Characterization of acoustic and thermal properties of treated and untreated PEFB-fiberglass composites for HVAC insulation applications

Abstract The palm oil industry generates substantial waste, with Malaysia alone producing over twenty-six (26) million tons of palm empty fruit bunches (PEFB) annually, posing significant environmental challenges. This study evaluates the suitability of PEFB-fiberglass (FG) composites as insulation materials, particularly for heating, ventilation, and air conditioning (HVAC) applications. The research focuses on characterizing the physical properties of treated and untreated PEFB-FG composites and analysing their thermal conductivity and sound absorption properties. A comprehensive methodology was employed, incorporating Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), and water contact angle (WCA) assessments to evaluate the physical properties of the composite samples. The thermal conductivity and sound absorption measurements were conducted using a heat flow meter and the impedance tube method by ASTM C518 and ASTM E1050 standards. The findings reveal that FTIR analysis indicates the formation of new chemical bonds in treated PEFB fibers, achieved by partially reducing the hemicellulose and lignin content which enhanced fiber interaction. The hydrophobic properties of treated PEFB samples prevented water absorption on the contact surface of fiber with the contact angles of 135° for NaOH treatment and 131° for silane treatment. The treated composites demonstrate improved thermal stability at a temperature of 400 °C and lower thermal conductivity of 0.032 W/mK., exhibiting optimal insulating HVAC characteristics. Furthermore, treated samples exhibit enhanced water resistance and hydrophobicity compared to untreated samples. The sound absorption analysis indicates that treated PEFB-FG composites outperform untreated counterparts at high frequencies, with sound absorption coefficients (α) of 0.68 as a good absorption comparable to those of conventional insulation materials like glass wool and rock wool. This study concludes that PEFB-FG composites treated with silane and NaOH improve hydrophobicity and thermal stability and represent a viable and sustainable alternative to conventional insulation materials, aligning with broader sustainability goals in industrial applications.