聚醚多元醇中环状齐聚物的去除

主要介绍和归纳了目前文献报道过的各种从聚醚多元醇中分离环状齐聚物的方法 ,并对各种方法进行了评述     

用C_1柱的反相液相色谱对辛基酚聚氧乙烯醚型非离子表面活性剂快速分离和测定其氧乙烯聚合物分布(英)(待续)

提出了一个迅速、简单、可重复进行的反相ＨＰＬＣ法, 用来分离和定性辛基酚聚氧乙烯醚表面活性剂的各种齐聚物组分。使用一支Ｃ１ 三甲基硅烷基（ＴＭＳ） 色谱柱得到很高的分离度和灵敏度。本方法对聚乙氧基化的辛基酚聚氧乙烯单元直到４０ 的ＰＥＯＰ表面活性剂（ 摩尔质量分布大约达到２０００） 进行了成功的分离和鉴定。８ 种ＰＥＯＰ表面活性剂的齐聚物分布的情况给予了计算和图形描述。对流动相组成和制备所用的溶剂对齐聚物分离影响进行了详细的研究。     

用C1柱的反相液相色谱对辛基酚聚氧乙烷醚型非离子表面活性剂快速 …

提出了一个迅速、简单、可重复进行的反相ＨＰＬＣ法,用来分离和定性辛基酚聚氧乙烯醚表面活性剂的各种齐聚物组分使用一支Ｃ１三甲基硅烷基（ＴＭＳ）色谱柱得到很高的分离度和灵敏度。本方法对聚乙氧基化的辛基酚聚氧乙烯单元直到４０的ＰＥＯＰ表面活性剂（摩尔质量分布大约达到２０００）进行了成功的分离和鉴定。８种ＰＥＯＰ表面活性剂的齐聚物分布的情况给予了计算和图形描述。对流动相组成和制备所用的溶剂对齐聚物分离影响     

专利摘登

由含环状聚酯齐聚物的混合物制造高聚合度聚酯将特性黏度 [η]=0 .5～ 1.5的聚酯与质量为其1.5至 9.5倍的环状聚酯齐聚物进行混合并加热 ,可以制得 [η]≥ 0 .6 5的聚酯。这种聚酯是在适当的聚合速度和能防止产物发黄的温度下制得的。例如 :将 2kg[η]=0 .75的PET切片、8kg粉末化的环状PET齐聚物和 0 .95 g钛酸四异丙酯进行混合 ,在 10 0℃真空下捏和 ,在 2 80℃熔融 30min ,挤压 ,造粒 ,制得 [η]=1.4 5和Hunterb值为 4 .9的聚酯。JP 2 0 0 2 2 6 5 5 76具有良好可加工性用于制造液体食品容器的改性PET切粒将 (A)熔融聚合的PET和 (B…     

改良型聚苯硫醚的齐聚物研究

用质谱法研究了硫磺溶液法合成改良型聚苯硫醚（ＰＰＳ）的齐聚物组成，并与硫磺溶液法合成用聚聚苯硫醚的齐聚物组成进行了对比分析。结果表明：改良型ＰＰＳ除有与通用型ＰＰＳ相同的齐聚物外，不家双蜞线型苯硫醚齐聚物ＨＳ－Ｈ６Ｈ４Ｓ，Ｘ＝１，２，３，单巯基含一个二硫键的线型苯硫醚齐聚物Ｃ６Ｈ５－ＳＳＨ，Ｘ＝６和苯硫醚太三聚体，δ＝３，与通用型不同的是：无双氯端基的线型苯硫昌的Ｃｌ＝－Ｃ６Ｈ４Ｃｌ和苯硫醚环状六     

浓缩液中环状二聚体的含量及晶形分析

以己内酰胺聚合装置中不同浓度的萃取水和浓缩液为研究对象,通过高效液相色谱对其中的环状二聚体进行了定性定量分析,研究了不同浓度浓缩液中环状二聚体的结晶形态,并对环状二聚体的吸附团聚行为进行了静态模拟。结果表明:环状二聚体在浓缩液中以β晶型存在;浓缩液浓度越高,环状二聚体的聚集密度越高,团聚现象越严重;即使在低浓度的萃取水中,环状二聚体也会吸附己内酰胺发生团聚;红外光谱和X衍射分析表明随着浓缩液浓度的增加,环状二聚体的特征峰强度逐渐减弱直至消失,而己内酰胺的特征峰强度则越来越强。     

