高分子材料工程专业英语翻译.doc

高分子材料工程专业英语翻译UNIT 1 What are Polymer 第一单元 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 as high as several hundred thousand even more than thousand thousands. These big molecules or macro-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 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。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。这些大分子或“高分子”由许多小分子组成。小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。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具有同种分子量化合物组成的高聚物。另一方面独特的环可以大小不同、材料不同相连接后形成具有不同分子量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 meaning part 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. The picture is simply as follows: 许多单元相连接给予了聚合物一个名称poly意味着“多、聚、重复”mer意味着“链节、基体”希腊语中。例如称为丁二烯的气态化合物分子量为54化合将近4000次得到分子量大约为200000被称作聚丁二烯合成橡胶的高聚物。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 676767 butadiene-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 as small a molecule weight as 54 grow to become a giant molecule polymer of 544 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 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 softer and ultimately turns into a very viscous tacky molten mass. Further heating of this hot viscous molten polymer does convert it into various gases but it is no longer polyethylene. Fig. 1.1 . 因而能够看到分子量仅为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。实质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这样的一般化合物。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。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。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不会转变成各种气体但它不再是聚乙烯如图1.1。 固态苯液态苯气态苯 加热5.5 加热80 固体聚乙烯熔化的聚乙烯各种分解产物-但不是聚乙烯 加热 加热 图1.1 低分子量化合物苯和聚合物聚乙烯受热后的不同行为 Another striking difference with respect to the behavior of a polymer and that of a low molecular weight compound 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 into 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 immediately. The globules of polyvinyl alcohol 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 polymer 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 salt 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 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. 发现另一种不同的聚合物行为和低分子量化合物行为是关于溶解过程。例如让我们研究一下将氯化钠慢慢地添加到固定量的水中。盐代表一种低分子量化合物在水中达到点叫饱和点溶解但此后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。饱和盐溶液的粘度与水的粘度不是十分不同但是如果我们用聚合物替代譬如说将聚乙烯醇添加到固定量的水中聚合物不是马上进入到溶液中。聚乙烯醇颗粒首先吸水溶胀发生形变经过很长的时间以后进入到溶液中。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。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。另一个特点是在水中聚乙烯醇不会像过量的氯化钠在饱和盐溶液中那样能保持其初始的粉末状态。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粘度的增加是典型聚合物溶于溶液中的特性这些特性主要归因于聚合物大分子的尺寸。如图1.2说明了低分子量化合物和聚合物的溶解行为。 氯化钠的溶解 氯化钠晶体加入到水中晶体进入到溶液中.溶液的粘度不是十分不同于水的粘度形成饱和溶液.剩余的晶体维持不溶解状态. 聚合物的溶解 聚乙烯醇碎片加入到水中碎片开始溶胀碎片慢慢地进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 图1.2 低分子量化合物氯化钠和聚合物聚乙烯醇不同的溶解行为 第一单元阅读材料 很多情况下聚合物链都是线性的在求聚合度与伸展链长世我们设想链仅有两个端点。尽管线性聚合物很重要但它们不是唯一类型可能的分子。支链和交联的分子也是十分重要的。当我们说到支链聚合物时我们是说它存在多余的聚合链。这些链是从线性分子的主链上发散出来的。在重复单元上类似甲基与苯基的成分不被考虑成支链。一般支链被引入一个分子是通过有目的的加入一些能够成为支链的单体。让我们想象聚酯的形成。双官能团酸与醇的存在使聚合物链增长。这些双官能团分子在它们的末端形成酯基合并成链。另一方面三官能团的酸与醇生成线性分子时通过反应它们的两个官能团。如果第三个也参与反应并且所得到的链继续增长一支链就被引入最先的链中。