The effect of dynamic tube dilation on chain stretch in nonlinear polymer melt rheology

The analysis of experimental data in elongational flow of mono and bidsperse polystyrene melts shows that: ► Chain stretch is associated with a reduction of the tube diameter. ► The pressures exerted by a polymer chain on the walls of an anisotropic confinement are anisotropic. ► The increasing interchain tube pressure limits chain stretch. ► Dynamic tube dilation leads to an increase in the tube diameter and reduces the interchain tube pressure. ► Quantitative agreement between experiments and model can be obtained based exclusively on linear viscoelasticity.