scholarly journals Sound Absorption Properties of DFs/EVA Composites

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 811 ◽  
Author(s):  
Lihua Lyu ◽  
Yingjie Liu ◽  
Jihong Bi ◽  
Jing Guo
Keyword(s):  
Fractal Dimension ◽  
Absorption Coefficient ◽  
Hot Pressing ◽  
Mass Fraction ◽  
Sound Absorption ◽  
Fractal Theory ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Pressing Method ◽  
Matlab Programming

Using discarded feather fibers (DFs) and ethylene vinyl acetate (EVA) copolymer, the DFs/EVA composites with good sound absorption performance were prepared by hot-pressing method. The effects of hot-pressing temperature, mass fraction of DFs, density and thickness of composites on the sound absorption properties were studied by the controlling variable method. The sound absorption properties of the composites were studied by the transfer function method, and under the optimized technological conditions, the sound absorption coefficient of the composites was above 0.9 and the sound absorption band was wide. According to the box counting method based on the fractal theory, the fractal dimension of DFs/EVA sound absorption composites was calculated through Matlab programming, and the relationship between the fractal dimension and the mass fraction of DFs, the volume density of the composites were analyzed, then the quantitative relationship between the fractal dimension and the maximum sound absorption coefficient was deduced, which played a major role in the sound absorption design of porous sound absorption materials.

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

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2845 ◽  
Author(s):  
Lihua Lyu ◽  
Yuanyuan Tian ◽  
Jing Lu ◽  
Xiaoqing Xiong ◽  
Jing Guo
Keyword(s):  
Absorption Coefficient ◽  
Flame Retardant ◽  
Magnesium Hydroxide ◽  
Hot Pressing ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Pressing Method ◽  
Kapok Fiber ◽  
Properties Of Composites

In order to improve the utilization rate of kapok fiber, flame-retardant and sound-absorption composites were prepared by the hot pressing method with kapok fiber as the reinforced material, polyε-caprolactone as the matrix material, and magnesium hydroxide as the flame retardant. Then, the effects of hot pressing temperature, hot pressing time, density of composites, mass fraction of kapok fiber, thickness of composites, and air layer thickness on the sound-absorption properties of composites were analyzed, with the average sound absorption coefficient as the index. Under the optimal process parameters, the maximum sound absorption coefficient reached 0.830, the average sound absorption coefficient was 0.520, and the sound-absorption band was wide. Thus, the composites belonged to high-efficiency sound-absorbing material. The flame-retardant effect of magnesium hydroxide on the composites was investigated, and the limiting oxygen index could reach 31.5%. Finally, multifunctional composites based on kapok fiber with flame retardant properties, and sound-absorption properties were obtained.

scholarly journals Sound-Absorption Performance and Fractal Dimension Feature of Kapok Fibre/Polycaprolactone Composites

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1000 ◽  
Author(s):  
Lihua Lyu ◽  
Duoduo Zhang ◽  
Yuanyuan Tian ◽  
Xinghai Zhou
Keyword(s):  
Composite Material ◽  
Fractal Dimension ◽  
Absorption Coefficient ◽  
Mass Fraction ◽  
Sound Absorption ◽  
Volume Density ◽  
Sound Absorption Coefficient ◽  
Pressing Method ◽  
Absorption Frequency ◽  
Absorption Performance

This article introduces a kind of composite material made of kapok fibre and polycaprolactone by the hot-pressing method. The effects of volume density, mass fraction of kapok fibre, and thickness on the sound-absorption performance of composites were researched using a single-factor experiment. The sound-absorption performance of the composites was investigated by the transfer function method. Under the optimal process parameters, when the density of the composite material was 0.172 g/cm3, the mass fraction of kapok was 40%, and the thickness was 2 cm, the composite material reached the maximum sound-absorption coefficient of 0.830, and when the sound-absorption frequency was 6300 Hz, the average sound-absorption coefficient was 0.520, and the sound-absorption band was wide. This research used the box dimension method to calculate composites’ fractal dimensions by using the Matlab program based on the fractal theory. It analysed the relationships between fractal dimension and volume density, fractal dimension and mass fraction of kapok fibre, and fractal dimension and thickness. The quantitative relations between fractal dimension and maximum sound-absorption coefficient, fractal dimension, and resonant sound-absorption frequency were derived, which provided a theoretical basis for studying sound-absorption performance. The results showed that kapok fibre/polycaprolactone composites had strong fractal characteristics, which had important guiding significance for the sound-absorption performance of kapok fibre composites.

