Sound absorption properties of thermally bonded nonwovens based on composing fibers and production parameters

Abstract

This article reviews the noise absorption capacity of thermally bonded nonwovens in the range of audible frequencies (125-2500 Hz). First, we focus on the effects of the properties of the fibers, which constitute nonwovens, on the sound absorption properties, and then we consider the web orientation angle of nonwovens. We also investigate a composite model of the sound absorption properties of nonwovens, including the surface roughness and panel vibration. We have used an impedance tube interferometer, which provides the normal incidence sound absorption coefficient of materials, for the determination of the noise absorption properties of nonwovens produced under different conditions. The noise absorption capacity of nonwovens depends primarily on the thickness and surface characteristics of specimens, but the effects of the fiber contents are only marginal. Interestingly, when there is a panel in front of nonwovens, the noise absorption capacity increases significantly at low and medium frequencies (250 -1000 Hz).

Acoustic–electric conversion and piezoelectric properties of electrospun polyvinylidene fluoride/silver nanofibrous membranes

“…The NRC value for the acoustic foam sample is 0.33, which is higher than that of the thermally bonded PET nonwovens (NRC = 0.31 at a thickness of 15 mm) but lower than that of the thicker samples of the thermally bonded PET nonwovens (NRC = 0.59, at a thickness of 30 mm) [43]. According to basic acoustic principles, the NRC of samples increases with the frequency and thickness of the nonwovens [43]. The NRC for the PVDF/AgNP/ acoustic foam sample is 0.58, which is 55% higher than that obtained for the acoustic foam sample.…”

“…Besides, to quantitatively compare sound-absorption performances, the noise reduction coefficient (NRC) was determined. The NRC is the average of sound-absorption coefficients at 250, 500, 1000, and 2000 Hz and is often used as an objective measure for practical sound absorption ability at audible frequency [43]. The NRC value for the acoustic foam sample is 0.33, which is higher than that of the thermally bonded PET nonwovens (NRC = 0.31 at a thickness of 15 mm) but lower than that of the thicker samples of the thermally bonded PET nonwovens (NRC = 0.59, at a thickness of 30 mm) [43].…”

“…The NRC is the average of sound-absorption coefficients at 250, 500, 1000, and 2000 Hz and is often used as an objective measure for practical sound absorption ability at audible frequency [43]. The NRC value for the acoustic foam sample is 0.33, which is higher than that of the thermally bonded PET nonwovens (NRC = 0.31 at a thickness of 15 mm) but lower than that of the thicker samples of the thermally bonded PET nonwovens (NRC = 0.59, at a thickness of 30 mm) [43]. According to basic acoustic principles, the NRC of samples increases with the frequency and thickness of the nonwovens [43].…”

Preparation and Properties of Foamed Cellulose-Polymer Microsphere Hybrid Materials for Sound Absorption

“…In total, four kinds of PMs (F-36D, F-36, F-48, F-50) were investigated to explore the influence of heating temperature on the PMs and determine an accurate reaction temperature. The changes in thickness of PMs at different temperatures (Lee and Chang 2004), PM content, and basis weight are shown in Figs. 4a-d, Fig.…”

Multilayered epoxy/glass fiber felt composites with excellently acoustical and thermal insulation properties

“…Nowadays, noise as one kind of severe pollution has become a looming problem, especially in urban areas . Therefore, soundproof materials have attracted a considerable research interest in building trade.…”