Sound Absorption Performance of the Poplar Seed Fiber/PCL Composite Materials

Abstract

Composite materials were prepared by the hot pressing method using poplar seed fibers and polycaprolactone (PCL) as the raw materials to solve the problems related to the recycling of waste fibers. The effects of mass fraction of poplar seed fibers, the volume density, and thickness on the sound absorption performance of the resulting composite materials were studied. The sound absorption coefficient curves of the composite material were obtained by the acoustic impedance transfer function method. The sound absorption coefficient of the composite material that was prepared under the optimal process conditions was higher than 0.7, and the effective sound absorption frequency band was wide. According to the box counting dimension method, which is based on the fractal theory, the fractal dimensions of the composite materials were calculated while using the Matlab program. The relationships between the fractal dimensions and the volume densities, mass fractions of poplar seed fibers, and thicknesses of the composite materials were also analyzed. Subsequently, the quantitative relationship between the fractal dimension and the sound absorption property parameters of the composite material was established in order to provide a theoretical basis for the design of the sound absorption composite material.

Flexible ceramic nanofibrous sponges with hierarchically entangled graphene networks enable noise absorption

“…The FCNS-5 and FCNS-18 showed good high-frequency and low-frequency sound absorption, respectively. Notably, the absorption coefficient of sandwiched FCNSs always outperformed that of the FCNS-5 and FCNS-18 in almost all frequency bands from 63 to 6300 Hz 12,27 (see Supplementary Methods), and the NRC of sandwiched FCNSs achieved 0.56, satisfying the requirement of high-efficiency sound absorption materials (NRC ≥ 0.56) 63 , whereas the values for FCNS-5 and FCNS-18 were only 0.40 and 0.32, respectively. Additionally, the design values of sound absorption coefficients of sandwiched FCNSs were also calculated based on the above-mentioned JCA module, and a detailed comparison between experimental values and designed values is described in Supplementary Discussions.…”

Flame-Retardant and Sound-Absorption Properties of Composites Based on Kapok Fiber

“…When the density was less than 172 kg/m 3 , with the increase in the density of the composites, the number of micropores in the composites with the same thickness increased, thus improving the sound-absorption properties of the composites. However, with the increased density of the composites, the pore size and number of micropores in the composites decreased, which reduced the friction and vibration between the air and fibers in the composites, thus reducing the consumption of sound energy and the sound-absorption properties [18]. According to the above analysis in Figure 5, the density of 172 kg/m 3 was the best process parameter.…”

The Influence of Physical Properties and Increasing Woven Fabric Layers on the Noise Absorption Capacity

“…The I variant generally showed that the tested materials could not be classified as sound absorber materials since their NRC values were less than 0.2, as specified in [29,30]. The second variant (II) results showed the greatest sound reduction compared to the other variants.…”

“…A sound-absorption material is generally required to have a noise reduction coefficient (NRC) value greater than or equal to 0.20. Practically useful materials have an NRC higher than 0.4, while materials with an NRC greater than 0.56 are referred to be high-efficiency sound-absorbing materials [3,29,30]. The amount of reflected sound waves from the tested surface are presented in percentages.…”