Preparation and Characterization of Sound-Absorbent Based on Polystyrene Reinforced Primary Sludge and Fly Ash from Pulp Mill

. Efforts to utilize and improve the value of pulp waste have been done by using primary sludge (still containing cellulose) and fly ash as a filler to produce composite foam polystyrene (PS)- based as sound absorbent. In this study, the composite foam was produced by mixing primary sludge and fly ash with several compositions such as PS, PS/PS-g-MA/primary sludge/fly ash (80/10/10/0), (80/10/7/3), (80/10/5/5), (75/10/10/5), and (75/10/12/3). The composite was characterized based on ISO 11654:1997, mechanical properties, thermal analysis using TGA and DSC, morphology using SEM, crystallinity using XRD, and chemical analysis using FTIR. The results showed that the band at 1600.63 cm -1 was sharper due to a chemical reaction being formed between PS, primary sludge, and fly ash. The XRD analysis showed a new diffraction peak in the 2  = 21-24 o . The morphology analysis showed that primary sludge and fly ash were uniformly dispersed into PS, increasing the mechanical properties and decreasing the melting point of the PS foam composite. The sound-absorbing composite produced had qualified ISO 11654:1997 on the rating level of the sound absorption coefficient on materials for rooms with sound absorption classes D and C with the value of  w 0.328-0.793.