高分子材料工程專業(yè)英語翻譯

1、高分子材料工程專業(yè)英語翻譯UNIT 1 What are Polymer 第一單元什么是高聚物What are polymers For one thing they are complex and giant molecules and are different from low molecular weight compounds like say common salt. To contrast the difference the molecular weight of common salt is only 58.5 while that of a polymer can be a

2、s high as several hundred thousand even more than thousand thousands. These big molecules ormacro-molecules are made up of much smaller molecules can be of one or more chemical compounds. To illustrate imagine that a set of rings has the same size and is made of the same material. When these things

3、are interlinked the chain formed can be considered as representing a polymer from molecules of the same compound. Alternatively individual rings could be of different sizes and materials and interlinked to represent a polymer from molecules of different compounds. 什么是高聚物首先他們是合成物和大分子而且不同于低分子化合物譬如說普通的

4、鹽。與低分子化合物不同的是普通鹽的分子量僅僅是58.5而高聚物的分子量高于105甚至大于106。這些大分子或“高分子”由許多小分子組成。小分子相互結合形成大分子大分子能夠是一種或多種化合物。舉例說明想象一組大小相同并由相同的材料制成的環(huán)。當這些環(huán)相互連接起來可以把形成的鏈看成是具有同種分子量化合物組成的高聚物。另一方面獨特的環(huán)可以大小不同、材料不同相連接后形成具有不同分子量化合物組成的聚合物。This interlinking of many units has given the polymer its name poly meaning many and mer meaning part

5、in Greek.As an example a gaseous compound called butadiene with a molecular weight of 54 combines nearly 4000 times and gives a polymer known as polybutadiene a synthetic rubber with about 200 000molecular weight. The low molecular weight compounds from which the polymers form are known as monomers.

6、 The picture is simply as follows: 許多單元相連接給予了聚合物一個名稱poly意味著“多、聚、重復”mer意味著“鏈節(jié)、基體”希臘語中。例如稱為丁二烯的氣態(tài)化合物分子量為54化合將近4000次得到分子量大約為200000被稱作聚丁二烯合成橡膠的高聚物。形成高聚物的低分子化合物稱為單體。下面簡單地描述一下形成過程butadiene butadiene 676767butadiene-polybutadiene 4 000 time 丁二烯丁二烯67丁二烯聚丁二烯4000次One can thus see how a substance monomer with

7、as small a molecule weight as 54 grow to become a giant molecule polymer of 54×4 000200 000 molecular weight. It is essentially the giantness of the size of the polymer molecule that makes its behavior different from that of a commonly known chemical compound such as benzene. Solid benzene for

8、instance melts to become liquid benzene at 5.5 and on further heating boils into gaseous benzene. As against this well-defined behavior of a simple chemical compound a polymer like polyethylene does not melt sharply at one particular temperature into clean liquid. Instead it becomes increasingly sof

9、ter and ultimately turns into a very viscous tacky molten mass. Further heating of this hot viscousmolten polymer does convert it into various gases but it is no longer polyethylene. Fig. 1.1 . 因而能夠看到分子量僅為54的小分子物質單體如何逐漸形成分子量為200000的大分子高聚物。實質上正是由于聚合物的巨大的分子尺寸才使其性能不同于象苯這樣的一般化合物。例如固態(tài)苯在5.5熔融成液態(tài)苯進一步加熱煮沸成氣

10、態(tài)苯。與這類簡單化合物明確的行為相比像聚乙烯這樣的聚合物不能在某一特定的溫度快速地熔融成純凈的液體。而聚合物變得越來越軟最終變成十分粘稠的聚合物熔融體。將這種熱而粘稠的聚合物熔融體進一步加熱不會轉變成各種氣體但它不再是聚乙烯如圖1.1。固態(tài)苯液態(tài)苯氣態(tài)苯加熱5.5加熱80固體聚乙烯熔化的聚乙烯各種分解產(chǎn)物-但不是聚乙烯加熱加熱圖1.1 低分子量化合物苯和聚合物聚乙烯受熱后的不同行為Another striking difference with respect to the behavior of a polymer and that of a low molecular weight com

