Natural Rubber 、Synthetic Rubber and Reclaimed Rubber

Natural Rubber 、Synthetic Rubber and Reclaimed Rubber
Natural Rubber is a high molecular weight hydrocarbon which comes from the latex of many plants and is obtained by coagulation with chemicals, by drying, electrical coagulation and other processes. The most important producer is Hevea Brasiliensis. The wild rubber produced form latex contains, besides the hydrocarbon, small quantities of protein, carbohydrates, resin-like substances, mineral salts and fatty acids. These other constituents act in part as natural accelerators and anti-oxidants and give the product processing properties which do not exist in the pure hydrocarbon.
［Natural rubber is cis-1, 4-polyisoprene with the empirical formular (C5H8)n］and the structural formular.
CH3
︳
[—CH2—C＝CH—CH2—]
When vulcanized, rubber becomes highly extensible, shows fast recovery, and is highly elastic.
“Synthetic rubber” is the common term, in fact incorrect, for chemically different polymers with rubber-like properties. Since the term rubber applies to the original product, i.c. polyisoprene, the term synthetic rubber should strictly lerased only for synthetic “Natural Rubber”(cisl,4-polyisoprence). For polymers, with rubbery properties, which do not have an identical structure to natural rubber, the terms artificial rubber, chemical rubber or synthesized rubber have been suggested. In modern usago the term rubber no longer refers to a chemically defined product but relates so physical properties, all synthetic polymers with properties similar to those of natural rubber may therefore be classified as properties rubbers.
In general, it may be stated tht synthetic rubber do not have all qualities of natural rubbers, but their special properties have made them more suitable than natural rubber for certain applications and they have achieved a phenomenal technical importance.
Reclaimed rubber is obtained by treating scrap vulcanized rubber by one of several methods, so that it becomes plastic again and can be handled on a mill and incorporated in a rubber compound, together with crude rubber.
Reclaimed rubber contains all the ingredients of the original compound, except for the uncombined, or free sulfur. It was first used for economical resean that is to reduce the manufacturing cost. However, it was found that has also other advantages in addition to its lower cost. It fancilitates mastication and has very beneficial effect on calendaring and extruding. The quantity used varies to a great extent and some compounds are based exclusively on reclaimed rubber. However, reclaimed rubber affects some of the mechanical properties of the vulcanize ate unfavorably. Therefore, it is not used in case where high abrasion of tear resistance or tensile strength is required.
Now Words and Expressions
1.natural 天然的，自然的，简单的
2.synthetic 人工的，合成的
3.reclaim 收回，改正
4.molecular 分子的
5.hydrocarbon 烃，碳氢化合物
6.latex 胶乳
7.coagulation 凝固，凝结，凝聚
8.producer 生产者
9.Hevea Brasiliensis 巴西三叶橡胶树
10.wild 野生的
11.quantity 数量，数
12.protein 蛋白质
13.carbohydrate 碳水化合物
14.resin-like 类树脂的
15.substance 物质
16.mineral 矿物，矿质的
17.salt 盐
mineral salt 金属盐
18.fatty 脂肪的
fatty acid 脂肪酸
19.constituent 成分，组分
20.accelerator 促进剂
21.oxidant 氧化剂
anti-oxidant 防老剂，抗氧剂
22.process 方法，过程
23.exist 存在
24.pure 纯的，纯净的
25.cis-polyisoprene 顺式聚异戊二烯
26.empirical 经验主义的，以经验为根据的
27.formula 式，公式，配方
28.structural 结构上的
29.extensible 可伸长的
30.recovery 复原，复原性
31.in fact 事实上，实际上
32.incorrect 不正确的
33.polymer 聚合物
34.original 最初的，原来的
35.i.e. 那就是，即
36.strict 严格的
37.identical 同一的，完全相同的
38.artificial 人工的，人造的
39.synthesise 合成，综合
40.usage 使用，用法，惯例，习惯
41.refer 读到，提到
refer to 参考，查阅，指
42.define 解释，给……下定义
43.relate 叙述，讲，有关，涉及（to）
44 classify 分类，分级，把…分类
45.state 陈述
46.quality 质量
47.suitable 合适的
48.application 使用，应用
49.phenomenal 惊人的
50.scrape 刮，削，擦
51.mill 开炼机
52.incorporate 加入，综合的
53.compound 化合物，胶料
54.crude 天然的，未加工的
55.ingredient 配料，配合剂
56.uncombined 未化合，未结合
57.economical 经济的，节约的
58.manufacture 制造
59.cost 成本，花费
60.in addition 另外
61.facilitate 使容易，使便利，推进
62.mastication 塑炼
63.beneficial 有益的，有利的
64.calendar 压延机，压延
65.extrude 挤出，压出
66.extent 范围，广阔，程度
67.to be based on 以…为根据，根据
68.exclusive 孤高的，排外的，专有的，唯一
69.vulanizate 硫化胶
70.unfavorably 不利的，不顺利地
71.case 情况，事例
72.abrasion 摩擦，磨损
73.tear 撕裂
74.resistance 抗耐性，耐力
75.tensile 拉力的，抗张力的
76.strength 力，强度