国产复合引发剂在聚氯乙烯树脂生产中的应用

文章从悬浮聚合引发剂的选择、分析，介绍了105m3聚合釜使用国产TX23／TX36复合引发剂替代EHP单一引发剂生产PVCSG-7型树脂的情况。采用国产复合引发剂不但解决了悬浮聚合反应后期的超温超压现象，还提高了聚合釜的生产能力，降低了树脂成本，提高了产品在市场上的竞争力。     

EHP水服液在PVC生产的应用

1 EHP水乳液应用性实验 1.1小试 在配方、工艺条件及引发剂用量相同的条件下，分别使用天津有机化工二厂生产的EHP甲苯溶液和太原化学工业公司生产的EHP水乳液作为引发剂，在30L小釜中进行PVC-SG1树脂生产的小试研究。使用两种引发剂所需的反应时间对比如下：     

聚合引发剂TX23替代EHP的应用对比

对聚合引发剂TX23替代EHP的可行性进行了论证并试用,介绍了Tx23和EHP引发剂的性能和分解原理,对使用TX23和EHP引发剂生产的树脂的质量、加工性能、母液水等性能进行了对比,找出优缺点,进而拓宽PVC树脂聚合使用的引发剂种类,提高了PVC树脂产品的质量。     

EHP水乳液在PVC生产中的应用

1　 EHP水乳液应用性实验1 .1　小试在配方、工艺条件及引发剂用量相同的情况下 ,分别使用天津有机化工二厂生产的 EHP甲苯溶液和太原化学工业公司生产的 EHP水乳液作为引发剂 ,在 3 0 L小釜中进行 PVC-SG1树脂生产的小试研究。使用两种引发剂所需的反应时间对比如下 :聚合批次　　引发剂种类　　聚合时间 /min　　 1　　　 EHP水乳液 　　　 2 50　　 2　　　 EHP水乳液 　　　 2 50　　 3　　　 EHP水乳液 　　　 2 60　　 4　　　 EHP甲苯溶液　　　 2 4 0　　 5　　　 EHP甲苯溶液　　　 2 60可见 ,使用两种不同形式的引…     

TX99在聚合中的应用

宝硕化工分公司用于氯乙烯聚合的引发剂已从开始的偶氮二异丁氰(AIBN)过渡到过氧化碳酸酯类。最近几年一直采用单一的EHP引发剂。但是，自实施聚合过程中注水的工艺后，初期水油比一步步调整，氯乙烯入料量不断提高，单一的EHP引发剂诱导的反应过程出现了反应后期翘尾、超温超压的现象，被迫提前终止反应，降低了聚合收率。这     

EHP水乳液在PVC生产中的应用

研制成功一种EHP水乳液,将其作为悬浮PVC生产中的聚合物引发剂,制得的SG1型PVC树脂与EHP甲苯溶液作为聚合引发剂时产品质量相当甚至更优,在完成小试与中试的基础上已有批量生产,应用性试验证明使用效果良好,在悬浮PVC生产中EHP水乳液完全可以替EHP甲苯溶液。     

氯乙烯悬浮聚合复合引发剂体系的中试研究

提出了生产3种牌号PVC树脂的复合引发剂配方。中试结果表明:采用悬浮法生产S-700、S-1000和S-1300 PVC树脂时宜分别采用Tx-36和Tx-23、EHP和Tx-99、Tx-99和Tx-23复合过氧化物引发剂体系,聚合时间可控制在3.2~3.8 h,反应过程平稳,反应速率快,生产的PVC树脂质量优良。     

提高EHP水乳液贮存稳定性的探讨

本文主要叙述了国产氯乙烯悬浮聚合引发剂EHP水乳剂的性能、特点及贮存稳定性与国外同类产品的比较,同时对影响EHP水乳剂贮存稳定性的因素作了较深入探讨。     

高聚合度PVC中试配方的调整

在中试装置中对高聚合度PVC（P4000型）配方进行调整：增加TX99和EHP复合引发剂的用量,添加扩链剂C和第3分散剂（醇解度≥88％聚乙烯醇）,使聚合温度由30℃提高到40℃、聚合时间缩短2h,且提高了转化率,改善了树脂的表观密度。     

高效引发剂（TX—99）在大釜（127M^3）生产WS—1300S树脂中的应用

聚氯乙烯装置自开车以来，在127M^3大釜生产WS—1300S树脂时，一直使用的是单一引发剂EHP(过氧化二碳酸二乙基己酯)，其缺点在于反应前期速度较慢，而后期反应速率加快，釜温难以控制，易出现翘尾现象，整个反应时间偏长。TX—99是一种高活性引发剂，应用于WS—1300S树脂生产中可加快聚合前期的反应速度，使反应放热峰前移，达到整个聚合过程平稳放出反应热，缩短聚合反应时间的目的。TX—99在300L釜试验中已取得了成功并已通过公司评审，为此，S—PVC车间在127m^3釜上将TX—99与EHP复合使用于生产WS—1300S树脂，从而缩短了聚合反应时间，提高了生产能力。     

