发布时间 : 星期日 文章河北科技大学高分子材料专业外语翻译更新完毕开始阅读
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2000～20000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）： 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1000～5000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（1：1000～1：10000），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。此外离子引发剂和自由基引发剂有的是金属络合物引发剂（例如，通过四氯化钛或三氯化钛与烷基铝的反应可以得到），Z引发剂在聚合反应中起到了重要作用，它们催化活
动的机理还不是十分清楚。
UNIT 3 Step-Growth Polymerization
第三单元 逐步聚合
Many different chemical reactions may be used to synthesize polymeric materials by step-growth polymerization. These include esterification, amidation, the formation of urethanes, aromatic substitution, etc. Polymerization proceeds by the reactions between two different functional groups, e.g., hydroxyl and carboxyl groups, or isocyanate and hydroxyl groups.
许多不同的化学反应通过逐步聚合可用于合成聚合材料。这些反应包括酯化、酰胺化、氨基甲酸酯、芳香族取代物的形成等。通过反应聚合反应在两种不同的官能团，如，羟基和羧基，或异氰酸酯和羟基之间。
All step-growth polymerization fall into two groups depending on the type of monomer(s) employed. The first involves two different polyfunctional monomers in which each monomer possesses only one type of functional group. A polyfunctional monomer is one with two or more functional groups per molecule. The second involves a single monomer containing both types of functional groups. The synthesis of polyamides illustrates both groups of polymerization reactions. Thus, polyamides can be obtained from the reaction of diamines with diacids.
所有的逐步聚合反应根据所使用单体的类型可分为两类。第一类涉及两种不同的官能团单体，每一种单体仅具有一种官能团。一种多官能团单体每个分子有两个或多个官能团。第二类涉及含有两类官能团的单种单体。聚酰胺的合成说明了聚合反应的两个官能团。因此聚酰胺可以由二元胺和二元酸的反应或氨基酸之间的反应得到。
The two groups of reactions can be represented in a general manner by the equations as follows
两种官能团之间的反应一般来说可以通过下列反应式表示