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Title: Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS

Abstract

We present an investigation into the dynamic relaxation mechanisms of a polybutadiene blend composed of a four-arm star (10 wt. %) and a linear polymer matrix in the presence of an applied shear flow. Our focus was the response of the star polymer, which cannot be unambiguously assessed via linear viscoelastic measurements since the signature of the star polymer can barely be detected due to the dominant contribution of the linear matrix. By utilizing small-angle neutron scattering (SANS) coupled with a Couette shear device and a deuterated matrix polymer, we investigated the dynamics of the minority star component of the blend. Our results confirm that the stars deform anisotropically with increasing shear rate. We have compared the SANS data with predictions from the well-established scattering adaptation of the state-of-the-art tube model for entangled linear polymer melts undergoing shear, i.e., Graham, Likhtman, Milner, and McLeish (GLaMM) approach, appropriately modified following earlier studies in order to apply to the star. This modified model, GLaMM-R, includes the physics necessary to understand stress relaxation in both the linear and nonlinear flow regimes, i.e., contour length fluctuations, constraint release, convective constraint release, and chain retraction. The full scattering signal is due to the minority starmore » component and, although the contribution of the linear chains is hidden from the neutron scattering, they still influence the star polymer molecular dynamics, with the applied shear rate ranging from approximately 8 to 24 s–1, below the inverse relaxation time of the linear component. This study provides another confirmation that the combination of rheology and neutron scattering is an indispensable tool for investigating the nonlinear dynamics of complex polymeric systems.« less

Authors:
 [1];  [1];  [1];  [2];  [1]; ORCiD logo [3];  [3]; ORCiD logo [4]; ORCiD logo [4]; ORCiD logo [5];  [1]
  1. Univ. of California, Santa Barbara, CA (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source II (NSLS-II); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. King Abdullah Univ. of Science and Technology, Thuwal (Saudi Arabia)
  4. Univ. of Crete, Heraklion, Crete (Greece)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); European Commission (EC)
OSTI Identifier:
1661636
Report Number(s):
BNL-216377-2020-JAAM
Journal ID: ISSN 0148-6055
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Rheology
Additional Journal Information:
Journal Volume: 64; Journal Issue: 3; Journal ID: ISSN 0148-6055
Publisher:
Society of Rheology
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Convective constraint release; Rheo-SANS; Mechanical stress; Neutron scattering; Polymers

Citation Formats

Andriano, L. T., Ruocco, N., Peterson, J. D., Olds, D., Helgeson, M. E., Ntetsikas, K., Hadjichristidis, N., Costanzo, S., Vlassopoulos, D., Hjelm, R. P., and Leal, L. G. Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS. United States: N. p., 2020. Web. doi:10.1122/1.5121317.
Andriano, L. T., Ruocco, N., Peterson, J. D., Olds, D., Helgeson, M. E., Ntetsikas, K., Hadjichristidis, N., Costanzo, S., Vlassopoulos, D., Hjelm, R. P., & Leal, L. G. Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS. United States. https://doi.org/10.1122/1.5121317
Andriano, L. T., Ruocco, N., Peterson, J. D., Olds, D., Helgeson, M. E., Ntetsikas, K., Hadjichristidis, N., Costanzo, S., Vlassopoulos, D., Hjelm, R. P., and Leal, L. G. Thu . "Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS". United States. https://doi.org/10.1122/1.5121317. https://www.osti.gov/servlets/purl/1661636.
@article{osti_1661636,
title = {Microstructural characterization of a star-linear polymer blend under shear flow by using rheo-SANS},
author = {Andriano, L. T. and Ruocco, N. and Peterson, J. D. and Olds, D. and Helgeson, M. E. and Ntetsikas, K. and Hadjichristidis, N. and Costanzo, S. and Vlassopoulos, D. and Hjelm, R. P. and Leal, L. G.},
abstractNote = {We present an investigation into the dynamic relaxation mechanisms of a polybutadiene blend composed of a four-arm star (10 wt. %) and a linear polymer matrix in the presence of an applied shear flow. Our focus was the response of the star polymer, which cannot be unambiguously assessed via linear viscoelastic measurements since the signature of the star polymer can barely be detected due to the dominant contribution of the linear matrix. By utilizing small-angle neutron scattering (SANS) coupled with a Couette shear device and a deuterated matrix polymer, we investigated the dynamics of the minority star component of the blend. Our results confirm that the stars deform anisotropically with increasing shear rate. We have compared the SANS data with predictions from the well-established scattering adaptation of the state-of-the-art tube model for entangled linear polymer melts undergoing shear, i.e., Graham, Likhtman, Milner, and McLeish (GLaMM) approach, appropriately modified following earlier studies in order to apply to the star. This modified model, GLaMM-R, includes the physics necessary to understand stress relaxation in both the linear and nonlinear flow regimes, i.e., contour length fluctuations, constraint release, convective constraint release, and chain retraction. The full scattering signal is due to the minority star component and, although the contribution of the linear chains is hidden from the neutron scattering, they still influence the star polymer molecular dynamics, with the applied shear rate ranging from approximately 8 to 24 s–1, below the inverse relaxation time of the linear component. This study provides another confirmation that the combination of rheology and neutron scattering is an indispensable tool for investigating the nonlinear dynamics of complex polymeric systems.},
doi = {10.1122/1.5121317},
journal = {Journal of Rheology},
number = 3,
volume = 64,
place = {United States},
year = {2020},
month = {4}
}