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Author: search.filters.author.Kalasee, WacharaSubject: search.filters.subject.coffee silver skin

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    Sound Absorption Behavior Related to Reduce the Melamine-Urea-Formaldehyde (MUF) Adhesives for the Coffee Silver Skin Board Production
    (2023-01-01)
    Ekvanich, Visit
    ;
    Lakachaiworakun, Putipong
    ;
    Kalasee, Wachara
    ;
    Dangwilailux, Panya
    The development of sound-absorbing panels which used coffee-silver-skin (CS) and melamine-urea-formaldehyde (MUF) as a composite board was studied. In this experiment, the objective was to examine the impact on the sound absorption coefficient (SAC) when incorporating wood husk into the composite board, specifically in the cases of CS (100%) and CS (90%) mixed with wood husk (10%), while simultaneously reducing the amount of MUF adhesive and adding corn starch (25%). It was observed that as the MUF content of the board decreased to 75%, the sound absorption coefficient average (SAA) were found to be 0.59 and 0.62 for the middle- and high-frequency ranges, respectively. For the frequency range higher than 3.15 kHz, the maximum SAC value of sample boards was 0.91 and the noise reduction coefficient (NRC) value was 0.47. While, the result showed the maximum SAC and the NRC value of sample boards were 0.93 and 0.48, respectively above the frequency range higher than 1.25 kHz for decreasing the MUF adhesive of board to 50%. Similarly, the addition of wood husk and corn starch mixed to CS could increase the SAA value of sample boards in the middle- and high-frequency range.
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    Sound Absorption of Natural Fiber Composite from Sugarcane Bagasse and Coffee Silver Skin
    (2023-01-01)
    Kalasee, Wachara
    ;
    Lakachaiworakun, Putipong
    ;
    Eakvanich, Visit
    ;
    Dangwilailux, Panya
    This study aimed to develop a sound-absorbing composite using sugarcane bagasse (SB) and coffee silver skin (CS) as raw materials. The composite boards were manufactured by bonding the fibers with Melamine Urea-Formaldehyde adhesive, ensuring a consistent thickness of 30 mm. Various densities were employed, namely 380, 450, and 520 kg/m<sup>3</sup>. The samples were fabricated with different fiber ratios, including SB100%, SB75% with CS25%, and SB50% with CS50%. The sound absorption coefficient (SAC) and noise reduction coefficient (NRC) were measured using the impedance tube method within a frequency range of 63–6,300 Hz. The experimental results revealed that the mixing ratio of CS exerted a notable influence on enhancing the SAC, while the density of the composite board exhibited a significant impact on increasing both the SAC and NRC. Among the densities tested, the optimal value was observed at 520 kg/m<sup>3</sup>, yielding a SAC value of 0.65 at a frequency of 1,000 Hz and an NRC value of 0.55 for the SB50-CS50 composite plate. These findings underscore the importance of considering the CS mixing ratio and composite board density when aiming to optimize sound absorption properties.