The progress of humanity from the primitive state to the present day’s highly advanced technology has been closely associated with dependence on wood. The relative ease of working it and its almost universal availability has made wood an essential material for human survival. Wood has been used for shelter, fuel, weapons, and tools since prehistoric times. As technology developed, wood came to be used for boats, vehicles, bridges, buildings, furniture, man- made boards, pulp and paper, and art crafts etc. Chapter 1 Introduction / 绪论

A comprehensive knowledge of the characteristics of any material is essential to its best utilization. This is especially true with wood because of the manner of its formation and its complex cellular and cell wall structure.

 Ⅰ. Characteristic properties of wood — 木材的特性  Ⅱ. Variability of wood Properties — 材性变异  Ⅲ. Wood as an industrial raw material — 木材作为工业原材料  Ⅳ. Wood as a construction material — 木材作为建筑材料  Ⅴ. Knowledge of wood and better use — 木材知识与木材合理利用 Topical highlights:

Ⅰ. Characteristic properties of wood All wood, regardless of its botanical origin, possesses certain characteristics in common. These are summarized as follows. 1. Wood is cellular in structure 2. Wood is anisotropic in nature 3. Wood is a hygroscopic substance 4. Wood is biodegradable 5. Wood is combustible 6. Wood is inert to chemicals 7. Wood is durable when used properly 8. Wood has excellent insulating properties

Ⅱ. Variability of wood properties 材性变异 Wood is an inherently variable substance because of its origin as a product of metabolism of the living tree. As a result, its properties are subject to wide variations brought about by the physiology of the trees and the external factors affecting its growth. The variations can be summarized into three categories. Variability between species Variability between trees of the same species Variability between parts of the same tree

Ⅲ. Wood as an industrial raw material 木材作为工业原材料 Most of characteristics of wood that make it an outstanding industrial and construction material are traceable to one or more of its basic properties and to its manner of origin. Conversely its faults are derived from the same basic characteristics. A comprehensive knowledge of the structure of wood, its chemical and physical behavior, and the causes of its variability as they affect its utilization is therefore the basis of present and potential utilization. Furniture industry Wood panel industry House construction Pulp and paper industry Production of chemicals Production of energy

Ⅳ. Wood as a construction material 木材作为建筑材料 When wood is employed in its basically unaltered form in construction, furniture, containers, power transmission lines, transportation, and a host of other applications, it offers the greatest challenge and opportunity to the designer and user. This is true because wood is universally available in a large variety of shapes and sizes with greater diversity of unique characteristics than are found in other major structural materials. When used as a construction material, wood has the following advantages. Wood can be cut and worked into various shapes Wood has a high strength to weight ratio Wood is a good energy absorbing material Wood is dimension stable to temperature

Ⅵ. Knowledge of wood and better use 木材知识与木材合理利用  Wood may also has some disadvantages, but many of these disadvantages could be overcome by intelligent use of wood, based on comprehensive knowledge of its properties.  It should never be forgotten that wood is the only major raw material with a wide range of industrial uses, which is renewable, and hence capable of meeting the needs of a nation in perpetuity. It is therefore inconceivable that this priceless material should be either grown or used without due consideration of the known scientific facts concerning its nature.  We may use wood with intelligence only if we understand wood.

Reflection and practice: 1. Advantages of wood used as a construction materials? 2. Characteristic properties of wood? 3. Uses of wood as an industrial material?