A Study of The Sound Absorption Properties of Layered Composites on Chicken Feather Fibers

Biocomposites made from animal fibers have now been developed into alternative materials for room acoustics. This study presents a material study on the sound absorption ability of chicken feather fiber composites made experimentally by layered methods of various matrix compositions. Testing the absorbability of material sound using an Impedance tube or Kundt tube method (ISO 10543-2), at a frequency of 200 Hz to 1600 Hz (Medium Sounds). The results revealed that chicken feather fiber composites (CFFC) performed well in sound absorption when using a matrix made from starch. Chicken feather fiber composites (CFFC) perform well in the medium to high-frequency range and can be recommended as indoor sound-absorbing materials.


Introduction
Biocomposites known as composites made from natural fibers have been widely developed as special acoustic alternative materials in the room.Generally, natural fibers available in Indonesia are vegetable fibers such as cotton, coconut husk, bamboo, and others; while animal fibers, such as silk, wool, and collagen fibers [1].Natural fiber has basic characteristics including biodegradability, low use of chemicals in the process, renewability, ease to process and abundant availability, and cheap [2].The use of natural fibers as acoustic materials must consider the characteristics of the physical properties inherent in the material [3].
Today the process of making composite materials is very necessary technological innovation in its processing so that it can become composite panels that can be of economic value, tough and strong.Coated composites or laminate composites have better mechanical properties than metals.In lamina composites, reinforcement and matrix produce a combination of mechanical properties that are different from the basic properties of each matrix and reinforcement so that it greatly affects the final properties of the composite formed, both physical and mechanical properties [4].Composite layers are twodimensional layers or panels that have a higher strength direction.The coating process is carried out by combining the best aspects of each layer to obtain useful materials [5].The addition of the number of layers to the fiber composite has the effect that the higher the fiber volume fraction causes the matrix volume fraction to be less, resulting in weaker bonds between the matrix and the fiber [6] Factors that can affect the acoustic properties of a fiber composite material include fiber size, temperature, porosity, flow resistivity, density, thickness, compression, and design [7].Composite materials that function well as sound absorbers in the form of determining the properties of fibers, 7th International Conference on Noise, Vibration and Comfort (NVC 2023) thickness, and density of samples need to be considered [8].The research on chicken feather fiber developed into composite panels shows that processing conditions, percent weight of reinforcing fiber, thickness, and density have a significant impact on NRC values [9].The use of chicken feather fibers compared directly to glass wool showed a coefficient of absorption at a certain frequency, somewhat higher [10].
This study presents a material study on the sound absorption ability of chicken feather fiber composites made experimentally by layered methods of various matrices.Testing of material sound absorption efficacy using impedance tube or Kundt tube method (ISO 10543-2).Impedance tubes are considered a very important tool for determining the value of the coefficients of absorption, reflection, and sound transmission [11].Material characteristics will be analyzed at frequencies of 200 Hz to 2000 Hz (Medium Sounds).

Composition of composite materials
The thickness and density of the chicken feather fiber composite (CFFC) test material for each layer are the same value, namely 0.75 cm and 0.27 gr/cm3.Especially for the use of matrix for CFFC test materials, it is divided into three types, namely (1) Starch; (2) PVaC; and (3) No matrix.The manufacturing process is in the form of Pulverized, with a Hydraulic cold press.The material composition for each layer is in Table 1.Chicken Feather Fiber -PVC CFF-P 0,75 0,27 PVC Chicken Feather Fiber -Non-Matriks CFF-N 0,75 0,27

Layered composite process
The shape of the layer structure of the test material can be seen in Figure 1.The structure of the test material layer consists of a composite of chicken feather fiber (CFFC) given a layer of PVaC adhesive and then arranged alternately until it reaches four layers.The test material that has been arranged is then pressed until it reaches a thickness of 3 cm and then dried using an oven.The manufacturing process of CFFC test materials is seen in Figure 2. The physical form in the form of a composite surface layer and top and side views of the CFFC test material can be seen in Table 2.

