高分子材料工程专业英语翻译教学文稿.doc
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1、高分子材料工程专业英语翻译精品文档Unit 1 What are polymers?What are polymers? For one thing, they are complex and giant molecules and are different from low molecular weight compounds like, say, common salt.什么是高聚物?首先,他们是合成物和大分子,而且不同于低分子化合物,譬如说普通的盐。To contrast the difference, the molecular weight of common salt is on
2、ly 58.5, while that of a polymer can be as high as several hundred thousand, even more than thousand thousands.与低分子化合物不同的是,普通盐的分子量仅仅是58.5,而高聚物的分子量高于105,甚至大于106。These big molecules or macro-molecules are made up of much smaller molecules, can be of one or more chemical compounds.这些大分子或“高分子”由许多小分子组成。小
3、分子相互结合形成大分子,大分子能够是一种或多种化合物。To illustrate, imagine that a set of rings has the same size and is made of the same material. When these things are interlinked, the chain formed can be considered as representing a polymer from molecules of the same compound.举例说明,想象一组大小相同并由相同的材料制成的环。当这些环相互连接起来,可以把形成的链看成是
4、具有同种化合物组成的高聚物。Alternatively, individual rings could be of different sizes and materials, and interlinked to represent a polymer from molecules of different compounds.另一方面,环可以大小不同、材料不同, 相连接后形成具有不同化合物组成的聚合物。This interlinking of many units has given the polymer its name, poly meaning many and mer meani
5、ng part (in Greek).聚合物的名称来自于许多单元相连接,poly意味着“多、聚、重复”,mer意味着“链节、基体”(希腊语中)。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.例如:气态化合物丁二烯的分子量为54,
6、连接4000次可得到分子量大约为200000的聚丁二烯(合成橡胶)高聚物。The low molecular weight compounds from which the polymers form are known as monomers. The picture is simply as follows:形成高聚物的低分子化合物称为单体。下面简单地描述一下形成过程:butadiene + butadiene + + butadiene-polybutadiene(4 000 time)丁二烯 丁二烯丁二烯聚丁二烯(4000次)One can thus see how a substan
7、ce (monomer) with as small a molecule weight as 54 grow to become a giant molecule (polymer) of (544 000)200 000 molecular weight.能够知道分子量仅为54的小分子物质(单体)如何逐渐形成分子量为200000的大分子(高聚物)。It is essentially the “giantness” of the size of the polymer molecule that makes its behavior (different from that of a com
8、monly known chemical compound such as benzene.) 实质上正是由于聚合物的巨大分子尺寸才使其性能不同于像苯这样的一般化合物(的性能)Solid benzene, for instance, melts to become liquid benzene at 5.5 and , on further heating, boils into gaseous benzene.例如固态苯在5.5熔融成液态苯,进一步加热,煮沸成气态苯。As against this well-defined behavior of a simple chemical comp
9、ound, a polymer like polyethylene does not melt sharply at one particular temperature into clean liquid.与这类简单化合物明确的行为相比,像聚乙烯这样的聚合物不能在某一特定的温度快速地熔融成纯净的液体。Instead, it becomes increasingly softer and, ultimately, turns into a very viscous, tacky molten mass. Further heating of this hot, viscous, molten
10、polymer does convert it into various gases but it is no longer polyethylene. (Fig. 1.1) .而聚合物变得越来越软,最终变成十分粘稠的聚合物熔融体。将这种热而粘稠的聚合物熔融体进一步加热,它会转变成不同气体,但它不再是聚乙烯(如图1.1)Another striking difference with respect to the behavior of a polymer and that of a low molecular weight compound concerns the dissolution
11、process.聚合物行为和低分子量化合物另一不同的行为为溶解过程。 Let us take, for example, sodium chloride and add it slowly to fixed quantity of water. The salt, which represents a low molecular weight compound, dissolves in water up to a point (called saturation point) but, thereafter, any further quantity added does not go in
