Estimation of sound transmission loss of polymer/hollow microsphere composites

The sound insulation behavior of inorganic hollow microsphere-filled polymer composites was analyzed by means of acoustics theory to reveal the sound insulation mechanisms in the present paper. On the basis of it, a physical model of the sound wave transfer in the composite system was established, and a corresponding sound transmission loss equation was derived. The sound transmission loss ([Formula: see text]) of the hollow glass bead-filled polypropylene composites was estimated by using this equation. The results showed that the calculated sound transmission loss increased linearly with increasing the filler volume fraction, and the values of the [Formula: see text] increased nonlinearly with increasing sound frequency. The sensitivity of the sound transmission loss to sound frequency was significant at low sound frequency. The predicted [Formula: see text] was compared with the measured data from the composites and found that both the estimated [Formula: see text] and the measured data have a similar variation with increasing sound frequency or the filler volume fraction. This study would provide a basis for further development of sound insulation polymer composites.