8/23/2023 0 Comments Creep test low viscosity fluidsThe creep test consists of measuring the time dependent strain \(\epsilon (t) = \delta (t)/L_0\) resulting from the application of a steady uniaxial stress \(\sigma_0\) as illustrated in Figure 3. Figure 2: A generic modulus-temperature map for polymers. It provides a map of a vital engineering property, and is also a fingerprint of the molecular motions available to the material. Clearly, a plot of modulus versus temperature, such as is shown in Figure 2, is a vital tool in polymer materials science and engineering. b Experimental measurement of plastic creep under low constant stress, for the Leibler's benchmark vitrimer, at T 180 C. Neither the glassy nor the rubbery modulus depends strongly on time, but in the vicinity of the transition near \(T_g\) time effects can be very important. If the material is not crosslinked, the stiffness exhibits a short plateau due to the ability of molecular entanglements to act as network junctions at still higher temperatures the entanglements slip and the material becomes a viscous liquid. Differentiation of this expression gives the slope of the stress-strain curve at the origin as \(E_r = 3NRT\). Where \(\sigma\) is the stress, \(N\) is the crosslink density (\(mol/m^3\)), and \(\lambda = L/L_0\) is the extension ratio.
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