TIME AND TEMPERATURE DEPENDENCE OF CREEP MODULUS OF ELASTOMERS: A MATHEMATICAL ANALYSIS OF THE CREEP, USING BURGER MODEL

Many polymeric materials are susceptible to time-dependent deformation when the stress level is maintained constant; such deformation is termed viscoelastic creep. The time-dependent creep modulus it was analyzed and compared for natural and vulcanized rubber, at same temperature. In a one-dimensional creep test, the samples are subjected to a sudden stress that is maintained at a constant level duration the test, and the strain is measured as a function of time. Creep results are represented as a time-dependent creep modulus Ec(t)=σ0/ε(t). The experimental results indicate that creep modulus of natural rubber is greater than vulcanized rubber due to the crosslink's of vulcanized rubber.Also, it was analyzed the temperature dependence of creep modulus for both samples. The creep modulus is temperature sensitive and diminishes with increasing temperature. To permit a mathematical analysis of the creep for natural rubber at T1= 260C and σ= 0.069 MPa, it is used Burger model (the combined of Maxwell element and Kelvin-Voigt element) that exhibits all the essential features of viscoelasticity.