发布时间 : 星期二 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
(1.25 parts), the latex is coagulated by the addition of brine, followed by dilute sulfuric acid or aluminum sulfate. The coagulated crumb is washed, dried, and baled for shipment.
混合物在搅拌下50℃加热，每小时转化5%～6%，在转化率达70%～75%时通过加入“终止剂” 聚合反应终止，例如对苯二酚（大约0.1的重量百分含量），抑制自由基并避免过量支化和微凝胶形成。未反应的丁二烯通过闪蒸去除，苯乙烯在萃取塔中通过蒸汽萃取（剥离）。在加入抗氧剂后，例如N-甲基-β-萘胺（1.25的重量百分含量），加入盐水，其次加入稀释的硫酸或硫酸铝后乳液凝胶。凝胶碎片被洗涤、干燥并包装装运。
This procedure is still the basis for emulsion polymerization today. An important improvement is continuous processing illustrated in Fig. 14.1; computer modeling has also been described.
今天这种生产过程仍是胶体聚合反应的基础。如图14.1所示一个重要的进步是连续操作；也采用计算机模型描述。
In the continuous process, styrene, butadiene, soap, initiator, and activator (an auxiliary initiating agent) are pumped continuously form storage tanks through a series of agitated reactors at such a rate that the desired degree of conversion is reached at the last reactor. Shortstop is added, the latex warmed with steam, and the unreacted butadiene flashed off. Excess styrene is steam-stripped, and the latex finished as shown in Fig. 14.1.
在连续操作中，苯乙烯、丁二烯、肥皂、引发剂和活化剂（一种助引发剂）用泵从储罐通过一系列的混合反应器，泵送流率根据末釜的转化率控制。加入终止剂，乳液用蒸气加热，未反应的丁二烯被闪蒸。剩余的苯乙烯被蒸气剥离，如图14.1表示乳液完成。
SBR prepared from the original GR-S recipe is often called hot
rubber; cold rubber is made at 5℃ by using a more active initiator system. Typical recipes are given in Table 14.1 At 5℃ ,60% conversion to polymer occurs in 12~15h.
由常规丁苯制法制备的丁苯胶常称作热胶；冷胶通过使用一种更高活性的引发体系在5℃制成。典型的配方在表14.1中给出。5℃、60%转化率、12～15 h聚合物形成。
Cold SBR tire treads are superior to those of hot SBR. Polymers with abnormally high molecular weight (and consequently too tough to process by ordinary factory equipment) can be processed after the addition of up to 50 parts of petroleum-base oils per hundred parts of rubber (phr). These oil extenders make the rubbers more processible at lower cost and with little sacrifice in properties; they are usually emulsified and blended with the latex before coagulation.
冷丁苯橡胶轮胎优于那些热丁苯胶。具有异常高的分子量的聚合物（因此采用常规的工厂设备由于太粘稠而难以加工）在每一百份的橡胶中加入大于50份的石油基础油后能够加工。这些油添加剂使橡胶更易加工体现在低成本和性能方面低损耗；他们在凝胶之前通常乳化并与胶乳混合。
Recent trends have been toward products designed for specific uses. The color of SBR, which is important in many nontire uses, has been improved by the use of lighter-colored soaps, shortstops, antioxidants, and extending oils. For example, dithiocarbamates are substituted for hydroquinone as shortstop; the latter is used on hot SBR where dark color is not objectionable. A shortstop such as sodium dimethyldithiocarbamate is more effective in terminating radicals and destroying peroxides at the lower temperatures employed for the cold rubbers.
最近倾向于设计特殊用途的产品。丁苯橡胶的颜色，在许多非轮
胎使用中十分重要，通过使用浅色的肥皂、终止剂、抗氧剂和扩展油加以改进。例如，二硫化氨基甲酸盐替代对苯二酚作为终止剂；后者适用于不被人反对的黑色丁苯橡胶。在冷胶的制备中如二硫化氨基甲酸钠的终止剂在低温情况下对终止自由基和消灭过氧化物更有效。
Free-radical dissociative initiators that function by dissociation of a molecule or ion into two radical species are normally limited to inorganic persulfates in the case of butadiene polymerization.
在丁二烯聚合反应过程中自由基分解的引发剂即一分子分解或离子成两个自由基物种的引发剂通常限制于过硫酸盐。
The other important class of free-radical initiators, redox systems, contain two or more components that react to produce free radicals. Dodecyl mercaptan added to control molecular weight also appears to aid free-radical formation by reaction with persulfate. The commercial importance of such chain-transfer agents or modifiers cannot be overemphasized. Without molecular weight control the rubbers would be too tough to process.
其他重要的自由基引发剂类别，氧化还原体系，包含反应产生自由基的两种或多种组分。加入控制分子量的十二烷基硫醇与过硫酸盐反应也出现了助自由基的形成。这种链转移剂或调节剂具有极其重要的商业价值。不控制分子量橡胶将过于粘稠难以加工。
Unit 15 Heat Transfer Process 第十五单元 热传递工艺
The formation of polyvinyl chloride is an exothermic reaction. One of the functions of the reactor vessel is to provide the cooling surface for heat removal. The reactor size is limited by the ratio of reactor volume to cooling surface and the agitation system needed to maintain the
monomer-water mixture at the proper droplet size . Commercial reactors of 25000-to 50000-gal capacity are standard for suspension polymerization industry. The reactor productivity will depend on the heat transfer capacity of the vessel.。The higher the heat transfer capacity, the more polymer that can be made per unit of time.
聚氯乙烯的形成是放热反应。反应堆容器的一个职能是提供冷却散热。反应器的尺寸受限于体积与冷却面积的比例，另外反应器搅拌系统需要保持水-单体混合物维持在在适当的液滴尺寸。25000到50000加仑容量的商用反应堆是悬浮聚合行业标准。反应堆生产力将取决于其传热能力。更高的传热能力可使单位时间内生产更多的聚合物。
Reflux condenser utilization 回流冷凝器的使用
A reflux condenser functions by condensing vapor to lipuid and removing the latent heat of vaporization fron the system. In large reactors, a reflux condenser is the most effective way to increase the available cooling surface without increasing the length ratio of the reaction vessel. The use of a reflux condenser to provide additional cooling capacity in vinyl chloride polymerization reactors was discussed by Terwiesch (1976) for reactor of 50000-gal capacity. A Conoco (U. S .PAT.416242,1979) indicates that the reflux condenser should be used only after 5% of the monomer is converted to polymer, because utilization of the reflux condenser before 5% conversion results in extensive reflux condenser fouling and a coarser resin.
回流冷凝器的冷凝时通过冷却水汽并消除汽化潜热而工作的。对于大型反应器，回流冷凝器是最有效方法是在没有增加的长径比的情况下提高现有冷却表面的方法。1976年特尔维施展示了在50000加仑氯乙烯聚合反应中使用回流冷凝器提供额外的冷却能力。回流冷凝