INVESTIGATION INTO USING RICE HUSK AS MAJOR RAW MATERIALS IN PRODUCING PARTICLES BOARD
BY
ALHAJI LADAN SIDDI YABO
PGS/06/TEC/01012
SUPERVISOR:
PROFESSOR ABDU SALIHI
BEING A SEMINAR II PAPER SUBMITTED TO THE DEPARTMENT OF MECHANICAL ENGINEERING, FACULTY OF TECHNOLOGY, BAYERO UNIVERSITY, KANO, IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF M.ENG. DEGREE IN PRODUCTION ENGINEERING
November, 2010
Abstract
This project investigates the use of an agro-residue material (rice husk) as a major raw material in the production of Particle Boards. Rice husk was collected from a rice mill industry situated at Arkilla in Wamakko Local Government of Sokoto State. Cement bonded particleboards of 6mm thickness were produced from rice husks using production variables of cement/rice husk mixing ratios of 1.5:1 and 2.0:1, each with a nominal board density of 900kg/m3 and 1200kg/m3 from two categories of rice husk particles (fine and coarse) . The additives concentration of was maintained at 3%. The physical and mechanical properties, such as Water absorption (WA), Thickness Swelling (TS), Linear Expansion (LE), Modulus of Rupture (MOR), and Modulus of Elasticity (MOE), of the boards produced were determined. The Particleboards produced exhibited mean values ranging from 50.13% to 44.11% for WA, 2.01% to 0.082% for TS, 0.31% to 0.23% for LE, 1.83N/mm2 to 6.23N/mm2 for MOR, and 1087.9N/mm2 to 2694.9N/mm2 for MOE respectively for fine rice husk particles and 52.24% to 45.73 % for WA, 2.18% to 1.14% for TS, 0.39% to 0.29% for LE, 1.05N/mm2 to 6.05N/mm2 for MOR, and 984.3N/mm2 to 2332.37N/mm2 for MOE respectively for coarse rice husk particles. The result shows that an increase in cement/rice husk mixing ratio and density caused an increase in both MOR and MOE while there was decrease in WA, TS, and LE respectively. Based on the results obtained, boards produced at the highest cement/rice husk mixing ratio of 2.0:1 and board density 1200kg/m3 at additives concentration 3% were strongest and most dimensionally stable.
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After harvesting hundreds of samples at random are examined in our well-equipped quality control laboratory for final selection of stocks. The harvested paddy from our own farms and others on arrival at the Rice Mill is fed to the mechanical dryer for drying. The paddy fresh from harvesting has moisture contents of -19-20%, which is reduced to 12% in the dryer in multi passes. The tempering of ...
1.0 INTRODUCTION
1.1 History and Development of Particles Board Industry
Some experimental work on particle board production was carried out in both Europe and North America in 1940, but the first plant to produce particle board commercially was built in Bremen, Western Germany in 1941 (F.A.O, 1958).
It used wood and a phenol as binder. Work on the technical and scientific problems evolved in the immediate post-war years when Germany was confronted with a serious wood shortage. Urea resins were found to be suitable, and also considerable resin economics resulted from the use of homogeneous, engineered particles instead of heterogeneous wood chips. There were notable development also in the United Kingdom and Switzerland where the first three-layer board was marketed in 1945 (REMOND, 1967).
Many wood species were to be suitable. Meanwhile, the possibility of using agricultural residues instead of wood had explored, and first plant based on flux sheaves was put into operation in Belgium in 1947.
Particle board was first made, both in the experimental stage and commercial production, in first processes and the vast majority of the plants operating today employed multi-platen presses. The extrusion process was developed in Western Germany between 1947and 1949, and experienced a rapid but short-lived commercial expansion, for the product was unsatisfactory for many purposes because of it low strength characteristics. As a building and furniture material, particle board has undergone considerable technical evolution.
The industry’s geographical of both production facilities and market spreading all over the world. World production of particle board in 1973 was put at 31,671,000 by the Food and Agriculture organization. The main producing countries are U.S.A, West Germany, U.S.S.R., France, Belgium, and Italy. The rice husk, which is the outer fibrous layer of the rice kernel, constitutes approximately 20% of the weight of paddy grain being processed. The production of over 510 million tons of rice produces nearly 100 million tons of rice husks available from rice mills (Vellupillai et. al., 1997).
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Rice is the seed of a monocot plant. As a cereal grain, it is the most important staple food for a large part of the world’s human population, especially in East, South, Southeast Asia, the Middle East, Latin America, and the West Indies. It is the grain with the second highest worldwide production, after maize.
