Sustainable sound absorbers obtained from olive pruning wastes and chitosan binder

A significant interest in sustainable sound absorbing materials is fostering many researches on the use of recycled and vegetable products, that normally would have been sent to wastes, as compounds to obtain new building materials. One key issue when preparing new composite materials is the choice of the binder, which, in many cases, may significantly reduce the sustainability of the product by introducing synthetic and plastic elements. In the present paper olive tree pruning wastes bounded with chitosan are investigated to obtain sound absorbing materials. Experimental results showed that absorption coefficients as high as 0.9 can be obtained above 1 kHz using a 50 mm sample, and that a very good agreement with the phenomenological model for sound absorption through a rigid frame is obtained, suggesting that the model can be conveniently used to further improve the sound absorption characteristics of the samples.