端羟基聚环氧氯丙烷制备进展

介绍了环氧类单体阳离子开环聚合的反应机理,活性单体机理与活性链端机理相结合可解释反应过程中环状齐聚物的生成过程。归纳了合成端羟基聚环氧氯丙烷的各种催化体系,并对产物的后处理方法进行了总结。     

尼龙6连续聚合过程的流程模拟与调控

基于流程模拟软件Aspen Polymer Plus建立了己内酰胺水解聚合生产尼龙6的两段式工艺过程模型,利用该模型对某厂2万吨/年两段式生产工艺进行模拟,各聚合阶段内己内酰胺、环状二聚体含量、聚合物分子量,以及各聚合阶段温度分布和两聚合塔塔顶出水量等结果均与工业值吻合良好,模型可靠。在此基础上,进一步模拟考察了聚合反应过程中进料水含量、分子量调节剂含量、各聚合阶段温度和各聚合塔压力等因素对己内酰胺转化率、环状二聚体生成以及聚合产品分子量的影响,并进行了参数灵敏性分析。结果表明:较低的进料水含量、降低反应温度和前聚塔压力及提高后聚塔的真空度均有利于降低聚合产品中环状二聚体的含量;两个聚合塔下半段的温度变化对环状二聚体产生有显著影响,提高后聚塔真空度可显著提高聚合物分子量。以尼龙6连续聚合过程的环状二聚体含量调控为目标,在优化的操作条件下,尼龙6聚合物中环状二聚体的含量可降低约16%。     

己内酰胺环状二聚体研究进展

详细介绍了己内酰胺环状二聚体的形成原因、α晶型和β晶型的外观形貌和结构特征、以及两种晶形在极性溶剂和高温条件下的相互转变行为。系统阐述了环状二聚体的研究历史、指出了相关文献的错误描述,并结合最新研究成果,全面分析了环状二聚体在聚合和纺丝过程的形态变化,以及环状二聚体的存在对相应工艺和产品的危害。为聚合和纺丝工艺人员对工艺条件进行优化提供了具有价值的理论知识。     

TMDQ及其齐聚物的制备与分离

本文报道了从RD橡胶防老剂工业生产的“前馏份”中分离出2,2,4-三甲基1,2-二氢喹啉(TMDQ),再以此为原料进行聚合得到TMDQ的齐聚物,从齐聚物中分离出二聚物、三聚物和四聚物三个单体,供作RD质量分析用的对照品。     

Estimation and characterization of polyester oligomers

Oligomers were obtained from polyester samples by solvent extraction and dissolution methods. Dioxane, chloroform, and chlorobenzene were used for the extraction method, whereas dimethyl formamide and phenol : tetrachloroethane (1 : 1 mixture) were used for the dissolution method. The oligomers were separated and analyzed by a thin‐layer chromatographic technique. It was observed that extraction with chloroform and dissolution with phenol : tetrachloroethane gave higher oligomer contents. Also, the values were higher for as‐spun fibers. Thin‐layer chromatographic analysis showed that in all the cases lower oligomers were obtained with a maximum of the cyclic trimer, whereas the efficiencies of solvents varied for removal of higher oligomers. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1987–1991, 1999     

The modifying effect of weak aqueous solutions of ammonia on poly(ethylene terephthalate) materials

The effect of water and aqueous solutions of ammonia of 0.02–0.04 M concentration on poly(ethylene terephthalate) and fleecy knit fabric was comparatively investigated at high temperatures. It was found that migration of oligomers to the surface of the polymer, partial hydrolysis of cyclic oligomers to the linear form, and total hydrolysis to TPA are possible under the effect of water, but water affects the knit much less than the film. The presence of ammonia intensifies the processes that can take place with oligomers of PET at high temperatures to a significant degree. The concentration of ammonia in the system determines which of these processes will predominate. It was found that a 0.015–0.03 M concentration of ammonia is optimum for refining polyester fibre materials. __________ Translated from Khimicheskie Volokna, No. 6, pp. 15–18, November–December, 2006.     

