CHAPTER ONE
Medium-density fibreboard (MDF) is an engineered medium Density Fiberboard (MDF) product made by breaking down hardmedium Density Fiberboard (MDF) or softmedium Density Fiberboard (MDF) residuals Krotov et. al.(2012) into medium Density Fiberboard (MDF) fibres, often in a defibrator, combining it with wax and a resin binder, and forming panels by applying high temperature and pressure. MDF is generally denser than plywood. It is made up of separated fibres, but can be used as a building material similar in application to plywood Spence et. al. (2005). It is stronger and much denser than particle board. The name derives from the distinction in densities of fibreboard. Large-scale production of MDF began in the 1980s, in both North America and Europe. Over time, the term MDF has become a generic name for any dry process fibre board. MDF is typically made up of 82% medium Density Fiberboard (MDF) fibre, 9% urea-formaldehyde resin glue, 8% water and 1% paraffin wax. and the density is typically between 500 kg/m3 and 1,000 kg/m3. The range of density and classification as light, standard, or high density board is a misnomer and confusing. The density of the board, when evaluated in relation to the density of the fibre that goes into making the panel, is important. A thick MDF panel at a density of 700–720 kg/m3 may be considered as high density in the case of softmedium Density Fiberboard (MDF) fibre panels, whereas a panel of the same density made of hard medium Density Fiberboard (MDF) fibres is not regarded as so. The evolution of the various types of MDF has been driven by differing need for specific applications.
Plywood is a sheet material manufactured from thin layers or "plies" of medium Density Fiberboard (MDF) veneer that are glued together with adjacent layers having (Kozlowski, et. al.,1996) their medium Density Fiberboard (MDF) grain rotated up to 90 degrees to one another. It is an engineered medium Density Fiberboard (MDF) from the family of manufactured boards which includes medium-density fibreboard (MDF) and particle board (chipboard). All plywoods bind resin and medium Density Fiberboard (MDF) fibre sheets (cellulose cells are long, strong and thin) to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of medium Density Fiberboard (MDF) to split when nailed at the edges Mikhajlov (1963); it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across all directions Joyce (1970). There is usually an odd number of plies, so that the sheet is balanced—this reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it is very hard to bend it perpendicular to the grain direction of the surface ply Muller (2013). Smaller thinner plywoods and lower quality plywoods (see Average-quality plywood photo below and right) may only have their plies (layers) arranged at right angles to each other, though some better quality plywood products will by design have five plies in steps of 45 degrees (0, 45, 90, 135, and 180 degrees), giving strength in multiple axes. Plywood production requires a good log, called a peeler, which is generally straighter and larger in Krotov et. al. (1982) diameter than one required for processing into dimensioned lumber by sawmill. The log is laid horizontally and rotated about its long axis while a long blade is pressed into it, causing a thin layer of medium Density Fiberboard (MDF) to peel off (much as a continuous sheet of paper from a roll). An adjustable nosebar, which may be solid or a roller, is pressed against the log during rotation, to create a "gap" for veneer to pass through between the knife and the nosebar Voroshilov (1980). The nosebar partly compresses the medium Density Fiberboard (MDF) as it is peeled; it controls vibration of the peeling knife; and assists in keeping the veneer being peeled to an accurate thickness. In this way the log is peeled into sheets of veneer, which are then cut to the (Cassell’s, 1928) desired oversize dimensions, to allow it to shrink (depending on medium Density Fiberboard (MDF) species) when dried. The sheets are then patched, graded, glued together and then baked in a press at a temperature of at least 140 °C (284 °F), and at a pressure of up to 1.9 MPa (280 psi) (but more commonly 200 psi) to form the plywood panel. The panel can then be patched, have minor surface defects such as splits or small knot holes filled, re-sized, sanded or otherwise refinished, depending on the market for which it is intended.
1.1 Research Problem
Plywood is used in many applications that need high-quality, high-strength sheet material. Quality in this context means resistance to cracking, breaking, shrinkage, twisting and warping. MDF is basically glorified particle board. Just like particle board, MDF will soak up water and other liquids like a sponge and swell unless it’s very well sealed on all sides and edges with primer, paint, or another sealing product Anisov et. al. (1980). It was recommended that quality oil-based primer should be used because it consists of such fine particles, MDF doesn’t hold screws very well, and it’s very easy to strip the screw holes. Because it’s so dense, MDF is very heavy. This can make it more difficult to work with, especially if you don’t have a helper who can help you lift and cut the large sheets. MDF can’t be stained. Not only does it soak up stain like a sponge, but also because there’s no medium Density Fiberboard (MDF) grain on MDF, it looks awful when it’s stained. Because of the layers that show on the edge, you have to finish off the edges somehow. This can be done with iron-on edge banding or with pieces of lumber or decorative moulding. Plywood will often splinter on the edges when cut, so it’s harder to get a smooth cut with plywood than it is with MDF. Exterior glued plywood is suitable for outdoor use, but because moisture affects the strength of medium Density Fiberboard (MDF), optimal performance is achieved in end uses where the medium Density Fiberboard (MDF)'s moisture content remains relatively low. On the other hand, subzero conditions don't affect plywood's dimensional or strength properties, which makes some special applications possible. Plywood is also used as an engineering material for stressed-skin applications. Denser than plywood or chipboard (the resins are heavy); Low grade MDF may swell and break when saturated with water; May warp or expand if not sealed; May release formaldehyde, which is a known human carcinogen and may cause allergy, eye and lung irritation when cutting and sanding associated with nasal sinus cancer and nasopharyngeal cancer, and possibly with leukaemia in June 2004; Dulls blades more quickly than many medium Density Fiberboard (MDF)s.
1.2 Research Questions
1. What is the fire resistance of the Medium-density fibreboard (MDF) and plywood when used as building material?
2. What are the level of water absorption of Medium-density fibreboard and Plywood when used as building material?
3. What are the thermal resistance property of MDF and plywood?
1.3 Aim of the Study
The aim of this project is to compare the performance of MDF with plywood as a building material.
1.4 Objectives of the Study
a. To determine the fire resistance of the Medium-density fibreboard (MDF) and plywood when used as building material.
b. To investigate the level of water absorption of Medium-density fibreboard and Plywood when used as building material.
c. To determine the thermal resistance property of MDF and plywood
1.5 Research Method
Experimental method was adopted for the purpose of this project. The Medium-density fibreboard (MDF) and plywood were tested for fire resistance, water absorption and thermal properties.
1.6 Scope of the Study
In other to complete this research work within the stipulated time frame, this research focuses on comparative analysis of performance of MDF on plywood as a building material and to determine fire resistance, water absorption and thermal properties.
1.7 Significant of the Study
This research will allow the construction industry practitioners in Nigeria to have adequate knowledge of the performance of Medium-density fibreboard (MDF) with plywood as building material.
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