Rheotens tests and viscoelastic simulations related to high-speed spinning of Polyamide 6

2021

Acta Mech. Sin.

In the present paper, a structure-based viscoelastic model is employed to characterize and predict the viscoelastic properties of a wormlike micellar solution at 20 °C. Considering the effect of shear rate on linear viscoelastic property, a structural parameter f is obtained. Meanwhile, another structural parameter ζ is determined when the effects of time and shear rate are considered simultaneously. Both structural parameters are calculated by using linear interpolation method. The startup experiment can be described well by the model. The prediction on the shear stress in the ramping-up region of the hysteresis loop experiment shows an apparent relation between the rheological behaviors in the startup experiment and those in the hysteresis loop experiment. For the hysteresis loop experiment with 30 s time interval, the defect of the calculation in 0.001-0.01 s −1 is due to the lack of the ramping-down history effect. In addition, the model can improve completeness of perimental data used for characterizing rheological property.

Section: Introductionmentioning

confidence: 99%

Viscoelastic characterization and prediction of a wormlike micellar solution

2021

Acta Mech. Sin.

“…γ is the shear rate. The strain-dependent function h used is the Papanastasiou-Scriven-Macosko (PSM) function [9,[13][14][15].…”

Section: Methodsmentioning

confidence: 99%

Prediction of the Viscoelastic Properties of a Cetyl Pyridinium Chloride/Sodium Salicylate Micellar Solution: (II) Prediction of the Step Rate Experiments

2022

Polymers

The reliable viscoelastic characterization and prediction of micellar solution is still required in industrial applications of the solution, e.g., in surfactant flooding and pharmaceuticals. Based on the recent theoretical characterization of the viscoelastic properties of a cetyl pyridinium chloride/sodium salicylate (CPyCl/NaSal) wormlike micellar solution with a structuralized constitutive model in the work published in 2022, the present work predicted five groups of transient shear viscoelasticities of the solution experimentally obtained in 2010, which include the first normal stress difference (N1) versus time curve in the start-up experiment, the shear stress (τ12) in the start-up experiment, τ12 in the long-term start-up experiment, the stress relaxation upon cessation of steady shear flow, and the transient N1/τ12 in the step strain experiment. The study findings clearly show an improvement in the predictions of the viscoelastic properties of the micellar solution compared with those predicted previously. For example, the experimental N1/τ12 is 9 at the strain of 9 in the step strain experiment, and the corresponding previous and present predictions are 2.47 and 8.45, respectively.

“…The shear viscoelastic properties of variety of commercial or industry-grade polymer melts have been published, e.g., low-density polyethylene (LDPE) [2][3][4][5][6][7][8], linear low-density polyethylene (LLDPE) [9,10], high-density polyethylene (HDPE) [4,5,[10][11][12], polypropylene (PP) [13][14][15], polystyrene (PS) [4,16], and polyamide 6 (PA6) [17]. Five types of shear viscoelastic properties are usually included in these publications, which are: (1) linear viscoelastic property, i.e., frequency sweep at small strain, (2) steady shear viscosity, (3) steady first normal stress difference (N 1 ), (4) shear stress growth in step rate experiment, and (5) N 1 growth in step rate experiment.…”

Section: Introductionmentioning

confidence: 99%

“…The applications of the reported experimental viscoelastic properties of polymer melt that are seen in publications are mainly based on two aspects. One aspect is to examine the theoretical model of viscoelastic property of polymer melt [3,[5][6][7][8][9][10][11]13,[15][16][17][18][19][20][21][22], and the other is to simulate the flow in polymer processing numerically according to the published viscoelastic experimental data [23][24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

“…The accuracy of the theoretical simulation depends on the constitutive equation [25,26]. A large number of constitutive equations have been proposed, and 13 were listed in a recent review [28] on the use of constitutive equations in extrusion cast film processing, in which most are typical and often used in both polymer processing and viscoelastic characterization of the polymer melt, and some can be seen in the references above [3,[7][8][9][10][11]13,15,17,[19][20][21]. The choice of the constitutive equation in applications depends on the researcher because the researcher usually uses the model that can be used.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Viscoelastic Property of an LDPE Melt in Triangular- and Trapezoidal-Loop Shear Experiment

2021

Polymers

The time-dependent viscoelastic behaviors of a low-density polyethylene melt (LDPE) in a triangular- and trapezoidal-loop shear experiment reported previously are described here by an integral-type Rivlin–Sawyers (RS) constitutive equation. The linear viscoelasticity of the melt was obtained through a dynamic frequency sweep experiment at a small strain and fitted by a relaxation spectrum. The nonlinear viscoelasticity was characterized by viscosity. All the experimental viscoelastic behaviors of the melt can be divided into two types in terms of the predictions of the RS model: (1) predictable time-dependent viscoelastic behaviors at low shear rates or during short-term shear, and (2) unpredictable shear weakening behavior occurring at the high shear rate of 3–5 s−1 during long-term shear with the characteristic time interval of about 40–100 s. The influence of experimental error caused possibly by inhomogeneous samples on the viscoelasticity of the melt was analyzed, and the large relative error in the experiment is about 10–30%.