Development, Production, and Characterization of Acoustic Insulation Components Made from Industrial Hemp Residues

Bio-based products are leading the way toward a more sustainable future. They are playing a key role in combating climate change and global warming, which are primarily driven by using fossil fuels. This study demonstrates the potential of Finola hemp residues as feedstock for acoustic insulation components to replace synthetic fibers. The use of these residue fibers improves the resource efficiency of the crop and contributes to a circular economy. To enhance the fiber properties, Finola hemp residues were combined with cottonized hemp, crossbred sheep wool and polylactic acid (PLA). Nonwovens were produced using needle punching and thermal bonding techniques. Extensive experiments revealed the correlation of fiber and fabric properties with the acoustic insulation properties of the nonwoven structures. The needle punched samples consisting of Finola hemp and cottonized hemp fibers showed the highest air flow resistances. Thus, a maximum sound absorption coefficient of 0.99 at 9150 Hz was reached. The study highlights that the high sound absorption coefficients were achieved due to the high density of the sample caused by a high proportion of short and fine fibers and strong compression through the needle punching process. Moreover, a high number of layers was correlated with good sound absorption properties.