Paper Number
AC23 

Session
Additive Manufacturing and Composites

Title
Relaxation dynamics of deformed polymer nanocomposites as revealed by small-angle scattering and rheology

Presentation Date and Time
October 13, 2022 (Thursday) 10:55

Track / Room
Track 7 / Ontario

Authors (Click on name to view author profile)

  1. Sun, Ruikun (Michigan State University)
  2. Yang, Jie (Sichuan University)
  3. Patil, Shalin (Michigan State University)
  4. Liu, Yun (National Institute of Standards and Technology)
  5. Zuo, Xiaobing (Argonne National Laboratory)
  6. Lee, Andre (Michigan State University)
  7. Yang, Wei (Sichuan University)
  8. Wang, Yangyang (Oak Ridge National Laboratory)
  9. Cheng, Shiwang (Michigan State University)

Author and Affiliation Lines (in printed abstract book)
Ruikun Sun1, Jie Yang2, Shalin Patil1, Yun Liu3, Xiaobing Zuo4, Andre Lee1, Wei Yang2, Yangyang Wang5 and Shiwang Cheng1
1Michigan State University, East Lansing, MI 48824; 2Sichuan University, Chengdu, Sichuan 610065, China; 3National Institute of Standards and Technology, Gaithersburg, MD 20899; 4Argonne National Laboratory, Lemont, IL 60439; 5Oak Ridge National Laboratory, Oak Ridge, TN 37831

Speaker / Presenter 
Wang, Yangyang

Keywords
composite rheology

Text of Abstract
The relaxation dynamics of deformed polystyrene/silica nanocomposites with non-attractive polymer-nanoparticle interactions are studied by a combination of small-angle scattering techniques and rheology. Small-angle x-ray scattering measurements and rheology show clear signatures of nanoparticle aggregation that enhances the mechanical properties of the polymer nanocomposites (PNCs) in the linear viscoelastic regime and during the initial phase of stress relaxation along with accelerated relaxation dynamics. Small-angle neutron scattering experiments under the zero-average-contrast condition reveal, however, smaller structural anisotropy in the PNCs than the neat polymer matrix, as well as accelerated anisotropy relaxation. In addition, the degrees of anisotropy reduction and relaxation dynamics acceleration increase with increasing nanoparticle loading. These results are in sharp contrast to the prevailing viewpoint of enhanced molecular deformation in deformed PNCs. Furthermore, the observed acceleration of stress relaxation and reduction in structural anisotropy point to two types of nonlinear effects in the relaxation dynamics of PNCs at large deformation.