材料专业英语-Lesson 5课件

1、 Lesson 4 Radical Combination Reaction自由基偶合反应 Lesson 4 Radical Combination ReactionThe rate of combination of simple radicalsSimple collision theoryThe rate of atom combinationDiatomic moleculeThe bond dissociation energyActivated speciesCollision Vibration and rotationLesson 5 Emulsion Polymerizati

2、on 乳液聚合An important feature of emulsion polymerization is the possibility to combine the properties of two or more monomers into one polymer. This process is called copolymerization and is usually carried out in two steps: first one monomer is polymerized to form a seed latex containing the first po

3、lymer and after that the seed latex is further polymerized with the other monomer(s) to make polymer chains with the desired properties.Emulsion Polymerization Advantages of emulsion polymerization include:Emulsion polymerization can produce high molecular weight polymers at high polymerization rate

4、s. By contrast, in bulk polymerization, there is a tradeoff between molecular weight and polymerization rate. tradeofftred,f n. 权衡A high conversion can be reached without the use of toxic and flammable solvents, the use of water provides a very good heat transfer and thus a good temperature control.

5、Since polymer molecules are contained within the particles, the viscosity of the reaction medium remains close to that of water and is not dependent on molecular weight.The molecular weight can be easily controlled by the use of chain transfer agents.The final product can be used as is and does not

6、generally need to be altered or processed. Disadvantages of emulsion polymerization include:Surfactants remain in the polymer or are difficult to remove.For dry (isolated) polymers, water removal is an energy-intensive(耗能的 ) processCan not be used for condensation, ionic or Ziegler-Natta polymerizat

7、ion, although some exceptions(例外) are known. surfactant sfkt()nt n. 表面活性剂 乳液聚合-单体在水中分散成乳液状态的聚合。 传统（或经典）乳液聚合体系的基本配方由单体、水、水溶性引发剂和水溶性乳化剂四组分构成。 Emulsion Polymerization 乳液聚合机理： 遵循自由基聚合规律，但存在独特的反应机理和成粒机理： 在水相中引发、胶束成核，在胶束或胶粒的隔离环境下增长，自由基寿命长，另一自由基进入胶粒后，才终止；兼具高速率和高聚合度。mechanism meknizm n. 机制；机理mechanistic mek

8、nistikadj. 机械论的；机理的element elimnt n. 元素；要素；元件；电池；电极；小单位； Most of condensation polymerization belong to step polymerization mechanism.condensation ,kndensein n. 缩合，凝聚大部分缩聚属于逐步聚合机理 1.not only but （also） ，also可以省略，“不但而且”，在句中常用来连接两个对等的成分，连接主语、谓语动词、宾语、宾语补足语、表语、状语、从句、句子等。Not only I but also Tom and Mary a

9、re fond of watching television.The Americans and the British not only speak the same language but also share a large number of social customs.英国人和美国人不但语言相同，而且有很多相同的风俗习惯。不仅我，而且汤姆和玛丽都喜欢看电视。The water absorbs much of the heat of polymerization and facilitates reaction control, and the product is obtaine

10、d in a relatively non-viscous and easily handled form, to be used as such or readily to be converted into solid polymer after coagulation, washing and drying.facilitate fsiliteit vt. 使容易 relatively reltivli adv. 相对地non-viscous 无粘性的 form f:m n. 形式，形状；表格readily redili adv. 容易地；无困难地 convert into 转变；把转化

11、成coagulation kugjulein n. 凝聚，凝固，凝结；凝结物 Viscous visks adj. 粘性的；黏的readily redili adv. 很快地；容易地；乐意地；无困难地 这些零件在五金商店容易买到。 (2)The humid（潮湿的） conditions that spread rust （病菌） most readily have recently been lacking in most places. 最有利于传播病菌的湿润条件最近在大部分地区都不具备。 (1) The components are readily available in hardwa

12、re stores(五金店).(2) Emulsion polymerization are open to great variation, from variation,vriein n. 变化 open to: 对开放；愿接受的 乳液聚合容易接受巨大的变化，从not open to visitors. 谢绝参观 open to suggestions. 广纳建议 ratio reiiu n. 比，比例 rate reitn. 率；比率; 速度；速率; (利息等的)费率（1）The ratio of domestic sewage（生活污水） to textile wastes（纺织废水）

13、 has no effect on the treatability（处理能力）.生活污水与纺织废水的比例对处理能力无影响。The higher levels approach the limit which can be achieved by direct polymerization and owing to the substantial amount of heat to be dissipated can often only be obtained by incremental addition of monomer.level levl n. 水平；标准 approach pr

14、ut vt. 接近；limit limit n. 限制;限度;vt. 限制； substantial sbstnl adj. 大量的； amount maunt n. 数量；总额 substantial amount of 大量 dissipate disipeit vt. 使消散 incremental ,inkrimentl adj. 增加的monomer mnm n. 单体；单体与水相比较高就会达到直接聚合允许的极限，由于反应放出大量的聚合热需要排散，所以此时往往只能用不断补加单体的办法来获得聚合物. (1)He will not do it for nothing.他不会无缘无故做这件

15、事。（他做这件事定有企图。） (2)None of us will leave school without learning any thing.我们毕业时定会学有所成。 frequently fri:kwntli adv. 频繁地，经常地；时常infrequently infri:kwntli adv. 很少发生地not infrequently (1)Be sure to find a substantial amount of information to draw you conclusions.务必要找到大量的资料去得出你的结论。(2) Curing agent mixed wit

16、h the monomer will induce polymerization.curingkjuri 固化固化剂与这种单体混合将引起聚合反应。monomeremulsifierimlsifai initiatorcomplex initiator systemauxiliary stabilizer :ziljri Chain transfer agent单体乳化剂引发剂辅助稳定剂链转移剂复合引发体系 Except in the case of diatomic molecules, the bond-dissociation energy is different from the bond energy, which is an average calculated from the sum of the bond-dissociation energies of all bonds in a molecule.For example, an HO-H bond of a water molecule (H-O-H) has 493.4 kJ/mol of bond-diss