Figure 5
The two-panel chart is labeled a and b. Panel a plots normalized shear modulus, expressed as G divided by G zero, on the vertical axis against time in seconds on the horizontal axis. Three curves correspond to temperatures of 160 degrees Celsius, 180 degrees Celsius, and 200 degrees Celsius. In all cases, the normalized modulus decreases with increasing time, indicating stress relaxation, with faster decay at higher temperature. A horizontal dashed reference marks the level of 1 divided by e, which defines the characteristic relaxation point. Panel b plots the characteristic relaxation time, tau star, in seconds on the vertical axis using a logarithmic scale against 1000 divided by temperature in inverse kelvin on the horizontal axis. Discrete data points follow an approximately linear trend. A vertical dashed reference indicates the vitrification temperature, labelled as T subscript v equal to 108 degrees Celsius, showing that relaxation time increases as temperature decreases.Stress relaxation curves versus time (a) and the Arrhenius plot of relaxation times of N5(b)