Kapok fiber is natural fiber that has outstanding properties, among others are light, flexible to be formed and porous.
The Kapok tree (Ceiba Pentandra) is available in many places in Indonesia, also in Thailand. How ever in Indonesa, the plantation managed by government is just a small part of all available potency.
The forest of Kapok trees in Nusa Tenggara is still unused. The aim of the research was to used kapok fiber as material for absorbing sound energy, either to reduce sound reflection energy, or as a material that reduce the transmission of sound energy from inside to outside of room, vice-versa. Sound absorbption materials made of Kapok fiber have been prepared and tested.
The material is able to absorb sound energy that fall on its surface, using loose kapok fiber that put inside of textile sack. The dimension of the sack is 1.2 x 1.2 m2, and 5 cm thickness, and the density of Kapok fiber is 16 kg/m3. Nine piece of sacks were placed on the floor of the test room of random absorption coefficient ( a r), to meet the minimum area of the test sample is 10 m2. The comparson samplr was glasswool with the same density and dimension.
The result shows that at low frequency of 150 to 800 Herz thea rkp is higher than that of glass wool ( argw), whilst for the frequency higher than 800 Hz up to 4 kHz, the arkp is a little bit lower than argw. (see the graph of Random Absorpsion Coefficient). Kapok fiber panels with the dimension of 69 x 69 cm2, thickness of 2.5 cm and the density of 100 kg/m3 and 200 kg/m3 have also been made.
The panels were used as samples of sound energy Transissin Loss (TL) test in order to find the Sound Transmission Class (STC). The STC test were also done n the glasswool and the loose kapok fiber that were sandwiched beetweem triplex panels with the dimension of 69 x 69 cm2 and 5 cm thickness. The test result shows that the STC of kapok panels with the density of 200 kg/m3 is 21 higher than that kapokpanel with the density of 100 kg/m3 i.e. 19.
Whilst the STC of loose kapok fiber is 22 higher than that of glass wool .e. 21. This means that Kapok fiber can be used as sound absorption material to control acustics condition in rooms or passenger cabins. Its also shown that kapok fiber can be used as soundproofing material.
2005 Asian Physics Symposium Proceedings, ISBN:979-98010-2-8. p.220-224
