Mechanical plasticization ,Plasticization (2)

Plasticization (2)
Mechanical plasticization can also be performed in an interal mixer. An internal mixer consists of two horizontal rotors with nogs or protrusions, encased by a jacket. The Bride ‘Banbury mixer’ has a friction ratio between the rotors, and the work is carried out between the rotors and the jacket. In the Francis Shaw ‘intermix’, however, the rotors run at even speed, and the nogs are designed to produce a friction ratio between the rotors. The work in this machine is done between the rotors, rather than between rotors and jacket. Internal mixer is fitted with a pneumatically operated ram to ensure that the rubbers and the rotors are in contact.
This is a very powerful machine which plasticize at a high speed (40 r.p.m.) and high temperature (270-320 oF). The operation can be completed in a few minutes. The capacity of a large internal mixer is about 500 pounds of rubber, which is much higher than that of a two roll mill. The plasticized rubber is discharged at the bottom of the machine through a drop door which opens automatically when the operation is completed.
Heat Plasticization
It is effected in an oven for about 24 hours at 300-400oF in the presence of air at atmosphere. The process may be made continuous by modifying the oven to the form of chutes or tunnels whose output may amount to several tons an hour.
Chemical Plasticization
This term is used to cover the softening of rubber by peptizing agent. It can be carried out both on mixing mills and internal mixers. The peptizing or softening effect takes place only at temperature about 175 oF. It is more rapid and economical than mechanical plasticizing under certain conditions.




New Words and Expressions
1. perform 完成，进行，表现
2. rotor 转子（一般指空炼机）
3. nog （密炼机转子）凸棱
4. protrusion 凸棱
5. encase 装在…内
6. jacket 短上衣，护封，夹套
7. friction 摩擦，摩擦力
8. rather than 而不是……
9. fit 装配，使适合
10. pneumatically 靠压缩空气，气动，风动
11. ram 上顶栓（密炼机），柱塞
a pneumatically operated ram 气动的上顶栓
12. ensure 确保
13. contact 接触，联系 使联系
14. powerful 强力的
15. capacity 能力，本领，容量
16. discharge 排料，卸料
17. a drop door 卸料门
18. automatically 自动地
19. oven 烘箱
20. atmosphere 大气，大气压
atmosphere pressure 大气压
21. continuous 连续的
22. chute 斜道
23. tunnel 隧道，地道，坑道
24. amount 量，数量，合计，总数
合计，等于
amount to 总共达，等于
25. peptize 塑解
peptizing agent 塑解剂
26. rapid 迅速