Universality of steady shear flow of Rouse melts
- PDF / 853,180 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 76 Downloads / 160 Views
ORIGINAL CONTRIBUTION
Universality of steady shear flow of Rouse melts Leslie Poh 1,2 & Esmaeil Narimissa 1,2
&
Manfred H. Wagner 3
Received: 19 June 2020 / Revised: 8 August 2020 / Accepted: 8 August 2020 / Published online: 29 August 2020 # The Author(s) 2020
Abstract The data set of steady and transient shear data reported by Santangelo and Roland Journal of Rheology 45: 583–594, (2001) in the nonlinear range of shear rates of an unentangled polystyrene melt PS13K with a molar mass of 13.7 kDa is analysed by using the single integral constitutive equation approach developed by Narimissa and Wagner Journal of Rheology 64:129–140, (2020) for elongational and shear flow of Rouse melts. We compare model predictions with the steady-state, stress growth, and stress relaxation data after startup shear flows. In characterising the linear-viscoelastic relaxation behaviour, we consider that in the vicinity of the glass transition temperature, Rouse modes and glassy modes are inseparable, and we model the terminal regime of PS13K by effective Rouse modes. Excellent agreement is achieved between model predictions and shear viscosity data, and good agreement with first normal stress coefficient data. In particular, the shear viscosity data of PS13K as well as of two polystyrene melts with M = 10.5 kDa and M = 9.8 kDa investigated by Stratton Macromolecules 5 (3): 304–310, (1972) agree quantitatively with the universal mastercurve predicted by Narimissa and Wagner for unentangled melts, and approach a scaling of Wi−1/2at sufficiently high Weissenberg numbers Wi. Some deviations between model predictions and data are seen for stress growth and stress relaxation of shear stress and first normal stress difference, which may be attributed to limitations of the experimental data, and may also indicate limitations of the model due to the complex interactions of Rouse modes and glassy modes in the vicinity of the glass transition temperature. Keywords Unentangled polymer melt . Single integral constitutive equation . Rouse relaxation spectrum . Universal viscosity master curve . Polystyrene
Introduction The scarcity of reliable shear flow data of unentangled polymers in the nonlinear-viscoelastic regime has made the understanding and modelling of shear flow behaviour of unentangled polymers challenging. A set of rare transient data reported by Santangelo and Roland et al. (2001) in the nonlinear range of shear rates on a monodisperse unentangled
* Esmaeil Narimissa [email protected] * Manfred H. Wagner [email protected] 1
Department of Chemical Engineering, Technion–Israel Institute of Technology (IIT), Technion City, 32 000 Haifa, Israel
2
Department of Chemical Engineering, Guangdong Technion–Israel Institute of Technology (GTIIT), Shantou 515063, China
3
Polymer Engineering/Polymer Physics, Berlin Institute of Technology (TU Berlin), Ernst-Reuter-Platz 1, 10587 Berlin, Germany
polystyrene melt (PS13K) was recently modelled by Ianniruberto and Marrucci (2020) using Brownian dynamics simulation of Fraenke
Data Loading...
