发布时间 : 星期二 文章娌冲寳绉戞妧澶у楂樺垎瀛愭潗鏂欎笓涓氬璇炕璇?- 鐧惧害鏂囧簱更新完毕开始阅读
stabilizers, ion-exchange resins, etc. 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. Besides, these polymers are extensively used as the antioxidants, flame retardants, corrosion inhibitors, flocculating agents, antistatic agents and the other technological applications. 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.
近年来，功能化聚合物材料的使用方面有了飞速的发展。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。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。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。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。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。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 12 Bulk Polymerization
第十二单元 本体聚合
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. 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. 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.
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.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。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. 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. 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. The design engineer must confront the polymer in its most intractable form, i. e., as a high viscosity solution or polymer melt.
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。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。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。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。
The revised definition makes no sharp distinction between bulk and solution polymerizations and thus reflects industrial practice. Several so-called bulk processes for polystyrene and ABS? use 5%~15% solvent as a processing aid and chain-transfer agent. Few successful processes have used the very large amounts of solvent needed to avoid high viscosities in the continuous phase, although this approach is sometimes used for laboratory preparations.
在修正定义中本体和溶液聚合没有明确的界限，所以能应用于工业中。聚苯乙烯和ABS的本体过程使用5%~15%溶剂作为加工助剂和链转移剂。尽管有时实验室制备中使用了大量的溶剂避免连续相中的高粘度，但在成功的工艺中很少使用这种方法。
Bulk polymerizations often exhibit a second, discontinuous phase. They frequently exhibit high exothermicity, but this is more characteristic of the reaction mechanism than of bulk polymerization as such. Bulk polymerizations of the free-radical variety are most common, although several commercially important condensation processes satisfy the revised definition of a bulk polymerization.
本体聚合往往出现第二个非连续相。他们常常表现出高放热性，但这一特点更多的是来自于反应机理，而不是本体聚合。虽然有一些商业化的缩聚满足本体聚合的修订定义，但自由基聚合最常用于本体聚合。
In all bulk polymerizations, highly viscous polymer solutions and melts are handled. This fact tends to govern the process design and to a lesser extent，the process economics. Suitably robust equipment has been developed for the various processing steps, including stirred-tank and tubular reactors, flash devolatilizers, extruder reactors, and extruder devolatilizers.Equipment costs are high based on working volume, but the volumetric efficiency of bulk polymerizations is also high. If a polymer can be made in bulk, manufacturing economics will most likely favor this approach.
在所有的本体聚合中都处理高粘度的聚合物溶液和熔体。(本体聚合过程的高粘现象)支配聚合过程的设计和工艺的经济效益。人们研制了耐用的设备用于不同的处理步骤，包括搅拌式和管式反应器中，闪蒸脱挥发，挤出机反应器和挤出机脱挥发器。这些设备单位单位体积成本高，但本体聚合的体积效率也很高。如果某一聚合物可以通过本体聚合生产，经济学上该工艺是最适宜的。
It is tempting to suggest that polymer processes will gradually evolve toward bulk.? Recently, the suspension process for impact polystyrene has been supplanted by the bulk process, and the emulsion process for ABS may similarly be replaced. However, the modern gas-phase process for polyethylene appears to represent an opposite trend. It seems that polymerization technology tends to eliminate solvents and suspending fluids other than the monomers themselves.When the monomer is a solvent for the polymer, bulk processes as described in this article are chosen. When the monomer is not a solvent, suspension and slurry processes like those for polyethylene and polypropylene are employed. Hence, it is worthwhile avoiding a highly viscous continuous phase, but not at the price of introducing extraneous material.
有一种观点认为聚合物生产将逐渐向本体聚合发展。最近抗冲击