Abstract
In this research, we conducted a detailed experimental investigation into how strain affects the thermal conductivity of Ecoflex elastomer, utilizing a newly developed method for measuring thermal conductivity under mechanical strain for the first time. In situ thermal conductivity measurement apparatus was developed by combining KLA T150 nanoscale tensile tester and a custom fabricated thermal measurement sensor. The development of experimental method for measuring the thermal conductivity of nanomaterials under mechanical testing simultaneously will contribute to the development of novel materials for flexible electronics by helping us to better understand the strain effect on their thermal performance. Interestingly, the thermal conductivity of Ecoflex elastomer is shown to increase with an increase in tensile strain until the engineering strain reaches 20%. This is understood to be due to the straightened polymer chains, which makes the phonon transport to be more efficient through the stiffened polymer chains. At very high degrees of mechanical strain, the thermal conductivity may decrease due to the disruption of filler-to-filler connections and increased phonon-boundary scattering between polymer chains and magnetic powders. This is caused by the reduced spacing resulting from the increased mechanical strain. The findings from this study are expected to propel the advancement of future flexible electronics by facilitating the creation of a foundational elastomer.