11、pound concerns the dissolution process. Let us take for example sodium chloride and add it slowly to s fixed quantity of water. The salt which represents a low molecular weight compound dissolves in water up to s point called saturation point but thereafter any further quantity added does not go int

12、o solution but settles at the bottom and just remains there as solid. The viscosity of the saturated salt solution is not very much different from that of water. But if we take a polymer instead say polyvinyl alcohol and add it to a fixed quantity of water the polymer does not go into solution immed

13、iately. The globules of polyvinylalcohol first absorb water swell and get distorted in shape and after a long time go into solution. Also we can add a very large quantity of the polymer to the same quantity of water without the saturation point ever being reached. As more and more quantity of polyme

14、r is added to water the time taken for the dissolution of the polymer obviously increases and the mix ultimately assumes a soft dough-like consistency. Another peculiarity is that in water polyvinyl alcohol never retains its original powdery nature as the excess sodium chloride does in a saturated s

15、alt solution. In conclusion we can say that 1 the long time taken by polyvinyl alcohol for dissolution 2 the absence of a saturation point and 3 the increase in the viscosity are all characteristics of a typical polymer being dissolved in a solvent and these characteristics are attributed mainly to

16、the large molecular size of the polymer. The behavior of a low molecular weight compound and that of a polymer on dissolution are illustrated in Fig.1.2. 發(fā)現(xiàn)另一種不同的聚合物行為和低分子量化合物行為是關于溶解過程。例如讓我們研究一下將氯化鈉慢慢地添加到固定量的水中。鹽代表一種低分子量化合物在水中達到點叫飽和點溶解但此后進一步添加鹽不進入溶液中卻沉到底部而保持原有的固體狀態(tài)。飽和鹽溶液的粘度與水的粘度不是十分不同但是如果我們用聚合物替代譬如說

17、將聚乙烯醇添加到固定量的水中聚合物不是馬上進入到溶液中。聚乙烯醇顆粒首先吸水溶脹發(fā)生形變經(jīng)過很長的時間以后進入到溶液中。同樣地我們可以將大量的聚合物加入到同樣量的水中不存在飽和點。將越來越多的聚合物加入水中認為聚合物溶解的時間明顯地增加最終呈現(xiàn)柔軟像面團一樣粘稠的混合物。另一個特點是在水中聚乙烯醇不會像過量的氯化鈉在飽和鹽溶液中那樣能保持其初始的粉末狀態(tài)?？傊覀兛梢灾v1聚乙烯醇的溶解需要很長時間2不存在飽和點3粘度的增加是典型聚合物溶于溶液中的特性這些特性主要歸因于聚合物大分子的尺寸。如圖1.2說明了低分子量化合物和聚合物的溶解行為。氯化鈉的溶解氯化鈉晶體加入到水中晶體進入到溶液中.溶液的粘

18、度不是十分不同于水的粘度形成飽和溶液.剩余的晶體維持不溶解狀態(tài). 聚合物的溶解聚乙烯醇碎片加入到水中碎片開始溶脹碎片慢慢地進入到溶液中形成粘稠的聚合物溶液.溶液粘度十分高于水的粘度圖1.2 低分子量化合物氯化鈉和聚合物聚乙烯醇不同的溶解行為第一單元閱讀材料很多情況下聚合物鏈都是線性的在求聚合度與伸展鏈長世我們設想鏈僅有兩個端點。盡管線性聚合物很重要但它們不是唯一類型可能的分子。支鏈和交聯(lián)的分子也是十分重要的。當我們說到支鏈聚合物時我們是說它存在多余的聚合鏈。這些鏈是從線性分子的主鏈上發(fā)散出來的。在重復單元上類似甲基與苯基的成分不被考慮成支鏈。一般支鏈被引入一個分子是通過有目的的加入一些能夠成為

19、支鏈的單體。讓我們想象聚酯的形成。雙官能團酸與醇的存在使聚合物鏈增長。這些雙官能團分子在它們的末端形成酯基合并成鏈。另一方面三官能團的酸與醇生成線性分子時通過反應它們的兩個官能團。如果第三個也參與反應并且所得到的鏈繼續(xù)增長一支鏈就被引入最先的鏈中。有時支鏈的生成是由于一個原子脫離原先線性分子使其有活性而伴隨鏈的增長這種偶然發(fā)現(xiàn)支鏈的分子一般還是叫線性分子的盡管重要支鏈的存在對聚合物性質有影響大多有顯著地結晶趨向。引入聚合物支鏈的數(shù)量是另外一個必須被詳細說明的不同點。以便充分描述分子的特征。當僅僅只有微量的分支存在結合點的濃度時非常低的以至于它們僅和鏈末端的數(shù)量有關。例如兩個單獨的線性分子一共含

