AM-FM of Latex, Rubber and Epoxy

(a) AM ? Loss Tangent and (b) FM ? Stiffness maps acquired with the first and second resonance respectively. (c) the Loss Tangent histogram and (d) Stiffness histograms. As expected from the bulk data, the loss tangents of the rubber and latex are larger than the epoxy and clearly separated from each other (~1.5 for latex and ~2 for the natural rubber) in the Loss Tangent histogram (c). The bulk moduli for the latex and rubber are quite close, ~40 MPa and 43 MPa respectively. Despite being so close, the two materials are clearly separated in the Stiffness histogram (d).