Viscoelastic behavior of polyisobutylene under constant rates of elongation

Abstract

AbstractThe use of stress‐strain curves to characterize the linear viscoelastic properties of rubberlike materials is discussed. Tensile stress‐strain curves for a high molecular polyisobutylene were measured at ten temperatures between −54 and 85°C. and at strain rates between 0.104 and 0.104 × 10−3 sec.−1. At a single temperature, the data superpose on a double logarithmic plot of stress divided by strain rate against strain divided by strain rate. By superposing data obtained at different temperatures, the temperature dependence of viscosity was obtained. All data for elongation up to 100% were combined to give a single reduced stress‐strain curve, which extends over ten decades of reduced time. From the reduced curve, the stress‐relaxation modulus was calculated and found to agree satisfactorily with published data.