Sound Absorption Property of Agricultural Lignocellulsic Residue Fiber Reinforced Polymer Matrix Composites

Abstract

In this research, the sound absorption coefficients of polymer matrix reinforced lignocellulosic fiber composites were investigated. The sound absorbing characteristic of composites was investigated in the impedance tube, according to transfer function method. A two microphone setup was fabricated according to American society for testing materials ASTM E1050-10 and it is used to measure sound absorption coefficients of composites. In this investigation, the influences of two kinds of polymer matrix (Polypropylene and Urea-formaldehyde) and two kinds of natural fibers (rice straw and kenaf) were studied for sound absorption coefficients. Four samples of novel sound absorbers were made with different matrix and fibers composition, Sample 1 and 2 was made of rice straw reinforced with polypropylene and Urea-formaldehyde and Sample 3 and 4 was made with kenaf fiber reinforced with polypropylene and Urea-formaldehyde matrix. Sound absorption coefficients were measured at frequencies from 300 Hz to 2000 Hz. The results showed when the frequencies increased, sound absorption increased until it reached a frequency of 2000 Hz but at 1200 Hz sound absorption decreased for all the samples this is due to specific character of natural fibers. From the result, the kind of natural fiber did not have significant influences on sound absorption coefficients. As results it was found that the matrix influence more in sound absorption properties in low frequencies; and due to that fact the above composites are low sound absorbing materials; but still they are better than other construction materials available in sound absorbing properties.