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combination of (1) and (2).
可以用如下三种方法将所需要的活性官能团引入到聚合物主链上:(1)在合成主链聚合物时通过带有所需官能团的单件的均聚或共聚,使聚合物带上官能团;(2)将预先制成的未功能化的主链聚合物进行化学改性;(3)将(1)和(2)两种方法结合起来。”
Each of the two approaches has its own advantages and disadvantages, and one approach may be preferred for the preparation of a particular functional polymer when the other would be totally impractical.
两种途径中的每一种都有自身的优点和缺点,对特殊功能聚合物的制备而言,所选的方法或许是合适的,而另一种方法无法实现。
The choice between the two ways to the synthesis of functionalized polymers depends mainly on the required chemical and physical properties of the support for a specific application.
功能聚合物合成的两种方法中,如何选择主要取决于特殊应用要求的主链聚合物的化学和物理性质。
Usually the requirements of the individual system must be thoroughly examined in order to take full advantage of each of the preparative techniques. 必须考虑不同体系的要求来充分利用不同制备方法。
Rapid progress in the utilization of functionalized polymeric materials has been noted in the recent past.
近年来,功能化聚合物材料的使用方面有了飞速的发展。
Interest in the field is being enhanced due to the possibility of creating systems that combine the unique properties of conventional active moieties and those of high molecular weight polymers.
由于能够制造出兼有活性官能团特性和高分子量聚合物性能的功能聚合物-所以人们对(功能聚合物)这个领域的兴趣与日俱增。
The successful utilization of these polymers are based on the physical form, solvation behavior, porosity, chemical reactivity and stability of the polymers.
这些聚合物的成功利用主要基于功能聚合物的物理形态,溶液行为,空隙率,化学活性及稳定性。
The various types of functionalized polymers cover a broad range of chemical applications, including the polymeric reactants, catalysts, carriers, surfactants, stabilizers, ion-exchange resins, etc.
功能聚合物类型覆盖化学应用的各个领域,包括聚合物试剂,催化剂,载体,表面活性剂,稳定剂,离子交换树脂等。
In a variety of biological and biomedical fields, such as the pharmaceutical, agriculture, food industry and the like, they have become indispensable materials, especially in controlled release formulation of drugs and agrochemicals.
在生物学及生物医学领域中,如药物,农业,食品工业等,功能聚合物是不可缺少的材料,尤其在药物和农药的控制释放配方上。
Besides, these polymers are extensively used as the antioxidants, flame retardants, corrosion inhibitors, flocculating agents, antistatic agents and the other technological applications.
此外,这些聚合物被广泛地用做抗氧化剂,阻燃剂,缓蚀剂,絮凝剂,抗静电剂及
其他技术应用。
In addition, the functional polymers possess[p?’zes+ broad application prospects in the high technology area as conductive materials, photosensitizers, nuclear track detectors, liquid crystals, the working substances for storage and conversion of solar energy, etc. 另外,功能聚合物在高科技领域具有广阔的应用前景。如导电材料,光敏剂,核径迹探测器,液晶,用于太阳能的转化与储存等。
UNIT 13 Reactor Types
Reactors may be categorized in a variety of ways, each appropriate to a particular perspective.
反应器有许多分类方法,各自适用于特定的目的。
For example, Henglein (1969) chooses a breakdown based on the source of energy used to initiate the reaction (i.e., thermal, electrochemical, photochemical, nuclear).
例如,Henglein(1969)基于用于产生反应的能量来源(即热量,电化学能,光化学能,核能)选择了一种分类法。
More common breakdowns are according to the types of vessels and flows that exist. 更常见的分类是按照容器和流量的类型。 Batch Reactors 1. 间歇反应器
The batch reactor (BR) is the almost universal choice in the chemist’s laboratory where most chemical processes originate.
在化学实验室中通常大多数的化学过程选择间歇反应器。
The reason is the simplicity and versatility of the batch reactor, whether it be a test tube, a three-neck flask, an autoclave, or a cell in a spectroscopic instrument.
原因是间歇反应器简单和通用,它可以是一支试管,一个三颈瓶,一个高压釜,也可以是一个光谱仪器的比色皿。
Regardless of the rate of the reaction, these are clearly low production rate devices. As scale up is desired, the most straightforward approach is to move to a larger batch reactor such as a large vat or tank.