1.2 STATEMENT OF THE PROBLEM
The environmentally sound disposal or use of large quantities of rice husk is a challenging issue associated with growing rice production. Rice husk is an agricultural residue which has not been used as a raw material on industrial scale in Nigeria. The environment is polluted by it and becomes a problem to manage, which is why an investigation needed to be carried out to see if it can be used as a raw material in producing particle boards. Rice husk (also called rice hulls or paddy husk) are a by-product of the rice processing industry. At present, rice husks have no large scale commercial use. Consequently, where rice is processed in large quantities, considerable waste disposal problems are encountered.
1.3 SIGNIFICANCE OF THE RESEARCH
The significance of the research is that it will lead to utilizing the heaps of rice husks waste as industrial raw materials, support Government in creating employment and alleviating poverty in the country, as well as support the campaign on climate change mitigation through utilization of agro residue wastes for the benefit of mankind.
1.4 AIM AND OBJECTIVES
The aim of this work is to investigate the production of particle board from rice husks at different production variables (mixing ratio level, density, and particle size), determine the physical and mechanical properties such as the WA, TS, LE, MOE, and MOR of the particle boards produced and compares the properties of those produced from fine and coarse rice husks.
METHODOLOGY
The methodology used for the work include visiting Rice Mills to verify the different sizes of rice husk particles available, measuring and taking to laboratory for analyzing the physical characteristic and chemical compositions. An investigation was also made on the type of adhesive and additives to use as binder in the production of particle boards. A mould was then designed, produced and used to manufacture particle boards from rice husks. The particle boards produced were then tested and their properties compared with those of existing particle boards in Nigerian markets.
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1.6 SCOPE OF THE RESEARCH
The scopes of the research are limited to:-
Investigating the suitability of using rice husk as major raw materials in producing particles board;
Fabricating a simple mold to produce a sample of rice husk particle board;
Testing of the molded particleboard in the laboratory; and
Comparing the characteristics of rice husk particle board with the existing particle boards in Nigerian markets.
2.0 LITERATURE REVIEW
2.1 Particle Board Materials
”Particle Board”, or ”Particleboard”, (or ”chipboard” in the UK, Australia and some other countries) is an engineered wood product manufactured from wood particles, such as wood chips, sawmill shavings, or even saw dust, and a synthetic resin or other suitable binder, which is pressed and extrusion extruded. Particleboard is a composite material.
“Rice Husk” is the outer layer of rice grain which is removed during rice processing. It is composed of mainly organo cellulose material. (Haxo, H. E.and P. K. Mehta. 1975.)
2.2 Applications of Particle Board
Particle boards are substitutes for solid wood and plywood. Due to the growing deforestation, the natural wood is becoming more and more scare. Particle boards are made from agricultural wastes like jute sticks, non-commercial waste wood chips, sawdust etc. and bonded by resins. Particle boards are used as cheaper substitute of wood in the Manufacture of various furniture items like table tops, door/window panels, show cases, partitions fridge taps, sewing machine cover etc. Particle boards are also used as ceiling tiles. Due to this, it has got very good scope for marketing. Most of the above items are used in bulk by the manufacturers of fridges, sewing machine etc. There is bright future of particle board.
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2.3 Researches Carried out on Particle Board:-
2.3.1 Particle Board of Groundnut shell
A study of the suitability of groundnut shells as a basic raw material in the production of particle boards in Nigeria has been made as a theses. The researcher produce a medium density particle board from groundnut shell by using “flat pressed method”, using urea-formaldehyde UF as the resin and test the particle board in accordance with British Standards (ABU Zaria 1977)
2.3.2 Particle Board of Bagasse
Bagasse is depicted in a special machine in two stages, dried, mixed with a binder, and hot pressed in the same way as boards made from wood particles. The boards produced ranged in thickness from 8 to 35 mm, and in density from 0.30 to 0.75 g/cm3. Strength properties are comparable to those of similar boards made of jute sticks, hemp shivers, flax shivers, and various wood species. Bagasse particleboards can be used as flooring, wall partitions, ceilings, roofing’s, and furniture. (Hesch, R.1967).
