Exploring the potential of recycled polypropylene-waste jute fiber composites for sound insulation: An experimental and theoretical analysis

This study explores the potential of panels made from Recycled Polypropylene (RPP) and Waste Jute Fiber (WJF) for sound insulation applications. Two types of panels were fabricated by the compression molding process: Neat RPP and a composite of RPP reinforced with a WJF interlayer (RPP/WJF/RPP). The physical properties, namely density and mechanical properties, such as tensile strength and modulus, were examined for both panels. The vibration properties of the panels were evaluated through a modal analysis conducted according to ASTM E756-05 guidelines, while sound insulation was assessed by measuring normal incidence sound transmission loss (STL) using a four-microphone impedance-tube setup following ASTM E2611-19 standards. The RPP/WJF/RPP composite, with a density of 913 kg/m³, is 2.47% higher than that of Neat RPP, which is 891 kg/m³, and exhibited an increased tensile strength of 12.01 MPa, compared to 10.03 MPa for Neat RPP. In the second vibration mode, the composite's damping ratio of 3.62% outperformed Neat RPP's 2.48%. Furthermore, the composite's measured average STL was 38.6 dB, exceeding the Neat RPP's average of 37.7 dB. This enhancement in STL is likely attributed to the composite's higher surface density (5.21 kg/m²) relative to Neat RPP (4.72 kg/m²), contributing to its improved sound insulation properties. The theoretical average STL values, predicted using the Mass