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Fibre Saturation Point
Fibre saturation point is a term used in wood mechanics and especially wood drying, to denote the point in the drying process at which only water bound in the cell walls remains - all other water, called free water, having been removed from the cell cavities. Further drying of the wood results in strengthening of the wood fibres, and is usually accompanied by shrinkage. Wood is normally dried to a point where it is in equilibrium with the atmospheric moisture content or relative humidity, and since this varies so does the equilibrium moisture content The equilibrium moisture content (EMC) of a hygroscopic material surrounded at least partially by air is the moisture content at which the material is neither gaining nor losing moisture. The value of the EMC depends on the material and the rela .... Laboratory testing has found the average FSP in many types of wood to be approximately 26%. Individual species may differ from the average.Principles of Wood Science and Technology: I S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wood Drying
Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method. There are two main reasons for drying wood: ; Woodworking:When wood is used as a construction material, whether as a structural support in a building or in woodworking objects, it will absorb or expel moisture until it is in equilibrium with its surroundings. Equilibration (usually drying) causes unequal shrinkage in the wood, and can cause damage to the wood if equilibration occurs too rapidly. The equilibration must be controlled to prevent damage to the wood. ; Wood burning: When wood is burned (firewood), it is usually best to dry it first. Damage from shrinkage is not a problem here, as it may be in the case of drying for woodworking purposes. Moisture affects the burning process, with unburnt hydrocarbons going up the chimney. If a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Wall
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. Cell walls are absent in many eukaryotes, including animals, but are present in some other ones like fungi, algae and plants, and in most prokaryotes (except mollicute bacteria). A major function is to act as pressure vessels, preventing over-expansion of the cell when water enters. The composition of cell walls varies between taxonomic group and species and may depend on cell type and developmental stage. The primary cell wall of land plants is composed of the polysaccharides cellulose, hemicelluloses and pectin. Often, other polymers such as lignin, suberin or cutin are anchored to or embedded in plant cell walls. Algae possess cell walls made of glycoproteins and polysaccharides such as carrageenan and agar that are absent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strength Of Materials
The field of strength of materials, also called mechanics of materials, typically refers to various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the response of a structure under loading and its susceptibility to various failure modes takes into account the properties of the materials such as its yield strength, ultimate strength, Young's modulus, and Poisson's ratio. In addition, the mechanical element's macroscopic properties (geometric properties) such as its length, width, thickness, boundary constraints and abrupt changes in geometry such as holes are considered. The theory began with the consideration of the behavior of one and two dimensional members of structures, whose states of stress can be approximated as two dimensional, and was then generalized to three dimensions to develop a more complete theory of the elastic and plastic behavior of materials. An important founding pion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equilibrium Moisture Content
The equilibrium moisture content (EMC) of a hygroscopic material surrounded at least partially by air is the moisture content at which the material is neither gaining nor losing moisture. The value of the EMC depends on the material and the relative humidity and temperature of the air with which it is in contact. The speed with which it is approached depends on the properties of the material, the surface-area-to-volume ratio of its shape, and the speed with which humidity is carried away or towards the material (e.g. diffusion in stagnant air or convection in moving air). Equilibrium moisture content of grains The moisture content of grains is an essential property in food storage. The moisture content that is safe for long-term storage is 12% for corn, sorghum, rice and wheat and 11% for soybeanSadakam, Samy Grain Drying Tools: Equilibrium Moisture Content Tables and Psychrometric Charts. Univ. Arkansas, FSA1074 At a constant relative humidity of air, the EMC will drop by a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timber Seasoning
Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). Lumber has many uses beyond home building. Lumber is sometimes referred to as timber as an archaic term and still in England, while in most parts of the world (especially the United States and Canada) the term timber refers specifically to unprocessed wood fiber, such as cut logs or standing trees that have yet to be cut. Lumber may be supplied either rough- sawn, or surfaced on one or more of its faces. Beside pulpwood, ''rough lumber'' is the raw material for furniture-making, and manufacture of other items requiring cutting and shaping. It is available in many species, including hardwoods and softwoods, such as white pine and red pine, because of their low cost. ''Finished lumber'' is supplied in standard sizes, mostly f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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