2.4 Adhesives in Particle Boards
Adhesives are an essential and extensively used in wood based composite products. Adhesive type and cure schedule vary according to the composite application. Adhesives used in the manufacture of particleboard should be flexible and soft to respond to the dynamic effects of swelling and shrinkage, yet impart required strength. The adhesive must also withstand the rigors of particleboard manufacturing while sufficient flow to increase particle coverage. Excessive flow however, will displace adhesive droplets from the glue line into the interstices producing particleboards with inferior properties. Similarly, insufficient flow reduces surface coverage resulting in substandard particleboards. (Dr. Anbu Clemensis Johnson)
2.4.1 Synthetic adhesives
Commonly used synthetic adhesives in the manufacture of particleboards are phenol-formaldehyde and urea-formaldehyde.
Phenol-formaldehyde (PF)
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PF resin creates strong, water resistant bonds, but requires the longest press times and highest temperatures. Cured PF are inherently dark and are undesirable for decorative products such as furniture and paneling.
Urea-formaldehyde (UF)
UF resin is inexpensive and is used where surface smoothness is required but not high water resistance. UF is extensively used in particleboard manufacturing for interior applications such as furniture and cabinetry. However, it has a disadvantage of formaldehyde emissions at high temperature. Chemical bonds between urea and formaldehyde are weaker than PF and are easily cleaved by moisture.
2.4.2. Natural Adhesives
In early 1900’s adhesives were derived from agricultural resources until the introduction of petroleum resins in the early 1930’s. In recent times the term “biodegradable” is commonly used to denote environmentally friendly products, which in plastics describe all degradable plastics through microorganisms such as bacteria, fungi, and algae. The main challenges with the use of biodegradable Adhesives are that they are predominantly water soluble. This limitation limits its outdoor applications or moisture rich environment.
Soybean adhesive
Soybean is inexpensive and widely available food material. Soy protein concentrate as such or modified with alkali can be used as an adhesive. (Dr. Anbu Clemensis Johnson)
Starch adhesive
Starch is an easily available and inexpensive biodegradable material. (Dr. Anbu Clemensis Johnson)
2.4.3 Portland Cement
In the most general sense of the word, a ”’cement”’ is a binder, a substance which sets and hardens independently, and can bind other materials together. The word “cement” traces to the [[Ancient Rome Romans]], who used the term ”opus caementicium” to describe masonry which resembled concrete and was made from crushed rock with burnt [[Calcium oxide lime]] as binder. The volcanic ash and pulverized brick additives which were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment and cement.
The cement binder provides a durable surface as well as one that can be easily embossed and colored with a range of processing methods to provide a variety of products that are easily machined with conventional wood-working tools. Although, as stated earlier, it is important to note that cement-bonded composite panel products are not a novel concept, some of which have been on the market for over a century (Papadopoulos,2006).
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3.0 EXPERIMENTATION
3.1 Experimental Design
The experimental design used in this project is 2x2x3 factorial in a complete randomized design, the combination of which gives 12 treatments. The following production variables were used:
Board density of 900kg/m3 and 1200 kg/m3.
Mixing ratio of cement –rice husk particle, 1.5:1 and 2.0:1
Additive concentration (CaCl2) = 3%.
Board thickness = 6mm
Moisture content = approximately 12%
Board size = 350mm x 350 mm x 6mm
Pressing pressure = 1.23 N /mm2
(Erakhrumen, 2008)
3.2 TESTING OF THE BOARD PROPERTIES
Each board was cut into test specimens as stated below: 152mm x152mm x 6mm was used to investigate the Thickness Swelling, Water Absorption, and Linear Expansion. 194mm x 50mm was used to investigate Modulus of Rupture and Modulus of Elasticity as the standard test for testing dimensional stability of a particle board. (American National Standard of Particle board)
3.3 Water Absorption
This is a measure meant to test the dimensional stability of board, to have this test done; test specimens were soaked in cold water for moisture uptake for 24 hours. Later the new weight was measured using highly sensitive weighing balance. It is therefore measured in grams. Water absorption was then expressed as the percentage of increase in weight of the board over the original or initial weight. This is expressed as:
WA = Water absorption was determined from the experiment carried on each specimen and WA was calculated using the formula; and required data was obtained. .
3.4 Thickness Swelling
The same procedure was used to determine the thickness swelling, using the same specimens at the same period of time for soaking. The thickness of the boards was measured using electronic veneer caliper before soaking and after soaking for 24hours. The thickness swelling was expressed as the percentage of increase in thickness of the board over the original thickness. Thickness swelling was expressed as;
T5 = Thickness swelling was determined from the experiment carried on each specimen and TS was calculated using the formula; and required data was obtained.