不管反应速率如何,间歇反应器生产率较低。当反应放大时,大多可直接的移至一个较大的间歇反应器进行,例如一个较大的大桶或罐。
Commercial batch reactors can be huge, 100 000 gal or more. The cycle time,often a day or more,typically becomes longer as reactor volume increases in order to achieve a substantial production rate with an inherently slow reaction.
商业间歇反应器比较庞大,体积为10万加仑或更大。对于慢化学反应,为提高生产率必须增加反应器体积,而这往往导致反应器的循环周期变长,常常以天计算。 Fabrication,shipping, or other factors place a limit the size of a batch reactor. For example, transportation capacity can limit the size of a batch reactor for which shop,as opposed to on—site,fabrication of the heat exchange surface is required.
制造、运输以及其他因素限制了反应器的规模,如由于需要在制造厂而不是现场制造间歇反应器的热交换器,这样间歇反应器的尺寸受运输能力的限制。
This limits the production rates for which batch reactors may be economically utilized. Also, batch reactors must be filled, emptied, and cleaned. For fast reactions these unproductive operations consume far more time than the reaction itself and continuous processes can become more attractive.
这限制了间歇反应器的有效利用,降低了产率。间歇反应器也必须装料、卸料和清洗。对于快反应来说,这些非生产性的操作消耗了多于反应本身的时间。这种情况下连续化过程更有吸引力。
2. Semibatch Reactors (SBR) 2.半间歇反应器
Some reactions may yield a product in a different phase from the reaction mixture. Examples would be liberation of a gas from a liquid-phase reaction or the formation of a precipitate in a fluid-phase reaction.
一些反应器可以从反应混合物的不同相态中生产出某种产品。例如液相反应中气体的释放,或流动相反应中沉淀的生成。
To drive the reaction to completion, it may be desirable to continuously separate the raw product phase. A semibatch operation may result as well from differing modes of feeding the individual reactants.
连续分离粗产物相可以使反应完全。半连续操作也来自于各种反应物的不同加入方式。
For reasons we will discuss later, it may be desirable to charge one reactant to the reactor at the outset and bleed a second reactant in continuously over time. Such reactors have both a batch and a flow character and, like batch reactors, are useful for slow reactions and low production rates. 这个原因我们以后讨论,我们一开始加入一种反应物,以后连续加入第二种反应物。这类反应器同时具有间歇和流动的特征,并且像间歇反应器一样适用于低生产速率的慢反应。
3. Continuous Stirred Tank Reactors (CSTR) 3. 连续流动搅拌反应器
It is a small step from the batch reactor to the CSTR. The same stirred vessel may be used with only the addition of piping and storage tanks to provide for the continuous in-and outflow.
从间歇反应器到连续流动搅拌反应器只是作了小的改进。同样的搅拌式容器可仅仅添加管道和储罐就可以提供连续进料和出料。
Faster reactions can be accommodated and larger production rates can be achieved because of the uninterrupted operation. CSTRs are most often used for liquid-phase reactions, such as nitration and hydrolysis, and multiphase reactions involving liquid with gases and/or solids. Examples would be chlorination and hydrogenation.
连续操作可加快反应并提高生产率。通常大多数连续流动搅拌反应器用于液相反应,如硝化和水解反应,和涉及液-气和/或液-固反应的多相反应,如氯化和加氢反应。 4. CSTR in Series
4.多级串联连续流动搅拌反应器
It was shown that considerable gains in production rate and economics can be achieved by passing the reacting mixture through a series of CSTRs. Again, we see how
easy it is to achieve a gradual scale up, say for a specialty chemical for which is increasing. CSTRs in series are usually used for liquid-phase reactions.
事实证明将反应混合物通过一系列多级串联连续流动搅拌反应器能够获得高产率和更经济。再者,这种反应器容易逐级放大,例如某种化学品的需求逐步增加时常这样做。多级串联连续流动搅拌反应器通常用于液相反应。 5.Tubular Reactors 5.管式反应器
As the production rate requirement increases, batteries of CSTRs become increasingly complex and tubular reactors become attractive. With the transition to tubular reactors, some versatility is lost and more process integration is required.
当需要增加生产率时,连续搅拌式反应器的串联更为复杂,而管式反应器则更为适用。由于管式反应器合并多步操作工艺,其失去了其它反应器操作多样性的特点。 Nevertheless, tubular reactors find extensive application in liquid-phase reactions, for example, polymerization, and are almost always the continuous reactor of choice for gas-phase reactions, for example, pyrolysis.