Electrochemically stimulated 2‐ethylhexyl phosphate (EHP) release through redox switching of conducting polypyrrole film and polypyrrole/poly (N‐methylpyrrole) or self‐doped polyaniline bilayers

2‐Ethylhexyl phosphate (EHP) released from poly(pyrrole 2‐ethylhexyl phosphate) (PP‐EHP) was investigated at open circuit and compared with electrochemically stimulated release during potential cycling. It was found that the fast EHP release from the PP‐EHP single layer is substantially retarded and that amounts of spontaneously and electrochemically released EHP can be reduced by constructing bilayers, consisting of a PP‐EHP inner layer and a poly(N‐methylpyrrole)‐poly(styrene sulfonate) (PNMP‐PSS) or self‐doped poly(aniline) sulfonate (SPANI) as the outer films. The presence of outer film over the PP‐EHP allowed surface‐property modification, as well as the control of the rate of EHP release, while electrochemically stimulated EHP release from inner films was not substantially hampered by the outer layer. The quantity of the EHP released was investigated using UV‐vis spectrophotometery and an electrochemical quartz‐crystal microbalance (EQCM) during reduction of PP‐EHP from single layer and bilayers through electrochemical stimulation. EHP was reincorporated to the inner film by applying an anodic potential and then the release of EHP was performed again. The results showed that the outer film could act as a barrier to ion‐and solvent‐transport between the inner film and electrolyte, yielding a more balanced counter‐directional movement of anions. © 2002 Society of Chemical Industry     

Dimerization of 2-Ethylhexylphosphonic Acid Mono-2-ethylhexyl Ester (HEH[EHP]) as Determined by NMR Spectrometry

ABSTRACT

The aggregation state of extractant molecules is an important consideration in characterizing or modeling solvent extraction systems used in hydrometallurgy. For example, previously reported efforts to measure organic-phase dimerization constants have required the presence of an additional phase, either aqueous phase or gas phase. NMR spectroscopy can be used to probe organic-phase inter-molecular interactions without requiring the presence of an additional phase, making it possible to study the simplest organic system, that contain only extractant and diluent. In this report, the dimerization of 2-ethylhexylphosphonic acid mono-2-ethylhexl ester (HEH[EHP]) in n-dodecane and in toluene was investigated by two different NMR-based methods: chemical shifts and Diffusion Ordered SpectroscopY (DOSY). The chemical-shift analysis requires monitoring the chemical shift of the acidic proton as the concentration of HEH[EHP] changes. DOSY is a 2D NMR technique used to probe the size of molecules. The size of diffusing species was related back to the average aggregate molecular weight via a calibration curve. Because the DOSY method had not been used in this manner before, a validation of the method using the interaction constant between HDEHP and CMPO was performed. After this validation, DOSY was applied to HEH[EHP] dimerization. DOSY results demonstrated that the chemical shift of the acidic proton was the peak most affected by the dimerization state of the HEH[EHP]. All other peaks, including that of ³¹P, were affected more significantly by the changing dielectric constant of the solution. The dimerization constants determined were significantly lower than those reported in prior literature, possibly due to the effect of water in the literature values.     

An Advanced TALSPEAK Concept Using 2-Ethylhexylphosphonic Acid Mono-2-Ethylhexyl Ester as the Extractant

A method for separating the trivalent actinides and lanthanides is being developed using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) as the extractant. The method is based on the preferential binding of the actinides in the aqueous phase by N-(2-hydroxyethyl)ethylenediamine-N,N’,N’-triacetic acid (HEDTA), which serves to keep the actinides in the aqueous phase while the lanthanides are extracted into an organic phase containing HEH[EHP]. The process is very robust, showing little dependence upon the pH or the HEH[EHP], HEDTA, and citrate concentrations over the ranges that might be expected in a nuclear fuel recycling plant. Single-stage runs with a 2-cm centrifugal contactor indicate that modifications to the process chemistry may be needed to increase the extraction rate for Sm, Eu, and Gd. The hydraulic properties of the system are favorable to application in centrifugal contactors.     

