Characterizing and modelling the sound absorption of the cellulose acetate fibers coming from cigarette butts.

This work deals an experimental and theoretical research about the porous structure and the acoustic performance of cellulose acetate coming from the used cigarette filters. The porous structure was studied through the measurement and the prediction (using an inverse methodology) of some non-acoustic properties (bulk density, fiber size, porosity or flow resistivity and tortuosity). The sound absorption performance was evaluated by comparing experimental measurements using an impedance tube according to ISO 10534-2 with the best-fit approach obtained using some empirical models (Delany and Bazley, Garai-Pompoli, Komatsu and Miki). The accuracy of empirical models to obtain the flow resistivity was relatively high showing differences lower than 8% in the case of the Miki model or lower than 12% in the case of Delany & Bazley model. Regarding the absorption spectra, the errors found were lower than 9% for all the empirical models used in this work. These results showed that using relatively simple models such as empirical models were able to predict accurately the acoustic behaviour of the cellulose acetate. Finally, the sound absorption spectra obtained for cellulose acetate were compared with those obtained for fibrous materials currently used in building sector, suggesting that this fibrous waste could act as a possible substitute to traditional ones, due to the similar relatively high NRC values obtained for both type of fibrous absorber (NRC = 0.65).