Paper Number
GN13                         My Program 

Session
Self-assemblies, Gels and Networks

Title
Shear induced aging in polymer-silica composites

Presentation Date and Time
October 20, 2025 (Monday) 4:05

Track / Room
Track 2 / Sweeney Ballroom B

Authors (Click on name to view author profile)

  1. Gray, Destiny D. (University of Illinois at Urbana-Champaign, Chemical and Biomolecular Engineering)
  2. Adrian, David (Dow Chemical)
  3. Ahn, Dongchan (Dow Chemical)
  4. Chen, Shawn (Dow Chemical)
  5. Kalyn, Froeschle (Dow Chemical)
  6. Heyl, Tyler (Dow Chemical)
  7. Hodgson, Matt (Dow Chemical)
  8. Hor, Jyo Lyn (Dow Chemical)
  9. Rogers, Simon A. (University of Illinois Urbana-Champaign, Chemical and Biomolecular Engineering)

Author and Affiliation Lines (in printed abstract book)
Destiny D. Gray1, David Adrian2, Dongchan Ahn2, Shawn Chen2, Froeschle Kalyn2, Tyler Heyl2, Matt Hodgson2, Jyo Lyn Hor2 and Simon A. Rogers1
1Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL 61801; 2Dow Chemical, Midland, MI 48640

Speaker / Presenter 
Gray, Destiny D.

Keywords
experimental methods; theoretical methods; gels; industrial applications; polymer blends; rheometry; selft-assemblies

Text of Abstract
Fumed silica is added to polymers as a reinforcement filler to enhance their mechanical properties, such as strength, stiffness, and abrasion resistance. Studying the rheological aging effects of these polymer-silica composites is crucial because it helps assess long-term durability, stability, and performance, ensuring the material's suitability for various applications, from automotive to biological products. The effect of aging on the viscoelastic behavior of untreated silica filled polydimethylsiloxane (PDMS) is investigated experimentally by performing strain-controlled oscillatory shear tests at various times since preshearing. We show that the material is rejuvenated after fully yielding, but it can return to its aged state by either waiting sufficiently long times under zero-shearing conditions, or by shear-induced aging at intermediate strains. This aging process has also been found to be reversible, and dependent on the shear history. Shear-induced aging is accompanied by overshoots in both the storage and loss moduli and is only observed by controlling the oscillatory strain amplitude from small to large strains. Performing the tests from large to small strains results in an overshoot in the loss modulus, but only a monotonic change in the storage modulus. Thus, we interpret the overshoot in the loss modulus as a competition between shear-induced aging and rejuvenation and is not an intrinsic material property. This aging behavior is modeled by incorporating a time-dependent modulus that captures the nonlinear, transient rheological characteristics of the material.