1、1 Foreign material： Chemical Industry 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolutio
2、n, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860
3、s with the exploitation of William Henry Perkins discovery if the first synthetic dyestuffmauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75%
4、of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under con
5、ditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world war
6、 in 1914. This initiated profound changes which continued during the inter-war years (1918-1939). Since 1940 the chemical industry has grown at a remarkable rate, although this has slowed significantly in recent years. The lions share of this growth has been in the organic chemicals sector due to th
7、e development and growth of the petrochemicals area since 1950s. The explosives growth in petrochemicals in the 1960s and 1970s was largely due to the enormous increase in demand for synthetic polymers such as polyethylene, polypropylene, nylon, polyesters and epoxy resins. The chemical industry tod
8、ay is a very diverse sector of manufacturing industry, within which it plays a central role. It makes thousands of different chemicals which 2 the general public only usually encounter as end or consumer products. These products are purchased because they have the required properties which make them
9、 suitable for some particular application, e.g. a non-stick coating for pans or a weedkiller. Thus chemicals are ultimately sold for the effects that they produce. 2. Definition of the Chemical Industry At the turn of the century there would have been little difficulty in defining what constituted t
10、he chemical industry since only a very limited range of products was manufactured and these were clearly chemicals, e.g., alkali, sulphuric acid. At present, however, many intermediates to products produced, from raw materials like crude oil through (in some cases) many intermediates to products whi
11、ch may be used directly as consumer goods, or readily converted into them. The difficulty cones in deciding at which point in this sequence the particular operation ceases to be part of the chemical industrys sphere of activities. To consider a specific example to illustrate this dilemma, emulsion p
12、aints may contain poly (vinyl chloride) / poly (vinyl acetate). Clearly, synthesis of vinyl chloride (or acetate) and its polymerization are chemical activities. However, if formulation and mixing of the paint, including the polymer, is carried out by a branch of the multinational chemical company w
13、hich manufactured the ingredients, is this still part of the chemical industry of does it mow belong in the decorating industry? It is therefore apparent that, because of its diversity of operations and close links in many areas with other industries, there is no simple definition of the chemical in
14、dustry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as the chemical industry. It is important to bear this in mind when comparing statistical information which is derived from several sour
15、ces. 3. The Need for Chemical Industry The chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates and then into a tremendous variety of other chemicals. These are then used to produce consumer products, which make our lives 3 more comfort
16、able or, in some cases such as pharmaceutical produces, help to maintain our well-being or even life itself. At each stage of these operations value is added to the produce and provided this added exceeds the raw material plus processing costs then a profit will be made on the operation. It is the a
17、im of chemical industry to achieve this. It may seem strange in textbook this one to pose the question do we need a chemical industry? However trying to answer this question will provide( ) an indication of the range of the chemical industrys activities, ( ) its influence on our lives in everyday te
18、rms, and ( ) how great is societys need for a chemical industry. Our approach in answering the question will be to consider the industrys contribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their
19、turn are clothing and (briefly) shelter, leisure and transport. (1)Food. The chemical industry makes a major contribution to food production in at least three ways. Firstly, by making available large quantities of artificial fertilizers which are used to replace the elements (mainly nitrogen, phosph
20、orus and potassium) which are removed as nutrients by the growing crops during modern intensive farming. Secondly, by manufacturing crop protection chemicals, i.e., pesticides, which markedly reduce the proportion of the crops consumed by pests. Thirdly, by producing veterinary products which protec
21、t livestock from disease or cure their infections. (2)Health. We are all aware of the major contribution which the pharmaceutical sector of the industry has made to help keep us all healthy, e.g. by curing bacterial infections with antibiotics, and even extending life itself, e.g. blockers to lower
22、blood pressure. (3)Clothing. The improvement in properties of modern synthetic fibers over the traditional clothing materials (e.g. cotton and wool) has been quite remarkable. Thus shirts, dresses and suits made from polyesters like Terylene and polyamides like Nylon are crease-resistant, machine-wa
23、shable, and drip-dry or non-iron. They are also cheaper than natural materials.Parallel developments in the discovery of modern synthetic dyes and the technology to bond them to the fiber has resulted in a tremendous increase in the variety of colors available to the fashion designer. Indeed they now span almost every color and hue of the visible spectrum. Indeed if a suitable shade is not available, structural modification of an existing dye to achieve this can
