Plasticizers or Softeners

Plasticizers or Softeners
Any material that can be added to rubber to either aid mixing, promote greater elasticity, produce tack, or extend (or replace) a portion of the rubber hydrocarbon (without a loss in physical properties), can be classified as a softener.
Making rubber plastic is an expensive operation that can be facililated by the use of plasticizers or softeners. Many substances, such as vegetable and mineral oils, waxes, paraffins, pitch, tar and resins have been used for this purpose. The principle plasticizers are the fatty acid, expecially stearic acid, pine tar, and the so-called mineral rubbers, which are natural asphalts.
The most important effects of plasticizers or softeners are as follows:
They reduce the cost of mechanical treatment necessary for plasticizing the rubber.
They facilitate the addition and uniform distribution of fillers.
They allow mastication performed at lower temperature, thus avoiding scorching of the compounded rubber.
They make highly filled rubber compounds sufficiently soft for moulding.
They increase the adhesiveness of the compound and give tackiness when this is desirable.
In the use of plasticizers of softeners, many factors should be considered so that the desired degree of plasticity and adhesiveness can be achieved, and sticking of the compound to rolls and its excess ive softening at elevated temperature can be avoided.
Also, too much plasticizer has a harmful effect on the mechanical and aging properties of the finished product. Therefore, plasticization is not a simple problem. Sometime several plasticizers are combined to obtain satisfactory results.
Softrners are used in relatively small quantities, 0.5 to 5.0 percent on the rubber, except in some very special cases where the mechanical properties are sacrificed in order to obtain other advantages.
In addition to the before mentioned types of softeners, new varieties have been developed form petroleum. They are found, in general, in the aromatic fractions obtained from refining highgrade lubricating oil by selective solvent methods, or by vacuum distillation. These softeners may be used in larger quantities without causing excessive reducing in the mechanical properties.
New Words and Expressions
1. plasticizer 增塑剂
2. softener 软化剂
3. promote 提升，增进，晋级
4. elasticity 弹性
5. tack 自粘
6. extend 充填，增充，延伸，扩大
7. portion 部分，一份
8. operation 操作，作业
9. expensive 昂贵的，高价的
10. paraffins 石蜡
11. pitch 沥青（石油），螺距，节距
12. tar 柏油
13. resin 树脂
14. principal 主要的
15. pine 原则，校长
pine tar 松树
16. mineral 松焦油
17. asphalt 矿质橡胶
18. plasticize 沥青（煤焦油）
19. uniform 增塑，塑炼
20. distribution 均匀的
21. perform 分布，分配
22. scorch 完成
23. sufficiently 焦烧
24. adhesiveness 足够地
25. tackiness 粘合性
26. factor 因素
27. degree 度，程度
28. stick 粘着
stick to 粘着，坚持，忠于
29. roll 辊筒
30. excessive 过量的，过渡的
31. elevate 上升
elevated 高尚的，高架的，高的
32. relatively 相对地
33. sacrifice 牺牲，损失，亏本
34. addition 附加物，增加，加法（数学）
in addition 又
in addition to 除……之外，加之
35. mention 提到，注意
before mentioned 前述的
36. variety 变化，种种，多样
37. petroleum 石油
petro 汽油（英）
gasoline, gasoline 汽油（美）
38. aromatic 芳香的
39. fraction 馏分，级分
40. refine 提炼，炼制
41. grade 级
42. lubricate 使润滑
lubricating oil 润滑油
43. selective 选择的
44. solvent 溶剂，溶解（的）
45. vacuum 真空
真空的
46. distillation 蒸馏
47. facilitate 使容易，使得到