Lesson 1　History of Natural Rubber

New Words

Notes

[1] Vulcanization heating an intimate mixture of rubber and sulfur to crosslink the rubber polymer network greatly improved rubber strength and elasticity and eliminated its deficiencies at temperature extemes. 硫化加热使橡胶和硫黄的均匀混合物交联形成橡胶聚合物网络，极大地改善了橡胶强度和弹性，并消除了橡胶在极端温度下的缺陷。

[2] Brazil became the primary source of rubber, but as rubber use grew questions arose as to this country’s ability to insure adequate supply from its wild rubber trees. 巴西成为橡胶的主要生产国，但随着橡胶用途的增加，这个国家没有能力保证橡胶的充足供应。

[3] Dunlop’s patenting of the pneumatic tire in England in 1888 ushered in the age of the bicycle as a prelude to the era of automobiles. 1888年，邓禄普在英格兰申请了充气轮胎专利，引领了自行车时代，成为汽车时代的前奏。

Exercises

1. Translate the following two paragraphs into Chinese.

Natural rubber can be defined as the coagulated, dried rubber prepared from latex extracted from the tree species Hevea brasiliensis. More than 200 species of plants produce natural rubbers but only one source, Hevea brasiliensis, is commercial today. Reasons for its preeminence are its high yield, longevity, and low resin content.

One natural rubber, guayule (银叶橡胶菊) from the tree species Parthenium argentatum, was of commercial importance early in this century. Despite promotion in World War Ⅱ as a substitute for natural rubber it has been unsuccessful commercially. Yields are not high and it does have high resin content. Its main attraction was that it could be grown in the Southwest region of the USA.

2. Put the following words and phrases into English.

弹性　　性能　　刚(韧)性　　柔性的　　混炼

成型　　硫化　　交联　　　　胶乳　　　防水的

What Exactly Does the Word “Rubber” Mean?

Rubber seems to be a fairly straightforward word. The word derives from a South American Indian word, meaning “weeping wood”. The dictionary definition of rubber is, a material that when stretched returns quickly to its “approximate original shape”. This definition fits the vulcanized material quite well. ASTM Standard D1566-98 has a detailed definition of rubber implying the vulcanized material. Unfortunately the rubber industry tends to be somewhat casual in the use of the term rubber. When a rubber product is made, the primary raw material is a polymer. This polymer often has some elasticity, but not always. It is then mixed with chemicals to make a rubber “compound” which is subsequently vulcanized. This compound is simply a physical mixture of chemicals and indeed a number of ingredients. The industry often calls both the polymer and the uncured compound, “rubber”. Unvulcanized silicone, for example, (both polymer and uncured compound) does not fit the dictionary definition too well, since it can have the consistency of butter. The word “rubber” used in the book for the primary raw polymer will be raw gum elastomer.

Some people use the term rubber, to mean NR only, but there have been instances when a customer asked for rubber (expecting the vendor to choose the right type, neoprene, natural, etc.), the vendor however assumed the customer was specifically asking for natural rubber, which in that case turned out to be the worst choice. Naturally, the vulcanized material is also called rubber, as indeed it should be. The word “elastomer” and “rubber” are often used by the industry to mean exactly the same thing, which is a waste of such an interesting word (elastomer), which maybe, could have been reserved exclusively to describe the raw polymer. ASTM Standard D1566-98 defines “elastomer” as “a term often used for rubber and polymers that have properties similar to those of rubber”．

Words and Expressions