Soft Matter at the Thermal Scale, Ch Rubber elasticity, swelling and gelation
Problem
A party balloon is made from a rubber whose Mooney-Rivlin constants are C1=0.18MPa and C2=0.09MPa, so that the nominal stress in uniaxial tension is σeng=(2C1+λ2C2)(λ−λ−2). Calculate σeng at a stretch λ=4.