Comparative Study on Sound Absorption Coefficient of Various Jute Composite Materials

Natural fibre composites are getting attention in noise reduction applications replacing conventional materials. They are being used in passive noise control in which jute is showing its prominence. Though conventional sound absorbing materials are used for passive control, they can be replaced by natural fibres as they are abundantly available and are in expensive. The present work is to test samples prepared from various jute materials with epoxy resin as bonding agent. Jute materials used for study are jute mats 190GSM, 420GSM and felt woven jute composite. Plain jute mat samples are designated as JM composites and samples prepared in combination of jute mat and felt woven jute are designated as JMW. The sound absorbing coefficient study is carried out experimentally using two microphone impedance tube test set up as per ISO 10534-2. Sound absorption comparative studies are carried out on perforated samples and sandwiched samples with air partition. It is observed that layered felt woven jute composites are having higher sound absorption coefficient than jute mat composites when several combinations of these are analysed. This might be due to felt woven jute composites are having lesser density. Maximum noise reduction coefficient of 0.97 at 1250 Hz and 0.96 at 622 Hz 1/3rd octave band frequency is obtained for 190GSM and 420GSM layered felt woven jute composites respectively. The highest NRC recorded among other samples prepared to improve sound absorption coefficient is found to be 0.93 at 922Hz 1/3rd octave band frequency with 10mm air gap and without perforations. The above value recorded for the sample of thickness 20mm, which is prepared with 190HSM jute mat and felt woven jute. A comparison is also established between composite samples and glass wool for thickness of 50mm. In comparison between 190GSM and 420GSM samples, it is advisable to choose 420GSM samples. 420GSM samples are having better bonding and are performing well in low frequency band.