Figure 1

Flow curves ($10\mathrm{w}\mathrm{t}\%$ PBD solution) obtained in both controlled rate (in squares) and stress (in circles) modes, where the diamonds display the master curve from the oscillatory shear measurements at several temperatures, the open circles denote the initial shear rates before the constitutive transition brings the sample to the stable fast flow branch with a $1/2$ slope, and the half-filled circles depict the hysteresis behavior observed upon reducing the applied stress. The inset is the storage and loss moduli $G^{\prime }$ and $G^{\prime \prime }$ vs the oscillation frequency, where the terminal chain disentanglement time ${\tau }_d$ is taken as the reciprocal of the crossover frequency.Reuse & Permissions

Figure 2

Transformation from coil (entangled) to stretched (disentangled) state as depicted by three different properties at two applied stresses: the apparent shear rate, normal stress $N_1(t)$, and averaged flow birefringence $\Delta n(t)$ as a function of time, where the four vertical arrows denote the specific times for which video pictures of the retardation from the cone and plate flow cell were taken and presented in Figs. 3. The data at 4 KPa refer to the lower X axis, and those at 6 KPa refer to the upper X axis.Reuse & Permissions

Figure 3

Top view of optical retardation $\sigma =6\mathrm{K}\mathrm{P}\mathrm{a}$ from the cone and plate geometry at $\sigma =6\mathrm{K}\mathrm{P}\mathrm{a}$ at different stages of the constitutive transition from the coiled to the stretched state.Reuse & Permissions

Figure 4

Measured shear rate ($7.5\mathrm{w}\mathrm{t}\%$ PBD solution) as a function of time at an applied stress of 2500 Pa, along with four video pictures of the retardation through the gap in a Couette flow cell made of two concentric cylinders with diameters equal to 15 and 14 mm, respectively, where the sample height is about 20 mm.Reuse & Permissions