12、to solution but settles at the bottom and just remains there as solid.例如,将氯化钠慢慢地添加到定量的水中。盐作为一种低分子量化合物,在水中溶解直到某一点(叫饱和点),但进一步添加, 盐不进入溶液中却沉到底部而保持原有的固体状态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, a
13、nd add it to a fixed quantity of water, the polymer does not go into solution immediately.饱和盐溶液的粘度与水的粘度接近.但是,如果我们用聚合物,如聚乙烯醇添加到定量水中,聚合物不是马上进入到溶液中。 The globules of polyvinyl alcohol first absorb water, swell and get distorted in shape and after a long time go into solution. 聚乙烯醇颗粒首先吸水溶胀,发生变形,经过很长时间后,(
14、聚乙烯醇分子)进入到溶液中。Also, we can add a very large quantity of the polymer to the same quantity of water without the saturation point ever being reached.同样地,我们可以将大量的聚合物加入到同样量的水中,不存在饱和点。As more and more quantity of polymer is added to water, the time taken for the dissolution of the polymer obviously increa
15、ses and the mix ultimately assumes a soft, dough-like consistency.将越来越多的聚合物加入水中,认为聚合物溶解的时间明显地增加,最终呈现柔软像面团一样粘稠的混合物。Another peculiarity is that, in water, polyvinyl alcohol never retains its original powdery nature as the excess sodium chloride does in a saturated salt solution. 另一个特点是,在水中聚乙烯醇不会像过量的氯化
16、钠在饱和盐溶液中那样能保持其初始的粉末状态。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 attr
17、ibuted mainly to the large molecular size of the polymer.总之,我们可以讲(1)聚乙烯醇的溶解需要很长时间,(2)不存在饱和点,(3)粘度的增加是聚合物溶于溶液中的典型特性,这些特性主要归因于聚合物大分子的尺寸。The behavior of a low molecular weight compound and that of a polymer on dissolution are illustrated in Fig.1.2. Unit 2 Chain PolymerizationMany olefinic and vinyl un
18、saturated compounds are able to form chain-like 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.Staudinger首先发现许多烯烃和不饱和烯烃通过打开双键可以形成链式大分子。二烯烃以同样的方式聚合,但仅消
19、除两个双键中的一个。 Such reactions occur through the initial addition of a monomer molecule to an initiator radical or an initiator ion, by which the active state is transferred from the initiator to the added monomer.这类反应是通过单体分子首先加成到引发剂自由基或引发剂离子上而进行的,靠这些反应活性中心由引发剂转移到被加成的单体上。In the same way by means of a cha
20、in 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.单体分子通过链式反应以同样的方式一个接一个地加上(每秒200020000个单体)直到活性中心通过不同的反应方式终止。The polymerization is a chain reaction in two ways: because of the reaction k
21、inetic and because as a reaction product one obtains a chain molecule. The length of the chain molecule is proportional to the kinetic chain length.聚合反应成为链式反应的两种原因:反应动力学和作为链式反应产物分子。链分子的长度与动力学链长成正比。One can summarize the process as follow (R. is equal to the initiator radical):链式反应可以概括为以下过程(R相当与引发剂自由基
22、):略One thus obtains polyvinylchloride from vinylchloride, or polystyrene from styrene, or polyethylene from ethylene, etc.因而通过上述过程由氯乙烯得到聚氯乙烯,或由苯乙烯获得聚苯乙烯,或乙烯获得聚乙烯,等等。The length of the chain molecules, measured by means of the degree of polymerization, can be varied over a large range through selectio
23、n of suitable reaction conditions.分子链长通过聚合度测量,可以通过选择适宜的反应条件大为改变Usually, with commercially prepared and utilized polymers, the degree of polymerization lies in the range of 1000 to 5000, but in many cases it can be below 500 and over 10000.商业制备和使用的聚合物,聚合度通常在10005000范围内,但在许多情况下可低于500或高于10000。This shou
24、ld not be interpreted to mean that all molecules of a certain polymeric material consist of 500, or 1000, or 5000 monomer units. In almost all cases, the polymeric material consists of a mixture of polymer molecules of different degrees of polymerization.这不应该把聚合物材料所有的分子理解为由500,或1000,或5000个单体单元组成。在几乎
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