Strain Energy Function of Poly(Propylene Oxide) and Polybutadiene Elastomers Estimated by General Biaxial Strain Testing
Shun SHIMIZU, Jungju LEE, Kenji URAYAMA and Toshikazu TAKIGAWA
Abstract:Stress-strain relations of poly(propylene oxide) (PPO) and polybutadiene (PB) elastomers are investigated by general biaxial strain testing where the strains in two orthogonal directions are varied independently. The data for general biaxial deformation provide an unambiguous basis to estimate the form of strain energy function (W) governing the stress-strain relations of elastomers. The function W (I1, I2) = C10(I1-3) + C01(I2-3) + C11(I1-3)(I2-3) + C20(I1-3)2 + C02(I2-3)2, where I1 and I2 are the first and second invariants of Green's deformation tensor and Cij (I,j=0,1,2) are the numerical coefficients, satisfactorily describes the data in the whole range of biaxial strain for the two elastomers. Key Words:Elastomers, Rubber, Rubber elasticity, Strain energy Function, Stretching