Rubber elasticity in the range of small uniaxial tensions and compressions. Results for poly(dimethylsiloxane)

Abstract

AbstractResults of uniaxial tension and compression experiments are reported on crosslinked polydimethylsiloxane (PDMS) networks in the unswollen state over the range 0.5 < α−1 < 1.2 where α is the extension ratio. Curves representing the reduced force [f] = f(V0/V)1/3(α – α−2)−1 plotted against α−1 can be approximated by straight lines for 0.5 < α−1 < 0.9, in agreement with the phenomenological Mooney equation. As α−1 approaches 1, however, they tend to level off and continue into the α−1 > 1 region with decreasing slope. These results are in agreement with the predictions of recent elasticity theories that incorporate the effect of junction‐chain entanglements in the elastic free energy.