20、有四個末端。如果其中一個分子的末端與另外一個分子的中間端形成一個“T”所得的分子有三個末端。很容易就可以總結出這種結果。如果一個分子有x個支鏈則它有x2個末端.如果分支相對很少的時候。支鏈分子有時被稱為梳型或星形的。梳型的是指支鏈是沿著一個主鏈散發(fā)出來的星形的是指所有分支是從一個結點散發(fā)出來的。如果結點的濃度相當高甚至支鏈上還有支鏈。最終到達一個點就是支鏈的數(shù)量是如此的多以至于聚合物分子變成為一個巨大的三維網(wǎng)狀結構。當?shù)竭_這種狀態(tài)分子就為所謂的交聯(lián)分子。這種情形整個宏觀的物體可認為僅需一種分子組成。組合成這個單體的力量是共價鍵而不是分子間作用力?？傊宦?lián)體的力學性能與其他沒有交聯(lián)結構的有很大的

21、不同。正如聚合物鏈不必是線性的一樣所有的重復單元也不一定要相同的。我們已經(jīng)提到像蛋白質那樣的分子他們都有很多不同的重復單元。合成的聚合物中那些僅僅只有一種重復單元的叫做均聚物那些含有多于一種重復單元的叫共聚物。注意這些定義是基于重復單元而不是單體。一個普通的聚酯并不是共聚物盡管他有酸與醇這兩種不同的單體。與此相比當不同的單體通過上述方法組合起來產(chǎn)生一條每個單體在聚合物中都保持各自的特性這樣共聚物就產(chǎn)生了。未經(jīng)修整的共聚物一般是那些只有兩個不同的重復單元。當發(fā)現(xiàn)三種重復單元的時候這種體系叫做三元共聚物當發(fā)現(xiàn)三種以上則叫做多元共聚物。當我們承認有一種重復單元的可能性時我們需要其他的不同點來描述聚合

22、物。首先我們要知道要多少類重復單元存在并且它們是什么。這就是相當于知道它們溶解后的存在成分。盡管有相似的末端在那因為聚合物的重復單元是結合在一起的并不是僅僅的混合。要定量的描述一個共聚物不同類的重復單元的相對數(shù)量必須詳細說明。因此共聚物的經(jīng)驗公式可以寫成這里是指分別的重復單元是指其重要單元的相對數(shù)量。從所知的聚合物分子量可以估計一個共聚物每一個單元的聚合度叫做當前后者的不明智性是顯而易見的。UNIT 2 Chain Polymerization 第二單元鏈式聚合反應Many olefinic and vinyl unsaturated compounds are able to form ch

23、ain-0like macromolecules through elimination of the double bond a phenomenon first recognized by Staudinger. Diolefins polymerize in the same manner however only one of the two double bonds is eliminated. Such reactions occur through the initial addition of a monomer molecule to an initiator radical

24、 or an initiator ion by which the active state is transferred from the initiator to the added monomer. In the same way by means of a chain reaction one monomer molecule after the other is added 200020000 monomers per second until the active state is terminated through a different type of reaction. T

25、he polymerization is a chain reaction in two ways: because ofthe reaction kinetic and because as a reaction product one obtains a chain molecule. The length of the chain molecule is proportional to the kinetic chain length. Staudinger第一個發(fā)現(xiàn)一例現(xiàn)象許多烯烴和不飽和烯烴通過打開雙鍵可以形成鏈式大分子。二烯烴以同樣的方式聚合然而僅限于兩個雙鍵中的一個。這類反應是通

