PhD Thesis Defense- Thomas Gambino

Published: May 28, 2019

Understanding of plasticizer effect on the temperature dependence of mechanical and dielectric relaxation function of polymers of interest for tire formulation

Candidate: Thomas Gambino

Supervisors: Ángel Alegría and Juan Colmenero

Research group: Polymers and Soft Matter group

When: June 4, 2019 (10:30h)

Where: CFM Auditorium

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The dynamic properties of linear elastomers are one of the lines of Michelin central research. Understanding the effect of the plasticizer on the temperature dependence of mechanical relaxation is a key point for improving the performance of a tyre, in particular to increase grip during braking, and reduced rolling resistance. In fact, during its period of use, the tyre must dissipate as much energy as possible during braking. However, we must minimize this process during regular bearing. Varying the glass transition temperature (Tg) of the system allows you to modify the domain of the frequency and temperature at which the material dissipates energy. The results obtained in this doctoral thesis allow to obtain a better understanding of the dynamics of the polymer mixtures, as well as the prediction of the mechanical properties of the high frequency that could be a determining point to facilitate an improvement in the design of materials with desired properties.

Figure 1. Intermediate scattering functions of pure SBR and the SBR component in the blend with deuterated PS. Lines are fits of stretched exponentials to the experimental results for t ≥ 2 ps. Insets show the normalized measured functions in the frequency domain, obeying the same symbol code.

Figure 2. Relaxation map (lines: descriptions of the DS times; symbols: QENS characteristic times at the Q-value matching the latter) of the blend components (dashed lines and empty symbols) compared with the neat materials (solid lines and full symbols). The inset shows DS results at 255K decomposed in the two contributions.