Effect of Sodium Hydroxide (NaOH) Treatment on Coconut Coir Fibre and its Effectiveness on Enhancing Sound Absorption Properties

Natural fibre has been conventionally and widely utilised as a sound absorber in order to replace the traditional synthetic absorber materials. In this study, coir fibre (CF) was prepared as an acoustic absorber and subjected to an additional surface treatment by using sodium hydroxide (NaOH) at various concentrations ranging from 1% to 8%. This was geared towards analysing the effect of alkalisation on the fibre morphology, diameter, and changes occurring in the CF functional groups, thus resulting in enhanced sound absorption properties. To this end, the fibre surface was analysed using a scanning electron microscopy (SEM) to study the surface morphology of treated and untreated CF materials, whereas the implementation of Fourier-transform infrared (FTIR) allowed an analysis of CF characterisation. The absorber sample was fabricated at a constant thickness of 45mm and a density of 0.4g/cm3 density prior to testing for the sound absorption coefficient (SAC) by using an impedance tube. The morphology of CF revealed the treated fibres to be free of impurities including lignin and hemicellulose layer, which were removed from their surface. This finding was supported by the peak changes observed on the FTIR spectra. Furthermore, the fibre diameter was reduced as the concentrations of NaOH increased. The results conclusively indicated that treated CF at the concentrations of 7% and 8% NaOH gained the highest SAC values across the low and high-frequency ranges, yielding an α coefficient average of 0.9 and above.

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Investigation Of Sound Absorption Properties Of Bark Cloth Nonwoven Fabric And Composites

Autex Research Journal ◽

10.1515/aut-2015-0010 ◽

2015 ◽

Vol 15 (3) ◽

pp. 173-180 ◽

Cited By ~ 11

Author(s):

Samson Rwawiire ◽

Blanka Tomkova ◽

Eulalia Gliscinska ◽

Izabella Krucinska ◽

Marina Michalak ◽

...

Keyword(s):

Sound Absorption ◽

Epoxy Polymer ◽

Nonwoven Fabric ◽

Natural Fibre ◽

Woven Fabric ◽

Absorption Properties ◽

Fibre Network ◽

Exploratory Investigation ◽

Absorbing Materials ◽

Fibre Morphology

AbstractThe quest for sound-absorbing materials that are not only environmentally friendly, but also sustainable is the foremost reason for natural fibre-acoustic materials. Bark cloth is a natural non-woven fabric that is largely produced from Ficus trees. An exploratory investigation of bark cloth a non-woven material and its reinforcement in epoxy polymer composites has been fabricated and investigated for the sound absorption properties so as to find the most suitable applications and also to see whether bark cloth can be used in some applications in place of man-made fibres. Three types of material species were investigated with their respective composites. The fibre morphology showed bark cloth to be a porous fabric that showed promising sound absorption properties at higher frequencies. The sound absorption results of four-layer material selections of Ficus natalensis, Ficus brachypoda and Antiaris toxicaria bark cloth showed sound absorption coefficient of 0.7; 0.71 and 0.91 at f > 6400 Hz, respectively. The bark cloth reinforced laminar epoxy composites had reduced sound absorption coefficients, which ranged from 0.1 to 0.35, which was attributed to decreased porosity and vibration in the bark cloth fibre network.

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Development of Natural Fibre Non-Woven Materials’ Application as Car Interiors for Noise Reduction

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.332-334.1531 ◽

2011 ◽

Vol 332-334 ◽

pp. 1531-1534 ◽

Cited By ~ 3

Author(s):

Ming Ma ◽

Yuan Bai ◽

Xiao Ming Qian

Keyword(s):

Noise Reduction ◽

Reference Point ◽

Sound Absorption ◽

Noise Control ◽

Natural Fibre ◽

Noise Sources ◽

Absorption Properties ◽

Vehicle Noise ◽

Nonwoven Materials ◽

Potential Market

This document mainly introduces the evaluation of vehicle noise, noise sources and noise control. The development of fibers used for noise reduction materials is described as well. Besides, it analyzes the advantages and the necessities of the natural fibre nonwoven materials applied for the noise control, illustrates the present research status and the factors that introduces the sound absorption properties of the natural fibre nonwoven composites used for noise reduction. The paper also gives some reference point for advice to the development of automotive nonwoven materials. it shows that natural fibre nonwoven materials have a huge potential market and worthy for scholars to make a further study.

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The effect of physical parameters on sound absorption properties of natural fiber mixed nonwoven composites

Textile Research Journal ◽

10.1177/0040517512441987 ◽

2012 ◽

Vol 82 (20) ◽

pp. 2043-2053 ◽

Cited By ~ 70

Author(s):

Merve Küçük ◽

Yasemin Korkmaz

Keyword(s):

Absorption Coefficient ◽

High Frequency ◽

Sound Absorption ◽

Natural Fiber ◽

Unit Area ◽

Air Permeability ◽

Physical Parameters ◽

Fiber Types ◽

Absorption Properties ◽

Nonwoven Fabrics

In this study, the effects of physical parameters on sound absorption properties of nonwoven fabrics were investigated. Eight different nonwoven composites including different fiber types mixed with different ratios were tested. Along with sound absorption properties, thickness, weight per area, and air permeability parameters of the samples were measured. The increase in thickness and the decrease in air permeability results in an increase in sound absorption properties of the material. The samples including 70% cotton and 30% polyester resulted in the best sound absorption coefficient in the mid-to-high frequency ranges. The increase in the amount of fiber per unit area resulted in an increase in sound absorption of the material. Addition of acrylic and polypropylene into a cotton and polyester fiber mixture increased the sound absorption properties of the composite in the low and mid-frequency ranges also.