3.5 Linear Expansion
This was also carried out by taking measurement of the initial length (L1) with the aid of a ruler at two different sides of the test specimen. They were soaked in water for 48 hours and the measurement of the final thickness (L2) was carried out at the designated two different sides. The linear expansion (%) was estimated using:
LE (%) =
Linear Expansion was determined from the experiment carried on each specimen and LE was calculated using the formula; and required data was obtained.
Where: LE = Linear Expansion (%)
L2 = Final length (mm)
L1 = Initial length (mm)
3.6 MECHANICAL PROPERTIES
3.6.1 Modulus of Rupture (Bending Strength)
The test specimens of 194mm×50mm×6mm board thickness were subjected to a force or load on the tensiometer with the support span. The specimens were supported by two rollers at each ends and loaded at the centers. The forward movement of the machine leads to gradual increase of load at the middle span until failures of the test specimens occurred. At the point of failure, the force exerted on the specimen that caused the failure was recorded. The modulus of rupture (MOR) of the test specimens was calculated using the formula;
MOR=
Where;
MOR= Modulus of Rupture, ρ= Failing load, L= Span between centers of support (mm).
b= Width of test specimen (mm), d= mean thickness of the specimen (mm).
3.6.2 MODULUS OF ELASTICITY
While the panel’s stiffness (MOE) was determined from the bending test performed on each specimen and MOE was calculated using the formula;
MOE (N/mm2) = was calculated and the required data is obtained.
Where;
MOE= Modulus of elasticity of panel stiffness, L= Span between centers of support (mm)
b= Mean thickness of the specimen (mm), H= Increment in deflection (mm).
4.0 DATA PRESENTATION AND ANALYSIS
4.1 Result and Discussion
Table 2:- Mean values of Water Absorption (WA), Thickness Swelling (TS), Linear Expansion (LE), Modulus of Rupture (MOR), Modulus of Elasticity (MOE) of cement bonded particle board produced from rice Husk.
Particle MRL Density kg/m3 Physical Properties Mechanical Properties
WA (%) TS (%) LE (%) MOR
(N/mm2) MOE (N/mm2)
Fine 1.5:1
2.0:1 900 50.13±2.06
46.52±0.66 2.01±0.72
1.26±0.59 0.31±0.03
0.29±0.02 1.83± 0.39
4.27±0.76 1087.9±154.09
1983.5±32.51
1.5:1
2.0:1 1200 47.04±1.14
44.11±0.12 1.82±0.08
0.08±0.14 0. 25±0.15
0.23±0.04 4.78±0.49
6.23±0.29 1987.4± 18.82
2694.9±447.99
Coarse
1.5:1
2.0:1 900 52.24±2.64
49.38±1.02 2.18±0.18
1.60±0.54 0.39±0.02
0. 28±.01 1.05±0.07
6.05±0.07 984.3±77.22
1732.7±225.97
1.5:1
2.0:1 1200 48.42±0.59
45.73±1.11 1.99±0.01
1.14±0.18 0.33±0.05
0. 29±0.03 3.76±0.47
6.05±0.07 1079.7±159.92
2332.4±313.94
Each value represents the mean value of 3 replicates
5.0 CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion
From the work carried out it can be concluded that:-
The water absorption (WA), thickness swelling (TS) and Linear Expansion (LE) physical properties of cement bonded boards decreases as the board density, and mixing ratio increased. Also, the modulus of Rupture (MOR) and Modulus of Elasticity (MOE) properties increase as the board density, and mixing ratio, increase; which means that the variable used in board production actually have effect on the board properties examined;
Any increase in board density and mixing ratio resulted in increase in mechanical and dimensional stability properties. From the result of Analysis of variance, there is significant difference (P) in the water Absorption (WA), thickness swelling (TS), linear Expansion (LE), Modulus of Rapture (MOR) and Modulus of Elasticity (MOE) of board at the levels of production variables used in the board’s manufacture;
Rice husk is suitable for board formation with the addition of additive and cement to produce a long lasting board of good quality.
5.2 Recommendations
Based on the above conclusion, this study recommends the following:
That the abundant rice husk in various rice mills in the country should be managed to be use as raw material for producing particle board.
That all the research institutes in Nigeria should embark on different means of producing cement bonded boards in order to increase the production capacity of the boards.
That government and other private firms should pump more money into this kind of research so as to increases the level of innovations and technology.
Large scale production and commercialization of particle board made from rice husk should be encouraged. This will reduce the pressure on the use of timber and enhance forest biodiversity.
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