调整磷化溶液的新方法—公式计算法

传统的磷化溶液调整方法是,通过调整游离酸度和总酸度,即酸比来进行(这里不涉及溶液净化及其它工艺条件),往往为控制某种比例而引起另一不需要的化学比例的变化,或溶液的溢出,给生产和质量带来诸多不利.笔者在多年的实践中,根据游离酸度和总酸度,以及分析、化验、调整、故障处理、产品质量等因素,总结出另一种调整方法,即数学公式计算法.一增加磷酸盐提高游离酸度、总酸度,求酸比.     

聚丙烯腈生产中游离酸含量的控制

分析了聚丙烯腈生产过程中影响聚合物中游离酸含量的因素,提出相应的控制措施。结果表明:稳定控制混合单体中二氧化硫的含量变化±0.03%,活化塔的pH值变化±0.2,消除二氧化硫的吸收作用,优化一道过滤系统的洗涤效果,有利于稳定控制聚合物中游离酸含量。     

金属磷化处理(二)

4　影响磷化的主要因素4.1　游离酸度 (ＦＡ)游离酸度是指由磷化液中游离磷酸所电离的游离Ｈ+ 浓度 ,用甲基橙作指示剂 ,用 0 .1ｍｏｌ Ｌ的ＮａＯＨ溶液滴定 10ｍｌ磷化液所消耗的ＮａＯＨ溶液的毫升数来表示 ,此数值被称为“点” ,1ｍｌ为一点。游离酸度是控制磷化液中成膜物质的组成形式、控制槽液中电离与水解平衡状况以及保持槽液稳定的重要因素。它直接影响磷化的难易、快慢以及磷化膜性能的优劣、槽液沉渣的多少。因此 ,磷化中游离酸度必须严格控制在工艺范围内 ,过高或过低都将对磷化造成不良影响。ＦＡ值过高 ,金属表面阳极氧化过…     

硫铵结晶槽倒液降酸系统的改造

介绍无饱和器法生产硫铵过程中结晶槽上部母液酸度对产品游离酸含量的影响以及在生产运行中控制产品游离酸含量采取的措施和达到的效果.     

淡盐水脱氯系统的降耗措施

针对淡盐水脱氯工序烧碱消耗高的问题,通过控制出槽淡盐水酸度和对脱氯控制指标进行优化,在确保将游离氯完全脱除的前提下,使自用碱消耗降低明显。     

脲醛树脂改性工艺中的酸度条件控制

普通脲醛树脂及氧化淀粉改性脲醛树脂的合成工艺中 ,酸度控制条件对合成产物稳定性、剪切强度、游离甲醛含量等性能影响的研究表明 ,缩合反应阶段尿素投入时体系pH值对脲醛树脂合成过程以及产物稳定性都有显著性影响。缩合阶段体系的pH值控制范围直接影响脲醛树脂的稳定性、粘合强度与游离甲醛含量。从脲醛树脂稳定性考虑 ,投入第三批尿素后的pH值应控制在 6 .0以上     

水处理药剂的监控方法

本专利介绍了一种可用于冷却水系统和锅炉水系统水处理药剂监控的方法。该方法可直接测量一种或多种活性聚合物组分。一般聚合物水处理剂在水系统中以游离或不游离状态存在。而游离聚合物占总聚合物量的比率决定了聚合物的药效，总的聚合物的量可以通过实际加入系统的药剂的量来确定，而游离聚     

环保型脲醛树脂胶粘剂的低温合成

本文根据尿素与甲醛加成一缩合反应机理，通过控制脲醛树脂生产过程中尿素与甲醛的摩尔比，加入聚乙烯醇改进其初粘性，加入三聚氰胺改进其耐水性并加入甲醛捕捉剂降低产品中的游离甲醛含量。采用二次缩聚工艺，控制脲醛比pH值以及反应温度来减少脲醛树脂中游离甲醛的含量。在较强酸度、低温度条件下实现了树脂的合成，减少了能源消耗。     

机床零件磷化常见的问题及改进措施

1机床零件磷化常见缺陷及防止方法 1．1磷化膜结晶粗糙多孔产生原因：磷化槽液中游离酸度过高,磷化液中氧化剂量不足,槽液中亚铁离子含量过高,零件表面有残酸,发生过腐蚀。防止方法：降低槽液中游离酸的含量,增加氧化剂比例,加双氧水进行调整,加强中和及水洗,控制酸洗浓度和时间。     

