Micromechanics-based model for the effect of uniaxial stretching on the effective thermal conductivity of particle filled elastomers

It is well established that stretching deformation significantly affects the effective thermal conductivity (ETC) of elastomer matrix composites. However, the influence of uniaxial elongation on the ETC may vary markedly depending on the type of fillers incorporated within the composite. Accordingly, the present study focuses on elastomers embedded with rigid particles, air voids and liquid metal droplets. A micromechanics-based model utilizing a double inclusion (DI) approach was formulated to analyze the variation in ETC as a function of applied strain. Finite element method (FEM) simulations were compared to evaluate the evolution of filler volume fraction, aspect ratio and interparticle spacing during stretching for three filler types characterized by different rigidity. Due to deformation-induced changes in filler aspect ratio, volume fraction and interparticle spacing, the proposed micromechanics model predicted anisotropic thermal conduction behaviors of the composites. Numerical results revealed that variations in the filler aspect ratio during elongation significantly affect the ETC. in contrast, alterations in inter-particle spacing and particle volume fraction exhibit comparatively minor effects. The complex factors underlying the observed variations in ETC were thoroughly elucidated. Incorporating these deformation-dependent parameters into the analytical framework enhances the model’s predictability to experiments and numerical simulations. This study offers a comprehensive elucidation of the thermal conduction mechanisms in elastomer composites containing various fillers subjected to large strains. The developed model provides valuable insights for the design and optimization of flexible composites with enhanced ETC.