Using two scaling exponents to describe the mechanical properties of swollen elastomers

• Swelling effects on mechanical properties of swollen elastomers are studied.
• Flory–Rehner free energy function is extended by introducing two scaling exponents.
• Elastic strain energy is separated into deviatoric and volumetric components.
• Extended model reproduces two swelling effects and predicts swelling-induced rupture.
• Predicted tendency explains experimental observations and elucidates the mechanism.

We study the ability of two scaling exponents to describe the mechanical properties of swollen elastomers. Swelling effects on the Young's modulus and osmotic pressure of swollen elastomers at equilibrium swelling are investigated using literature data and the Flory–Rehner free energy function. An extended model is developed by introducing two scaling exponents into elastic strain energy functions that are separated into deviatoric and volumetric components. This extended model satisfactorily reproduces the two different swelling effects, and also predicts swelling-induced rupture. The predicted tendency readily explains experimental observations well, i.e., swelling-induced rupture occurs when small extensions are applied in good solvents, and elucidates the mechanism of swelling-induced rupture of elastomers.