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Non-Equilibrium Filler Network Dynamics in Styrene-Butadiene Rubber Formulations with Commercially Relevant Filler Loadings

Presto, Dillon
http://rave.ohiolink.edu/etdc/view?acc_num=akron1680730033737903

Abstract Details

2023, Doctor of Philosophy, University of Akron, Polymer Science.
We have elucidated details of how the microscopic structure and dynamics of filler in reinforced rubbers influence mechanical properties. Studies were performed on highly loaded, silica-filled, crosslinked styrene-butadiene rubber (SBR). Properties of the compounds studied were varied by addition of silane coupling agents, silicas of different surface area, and by addition of well-characterized, anionically-polymerized, low molecular weight, dimethylamino end-functionalized SBR additives of linear or star molecular architecture. Samples were probed with a combination of Ultra-small Angle X-ray Scattering/Small Angle Scattering (USAXS/SAXS), X-ray Photon Correlation Spectroscopy (XPCS), and mechanical measurements. Investigation of samples with or without silane coupling agents confirms that coupling agents enhance filler dispersion. This enhanced dispersion leads to slower filler dynamics when the rubber is strained and a slower change in dynamics over time. These slower dynamics and slower evolution of dynamics correlate with slower macroscopic stress relaxation. Our work also examines the temporally heterogenous dynamics that underlie the stress relaxation process. During stress relaxation, filler dynamics intermittently speed up and slow down. These results indicate that while macroscopic stress relaxation appears to be a relatively simple process, the microscopic behavior is complex. Studies on rubbers containing high surface area, milled silica under dynamic strain reveal that while rubber containing milled silica and monosulfidic coupling agent shows a large Payne effect, the breakdown of filler is suppressed. We infer that debonding and/or yielding of bridging bound layers is responsible for the Payne effect in this sample. These bridging layers provide this rubber with a high modulus and low hysteresis. Addition of end-functionalized SBRs to rubber drastically affects mechanical properties. Rubber containing conventional silica and 20 kg/mol difunctional chains shows significantly reduced hysteresis relative to other samples containing conventional silica. We propose that 20k difunctional chains form loose bound layers which facilitate formation of bridging layers that reduce hysteresis. Samples containing milled silica and functional chains show a drastic reduction in hysteresis and filler breakdown relative to a control containing no functional chains. We propose that milled silica reduces the entropic penalty for functional chains to interact with the silica, and this could explain their significantly lower hysteresis
Mark Foster (Advisor)
Roderic Quirk (Other)
Jutta Luettmer-Strathmann (Committee Member)
Mesfin Tsige (Committee Member)
Junpeng Wang (Committee Member)
Li Jia (Committee Chair)
395 p.
Materials Science
Payne effect, rubber, hysteresis, tire, anionic polymerization, functionalized polymer, X-ray scattering, X-ray Photon Correlation Spectroscopy, SAXS, USAXS, stress relaxation, silica, filler, silane coupling agent, dynamics, structure, network

Recommended Citations

Citations

  • Presto, D. (2023). Non-Equilibrium Filler Network Dynamics in Styrene-Butadiene Rubber Formulations with Commercially Relevant Filler Loadings [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1680730033737903

    APA Style (7th edition)

  • Presto, Dillon. Non-Equilibrium Filler Network Dynamics in Styrene-Butadiene Rubber Formulations with Commercially Relevant Filler Loadings . 2023. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1680730033737903.

    MLA Style (8th edition)

  • Presto, Dillon. "Non-Equilibrium Filler Network Dynamics in Styrene-Butadiene Rubber Formulations with Commercially Relevant Filler Loadings ." Doctoral dissertation, University of Akron, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=akron1680730033737903

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.
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