26、過單體分子首先加成到引發(fā)劑自由基或引發(fā)劑離子上而進行的靠這些反應活性中心由引發(fā)劑轉移到被加成的單體上。以同樣的方式借助于鏈式反應單體分子一個接一個地被加成每秒200020000個單體直到活性中心通過不同的反應類型而終止。聚合反應是鏈式反應的原因有兩種因為反應動力學和因為作為反應產(chǎn)物它是一種鏈式分子。鏈分子的長度與動力學鏈長成正比。One can summarize the process as follow R. is equal to the initiator radical: 鏈式反應可以概括為以下過程R·相當與引發(fā)劑自由基略One thus obtains polyvinyl

27、chloride from vinylchloride or polystyrene from styrene or polyethylene from ethylene etc. 因而通過上述過程由氯乙烯得到聚氯乙烯或由苯乙烯獲得聚苯乙烯或乙烯獲得聚乙烯等等。The length of the chain molecules measured by means of the degree of polymerization can be varied over a large range through selection of suitable reaction conditions. U

28、sually with commercially prepared and utilized polymers the degree of polymerization lies in the range of 1000to 5000 but in many cases it can be below 500 and over 10000. This should not be interpreted to mean that all molecules of a certain polymeric material consist of 500 or 1000 or 5000 monomer

29、 units. Inalmost all cases the polymeric material consists of a mixture of polymer molecules of different degrees of polymerization. 借助于聚合度估算的分子鏈長在一個大范圍內可以通過選擇適宜的反應條件被改變。通常通過大量地制備和利用聚合物聚合度在10005000范圍內但在許多情況下可低于500、高于10000。這不應該把所有聚合物材料的分子量理解為由500或1000或5000個單體單元組成。在幾乎所有的事例中聚合物材料由不同聚合度的聚合物分子的混合物組成。Poly

30、merization a chain reaction occurs according to the same mechanism as the well-known chlorine-hydrogen reaction and the decomposition of phosegene. 聚合反應鏈式反應依照與眾所周知的氯氣-氫氣反應和光氣的分解機理進行。The initiation reaction which is the activation process of the double bond can be brought about by heating irradiation

31、 ultrasonics or initiators. The initiation of the chain reaction can be observed most clearly with radical or ionic initiators. These areenergy-rich compounds which can add suitable unsaturated compounds monomers and maintain the activated radical or ionic state so that further monomer molecules can

32、 be added in the same manner. For the individual steps of the growth reaction one needs only a relatively small activation energy and therefore through a single activation step the actual initiation reaction a large number of olefin molecules are converted as is implied by the term “chain reaction”.

33、 Because very small amounts of the initiator bring about the formation of a large amount of polymeric material 1:1000to 1:1000 it is possible to regard polymerization from a superficial point of view as a catalytic reaction. For this reason the initiators used in polymerization reactions are often d

34、esignated as polymerization catalysts even though in the strictest sense they are not true catalysts because the polymerization initiator enters into the reaction as a real partner and can be found chemically bound in the reaction product i.e. the polymer In addition to the ionic and radical initiat

35、ors there are now metal complex initiators which can be obtained for example by the reaction of titanium tetrachloride or titanium trichloride with aluminum alkyls which play an important role in polymerization reactions Ziegler catalysts The mechanism of their catalytic action is not yet completely

36、 clear. 雙鍵活化過程的引發(fā)劑反應可以通過熱、輻射、超聲波或引發(fā)劑產(chǎn)生。用自由基型或離子型引發(fā)劑引發(fā)鏈式反應可以很清楚地進行觀察。這些是高能態(tài)的化合物它們能夠加成不飽和化合物單體并保持自由基或離子活性中心以致單體可以以同樣的方式進一步加成。對于增長反應的各個步驟每一步僅需要相當少的活化能因此通過一步簡單的活化反應即引發(fā)反應即可將許多烯類單體分子轉化成聚合物這正如連鎖反應這個術語的內涵那樣。因為少量的引發(fā)劑引發(fā)形成大量的聚合物原料11000110000從表面上看聚合反應很可能是催化反應。由于這個原因通常把聚合反應的引發(fā)劑看作是聚合反應的引發(fā)劑但是嚴格地講它們不是真正意義上的催化劑因為聚合反應的催化劑進入到反應內部而成為一部分同時可以在反應產(chǎn)物既聚合物的末端發(fā)現(xiàn)。此外離子引發(fā)劑和自由基引發(fā)劑有的是金屬