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Title: Microstructural Origins of Nonlinear Response in Associating Polymers under Oscillatory Shear

The response of associating polymers with oscillatory shear is studied through large-scale simulations. A hybrid molecular dynamics (MD), Monte Carlo (MC) algorithm is employed. Polymer chains are modeled as a coarse-grained bead-spring system. Functionalized end groups, at both ends of the polymer chains, can form reversible bonds according to MC rules. Stress-strain curves show nonlinearities indicated by a non-ellipsoidal shape. We consider two types of nonlinearities. Type I occurs at a strain amplitude much larger than one, type II at a frequency at which the elastic storage modulus dominates the viscous loss modulus. In this last case, the network topology resembles that of the system at rest. The reversible bonds are broken and chains stretch when the system moves away from the zero-strain position. For type I, the chains relax and the number of reversible bonds peaks when the system is near an extreme of the motion. During the movement to the other extreme of the cycle, first a stress overshoot occurs, then a yield accompanied by shear-banding. Lastly, the network restructures. Interestingly, the system periodically restores bonds between the same associating groups. Even though major restructuring occurs, the system remembers previous network topologies.
Authors:
 [1] ;  [2]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. San Diego State Univ., San Diego, CA (United States)
Publication Date:
Report Number(s):
SAND2017-11681J
Journal ID: ISSN 2073-4360; POLYCK; 658235
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Polymers
Additional Journal Information:
Journal Volume: 9; Journal Issue: 11; Journal ID: ISSN 2073-4360
Publisher:
MDPI
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
National Science Foundation (pre Sandia employment); USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1411225