三塔精馏过程中精甲醇的酸度控制

精馏过程是控制精甲醇质量的关键环节,精馏操作的优劣与否,直接决定着精甲醇产品的质量等级。精甲醇的酸度是衡量精甲醇产品质量等级的重要指标之一,我国工业甲醇质量标准GB338-92中规定:优等品酸度(以HCOOH计)≤0·001 5%,一等品酸度≤0·003 0%,合格品酸度≤0·005 0%;美国联邦标准O-M-232G规定“AA”级精甲醇产品的游离酸(以HAc计)含量≤30×10-6。本文介绍我公司在甲醇三塔精馏工艺操作中对精甲醇酸度的控制方法。1甲醇中酸的来源在甲醇合成过程中,当合成气的水分含量高时,易发生如下反应:CO+H2O HCOOH在合成过程中还可能发生…     

Multiobjective dynamic optimization of batch free radical polymerization process catalyzed by mixed initiator systems

The optimal control policies for batch free radical polymerization of styrene catalyzed by a binary mixture of monofunctional initiators have been determined using a multiobjective dynamic optimization technique. The process objectives considered in the optimization include monomer conversion, polymer molecular weight, initiator residue level, and total reaction time. It is illustrated through model simulations and experiments that the performance of the batch polymerization process can be improved significantly through the use of optimal initiator mixture and polymerization temperature programming. This paper also illustrates how the multiobjection optimization technique can be used effectively to solve complex polymerization reactor optimization problems with detailed reaction models.     

原位聚合法制备压敏显色微胶囊

采用原位聚合法 ,以CVL溶液为芯材、三聚氰胺 甲醛预聚物为壁材 ,在酸性条件下制备压敏显色微胶囊 ,研究了影响压敏显色微胶囊制备的因素 ,提出用丙烯酸溶液作为调酸物质 ,通过采用逐步滴加法调节乳液的反应酸度 ,有效遏止了分散体系在调酸过程中的蓝变。     

分子印迹技术在传感领域中的研究及应用进展

分子印迹技术是一种高选择性分离技术,制备过程一般是将要分离的目标分子与功能单体通过共价或非共价作用进行预组装,与交联剂共聚制备得到印迹聚合材料.其制备方法经历了由最初的自由基聚合到悬浮聚合和乳液聚合及活性/可控聚合的变化,应用形态经历了由本体聚合物到微球再到分子印迹膜的发展.从分子印迹聚合物及分子印迹膜两个方面综述了分...     

Preparation and Performance of a Novel Water‐Soluble Cationic Polymer Containing β‐Cyclodextrin

Allyl‐β‐cyclodextrin is utilized to react with dimethyl diallyl ammonium chloride and acrylamide to synthesize a novel water‐soluble cationic polymer by redox free‐radical polymerization. The optimum polymerization conditions are determined by the single‐variable method, while the structure is characterized by Fourier transform infrared and scanning electron microscopy. In rheological experiments the polymer demonstrates superior properties compared to polyacrylamide. Interfacial tension and adsorption experiments prove the excellent performance of the polymer which can effectively decrease the interfacial tension and reduce the surfactant loss caused by stratum absorption in the process of polymer/surfactant flooding, thus indicating the potential application of the polymer for enhancing oil recovery.     

Inferential sensors for estimation of polymer quality parameters: Industrial application of a PLS-based soft sensor for a LDPE plant

Low-density polyethylene (LDPE) and ethylene vinyl acetate (EVA) copolymers are produced in free radical polymerization using reactors at extremely high pressure. The reactors require constant monitoring and control in order to minimize undesirable process excursions and meet stringent product specifications. In industrial settings, polymer quality is mainly specified in terms of melt flow index (MI) and density. These properties are difficult to measure and usually unavailable in real time, which leads to major difficulty in controlling product quality in polymerization processes. Researchers have attempted first principles modeling of polymerization processes to estimate end use properties. However, development of detailed first principles model for free radical polymerization is not a trivial task. The difficulties involved are the large number of complex and simultaneous reactions and the need to estimate a large number of kinetic parameters. To overcome these difficulties, some researchers considered empirical neural network models as an alternative. However, neural network models provide no physical insight about the underlying process. We consider data-based multivariate regression methods as alternative solution to the problem. In this paper, some recent developments in modeling polymer quality parameters are reviewed, with emphasis given to the free radical polymerization process. We present an application of PLS to build a soft-sensor to predict melt flow index using routinely measured process variables. Issues of data acquisition and preprocessing for real industrial data are discussed. The study was conducted using data collected form an industrial autoclave reactor, which produces LDPE and EVA copolymer using free radical polymerization. The results indicated that melt index (MI) can be successfully predicted using this relatively straightforward statistical tool.     

