2.1 Natural Fibre
According to the researcher, the natural fibres are the renewable sources that can be disposed at the end of its useful life (Dos Santos, 2009). This characteristic is called as biodegradable and it is an important characteristic that should have in a competent. Another researcher said that when compared with mineral wool, the insulation based on natural fibres has comparable and sometimes even better thermal technical characteristics for example heat capacity or the afore-mentioned thermal conductivity (Hroudova, 2011).
2.1.1 Rice Straw
Rice straw’s scientific name is Oryza sativa L is the vegetative part of the rice plant. According to the researcher, the rice straw may be burned and left on the field before the next ploughing, ploughed down as a soil improver or used as a feed for livestock (Kadam et al., 2000). Rice straw can be treated in order to improve its nutritive value. Those treatment are designed to improve the feed intake and digestibility. This improvement may be achieved by mechanical, chemical, heat and pressure treatments. In mechanical treatments, chopping and grinding the rice straw may reduce the time passage in the rumen and to improve feed intake (Doyle et al., 1986). Besides, rice straw particles has a very high porosity value inside rice straw and between particles, which has a dominant influence on thermal and moisture behaviour of the thermal insulating material (Kangcheng, 2015). Rice straw could be used as a biodegradable eco-friendly reinforcement at end-of-use in polypropylene composites, to minimize environmental pollution rather than to perform a strong reinforcing effect. (Grozdanov, 2006)
2.1.2 Coconut Husk
Coconut husk usually being wasted after the coconut fruit being extracted. It has a high amount of lignin and cellulose. The chemical composition of coconut husk consists of cellulose, lignin, pyroligeous acid, gas, charcoal, tar, tannin and potassium. These natural fibre can be transformed into a value-added fuel source which can be replace wood and other traditional fuel sources. Furthermore, the coconut husk could be a good thermal conductivity and need no chemical binder to manufacture. However, if it is tending to be applied in building sector, it should be protected from moisture due to its high moisture content and water absorption (Panyakaew et al., 2008).
2.1.3 Oil Palm Husk
Binder is a material or substance that used as reinforced material which holds materials together and sometimes could be a filler in between them. Binder also known as a binder or matrix. The binder acts as a glue which provide adhesion or coating in the making of natural fibre board. There are two types of synthetic binder which are thermoset and thermoplastic
2.2.1 Methylene Diphenyl Diiscyanate
2.3 Hot-Press Machine
Hot-press machine is a high pressure machine that used to consolidate and to cure the adhesive in the natural fibre board. In hot-pressing, the energy is directly delivered into the whole board and absorbed by the asymmetric molecules, and then the energy is transformed into heat. The basic principle of hot-pressing is the application of heat, which activates the chemical components of the raw material used. The raw material basically put inside the mould and then it placed inside the hot-pressing machine. The mould will be pressed depends on the parameters set up. According to the researcher, it is necessary to apply enough heat and pressure to melt lignin through the entire board, allowing good distribution of lignin between the fibres during the manufacturing process (Mancera et al., 2008; Zhou et al., 2010).
2.4 Effect towards Rice Straw Board using Hot-Press Machine
2.4.1 Thermal Insulation
The term of thermal insulation refers to the material that used to reduce the rate of heat transfer and the methods and processes used to reduce the amount of heat transfer. In heat transfer, conduction is the transfer of thermal energy neighbouring molecules in a substance due to a temperature gradient. Besides, thermal insulation prevents the heat from escaping or entering the container. Panyakaew (2011) stated that the production of low density thermal insulation boards made from coconut husk and bagasse without the use of chemical binding activities. The results is both thermal insulation boards have thermal conductivity values ranging from 0.046 W/mK to 0.068 W/mK which were close to those of conventional insulation materials such as cellulose fibres and mineral wool. The successful use of straw bales as thermal insulation within the envelope of buildings has been demonstrated by the increasing number of successful contemporary projects around the world. (Thomson, 2014; Shea, 2013). These environment-friendly thermal insulation materials are excellent insulating components for building materials as wall or ceiling for energy conservation except for relative lower bonding strength and sensitive to moisture and humidity. Then comparison of thermal conductivity of the selected material and other materials that are stated in the literature is given in Table….
(kg/m³) Thermal Conductivity (W/mK) Source
Oil Palm Fibre 100 0.0567 Manohar. 2012a
Sugarcane 686 0.0461 Manohar, 2012a
Coconut husk with phenol formadehyde 510-540 0.1036 Khedari et al., 2003
Bagasse 90-100 0.0483 Manohar et al., 2006
Corn Cub 211 0.1390 Pinto et al., 2012
Oil palm frond 108-141 0.0340-0.0830 Sihabut, 2010
Rice hull 149 0.0449 Yarbough et al., 2005
2.4.2 Moisture Content
Moisture content depends on the circumstances at the time of baling and during subsequent storage and transport. The impact of moisture content on thermal insulation conductivity varies with the type of insulation depending on the composition, properties and internal structure of the material used, which determine the modes of heat transfer and the moisture storage capacity of the material (Abdou, 2013).
