Polypropylene-lignocellulosic material composites as promising sound absorbing materials

Abstract

Composites made from polypropylene and lignocellulosic materials derived from plants were subjected to acoustic and mechanical investigations. Sound absorption coefficients for these composites were measured using the acoustic standing wave method in the frequency range from 1000 to 6500 Hz. This work shows that the frequency dependence of the sound absorption coefficient obtained for pure polypropylene can be modified by proper choice of the filler added to the polypropylene matrix. Fillers derived from hemp plant cause significant increase in the absorption coefficient starting from the frequency above 3000 Hz. The fillers obtained from rapeseed straw, beech and flax are recognized to suppress the sound in the frequency range from 3000 to 4000 Hz. The investigated composites can be recommended for application in the automotive industry and building as the construction materials absorbing the undesired noise.