ORGS3-1312
Molecular Friction as a Quantitative Design Parameter for Predicting Mechanical Responses of Model Network Elastomers
Topic
GS3. Graduate Student Oral Session III: Polymer Synthesis, Structure, Properties, and Processing
When and Where
Sep 28, 2026
15:24 - 15:36
Room 103
Session Chairs
Jiwon KIM
Junmin LEE
Youngwoon KO
Presenter(s)
Qiyue Cui (The University of Tokyo)
Co-Author(s)
Abstract
Elastomer mechanical performance is commonly framed as a trade-off between stiffness and stretchability. This study establishes molecular friction as a unified predictive parameter for elastomer mechanics. Model network elastomers with minimal structural heterogeneity were prepared by end-linking monodisperse three-arm random copolymers of n-butyl acrylate (nBA) and tert-butyl acrylate (tBA). Molecular friction was systematically tuned through copolymer composition, with the glass transition temperature (Tg) taken as its indicator.
Rheological measurements showed that increasing the weight fraction of tBA units (ftBA) is physically equivalent to decreasing testing temperature, enabling a time-temperature-composition superposition (TTCS) master curve. The corresponding shift factor, aTf, defines a reduced strain rate, ε̇· aTf, that unifies the composition, temperature, and strain rate dependence of uniaxial tensile test data.
Using this reduced strain rate, Young's modulus measured across compositions, temperatures, and strain rates collapsed onto a single master curve. Large-deformation stress data were also largely organized by the same parameter, though deviations increased at higher strain. A Mooney-Rivlin-type linearization, applied as an empirical curve-shape analysis, showed that the fitting parameters scale clearly with reduced strain rate within the range studied.
These results show that molecular friction can be converted from a qualitative concept into a quantitative predictive framework. The reduced strain rate organizes not only the small-strain modulus but also the large-deformation curve shape, while defining the limits of friction-based predictability.
Rheological measurements showed that increasing the weight fraction of tBA units (ftBA) is physically equivalent to decreasing testing temperature, enabling a time-temperature-composition superposition (TTCS) master curve. The corresponding shift factor, aTf, defines a reduced strain rate, ε̇· aTf, that unifies the composition, temperature, and strain rate dependence of uniaxial tensile test data.
Using this reduced strain rate, Young's modulus measured across compositions, temperatures, and strain rates collapsed onto a single master curve. Large-deformation stress data were also largely organized by the same parameter, though deviations increased at higher strain. A Mooney-Rivlin-type linearization, applied as an empirical curve-shape analysis, showed that the fitting parameters scale clearly with reduced strain rate within the range studied.
These results show that molecular friction can be converted from a qualitative concept into a quantitative predictive framework. The reduced strain rate organizes not only the small-strain modulus but also the large-deformation curve shape, while defining the limits of friction-based predictability.
