5. Right, okay. The samples were cooled 40°C 1000 60°C 92°C 80°C 100°C Relaxation modulus (MPa) 11200 1 12°C 125°C 135°C 0.001 0.01 0.1 10 100 1000 1 Time th) the stress relaxation modulus from a tensile test is plotted as a function of time, over an accessible time scale, for various temperatures. assumes a dimensionlass relaxation modulus (gR), which is independent upon the magnitude and direction of straining () _ E(t) gR t - - Eo [1] where E T0. 15.9, crack Storage modulus vs. temperature plots were obtained using DMA . This confirmed data of Nolan et al. Increasing the degree of crosslinking Right. 297. At constant strain, the stress relaxes faster at the higher temperature. increases • Expansion of material – somewhat more open structure & Viscoelastic material exhibits both elastic and viscous characteristics, and its deformation is temperature dependent. Relaxation modulus E ( t) is a characteristic of material viscoelasticity as used to describe the stress relaxation of materials with time ( t ). represented by the relaxation modulus function as follows (Christensen, 1971; Ferry, 1980) , (1)E t E e where is the equilibrium modulus, and and are the elastic components and relaxation time associated to the q-th 1 ≤ ≤ Maxwell model component. Stress Relaxation tests were conducted at 0.1N preload force and 2% step strain, also with a 5 minute temperature soak. Estimate (a) the stress relaxation modulus at a measuring time of 1 h at −80 °C, (b) the temperature at which the modulus for a measuring time of 10 −6 h is the same as that at −80 °C for a measuring time of 1 h. Make two schematic plots of the logarithm of relaxation modulus versus temperature for an amorphous polymer (curve C in Figure 15.8). modulus of the material. 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