Does wood have liquid state?
Some objects' latent heat can be obtained by doing the experiment to find out how much energy is required to change its phase. However, how can I find out the latent heat of poor condutors such as wood? I am not sure whether it has liquid state or not. What is the latent heat of fusion of wood and how to perform an experiment to find it out? Does wood really have liquid state? If it does, how to obtain the liquid state of wood without it being ignited?
- nicoleLv 71 十年前最愛解答
Wood is a solid material derived from woody plants, notably trees but also shrubs. Wood from the latter is only produced in small sizes, reducing the diversity of uses.
In its most common meaning, "wood" is the secondary xylem of a woody plant, but this is an approximation only: in the wider sense, wood may refer to other materials and tissues with comparable properties. Wood is a heterogeneous, hygroscopic, cellular and anisotropic material. Wood is composed of fibers of cellulose (40%–50%) and hemicellulose (15%–25%) held together by lignin (15%–30%).
2.2 Heartwood and sapwood
3 Different woods
4 Water content
5 See also
7 External links
A tree trunk as found at the Veluwe, The Netherlands
Artists can use wood to create delicate sculptures.
Wood has been used for millennia for many purposes. One of its primary uses is as fuel. It is also used as for making artworks, furniture, tools, and weapons, and as a construction material.
Wood has been an important construction material since humans began building shelters, houses, boats. It remains in common use today for wooden boats and wooden houses. In buildings made of other materials, wood will still be found as a supporting material (notably in roof construction) or exterior decoration. Wood to be used for construction work is commonly known as lumber in North America. Elsewhere, lumber will usually refer to felled trees, and the word for sawn planks (etc) ready for use will be timber.
Wood which in its native form is unsuitable for construction may be broken down mechanically (into fibres or chips) or chemically (into cellulose) and used as a raw material for other building materials such as chipboard, engineered wood, hardboard, medium-density fibreboard (MDF), oriented strand board (OSB). Also, wood fibres are an important component of most paper, and cellulose is used as a component of some synthetic materials.
A tree increases in diameter by the formation, between the old wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. Where there are clear seasons, this can happen in a discrete pattern, leading to what is known as growth rings, as can be seen on the end of a log. If these seasons are annual these growth rings are annual rings. Where there is no seasonal difference growth rings are likely to be indistinct or absent.
Within a growth ring it may be possible to see two parts. The part nearest the center of the tree is more open textured and almost invariably lighter in color than that near the outer portion of the ring. The inner portion is formed early in the season, when growth is comparatively rapid; it is known as early wood or spring wood. The outer portion is the late wood or summer wood, being produced in the summer. In white pines there is not much contrast in the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines, on the other hand, the late wood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored early wood. In ring-porous woods each season's growth is always well defined, because the large pores of the spring abut on the denser tissue of the fall before. In the diffuse-porous woods, the demarcation between rings is not always so clear and in some cases is almost (if not entirely) invisible to the unaided eye.
A knot, is a particular type of imperfection in a piece of timber, which reduces its strength, but which may be exploited for artistic effect. In a longitudinally-sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the roughly parallel fibres (grain) of the rest of the "flows" (parts and rejoins).
- RinkaLv 51 十年前