Novel aromatic macrocyclic oligomers: intermediates for the preparation of high-performance polymers

Recent studies aimed at the development of macrocyclic oligomers as the intermediates for the preparation of high-performance polymers are reviewed. Efficient methods for the preparation of a range of cyclic oligomers, such as aryl ether ketones, aryl ether phthalazines, aryl ether isoquinolines, aryl ether phthalazinones, and arylene sulfides, have been developed. Cyclization was achieved via a nucleophilic aromatic substitution reaction under high-dilution conditions. The cyclic aryl ether oligomers undergo a facile ring-opening polymerization to form high molecular weight polymer. Cyclic oligomers containing an aromatic sulfide linkage also undergo a facile free-radical ring-opening polymerization to form high molecular weight polymers which can be amorphous or crystalline. Due to their low molecular weights, these cyclic oligomers have very low melt viscosities which makes them attractive intermediates for a variety of applications for which the conventionally prepared high molecular weight polymers would not be suitable.     

己内酰胺水解聚合过程的计算机模拟

用文献实验数据验证了己内酰胺水解聚合过程动力学模型,并对不同反应温度下聚合产物组成（己内酰胺单体浓度与转化率、环状二聚体及水的浓度、数均聚合度和多分散性指数）进行了模拟,得到己内酰胺水解聚合过程用先高温后低温的程序控温方法,与其工业生产实际控温方法完全一致。     

PET中环状低聚物的表征及控制方法的研究进展

鉴于环状低聚物的诸多危害,归纳了PET中环状低聚物的表征方法,具体介绍了低聚物的分离方法及其性能的研究方法,重点总结了目前减少环状低聚物含量的一些新的措施和方法,以期为今后的相关研究提供参考,并提出应该建立工业上简便易行的环状低聚物含量检测方法。     

PET切片低聚物的萃取工艺及其表征

采用索氏萃取法从PET切片中提取低聚物,考察了切片尺寸、萃取时间与萃取量的关系;运用分子质量分布、紫外光谱、红外光谱、DSC进行了表征。结果表明：采用氯仿做萃取剂,80℃下连续回流提取18h可作为常规PET切片低聚物萃取终点的定量方法;提取出的低聚物是混合物,其主要成分为环状三聚物;环状低聚物在PET熔融结晶过程中起到了结晶成核剂的作用。     

Oligomerization of isocyanates by cyclic sulfonium zwitterions

Summary The cyclic sulfonium zwitterions (I) are very effective catalysts for the cyclotrimerization of isocyanates. Under certain conditions (high concentration of isocyanate in the reaction system or high reaction temperature) cyclic sulfonium zwitterions act as anionic initiators. This behavior is due to the reaction of the isocyanate with stabilizing molecules of water of cyclic sulfonium zwitterions followed by rapid polymerization of the initiator. This phenomenon can be easily utilized in the one-step preparation of stable NCO-terminated oligomers of difunctional isocyanates.The support of the Dow Chemical Company is gratefully acknowledged.     

Synthesis and ring‐opening polymerization of macrocyclic aromatic sulfide oligomers

A series of macrocyclic(arylene sulfide) oligomers were synthesized by reaction of 4,4′‐oxybis(benzenethiol) with a number of difluoro compounds in dimethylformamide (DMF) in the presence of anhydrous K₂CO₃ under high dilution conditions. The difluoro compound can be 4,4′‐difluorobenzophenone, bis(4‐fluorophenyl)sulfone or 1,3‐bis(4‐fluorobenzoyl)benzene. Detailed structural characterization of these oligomers by matrix‐assisted laser desorption and ionization‐time of flight‐mass spectroscopy (MALDI‐TOF‐MS) demonstrated their cyclic nature. The MALDI‐TOF‐MS technique has proved to be a powerful tool to analyze these cyclics. These cyclic oligomers are amorphous and highly soluble in DMF and N,N′‐dimethyl acetamide. Moreover, these cyclic(arylene sulfide) oligomers readily underwent ring‐opening polymerization in the melt at 285 °C in the presence of 2,2′‐dibenzothiazole disulfide, affording linear, high molecular weigh poly(aromatic sulfide)s. These polymers are insoluble in most common solvents. Copyright © 2004 Society of Chemical Industry     

PET中环状齐聚物的研究

介绍了PET中环聚物的结构、生成机理和研究方法,分析了环聚物的产生、组成和性质,提出了减少PET中环聚物含量的一些措施。