2.4.3 Board Density
2.4.4 Particle Size
2.5 Experimental Testing
2.5.1 Tensile Test
2.5.2 Hardness Test
2.5.3 Thermal Conductivity Test
2.5.4 Young’s Modulus Test
Rice is one of the most important staple food for most people in the world. Every year, the production of rice was the third-highest worldwide production. Therefore, there were a lot of rice straw are produced. straw is one of the natural fibre that has been used as part of building material for several years. Straw is derived from grasses and is regarded as a renewable building material since its primary energy input is solar and it can be grown and then harvested. Straw is springy tubular stalk of grasses for example wheat and rice which are high in tensile strength. Straw is composed of cellulose, hemicellulose, lignins and silica. Straw bales were first used in building construction over a century ago by settler in Nebraska, USA shortly after the invention of bailing machines. Straw bale are traditionally a waste product which the farmer do sell to customer as animal bedding or landscape supply due to their durable nature. Besides, Straw bale wall surprisingly resistant to the fire, vermin and decay.
2.1.3 Oil Palm
2.2 Benefits of Straw Bale Construction
A straw bale building is easy to modify, flexible enough to be used in many ways, solid and sizable, durable over time, and easily to maintain. It requires only simple tools and unspecialized labour, which can easily acquire and affordable in most locations around the world. Straw bale construction have different benefits such as beauty and comfort, ease of construction, energy efficiency, environmental benefits, sustainability and fire safety.
2.1.1 Beauty and Comfort
The bulk and subtle surface of the straw bale walls have special character and beauty. The wall create a comfort feeling to the people which not found in the thin flat walls that are produces from modern materials. When finished with natural plasters and paints, the rice straw bale walls can breathe resulting in fresh, energizing and clean indoor atmosphere compared to the low-oxygen of most homes. The high of thermal insulation value of rice straw bales also helps to create a very stable environment in hot weather instead of cold weather which suitable to the Malaysia’s climate. Furthermore, it also provides a good living conditions to most modern house in nowadays.
2.1.2 Ease of Construction
Building walls from rice straw is much less labour used and requires less skill to produce than using other materials such as concrete block, brick and stone. Rice straw bale building encourages some people creativity to ………..
2.1.3 Energy Efficient
Straw bale buildings are thermally efficient and conserve energy much better than the conventional construction, depending on the type of straw and the thickness of the wall. Besides, the straw bale building have a better in comforting and save energy compared to the conventional building systems. Moreover, straw bale building allows smaller heating or cooling systems to be installed …….One researcher have found that cotton stalk fibre which are the renewable natural resources to manufacture an environment friendly binderless fibreboard with a low thermal conductivity (0.059 W/mK – 0.082 W/mK) by high frequency heating, which is particularly suitable for ceiling and wall building applications to save energy (Zhou et al., 2010).
2.1.3 Environmental Benefits
Straw bale can provide so many benefits where the straw has become unwanted waste product. The slow rate of deterioration creates disposal problems for farmers because unlike nitrogen-rich hay, the straw cannot be used for animal fodder. The farmers need to get rid the straw by burning it which can cause black smoke and produce air pollution. To solve this problem……. According to the researcher, rice straw board was made successfully using the following methods which are cutting, soaking, refining, forming and drying method. No chemical adhesives or chemical compounds were added in whole making process this board which made the board is biodegradable and environment-friendly materials (Zhang, 2016).
2.1.5 Fire Safety
Building raw material are classified into four groups: not flammable (A), hardly flammable (B?), normally inflammable (B?), and easily inflammable (B?). These straw bales are classified into group B?. The benefit from this group is lack of oxygen in the compressed straw which make the results high fire resistance. Straw bales can burn in slowly but the potential for fire to take hold can be minimised. An experiment carried out by The National Research Council of Canada 1980 tests of plastered straw bales and found out that straw bale tend to be more resistant to the fire than the most conventional building materials. …….. According to the researcher, the plaster of straw-bale wall is an excellent fire barrier, possibly deserving as much as a three or four hour fire rating due to the fact that the bales contain vary little oxygen and are too dense to sustain fire (King, 1996). Another researcher said that the plaster coating effectively seals the already fire-resistant bales inside a non- combustible casement. The fire have to burn through the plaster in order to reach the straw. When plaster is combined with a massive bale wall, fire resistance is enhanced (Magwood, 2000).