scholarly journals Acoustic Panels Made of Paper Sludge and Clay Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 637
Author(s):  
Tomas Astrauskas ◽  
Tomas Januševičius ◽  
Raimondas Grubliauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Core Material ◽  
Paper Sludge ◽  
Frequency Range ◽  
Absorption Properties ◽  
Air Gaps ◽  
The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

Physical and Sound Absorption Properties of Spent Tea Leaf Fiber Filled Polyurethane Foam Composite

2014 ◽  
Vol 660 ◽  
pp. 541-546 ◽  
Author(s):  
Qumrul Ahsan ◽  
Chia Pooi Ching ◽  
Mohd Yuhazri bin Yaakob
Keyword(s):  
Absorption Coefficient ◽  
Polyurethane Foam ◽  
High Resistance ◽  
Sound Absorption ◽  
Filler Loading ◽  
Tea Plant ◽  
Sound Absorption Coefficient ◽  
Tea Leaves ◽  
Absorption Properties ◽  
Spent Tea Leaves

Spent tea leaves (STL) from tea producing factories can be considered as new resources for sound absorbing polyurethane (PU) matrix composite materials because STL are rich in polyphenols (tannins) which cause high durability, high resistance to fungal and termites, and high resistance to fire. The research aims to study the physical characteristics of STL and the effect of dispersion morphology of STL on the sound absorption properties of polyurethane foam composites by varying filler loading. Three grades of STL fibers either as received or granulated are used in this study, namely BM-FAE and SWBHE derived from the stalk while FIBER-FAE derived from the leaves of the tea plant. The PU/STL composites are fabricated through open molding method with a fiber loading of 16 wt. %. The fabricated composites are then subjected to physical and sound absorption testing as well as microscopic observations to analyze the distribution of filler in composite. The study shows that as-received FIBER-FAE spent tea leaves provide the best sound absorption coefficient and for composites using granulated fibers from any grade have lower sound absorption coefficient. These results show that a novel kind of sound absorption materials with the recycling of waste materials can be obtained for the solution of noise and environmental pollution.

scholarly journals Sound absorption properties of multi-layer structural composite materials based on waste corn husk fibers

2020 ◽  
Vol 15 ◽  
pp. 155892502091086
Author(s):  
Lihua Lyu ◽  
Jing Lu ◽  
Jing Guo ◽  
Yongfang Qian ◽  
Hong Li ◽  
...  
Keyword(s):  
Composite Materials ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Low Frequency ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Cavity Depth ◽  
Air Cavity ◽  
Corn Husk ◽  
Structural Composite

In order to find a reasonable way to use the waste corn husk, waste degummed corn husk fibers were used as reinforcing material in one type of composite material. And polylactic acid particles were used as matrix material. The composite materials were prepared by mixing and hot-pressing process, and they were processed into the micro-slit panel. Then, the multi-layer structural sound absorption composite materials were prepared sequentially by micro-slit panel, air cavity, and flax felt. Finally, the sound absorption properties of the multi-layer structural composite materials were studied by changing flax felt thickness, air cavity depth, slit rate, and thickness of micro-slit panel. As the flax felt thickness varied from 0 to 10 mm in 5 mm increments, the peak of sound absorption coefficient shifted to low frequency. The sound absorption coefficient in the low frequency was improved with the air cavity depth varied from 0 to 10 mm in 5 mm increments. With the slit rate increased from 3% to 7% in 2% increments, the peak of sound absorption coefficient shifted to high frequency. With the thickness of micro-slit panel increased from 2 to 6 mm in 2 mm increments, the sound absorption bandwidth was broaden, and the peak of sound absorption coefficient was increased and shifted to low frequency. Results showed that the highest sound absorption coefficient of the multi-layer structural composite materials was about 1 under the optimal process conditions.

Sound Absorption Properties of Fiber and Porous Materials

2005 ◽  
Vol 475-479 ◽  
pp. 2687-2690 ◽  
Author(s):  
Bo Young Hur ◽  
Bu Keoun Park ◽  
Dong-In Ha ◽  
Yong Su Um
Keyword(s):  
Absorption Coefficient ◽  
Porous Materials ◽  
Sound Absorption ◽  
Absorption Rate ◽  
Metal Foam ◽  
Acoustic Property ◽  
Glass Wool ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Reduction Coefficient

The porous materials, such as glass wool or foam, are generally used to attenuate noise. The most fundamental acoustic property of these porous materials is their sound absorption coefficient. The purpose of this paper is sintered fiber and porous materials sound absorption properties investigated. Sound absorption properties of sintered Al fiber has over 0.7 of sound absorption coefficient with 800-2000Hz frequency for 0.6 relative density and 10mm thickness. NRC (noise reduction coefficient) is 0.73. Metal foam have good sound absorption rate at 2000 ~ 4000Hz.

