Acoustical characteristics of oil palm mesocarp fibres
Natural fibres are availability biomass, plentiful in agricultural waste and eco�friendly materials. Currently, it is become the major reasons for emerging renewable materials in sustainable technology. Therefore, this study discusses the acoustical characteristics of agro-waste biomass fibres f...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2016
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| Subjects: | |
| Online Access: | http://eprints.uthm.edu.my/750/1/24p%20HANIF%20ABD%20LATIF.pdf http://eprints.uthm.edu.my/750/2/HANIF%20ABD%20LATIF%20WATERMARK.pdf |
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| Summary: | Natural fibres are availability biomass, plentiful in agricultural waste and eco�friendly materials. Currently, it is become the major reasons for emerging renewable
materials in sustainable technology. Therefore, this study discusses the acoustical
characteristics of agro-waste biomass fibres from oil palm Mesocarp as fibrous
acoustic material. Incorporated polyurethane (PU) had improved the sound
absorption coefficient (SAC), especially at low frequency range. The oil palm
Mesocarp fibres were mixed with four different percentages of PU, namely 10%,
20%, 30% and 40%. The measurement of SAC was done using an impedance tube
method (ITM). Moreover, there were two analytical models which are Delany�Bazley model and Johnson-Champoux-Allard model to validate the experimental
outcomes. There were several internal characteristics of the prepared samples
investigated namely flow resistivity, porosity, tortuosity, characteristic lengths, fibre
diameter, air gaps and thickness of sample. The flow resistivity, tortuosity, fibre
diameter, density of samples and characteristic lengths tend to increase with
percentage of PU binder. But, porosity was slightly decrease by adding more binder
into the sample. This study confirms that by increasing the thickness of samples, the
SAC were improved. Air gaps had great influence in adjusting amount of low
frequency range and moved the peaks toward lower frequency. The internal
characteristics have a positive and significant effect on Noise Reduction Coefficient
(NRC). The sample with 10% PU binder showed the greatest sound absorption
performance in most of low to mid frequency range and demonstrated highest value
of NRC of 0.66. Besides, sample with 20% PU binder demonstrated optimum SAC
which is very close to 1 at 1000 Hz. There is still space to improve the performance
of the Delany-Bazley Model, especially for natural fibre. Besides, the Johnson�Champoux-Allard model gives similar pattern of graph to ITM results and the model
predicts very well with better fit to acoustic behaviour. |
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