Plastics colourless

HOCHj CHjOH. Colourless, odourless, rather viscous hygroscopic liquid having a sweet taste, b.p. 197 C. Manufactured from ethylene chlorohydrin and NaHC03 solution, or by the hydration of ethylene oxide with dilute sulphuric acid or water under pressure at 195°C. Used in anti-freezes and coolants for engines (50 %) and in manufacture of polyester fibres (e.g. Terylene) and in the manufacture of various esters used as plasticizers. U.S. production 1979 1 900 000 tonnes. 

CH2=CHC = CCH = CH2. a colourless liquid which turns yellow on exposure to the air it has a distinct garlic-like odour b.p. 83-5°C. Manufactured by the controlled, low-temperature polymerization of acetylene in the presence of an aqueous solution of copper(I) and ammonium chlorides. It is very dangerous to handle, as it absorbs oxygen from the air to give an explosive peroxide. When heated in an inert atmosphere, it polymerizes to form first a drying oil and finally a hard, brittle insoluble resin. Reacts with chlorine to give a mixture of chlorinated products used as drying oils and plastics. 

HOOC-[CHa]8-COOH, CioH.aO. Colourless leaflets m.p. 134°C. Manufactured by heating castor oil with alkalis or by distillation of oleic acid. Forms an anhydride, m.p. 78 C. The esters of sebacic acid are used as plasticizers, especially for vinyl resins. 

Acrylic acid derivatives. Acrylic esters polymerise readily under the influence of oxygen, peroxides, light or heat to give colourless, glass-Uke plastics. 

In the massive form poly(vinyl chloride) is a colourless rigid material with limited heat stability and with a tendency to adhere to metallic surfaces when heated. For these, and other, reasons it is necessary to compound the polymer with other ingredients to make useful plastics materials. By such means it is possible to produce a wide range of products, including rigid piping and soft elastic cellular materials. 

Of these materials zein, the maize protein, has been used for plastics on a small scale. It can be cross-linked by formaldehyde but curing times are very long. Complicated bleaching processes have led to the production of almost colourless samples in the laboratory but the process cannot readily be extended to large-scale operation. The cured product has a greater water resistance than casein. Proteins from soya bean, castor bean and blood have also been converted into plastic masses but each have the attendant dark colour. 

China clay or kmlin, which is predominantly kaolinite, is particularly valuable because it is essentially free from iron impurities (and therefore colourless). World production in 1991 was 24.7M1 (USA 39%, UK 13%, Colombia, Korea and USSR 7% each). In the USA over half of this vast tonnage is used for paper filling or paper coating and only 130000 tonnes was used for china, crockery, and earthenware, which is now usually made from ball clay, a particularly fine-grained, highly plastic material which is predominantly kaolinite together with clay-mica and quartz. Some 800000 tonnes of ball clay is used annually in the USA for white ware, table ware, wall and floor tiles, sanitary ware, and electrical porcelain. 

Compound 1 is used as a solvent in the food, paint, resin/plastics, soap and woodpulp/paper industries, and as a plasticizer. Compound 2 is used as an intermediate for the manufacture of hydraulic fluid additives and cosmetics. Sulphonal (2 2-his(ethylsulphonyl)-propane), another important sulphone, is a colourless solid, stable to acids and alkalis, with hypnotic properties. 

Silicone liquids are used by dentists in the preparation of dentures. Dentures become waterproof, their material is not leached by saliva. Food particles do not stick to such dentures mucous membranes in the mouth are not irritated, which often happens when dentures are produced from organic plastic masses. If silicone toothpaste is used, teeth are covered with a colourless film that prevents them from tartar. 

What do they look like They may be crystalline solids, oils, waxes, plastics, elastics, mobile or volatile liquids, or gases, Familiar ones include white crystalline sugar, a cheap natural compound isolated from plants as hard white crystals when pure, and petrol, a mixture of colourless, volatile, flammable hydrocarbons. Isooctane is a typical example and gives its name to the octane rating of petrol. 

Phthalic acid esters are by far the largest and most widely used family of plasticizers (Fig. 6). More than 90% of phthalates produced in Europe are used to plasticize PVC. They are usually produced by reaction of phthalic anhydride with an excess of alcohol using p-toluenesulphonic acid as catalyst. The excess alcohol is recycled. Commercial phthalate esters are usually colourless and mostly odourless liquids. 

Many individual compounds. Colourless liquids rotten cabbage/garlic/skunk-like smell. Used as a stench gas odorant and as the starting point for synthesis of plastics, insecticides, etc. Irritants. Large exposure drowsiness, chemical pneumonitis. 

Many authors have the opinion that photodegradation of colourless plastic is mainly due to long-lived triplet states of the dissolved colorant. Such triplet states may be... 

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