Synthetic rubber

There is only one rubber obtained from natural sources in commercial quantities. There are several synthetically produced compounds that are classed as rubbers.

The butadiene-styrene rubber, now called SBR, constitutes the bulk of the synthetic rubber production. All the SBR-type rubbers are obtained by the emulsion polymerization of butadiene and styrene in various ratios. However, in the most commonly used type the ratio of butadiene and styrene is approximately 78 : 22.

The original or hot SBR is polymerized at a temperature of 122 ºF or higher and is used primarily for mechanical, goods.

The cold type, polymerized at 41 ºF, exhibits an improvement over the hot type in most physical properties. When used in light-duty tyres such as passenger car tyres, the cold-rubber compounds have proved equal or superior to natural rubber treads. However, they are inferior to natural rubber for truck tyres because of the greater heat build-up during flexion.

In general the compounding and processing methods used for all the SBR types are similar to those of natural rubber. Although natural rubber is superior with respect to lower heat build-up, resilience, and hot strength, the SBR types are more resistant to abrasion and weathering. However, carbon black or some other reinforcing fillers must be added to the butadiene-styrene rubber to develop the best physical qualities.

3. Divide the text into some logical parts and entitle them.

4. Translate the following sentences into English using lexical material of the text:

1. Существует всего лишь один вид каучука, получаемый в промышленных масштабах из природных источников.

2. Низкотемпературный каучук превосходит высокотемпературный по многим физическим свойствам.

3. Каучуки типа СКБ – более стойкие к стиранию и воздействию погодных условий по сравнению с натуральными каучуками.

4. Высокотемпературный каучук используется главным образом для производства механических изделий.

5. Для улучшения физических качеств бутадиен-стирольного каучука в него добавляют (газовую) сажу и некоторые другие наполнители усиливающего действия.

6. Полимеризация исходного или высокотемпературного каучука происходит при t 122º по Фаренгейту.

7. Низкотемпературный каучук уступает по качеству натуральному каучуку.

8. Все типы СКБ каучуков получают при эмульсионной полимеризации бутадиена и стирола в различной пропорции.

Text C

1. Pay attention to the following words and word combinations:

contributing factors – основополагающие факторы;

mixing process – процесс приготовления резиновой смеси;

mixed compound – смешанное соединение;

quality of raw materials – качество сырья;

consistency of products – консистенция (состав) продуктов;

carbon black – сажа;

end-user – конечный пользователь;

fillers – наполнители;

elimination – исчезновение;

feasible for smb. – возможный для кого-либо.

2. Read the text and be ready to say if the following sentences are true or false. Use the following phrases:

As far as I know …

It seems to be wrong (right) …

I cant’t agree with you …

I’m afraid you are mistaken …

On the contrary …

That’s right …

1. The major raw materials of the rubber industry are rubber, carbon black, different fillers, oils and various chemicals.

2. There hasn’t been a great change concerning high quality and consistency of products in the rubber industry during last decades.

3. The quality of raw materials doesn’t influence on the efficiency of the mixing process.

4. The degree of control of the mixing process is very important for the quality of the mixing compound.

5. Many rubber processors today have in place a supplier accreditation system, or audit.

6. The service of audit doesn’t lead to reduction of incoming raw material testing.

7. The automotive industry is one of the end-users of product made by rubber industry.

8. The processors of rubber industry have to establish the minimum requirements for suppliers.