Vocabulary List

indispensable – необходимый;

rubberized fabrics – прорезиненные изделия;

naphtha – лигроин, сырая нефть, керосин;

by-product – побочный продукт;

solvent – растворитель;

double-texture fabric – ткань, имеющая двойную структуру, ткань с наполнителем;

solution – раствор.

Text 15

Synthetic Rubber

Historical. – When it became clear that rubber could be broken down to isoprene it was natural that the reverse process should be attempted. As early as 1887 it was observed that, exposed to light in a sealed tube for a long time, isoprene underwent a change; on adding alcohol a tough rubbery mass was obtained. In 1902 the spontaneous polymerization of isoprene into rubber was recorded.

This spontaneous polymerization is an extremely slow process. After four years’ storage a sample of isoprene had become thick but had not yet yielded a solid polymer. In addition to isoprene, its isomers received attention and in 1900-1901 Kondakov prepared what was probably the first commercial production of synthetic rubber.

As well as isoprene, butadiene itself received attention. But it was not until 1910 that Lebedev reported it to yield a rubberlike polymer on heating. Butadiene is now the most important diene for the preparation of synthetic rubbers; it polymerizes far more readily than substituted dienes.

Synthetic Rubber Manufacture. – Synthetic rubber manufacture may be divided into two main steps – production of the monomers, and their polymerization. Manufacturing of monomers involves a series of steps, starting with the selected raw material. Both the selected raw material and the route followed may differ, still yielding the same end product. Butadiene, for example, the most important monomer so far utilized, may be synthesized from acetylene and also from alcohol.

Two direct methods are in current use for conversion of alcohol to butadiene. Both are due to the discoveries of Russian chemists. The acetaldehyde route from alcohol was first tried in Russia, a pilot plant being erected in Moscow, but the process was abandoned in 1922. In 1928, S. V. Lebedev and his collaborators were awarded a prize for a new method of producing synthetic rubber. The Lebedev process consists essentially in the direct conversion of ethyl alcohol to butadiene by a special mixed catalyst which removes both water and hydrogen.

Vocabulary List

break down – распадаться;

Reverse process – обратный процесс;

sealed tube – запечатанный сосуд;

Rubberlike – каучукоподобный;

spontaneous polymerization – самопроизвольная полимеризация;

yield – превращаться;

sample – образец;

route – метод/способ получения;

utilize – использовать;

conversion – превращение;

acetaldehyde – ацетальдегид, уксусный альдегид;

ethyl alcohol – винный спирт;

catalyst – катализатор;

remove – удалять.

Text 16

Direct Uses of Latex

Latex is compounded by introducing the ingredients in the form of very fine aqueous dispersion, colloidal where possible. Compounding is carried out in pebble mills, and also in special pieces of equipment known as colloidal mills. Generally speaking, the same ingredients are added to latex as to rubber; it should be noted that reinforcing fillers do not affect latex. It has been found desirable to add a certain number of special ingredients, the principal ones being as follows:

a) Dispersing agents, which prevent agglomeration of the colloidally - dispersed particles.

b) Stabilisers, to prevent coagulation during processing of the latex.

c) Thickeners, for increasing the viscosity of the mix as required.

d) Wetting agents, to reduce the surface tension of the latex thus enabling it to penetrate more easi1y into materials to be impregnated with it.

Various processes exist for the working up of latex mixes. In the dipping process a former (usually of porcelian, aluminium or glass) is dipped into the mix, and then withdrawn, the thin layer of latex adhering to it being then dried. An article of the desired thickness is obtained by repeated dripping. Electrodeposition is the process by which rubber is deposited from the latex when an electric current is passed through the bath, the particles of rubber being deposited on an anode in the form of the object to be reproduced. Latex may be used for impregnation and rubberising, not only of textiles but of many other materials, e.g. paper, leather fibres, and horsehair. Goods may also be made by moulding with latex. The field in which latex finds widest application is that of cellular goods mattresses, pillows – made of latex foam, usually obtained by beating the mix, then gellifying as in the case of moulding, followed by drying.