viscosity of the Silly Putty cylinder. It was found that stress induced in Silly Putty relaxes with a time constant of about 0.1 s, Young’s modulus for a rapid deformation is about 1.7 × 10⁶ N/m², and the viscosity for a slow compression is about 8 × 10⁴ Pa s. When subject to a short impact, Silly Putty vibrates as a result of compressional wave propagation through the material.