Interesting article about the velocity of sound of epoxy plus glass beeds

[Dave Waligora]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10220926/ Better link

ncbi.nlm.nih.gov

Preparation and Properties of Hollow Glass Microspheres/Dicyclopentadiene Phenol Epoxy Resin Composite Materials

With the development of the integrated circuit and chip industry, electronic products and their components are becoming increasingly miniaturized, high-frequency, and low-loss. These demand higher requirements for the dielectric properties and other aspects ...

[Dave Waligora]

TLDR: The specific acoustic impedance of the composite is 0.72 × 10⁶ rayl when the HGM content is 20 wt%, 70% lower than that of the epoxy resin. The minimum acoustic attenuation coefficient of the composite is 1.35 dB cm⁻¹ when the HGM content is 15 wt%. The acoustic response amplitude in the composite with 20 wt% HGMs is 76% less than that in the epoxy resin in the acoustic transmission test.