Elongational Viscosity of Narrow Molar Mass Distribution Polystyrene

Abstract

Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly with molar mass at fixed elongation rate.

Similarity solutions for breakup of jets of power law fluids

“…On the other hand, some experiments, see e.g. [1] show elongation thinning persisting at high elongation rates, at least over the range of observations (they find a power law exponent of a ∼ 0.5). Suspensions can also be elongation thinning.…”

A new look at extensional rheology of low-density polyethylene

“…A laser micrometer is used to measure the diameter of the thin mid-filament slice. In order to explore higher strains, an online control scheme, which was firstly used by Bach et al [19] and later published by Marin et al [20], is employed in both DTU-FSR and VADER-1000 to control the diameter at the mid-plane of the filament during stretching, so that a constant strain rate is ensured before sample breaking. Depending on the types of samples, the maximum value of Hencky strain that both DTU-FSR and VADER-1000 can reach is up to 7.…”

Mechanism of spontaneous hole formation in thin polymeric films

“…It initially consists of a 60-nm-thick polymeric film of a 390 kg/mole polystyrene, where we use a value of τ w /3 = 0.035τ max . 13,23 All material parameters can be found in Wagner et al 13 and Bach et al 23 After a time delay, the initial disturbance gradually evolves and the local thickness goes toward zero, which by definition is the critical point in time where the hole develops. Only one hole develops from a disturbance, and the surface remains flat between the holes.…”