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This study is focused on the development of sound absorbing materials based on natural fiber polymer composites. The natural fibers were modified through the alkaline treatment and the natural fiber polymer composites were fabricated using hot and cold compression hydraulic press machine. The sound absorption coefficients of the composites were measured using two-microphone transfer function impedance tube method. Characterizations of the natural fiber polymer composites were analyzed using scanning electron microscope and Fourier transform infrared spectroscopy. It was found that in all measured composites, the sound absorption coefficients increased as the frequency increased. Also, as the fiber loading increased, the sound absorption coefficients of the natural fiber polymer composites were increased. It was found that the alkaline treated fiber reinforced composites increased the sound absorption coefficients due to removal of impurities and change in the structure of composites. The alkaline treatment of fibers showed better adhesion interface between fiber and polymer as compared to untreated fibers. This can be seen clearly under morphological and spectral studies of the natural fiber polymer composites.

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This study focuses on the development of epoxy/luffa composites and the investigation of their mechanical and acoustical properties. The fibers underwent an alkalization treatment, and its effects on the mechanical and sound absorption properties of the composites were measured utilizing a universal testing machine and two-microphone transfer function impedance tube methods. The effects of chemical modifications on the fibers were studied using a scanning electron microscope (SEM). The thermal analyses of composites were conducted using thermo-gravimetric analysis (TGA). The composite's functional group was identified and evaluated using Fourier transform infrared spectroscopy (FTIR). The sound absorption coefficient of untreated and treated composites across a range of frequencies was very similar. Untreated composites appeared to perform better than those that were treated. Compared with untreated fiber composites, there was an improvement in the tensile strength of the treated fiber composites. The SEM characterization showed that the alkaline treatment changed the morphology of the fibers, resulting in a decrease in the sound absorption coefficients of the composites. The thermal characterization of composites showed that dehydration and degradation of lignin occurred in a temperature range of 40 to 260 °C, and the maximum percentage of cellulose was found to decompose at 380 °C.

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