Wood

Which type of wood absorbs water the quickest?

I. Introduction

A. Thesis statement: Different species of wood absorb water differently

II. Definition

A. What wood is

B. What wood consists of

III. Properties of wood.

A. Moisture content

B. Shrinkage

C. Permeability

D. Thermal properties

E. Electrical properties

F. Mechanical properties

G. Elastic properties

H. Strength

I. Vibration

IV. Properties of the woods that I am using

A. Pine

B. Maple

C. Cedar

D. Oak

E. Poplar

V. Previous experimentation

VI. Conclusion

Which type of wood absorbs water the quickest?

Wood is used for many things and some of these things reside outside where they are exposed to the elements. Different types of wood are affected differently by the weather and other natural elements. I have chosen to focus on the certain aspects of the effects of water on wood. I wish to show you that different species of wood absorb water differently.

One of the Earth's most treasured resources is wood. Wood is used to make hundreds upon hundreds of the product that we use in our everyday lives. Wood comes from trees and is found relatively everywhere. Wood is tough, strong, and easy to handle (World book). Wood is practically one of the best building agents in the world. It holds in heat extremely well, it cannot rust, and it can withstand a lot of heat. Wood, however, does have its own problems and its major problem is how it shrinks or swells depending on the absorption of water. There are two types of wood, softwood and hardwood. The names imply that the wood itself is hard or soft which is not true. Softwood is wood that comes from conifers trees whereas hardwood comes from deciduous trees. Conifers trees are con-baring trees and deciduous trees are trees with broad leaves that change color and fall in the autumn.

Wood is made up of tiny tube like cells that form into enduring tissue around the plant stem. These walls f cells are made up four main substances. These substances are cellulose, lignin, hemicellulose, and extractives. Cellulose is yielding and is made up of fibers. Lignin is a weighty material that is solid. It is located between the threads of cellulose and the wood cells. Lignin is what makes the wood durable and firm. Hemicellulose assists cellulose by holding the threads of the cellulose together. Extractives are the fats, gums, oils, and coloring matter located inside of wood. The proportion of these substances is different in all of the types of wood. These differences are what control whether or not a certain type of wood will be hard or soft, heavy or light, dull or colorful, or firm or supple.

Here are some of the properties that wood has: moisture content, shrinkage, permeability, thermal properties, electrical properties, mechanical properties, elastic properties, strength, and vibration. Moisture content is a very important factor in wood processing. Norma in-use moisture content of processed wood that has been dried ranges 8-13%. Water is held in wood in three ways: as water chemically bonded to hydroxyl groups in the wood substance of the cell wall, or as either free water or as water vapor in the cell cavities (Science and Technology Encyclopedia). Wood is at its fiber saturation point when all of the free water is taken from the cell cavities and the cell wall is soaked to its fullest. Shrinkage is what happens to the wood when it loses its water below the fiber saturation point. Wood is dimensionally stable when the water level of saturation is

above that point. Permeability is a measure of the flow of a liquid or gas through wood as a result of the total pressure gradient (Science and Technology Encyclopedia). It is influenced by the framework of the wood cells, the route of the flow, and the properties of the liquid being calculated. Another thing that affects permeability is the species, if the wood is sapwood or heartwood, and the physical and chemical properties of the liquid. The main thermal properties of wood are coefficient of thermal expansion, specific heat, and conductivity. When dry, wood is a poor conductor of heat but when wood is wet it can withstand a high degree of heat. Conductivity of heat is found out by density, moisture content, and the path of conduction. Specific heat on the other hand is wholly dependant on moisture content and temperature. When you measure the electrical resistance of wood, electrical moisture meter can correctly find out the moisture content of wood. Dielectric constant and the dielectric power factor for alternating current are some of the electrical properties found in wood. These properties depend on density, moisture content, the current frequency, the orientation of the grain, and the temperature. The power factor is a measure of the stored energy that is converted into heat (Science and Technology Encyclopedia). This factor is also affected by the same things as the dielectric properties.

Elastic, strength, and vibration

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