发布时间 : 星期四 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
器应在转化率大于5%的时使用，因为小于5%会导致在回流冷凝器中生成污垢和粗树脂的生成。
The reflux condenser operation envelope (a mount of reflux, startup time for reflux ) will depend on the ability of the reactor agitation system to reincorporate the refluxed monomer effectively into the polymerizing mass , and on the foaming tendency of the polymerization recipe . Venting procedures have been described to remove the noncondensable gases from the vapor phase of the reactor and reflux condenser. The level of noncondensable gases in the reactor has been evacuated prior to polymerization, and whether the polymerization process generates an inert gas. The use of azo initiator will result in the formation of nitrogen as a by-product of the initiator decomposition. In addition, a carbonate buffer system will produce CO2 gas if the aqueous phase becomes acidic. Both situations will result in the generation of inert, noncondensable gases which will reduce the efficiency of the reflux condenser.
回流冷凝器操作（安装回流，启动时间倒流）将取决于反应器搅拌系统有效再合并回流单体的能力，以及聚合配方的发泡性。抽真空被认为是在气相反应器和回流冷凝器消除冷凝性气体的方法。不凝性气体在反应器中的量可以通过是否聚合过程产生的惰性气体进行确定。利用偶氮引发剂会导致作为引发剂分解副产品的氮气的生成。此外，如果水相变成酸性，碳酸盐缓冲系统会产生二氧化碳气体。这两种情况都会导致产生惰性，不凝性气体，并降低回流冷凝器的效率。
2 .Reactor jacket operation夹套操作反应器。
The reactor jacket seres the dual purpose of the first heating the reaction mixture to polymerization tenperature by passing a high-temperature fluid through the jacket and then maintaining polymer slurry at a fixed temperature by passing a low-temperature fluid through
the jacket . In large reactors additional cooling is available through the use of a reflux condenser. In a batch polymerization process the reaction mass is heated as quickly as possible to the polymerization temperature so as to increase the productivity of the reactor. This requires that steam-heated water at about 180 to 190F be circulated in the jacket. It has been suspected that this type of heat-up process leads to increased wall fouling. An alternative approach would be to use preheated process water. The second alternative would be to sparge steam directly into the reactor. Director sparging into a reactor has many problems associated with product contamination and is not widely practiced. A third approach is to heat the reactor adiabatically by means of a very active initiator system.
夹套反应器具有双重目的，第一通过高温流体通过反应器使混合物加热到聚合温度，第二通过低温流体通过反应器维持聚合物泥浆在一个固定的温度。大型反应器中额外的冷却是通过使用回流冷凝器。在间歇聚合反应过程反应物质被尽可能地加快到聚合温度以提高生产力。这就要求流通在夹套反应器中的蒸汽热水保持在180到190F。这种类型的加热过程导致增加壁结垢。另一种方法是使用预热过程的水二是喷射蒸汽直接进入反应器。然而喷射到反应堆有许多的问题并会导致产品污染因此并没有得到广泛的应用。三是通过使用活性更高的引发系统加热绝热反应器。
3 Agitation system operation 搅拌系统
The suspension droplet is an easily deformed elastic body in constant motion within the reactor. The agitiation system, which is composed of rotating agitator and fixed baffles, serves to ensure steady heat transfer through mixing an to develop an mintain the size distribution of the monomer droplet in the water . As a trend it has been observed that structures within the reactor which lead to fluid dynamic
flow turbulence will increase reactor wall fouling. Therefore, baffle support braces need to be designed for the optimum fluid dynamic stability.
反应器中在不断运动的悬浮液滴是一个容易变形弹性体。搅拌系统是由旋转的搅拌器和固定挡板组成，以确保稳定传热通过混合引发并维持单体液滴在水中的粒度分布。能够引起流体动力学流动湍流这样结构的反应器会增加反应器壁结垢，这样一个趋势被发现了。因此，挡板支支架的设计需要考虑到最佳流体动力稳定性。
UNIT 24 Mechanical Properties of Polymers
第二十四单元 聚合物的机械性能
The mechanical properties of polymers are of interest in all applications where polymers are used as structural materials. Mechanical behavior involves the deformation of a material under the influence of applied forces.
聚合物的力学性能在聚合物作为结构材料的应用中广为关注。机械行为包括材料外力影响下材料的形变。
The most important and most characteristic mechanical properties are called moduli. A modulus is the ratio between the applied stress and the corresponding deformation. The reciprocals of the moduli are called compliances. The nature of the modulus depends on the na-ture of the deformation.The three most important elementary modes of deformation and the moduli(and compliances) derived from them are given in Table 22. 1，where the definitions of the elastic parameters are also given.Other very important, but more complicated, deformations are bending and torsion. From the bending or flexural deformation the tensile modulus can be derived. The torsion is determined by the rigidity.
最重要和最具特征的机械性能被称为模量。模量是施加应力和相
应形变的比例。模量的倒数称为柔量。模量性质取决于形变性质。表22-1给出了三种最重要的基本变形方式和由这些变形推导得到的模量(或柔量)．表中也给出了弹性指数的定义。其他非常重要，但更为复杂的是弯曲形变和扭转形变。拉伸模量可从弯曲或弯曲形变得出。扭转形变是由刚性决定的。
Cross-linked elastomers are a special case. Due to the cross-links this polymer class shows hardly any flow behavior. The kinetic theory of rubber elasticity was developed by Kuhn , Guth, James, Mark, Flory, Gee and Treloar. It leads, for Young's modulus at low strains, to the following equation：
交联弹性体是一种特殊情况。由于交联这类聚合物几乎没有任何流动行为。橡胶弹性动力学理论是由库恩，杰姆斯，马克，古思，弗洛里，吉和特雷洛尔提出的。这个理论导出了低应变杨氏模量的下列方程：
The paragraphs above dealt with purely elastic deformations, i. e. deformations in which the strain was assumed to be a time-independent function of the stress. In reality, materials are never purely elastic: under certain circumstances they have nonelastic properties.
以上段落的纯弹性变形，即形变中应变为应力的函数，和时间无关。现实中，材料不是纯弹性：在某些情况下他们有非弹性性能。
This is especially true of polymers, which may show nonelastic deformation under circumstances in which metals may be regarded as purely elastic. It is customary to use the expression viscoelastic deformations that are not purely elastic. Literally the term viscoelastic means the combinations of viscous and elastic properties. As the stress-strain relationship in viscous deformations is time-dependent, viscoelastic phenomena always involve the change of properties with