Statistical analysis of the effect of processing machine parameters on acoustical absorptive properties of needle-punched nonwovens

The object of this paper is to investigate the acoustic insulation properties of needle-punched nonwovens produced from recycled polyester waste blended with virgin polyester serving as supportive material. The research work also studies the effect of different processing parameters of needle punching nonwoven machines through the investigation of different needle speeds, lattice speeds, and penetration depths. Throughout the research work, several needles punched nonwoven fabrics were produced under different conditions as follows: Three needle speeds were applied: 280, 245, and 227 rpm. Three lattice speeds were applied: 0.72, 1.47, and 2.35 m/min. Three depths of penetration for the needles were applied: 26, 10, and 5 mm. Finally, different blends of waste/virgin polyester fibers were produced and tested: 40/60%, 20/80%, and 100% virgin polyester. The four parameters investigated had a statistically significant effect on the sound transmission losses obtained. It was proved that as the frequency increases, the needle speed gains importance while the needle penetration depth loses importance. The results of testing the different samples indicated that the highest sound transmission loss is attained using non-woven fabrics produced from virgin polyester fibers and prepared at high stitch density.