Heterogeneity Assisted Damping Enhancement of Low and High Frequency Mechanical Waves in a Soft Polymer Nanocomposite

Low-amplitude dynamic and morphological heterogeneities of a biphasic copolymeric matrix were amplified by soft nanoparticle loading and thermally induced phase separation (TIPS). The evolution of system concentration fluctuation size (ξ) was quantified as a function of quench depth in its closed-loop like phase diagram. The system characterization was then complemented by extracting its bimodal heterogeneity index as normalized interface length over area ( L/A ) from phase imaging analysis of atomic force microscopy (AFM). Both criteria were amplified by annealing temperature rise, resulting in damping enhancement under low and high frequency mechanical waves, shown by dynamic mechanical thermal analysis (DMTA) and ultrasound spectroscopy, respectively. At the highest annealing temperature, 160 °C, the morphogenesis led to simultaneous increase of effective damping temperature range (Δ T eff ) and maximum tan δ to 190 °C and 2, respectively. Finally, damping efficacy ( D eff, i.e., Δ T eff [tan δ] max ) and the ultrasound attenuation coefficient (α) were linearly proportional to ξ and L/A, while intercorrelated through a Williams–Landau–Ferry (WLF) type equation.