有时支链的生成是由于一个原子脱离原先线性分子使其有活性而伴随链的增长这种偶然发现支链的分子一般还是叫线性分子的尽管重要支链的存在对聚合物性质有影响大多有显著地结晶趋向。 引入聚合物支链的数量是另外一个必须被详细说明的不同点。以便充分描述分子的特征。当仅仅只有微量的分支存在结合点的浓度时非常低的以至于它们仅和链末端的数量有关。例如两个单独的线性分子一共含有四个末端。如果其中一个分子的末端与另外一个分子的中间端形成一个“T”所得的分子有三个末端。很容易就可以总结出这种结果。如果一个分子有x个支链则它有x2个末端.如果分支相对很少的时候。支链分子有时被称为梳型或星形的。梳型的是指支链是沿着一个主链散发出来的星形的是指所有分支是从一个结点散发出来的。 如果结点的浓度相当高甚至支链上还有支链。最终到达一个点就是支链的数量是如此的多以至于聚合物分子变成为一个巨大的三维网状结构。当到达这种状态分子就为所谓的交联分子。这种情形整个宏观的物体可认为仅需一种分子组成。组合成这个单体的力量是共价键而不是分子间作用力。总之交联体的力学性能与其他没有交联结构的有很大的不同。 正如聚合物链不必是线性的一样所有的重复单元也不一定要相同的。我们已经提到像蛋白质那样的分子他们都有很多不同的重复单元。合成的聚合物中那些仅仅只有一种重复单元的叫做均聚物那些含有多于一种重复单元的叫共聚物。注意这些定义是基于重复单元而不是单体。一个普通的聚酯并不是共聚物尽管他有酸与醇这两种不同的单体。与此相比当不同的单体通过上述方法组合起来产生一条每个单体在聚合物中都保持各自的特性这样共聚物就产生了。未经修整的共聚物一般是那些只有两个不同的重复单元。当发现三种重复单元的时候这种体系叫做三元共聚物当发现三种以上则叫做多元共聚物。 当我们承认有一种重复单元的可能性时我们需要其他的不同点来描述聚合物。首先我们要知道要多少类重复单元存在并且它们是什么。这就是相当于知道它们溶解后的存在成分。尽管有相似的末端在那因为聚合物的重复单元是结合在一起的并不是仅仅的混合。要定量的描述一个共聚物不同类的重复单元的相对数量必须详细说明。因此共聚物的经验公式可以写成 这里 是指分别的重复单元 是指其重要单元的相对数量。从所知的聚合物分子量 可以估计一个共聚物每一个单元的聚合度叫做 当前后者的不明智性是显而易见的。 UNIT 2 Chain Polymerization 第二单元 链式聚合反应 Many olefinic and vinyl unsaturated compounds are able to form chain-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 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. The polymerization is a chain reaction in two ways: because of the 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第一个发现一例现象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然而仅限于两个双键中的一个。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。以同样的方式借助于链式反应单体分子一个接一个地被加成每秒200020000个单体直到活性中心通过不同的反应类型而终止。聚合反应是链式反应的原因有两种因为反应动力学和因为作为反应产物它是一种链式分子。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 selection of suitable reaction conditions. 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. This should 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. 借助于聚合度估算的分子链长在一个大范围内可以通过选择适宜的反应条件被改变。通常通过大量地制备和利用聚合物聚合度在10005000范围内但在许多情况下可低于500、高于10000。这不应该把所有聚合物材料的分子量理解为由500或1000或5000个单体单元组成。在几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组成。 Polymerization a chain reaction occurs according to the same mechanism as the well-known chlorine-hydrogen reaction and the decomposition of phosegene. 聚合反应链式反应依照与众所周知的氯气-氢气反应和光气的分解机理进行。 The initiation reaction which is the activation process of the double bond can be brought about by heating irradiation ultrasonics or initiators. The initiation of the chain reaction can be observed most clearly with radical or ionic initiators. These are energy-rich compounds which can add suitable unsaturated compounds monomers and maintain the activated radical or ionic state so that further monomer molecules can 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”. Because very small amounts of the initiator bring about the formation of a large amount of polymeric material 1:1000 to 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 designated 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 initiators 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 clear. 双键活化过程的引发剂反应可以通过热、辐射、超声波或引发剂产生。用自由基型或离子型引发剂引发链式反应可以很清楚地进行观察。这些是高能态的化合物它们能够加成不饱和化合物单体并保持自由基或离子活性中心 以致单体可以以同样的方式进一步加成。对于增长反应的各个步骤每一步仅需要相当少的活化能因此通过一步简单的活化反应即引发反应即可将许多烯类单体分子转化成聚合物这正如连锁反应这个术语的内涵那样。因为少量的引发剂引发形成大量的聚合物原料11000110000从表面上看聚合反应很可能是催化反应。由于这个原因通常把聚合反应的引发剂看作是聚合反应的引发剂但是严格地讲它们不是真正意义上的催化剂因为聚合反应的催化剂进入到反应内部而成为一部分同时可以在反应产物既聚合物的末端发现。此外离子引发