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Sodium Bicarbonate Treatment on Mechanical and Morphological Properties of Coir Fibres

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.15.3.2018.12.0427 ◽

2018 ◽

Vol 15 (3) ◽

pp. 5562-5572 ◽

Cited By ~ 5

Author(s):

B. Bakri ◽

A. E. E. Putra ◽

A. A. Mochtar ◽

I. Renreng ◽

H. Arsyad

Keyword(s):

Mechanical Properties ◽

Sodium Bicarbonate ◽

Sodium Bicarbonate Solution ◽

Fibre Surface ◽

Natural Fibre ◽

Morphological Properties ◽

X Ray Diffraction ◽

Soaking Time ◽

Coir Fibre ◽

Suitable Treatment

Natural fibres as reinforcement of composite have been applied during the last decade. One of natural fibre has been used as reinforcement is coir fibre. As reinforcement of composite, such fibre needs treatment to improve compatibility with its matrix with suitable treatment. In this paper, surface treatment of such fibre was conducted using sodium bicarbonate (NaHCO3) solution with various densities and soaking time differences. Mechanical and morphological properties of coir fibre were investigated. Coir fibres were soaked in the 8 wt.%, 10 wt.%, and 12 wt.% sodium bicarbonate solution for 24 hours and 120 hours. After treatment, coir fibres were characterized with tensile testing, scanning electron microscope (SEM), Fourier transform infrared (FTIR) and x-ray diffraction (XRD). The results suggested that mechanical properties of coir fibre after sodium bicarbonate solution changed for all densities and soaking time. The coir fibre treated in 12 wt.% sodium bicarbonate for soaking time 120 hours has highest tensile strength. The surface morphology of fibre was analyzed by using SEM. It showed micropores on the fibre surface which may influence the mechanical properties of coir fibre.

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Sound Absorption Characteristics of Composite Panel Made from Coconut Coir and Oil Palm Empty Fruit Bunches Fibre with Polyester

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.18.3.2021.14.0691 ◽

2021 ◽

Vol 18 (3) ◽

pp. 9022-9028

Author(s):

M. Rusli ◽

R.S. Nanda ◽

H. Dahlan ◽

M. Bur ◽

M. Okuma

Keyword(s):

Absorption Coefficient ◽

Oil Palm ◽

Sound Absorption ◽

Natural Fibre ◽

Composite Panel ◽

Frequency Range ◽

Empty Fruit Bunches ◽

Coir Fibre ◽

Coconut Coir ◽

Absorption Characteristics

The development of pure natural fibres as sound absorptive material remains overlooked due to their lack of mechanical and moist properties, low durability, and vulnerability to be damaged by the environment. Certain fibre treatments are needed to improve such disadvantages. This paper investigates sound absorption characteristics of coconut fibre (coir) and oil palm fibre made from empty fruit bunches (OPEFB) fibre bonded by polyester that can protect them from the ambient environment in order to increase their durability. Two types of fibre-polyester composites have been tested. The first is the fibre-polyester composite (FPC) type, which is totally coated with polyester as the composite matrix. Another type is the fibre-polyester bonded composite (FPBC), in which the polyester is brushed into slice by a slice of the fibre layer in order to coat and bond the fibre, although porous among the fibre remains possible. A two-channel impedance tube is used in the measurement within 200 Hz to 3000 Hz of the frequency range. It is found that FPBC type panel has almost similar sound absorption characteristics to its purely natural fibre as it is able to maintain the panel porosity. The coconut coir fibre panel and its composite have a maximum absorption coefficient of almost 100% within the frequency range 1500-2000 Hz, considerably better than the OPEFB fibre, with only about 80% of the absorption coefficient. If the FPC layer exists, the sound absorption is reduced, and the frequency peaks are also shifted. Additions of the FPC panel layer thickness produced lower sound absorptions and shifted the peaks to the lower frequency range. The FPBC panel type is viable to protect the fibre from the environment without changing its sound absorption characteristics.

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Preparation of natural bio-based Eucommia ulmoides gum/styrene-butadiene rubber composites and the evaluation of their damping and sound absorption properties

Polymer ◽

10.1016/j.polymer.2020.123292 ◽

2021 ◽

Vol 213 ◽

pp. 123292

Author(s):

Renwei Cao ◽

Linhui Deng ◽

Zhibo Feng ◽

Xiuying Zhao ◽

Xiaolin Li ◽

...

Keyword(s):

Sound Absorption ◽

Styrene Butadiene Rubber ◽

Eucommia Ulmoides ◽

Butadiene Rubber ◽

Rubber Composites ◽

Absorption Properties ◽

Eucommia Ulmoides Gum ◽

Styrene Butadiene

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Acoustic Panels Made of Paper Sludge and Clay Composites

Sustainability ◽

10.3390/su13020637 ◽

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).

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