Test MethodInitial tensile behaviour of elastomers

At very small strains the tensile stress-strain relationship of elastomers is often fairly linear and therefore might be used for obtaining initial tensile modulus E. In this work we analysed initial tensile data of unfilled and carbon black filled vulcanised SBR samples to test if this is feasible.Strains from mechanical contact extensometer data have shown that the initial stress-strain dependence is nearly linear, as expected, but does not go through the origin, probably because of random initial time lag between force and extension times at crossing the zero point.Initial strains taken from the crosshead position have lower variation coefficients than initial strains from the mechanical contact extensometer data and, consequently, initial tensile modulus from the crosshead position also has lower variation coefficients than initial tensile modulus from the mechanical contact extensometer data.