Figure 5
(a) The ‘iso-stress’ curves show the strain changing with temperature at constant stress (labelled on the plot). The equilibrium rubber modulus of the x40 xLCE at 100 °C (in the isotropic phase) is E = 880 kPa, which gives the initial strain in all curves. At temperatures below Tv we see the classical effect of entropic elasticity, the rubber modulus linearly increasing with T. The onset of plastic flow occurs around 140–160 °C, with the network in free-flow above 250 °C. (b) Programming of the aligned monodomain in xLCE. With a sample kept at constant T = 250 °C (resulting in a higher rubber modulus E), we apply a tensile stress (labelled on the plot), and allow the plastic flow to reach 100% extension, at which point we consider the structure aligned, and take the sample out of the device. The time for this programming is several minutes, depending on the applied tensile load. (c) The initial polydomain and uniaxially aligned monodomain xLCE, programmed by its plastic flow to 100% elongtion. (d) The microscopy images between crossed polars indications alignment. (e) X-ray image confirming a good uniaxial nematic alignment, also letting us calculate the order parameter Q = 0.62.