Data analysis and processing
Testing the sound-absorbency of materials using impedance tubes or Kundt Tube method (ISO 10543-2) frequency range 0 Hz to 1600 Hz.The characteristics of sound absorption of CFFC test materials will be analyzed based on absorption at frequencies of 200 Hz to 1600 Hz (Medium Sounds).This frequency range was chosen because it conforms to the low-density value of the test material, this is in line with Elammaran Jayamani et al in [12], revealing that higher densities, will perform better at relatively lower frequencies. 7th

Sound absorption characteristics
The results of measuring data from the characteristics of CFFC sound absorption at frequencies of 200 Hz to 1600 Hz can be seen in Figure 3.The graph of the frequency range of 200 Hz to 800 Hz shows that all three test samples (CFF-S; CFF-P and CFF-N) have fluctuating absorption coefficient values, where the best absorption coefficient value is shown by CFF-S with a minimum value of 0.14 and a maximum value of 0.51.Furthermore, in the frequency range above 800 Hz, all three test samples (CFF-S; CFF-P, and CFF-N) show a constantly rising chart trend.The highest absorption coefficient obtained from each specimen is (1) CFF-S of 0.87; (2) CFF-P of 0.60: and (3) CFF-N of 0.71.
Comparison results of the three test samples (CFF-S; CFF-P and CFF-N) indicate that the absorption coefficient in the frequency range of the Medium Sounds type has a maximum value of 0.87 in CFF-S composites with the use of the Starch matrix type.The difference in absorption coefficient values of the three matrices indicates a difference in the amount of porosity that differs despite having the same density value.This situation can be caused by the use of PVaC type matrices binding fibers more tightly so as to reduce porosity, compared to starch type matrices that have higher porosity.Other causes can be irregular fiber structure.The properties of composite materials are strongly influenced by the nature and distribution of the constituent elements, shape, size, orientation and distribution of fillers, as well as the interaction between the two [13].Meanwhile, in composites that do not use a matrix, the use of more fiber material results in air movement, affecting the sound energy to be transmitted smaller, so that the coefficient value becomes large [14].

Classes of the sound absorption
The acoustic characteristics of CFFCs at the most important frequencies in general acoustic design practice, namely 125, 250, 500, 1000, and 1600 can be seen in table 3. The absorption coefficient value of each test sample at this frequency tends to increase significantly.At the lower frequency of 125 Hz the highest coefficient value in the CFF-P test sample was 0.09 and the lowest in the CFF-S test sample was 0.06.The frequency of 250 Hz is the highest absorption coefficient value in CFF-N of 0.27 and the lowest in CFF-P of 0.17.Furthermore, the frequency of 500 Hz maximum value in CFF-S and CFF-P test samples is 0.37 and the minimum value is 0.32 for CFF-N.while at high frequencies of 1000 Hz and 1600 Hz the maximum values in CFF-S are 0.60 and 0.87 for minimum values in CFF-P of 0.41 and 0.60.The difference in the number of absorption coefficients of the three test samples at lowmedium -high frequencies, has been described in the paragraph above, there are differences in the use of matrices that bind chicken feather fibers, causing differences in the amount of prosity in CFFC composites.Porous absorbers have more efficient sound absorption characteristics at high frequencies than at lower frequencies.Porous absorbers have more efficient sound absorption characteristics at high frequencies than at lower frequencies.Porous materials are the most widely used type of silencer, especially to reduce noise in narrow spaces such as housing and offices because porous materials are relatively cheaper and lighter than other types of silencers [15].The use of chicken feather fiber composites (CFFC) with a layered method is considered to perform well as a sound-absorbing material in the medium to high-frequency range.Materials with a minimum sound absorption coefficient value of 0.15 can be categorized as sound-absorbing materials [16].Furthermore, Doelle revealed that sound-absorbing materials have an absorption coefficient value above 0.3 [11].CFF-S with an absorption coefficient value of 0.87 can be included in the acoustic materials category based on SAC into the acoustic materials category B [12].The Sound Absorption Coefficient (SAC) table can be seen in Table 4.

Conclusion
Chicken feather fiber composites (CFFC) perform well in sound absorption when using a starch matrix.Chicken feather fiber composites (CFFC) perform well in the medium and high-frequency ranges.
Composites made from chicken feather fiber (CFFC) can be recommended as indoor sound-absorbing materials.Further testing with chicken feather fiber material should consider the high density, thickness and quality of the material.

Figure 1 .Figure 2 .
Figure 1.Form the layer structure of the Chicken Feather Fiber Composite (CFFC)

Figure 3 .
Figure 3. CFFC Sound absorption characteristics at frequencies of 200 Hz to 1600 Hz on Noise, Vibration and Comfort(NVC 2023)

Table 1 .
Material properties of each sheet chicken feather fiber composite (CFFC) International Conference on Noise, Vibration and Comfort (NVC 2023)

Table 3 .
Coefficient of absorption at a certain frequency