基于动态优化和反馈控制的聚合反应过程牌号切换策略

针对单反应器多牌号聚合物生产过程, 提出一种结合动态优化和反馈控制的牌号切换策略。以实验室规模的连续搅拌釜式反应器中苯乙烯聚合牌号切换为对象, 以原料消耗最少为优化目标, 利用迭代动态规划求得切换过程中反应条件和产品性能指标的优化轨迹。引入针对反应温度的路径约束, 使优化后的切换轨迹更易跟踪实现, 防止过渡过程中变量的剧烈波动。仿真结果表明, 这一切换策略可以显著减少牌号切换过渡时间及过渡过程中原料的消耗量, 并能够有效克服进料温度变化的干扰。     

New dinitroxide for stable free radical polymerization of styrene

A new dinitroxide (1,4‐di (1‐oxy‐2,2,6,6‐tetramethyl‐1‐piperidin‐4‐yl)‐xylene) (DTPX) was synthesized and successfully used in stable free radical polymerization of styrene. The results of the polymerizations showed that the DTPX was a suitable mediating agent for stable free radical polymerization of styrene. However, it was found that the dinitroxide mediating process resulted in a higher level of decomposition of the internal bisalkoxyamine linkage in the polymer chain, which resulted in polymers possessing a terminal alkoxyamine and an adjacent hydroxylamine, and the decomposition became more obvious at high conversion through monitoring the change of molecular weights with the conversion by gel permeation chromatography and the polymer structure by ¹H‐NMR. The reaction temperature showed obvious effects on the polymerization, and the polymerization of styrene at 110°C led to a better controlled polymerization than that at 125°C with narrower molecular weight distributions and slight decomposition of the nitroxide up to monomer conversions of 76.7%, however, the rate of the polymerization was decreased and an induction period appeared at 110°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1137–1145,2006     

Amphiphilic styrene–acrylic acid copolymers from the free‐radical retrograde‐precipitation polymerization (FRRPP) process

The free‐radical retrograde‐precipitation polymerization (or FRRPP) process, a free‐radical polymerization that occurs above the lower critical solution temperature (LCST), was extended to copolymer formation. Control over the rate of polymerization and entrapment of polymer radicals in the FRRPP process was used to generate tapered styrene–acrylic acid block copolymers. To show the effectiveness of the FRRPP process, the same procedure was used with solvents that are not LCST‐based precipitants for the polymer. Kinetic data show substantial chain termination in non‐FRRPP copolymerization systems. Molecular weight information also shows propagation control in the FRRPP system. Solubilization and emulsification studies also indicate the capability of the FRRPP system in generating a much higher proportion of amphiphilic tapered block copolymers in the solid product. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 426–431, 2003     

乙丙橡胶中试聚合工艺物料平衡关系

乙丙橡胶中试溶液聚合工艺是聚合反应气相与脱气系统气相汇总形成循环物流,循环物流中丙烯的组成是聚合物结构的主导因素,丙烯的相变是聚合反应温度的控制关键,因此,明确聚合、脱气、压缩环节丙烯的含量和状态,是物料衡算、热量衡算、动量衡算的关键因素,更是设备设计、工程控制的决定性因素。本文通过根据乙丙橡胶聚合工艺特点,明确聚合釜气液相乙烯、丙烯的物料分配原则,结合聚合反应热换热关系,通过对丙烯循环量、溶解量的计算,确定了聚合工艺物料状态及衡算关系。     

1,2-丁二烯在连续聚合SSBR中的抑凝机理及应用

以正丁基锂为引发剂、环己烷/己烷为溶剂,采用间歇聚合工艺模拟溶聚丁苯橡胶(SSBR)聚合过程的凝胶生成实验,考察了1,2-丁二烯的抑凝机理.结果表明:1,2-丁二烯具有明显抑凝作用,加入质量分数为(1～5)×10-5时,产品的凝胶质量分数在0.010％以内;其加入质量分数高于5×10-5时,产品的凝胶质量分数低于0.001％;1,2-丁二烯加入量质量分数超过1×10-4时,对聚合反应速率和单体转化率有影响.1,2-丁二烯作为抑凝剂可有效解决连续聚合SSBR工艺中的凝胶挂堵问题.