2.1.6 Thermal Efficienc
1. Zhou, X.Y., F. Zheng, H.G. Li, C.L. Lv, An environment-friendly thermal insulation material from cotton stalk fibers, Energy Build. 42 (7) (2010) pp.1070–1074.
2. Zhang, J., Wang, X., Kito, K., Effect of Heating Temperature on Strength of Rice Straw Bio-board. (2016) Vol. 45, No. 7 pp. 41-48.
3. King, B. P. E. 1996, Buildings of earth and straw. Text book. Ecological design press 1996,(ISBN 0-9644718-1-7), pp. 95–152.
4. Magwood, C. and Mack, P. 2000, Straw bale building, how to plan, design and build with straw. Text book, New Society Publishers (ISBN 0-86571-403-7) pp. 55-84.
5. Hroudova, J., Kout, P., Zach, J., 2011. Konplexní hodnocení vlastností p?írodních izola?ních material z technického konopí ur?eného do podlahonline, TZBinfo cited 20. 12. 2012. Available from Internet: http://stavba.tzb-info.cz/izolace-strechy-fasady/7290-komplexni-hodnoceni-vlastnostiprirodnich-zolacnich-materialu-z-technickeho-konopi-urcenych-do-podlah
6. Kadam, K. L. ; Forrest, L. H. ; Jacobson, W. A., 2000. Rice straw as a lignocellulosic resource: collection, processing, transportation, and environmental aspects. Biomass and Bioenergy, 18: 369-389
7. Doyle, P. T. ; Devendra, C. ; Pearce, G. R., 1986. Rice straw as a feed for ruminants. International Development Program of Australian Universities and Colleges Grozdanov A., Buzarovska A., Bogoeva-Gaceva G., Avella M., M.E. Errico, et al.. Rice straw as an alternative reinforcement in polypropylene composites. Agronomy for Sustainable Development, Springer Verlag/EDP Sciences/INRA, 2006, 26 (4), pp.251-255.
8. Mancera, C., Ferrando, F., and Salvado, J. (2008). “Cynara cardunculus as raw material for the production of binderless fiberboards: Optimization of pretreatment and pressing conditions,” Journal of Wood Chemistry and Technology 28(3), 207-226. DOI: 10.1080/02773810802347024
9. Zhou, X., Zheng, F., Li, H., and Lu, C. (2010). “An environment-friendly thermal insulation material from cotton stalk fibres,” Energy and Buildings 42(7), 1070-1074. DOI: 10.1016/j.enbuild.2010.01.020
10. Panyakaew S., Fotios S., New thermal insulation boards made from coconuthusk and bagasse, Energy Build. 43 (7) (2011) 1732–1739.
11. Thomson A., Walker P., Durability characteristics of straw bales in buildingenvelopes, Constr. Build. Mater. 68 (2014) 135–141
12. Shea A., Wall A., Walker P., Evaluation of the thermal performance of an inno-vative prefabricated natural plant fiber building system, Build. Serv. Eng. Res.Technol. 34 (4) (2013) 369–380.
13. Abdou A., Budaiwi I., The variation of thermal conductivity of fibrous insulationmaterials under different levels of moisture content, Constr. Build. Mater. 43(2013) 533–544.
14. Manohar, K., “Experimental investigation of building thermal insulation from agricultural by-products”, British J. of Applied Science;Technology, (2012b) vol. 2(3), pp. 227-239.
15. Khedari, J., Charoenvai, S., and Hirunlabh, J., “New insulating particleboards from durian peel and coconut coir”, Building and Environment, (2003) vol. 38, pp. 435-441.
16. Manohar, K., Ramlakhan, D., Kochhar, G. and Haldar, S., “Biodegradable fibrous thermal insulation”, J. of Brazilian Society of Mechanical Sciences and Engineering, vol. 28, (2006).
17. Pinto, J., Cruz, D., Paiva, A., Pereira, S., Tavares, P., Fernandes, L. and Varum, H., “Characterization of corn cob as a possible raw building material”, Construction and Building Materials, (2012) vol 34, pp.28-33.
18. Sihabut, T., and Laemsak, N., “Feasibility of producing insulation boards from oil palm fronds and empty fruit bunches”, Songklanakarin J. Sci. Technol, (2010) vol. 32(1), pp. 63-69.
19. Yarbrough, D.W., Wilkes, K.E., Graves, R.S. and Vohra, A., “Apparent thermal conductivity data and related information for rice hulls and crushed pecan shells”, Thermal Conductivity, (2005) vol. 27, pp. 222-230.