Fabrication and Sound Absorption Properties of Porous Fe0.2(Co20Ni80)0.8 Alloy Microfibers

2012 ◽  
Vol 538-541 ◽  
pp. 2220-2223
Author(s):  
Xiang Qian Shen ◽  
Hong Bo Liu ◽  
Qing Rong Liang ◽  
Xin Chun Yang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transformation Process ◽  
Sound Absorption Coefficient ◽  
Wave Tube ◽  
Absorption Properties ◽  
Thick Sample ◽  
Noise Absorption ◽  
Reduction Coefficient ◽  
Standing Wave Tube

The porous nanocrystalline Fe0.2(Co20Ni80)0.8 alloy microfibers with diameters of 2-4 μm have been prepared by the citrate-gel and phase transformation process. The sound absorption coefficient for microfibers samples is measured by the standing wave tube method and it is is over 0.8 for the 15 mm thick sample at the frequency range of 2300-6000 Hz, which is extended to 600-6300 Hz for the 40 mm thick sample. The band width with the sound absorption coefficient above 0.6 is wider than 4300 Hz for the 15 mm thick sample and 5800 Hz for the 40 mm thick sample. For the 40 mm thick sample, the maximum absorption coefficient, noise absorption coefficient, noise reduction coefficient and half-width of the absorption peak are 0.99, 0.59, 0.64 and 5828 Hz, respectively. These microfibers are promising advanced acoustic absorbers.

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

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1465 ◽  
Author(s):  
Yingjie Liu ◽  
Lihua Lyu ◽  
Jing Guo ◽  
Ying Wang
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Fractal Dimensions ◽  
Sound Absorption Coefficient ◽  
Process Conditions ◽  
Pressing Method ◽  
Absorption Frequency ◽  
Absorption Performance

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.

The Sound Absorption Properties Comparison of Metal Foams and Flexible Cellular Materials

2018 ◽  
Vol 933 ◽  
pp. 357-366 ◽  
Author(s):  
Li Si Liang ◽  
Xiao Lei Wu ◽  
Na Ni Ma ◽  
Jin Jing Du ◽  
Man Bo Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Metal Foam ◽  
Metal Foams ◽  
Cellular Materials ◽  
Glass Wool ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Average Value ◽  
Peak Value

The third octave sound absorption coefficient testing is conducted to compare the sound absorption properties metal foam and flexible cellular materials, by using sound absorption tester with the method of trasfer function sound absorption tester with the method of trasfer function. The sound absorption mechanisms are discussed by changing the parameters of sound absorption structure, such as the thickness of matrix materials and the thickness of cavity. The results show that pearl wool and glass wool exhibited excellent sound absorption properties. The peak value of sound absorption coefficient for pearl wool reaches to 0.991, and for glass wool, 0.985. The average sound absorption coefficient for pearl wool is 0.729, and for glass wool, 0.679. Among of three metal foams, the foamed aluminum material exhibited optimum sound absorption properties, and is superior to flexible sound absorption materials. The peak value of sound absorption coefficient reaches to 0.993, and the average value reaches to 0.781. This can be attributed to the flow resistance, porosity, thickness, cavity and structure factor, which influence the sound absorption of open cell materials.

Study on the Sound Absorption Properties of Several Kinds of Fibers

2011 ◽  
Vol 332-334 ◽  
pp. 959-962
Author(s):  
Yong Hua Ren ◽  
Xiao Ning Sun ◽  
Hong Song
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Cavity Length ◽  
Natural Fibers ◽  
Influence Factors ◽  
Sound Absorption Coefficient ◽  
Cotton Wool ◽  
Absorption Properties ◽  
Material Thickness ◽  
Noise Frequency

In this paper, four kinds of natural fibers (cotton, wool, silk and ramie) are studied. Three experimental programs are designed, and influence factors of sound absorption properties of porous sound absorption material are discussed. With the change of material thickness and cavity length, the variation of sound absorption coefficient is obtained in different noise frequency.

Sign in / Sign up

Export Citation Format

Share Document