Combining CMPO and HEH[EHP] for Separating Trivalent Lanthanides from the Transuranic Elements

Combining octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) into a single process solvent for separating transuranic elements from liquid high-level waste is explored. The lanthanides and americium can be co-extracted from HNO₃ into 0.2 mol/L CMPO + 1.0 mol/L HEH[EHP] in n-dodecane. The extraction is relatively insensitive to the HNO₃ concentration within 0.1–5 mol/L HNO₃. Americium can be selectively stripped from the CMPO/HEH[EHP] solvent into a citrate-buffered N-(2-hydroxyethyl)ethylenediaminetriacetic acid solution. Separation factors >14 can be achieved in the range pH 2.5–3.7, and the separation factors are relatively insensitive to pH—a major advantage of this solvent formulation.     

Effect of HEH[EHP] impurities on the ALSEP solvent extraction process

In solvent extraction processes, organic phase impurities can negatively impact separation factors, hydrolytic performance, and overall system robustness. The resulting inconsistent performance can affect the process-level viability of a separation concept, and thus knowledge of the impurities present, their effects on the process, and how to remove them are vital. Deleterious impurities may be introduced into a system from reagent synthesis, or result from degradation via radiolysis and hydrolysis during use. In this work, the acidic extractant, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP])—proposed for application in extractive processes aimed at separating trivalent minor actinides from lanthanides and other fission products—is characterized with respect to its common impurities and their impact on Am(III) stripping in the Actinide Lanthanide SEParation (ALSEP) system. To control impurities in HEH[EHP], existing purification technologies commonly applied for the acidic organophosphorus reagent were assessed and a new chromatographic purification method specific to HEH[EHP] is presented.     

Comparative study of stationary phases impregnated with acidic organophosphorus extractants for HPLC separation of rare earth elements

Chromatographic separation behavior of rare earth elements (REEs) on reversed-phase columns impregnated with di-(2-ethylhexyl) phosphoric acid (H[DEHP]), 2-ethylhexyl, 2-ethylhexyl phosphonic acid (H[(EH)EHP]) and di-(2,4,4-trimethylpentyl) phosphinic acid (H[TMPeP]) were compared utilizing nitric acid as eluent and ICP-MS for detection. Retention factors were determined and compared under the same eluting conditions using columns loaded with approximately 0.4 mmole of each extractant. The separation efficiency was evaluated from resolution data of the REEs acquired under same and optimized elution conditions for each column. The best separation for the entire series of REEs was obtained with H[(EH)EHP], H[DEHP] was found more appropriate for lighter REEs and H[TMPeP] was the best choice for separation of heavy REEs.     

Excitation density dependence of luminescence spectrum of electron-hole plasma in diamond

Time-resolved band edge luminescence spectrum in IIa diamond has been measured with the 5th harmonics of a pulsed YAG laser (5.82 eV) and an ICCD image intensifier of 5 ns gate width at 290 K. The time-resolved luminescence spectrum is decomposed into three components of free exciton (FE), excitonic complex (EC) and electron-hole plasma (EHP). The decay times of the FE and EC luminescence are 45 and 27 ns, respectively and that of the EHP luminescence has been seen to be shorter than the gate width, 5 ns. The low energy onset of the EHP luminescence spectrum has been observed to decrease with increasing excitation density and attains the onset of the electron-hole drop luminescence spectrum at the excitation density of 0.6 J/cm², at which the electron-hole pair density is 1.2 × 10²⁰ cm^? 3. Furthermore, the excitation density dependences of the FE, EC and EHP luminescence intensities are explained with the percolation theory.     

An Organic Liquid Membrane System for the Separation and Production of Histamine

Abstract

The recovery of histamine (Hm) produced by histidine decarboxylase (HD) from histidine (His) by using an organic liquid membrane system was investigated. The system was composed of two aqueous phases (phase I of pH 4.5 and phase II of pH 7.2) separated by a third organic chloroform phase containing di-(2-ethylhexyl) phosphoric acid (EHP) as a carrier. His could not be moved from phase I of pH 4.5, the optimum pH of HD into the organic layer. On the other hand, Hm was moved from phase I into the organic layer, and Hm was released from the organic layer into phase II. The removal of Hm from phase I into the organic layer increased at dose dependency with EHP concentration up to 50 mM and decreased at concentrations above 50 mM. According to these results, the recovery of Hm from His by HD was investigated. In this experiment phase I was pH 4.5 containing 1 mM His, 40 μg/mL pyridoxal-5-phosphate, and a suitable concentration of HD; and phase II was set at pH 7.2. 170 μM Hm (3 h later) and 760 μM (8 h later) were transported into phase II by using 120 μg/mL HD and 50 mM EHP, as confirmed by HPLC.     

引发剂BNP替代EHP在PVC-SG5树脂生产中的应用

研究了BNP作为引发剂等量替代EHP在PVC-SG5树脂生产中的应用,考察了生产的PVC-SG5树脂的质量(包括黏数、白度、增塑剂吸收量、表观密度、250μm筛余物及“鱼眼”数等)。