Paper Number
AC24
Session
Additive Manufacturing and Composites
Title
Uniaxial extension of polymer nanocomposites with well-dispersed nanoparticles: Stress overshoot and strain hardening
Presentation Date and Time
October 13, 2022 (Thursday) 11:15
Track / Room
Track 7 / Ontario
Authors
- Sun, Ruikun (Michigan State University)
- Cheng, Shiwang (Michigan State University)
Author and Affiliation Lines
Ruikun Sun and Shiwang Cheng
Michigan State University, East Lansing, MI 48824
Speaker / Presenter
Sun, Ruikun
Keywords
composite rheology
Text of Abstract
The inclusion of nanoparticles can modify strongly the rheological properties of polymer nanocomposites (PNCs). Significant progress has been made on the linear viscoelastic properties. Important molecular mechanisms have been identified that affect the rheology of PNCs, including hydrodynamic effect, nanoparticle-nanoparticle network, polymer bridging, etc. In contrast, the influence of nanoparticles on the nonlinear rheological responses of polymer nanocomposites remains poorly characterized. In this work, we study the uniaxial extension of polymer nanocomposites with well-dispersed nanoparticles at dilute and intermediate nanoparticle concentrations. Important characteristics of nonlinear viscoelastic properties, such as stress overshoot and strain hardening, have been characterized. In general, PNCs show significantly higher macroscopic stress than the neat polymer at the same deformation conditions. Interestingly, PNCs exhibit almost identical scaling between overshoot stress and the deformation rate as s~? ?^0.3, regardless of polymer molecular weights and nanoparticle loadings. Moreover, PNCs exhibit a non-monotonic strain hardening response that does not observe in neat polymers. We explain these observations through the external deformation-induced microstructure rearrangement as well as their influence on entanglement dynamics in PNCs.