Acoustic and dielectric properties of epoxy resin/hollow glass microsphere composite acoustic materials

Epoxy resin/hollow glass microsphere (HGM) composite acoustic materials for potential applications in the acoustic and electronic fields were prepared with epoxy resin as the matrix and HGMs as the filler. The effects of the HGM content on the sound propagation characteristics and dielectric properties of the composites were investigated. The results show that the specific acoustic impedance of the epoxy resin matrix is reduced effectively by addition of HGMs. The specific acoustic impedance of the composite is 0.72 x 10(6) 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. In addition, the dielectric constant and dielectric loss of the composites are also reduced with addition of HGMs. The epoxy resin/HGM composite acoustic materials have potential applications in the fields of acoustic transducers, sound-absorbing materials, and electronic materials requiring a low dielectric constant.