尽管如此,管式反应器在聚合反应等液相反应中起着广泛作用。高温裂解等气-液反应也几乎总是选择管式连续反应器。
Exceedingly high production rates can be achieved with tubular reactors either by increasing the diameter of the tube or more commonly by using a sufficient number of tubes in parallel.
管式反应器通过增加管的直径, 或使用大量的并列管能够获得非常高的产率。 6. Recycle reactors 6. 循环反应器
Recycle reactor can be batch, CSTR, tubular, and so on in nature with the purpose of the recycle varying from one case to the next. Many large-scale commercial processes incorporate the recycle of one or more streams back to an earlier point in the process to conserve raw materials.
循环反应器出于循环变化的目的不同,可以是间歇反应器、连续流动搅拌反应器、管式反应器等等。为节省原料,许多大规模工艺过程将一个或多个反应流循环回到较早的反应点。
This practice often results in the accumulation of impurities, which in turn requires separation. Usually it is not simply the reactor outlet stream that is recycled back to the reactor inlet, but it can be. For example in a batch reactor the reacting mixture can be recycled, or pumped around, through a heat exchanger to provide thermal control. 这一工艺通常导致了杂质的累积和相关的分离过程。通常循环不是简单地将反应器的出料返回到入口,当然也可以这样。例如,在间歇反应器中反应混合物可以回收,或用循环,并通过热交换器来控制热量。
Recycle reactor have also found valuable application in the laboratory and pilot plant because of their special characteristics. At one extreme, in which all of the product is recycled (no net flow), the reactor is the exact equivalent of the well-stirred batch reactor. 根据其特性,循环反应器也很好地应用于实验室和中试车间。一个极端情况是将所有的产物循环(没有净的流出),此时循环反应器等效于全混间歇反应器。
At the other extreme of no recycle, the reactor is simply the tubular variety. If there is
some net flow but the recycle rate is high, the overall reactor performs like a CSTR. Yet the reaction tube itself behaves like differential tubular reactor. This versatility of the recycle reactor can be exploited to great advantage in research and development.
另一个极端情况是没有循环,反应器只是管式反应器。如果有净的流出但循环率很高,反应器类似于连续流动搅拌反应器运行,然而反应器本身性质和微分管式反应器相似。我们在研发中可以很好地开发循环反应器的多样性。
UNIT 14 Bulk Polymerization
Bulk polymerization traditionally has been defined as the formation of polymer from pure, undiluted monomers. Incidental amounts of solvents and small amounts of catalysts, promoters, and chain-transfer agents may also be present according to the classical definition.
传统意义上,本体聚合为从纯的未被稀释的单体形成聚合物的方法。可能还有少量溶剂和催化剂,促进剂和链转移剂
This definition, however, serves little practical purpose. It includes a wide variety of polymers and polymerization schemes that have little in common, particularly from the viewpoint of reactor design.
但是这个定义没有实际用途。特别是从反应器设计的角度看,它包括各种各样的聚合物和聚合反应,相同点很少。
The modern gas-phase process for polyethylene satisfies the classical definition, yet is a far cry from the methyl methacrylate and styrene polymerization which remain single-phase throughout the polymerization and are typically thought of as being bulk. 根据传统的定义,现代的气相聚乙烯工艺属于本体聚合过程,但与通常认为的甲基丙烯酸甲脂和苯乙烯的典型本体聚合过程截然不同,后者在整个聚合反应过程中始终保持单相体系。
A common feature of most bulk polymerization and other processes not traditionally classified as such is the need to process fluids of very high viscosity.
大多数本体聚合和其他没有被定义为本体聚合的工艺的一个共同特点是需要处理非常高粘度的流体。
The high viscosity results from the presence of dissolved polymer in a continuous liquid phase. Significant concentrations of a high molecular-weight polymer typically increase fluid viscosities by 104 or more compared to the unreacted monomers. 聚合物溶解在连续液相产生高粘度。高浓度的高分子量聚合物通常比未反应的单体增加粘度104倍或更多。
This suggests classifying a polymerization as bulk whenever a substantial concentration of polymer occurs in the continuous phase. Although this definition encompasses a wide variety of polymerization mechanisms, it leads to unifying concepts in reactor design.
所以在连续相中有高浓度聚合物时聚合反应可定义为本体聚合。虽然这个定义包含了不同的聚合机理,但它统一了反应器设计方面的概念。
The design engineer must confront the polymer in its most intractable form, i. e. , as a high viscosity solution or polymer melt.
设计工程师必须面对聚合物最难处理的形式,也就是,高粘度溶液或聚合物熔体。