HDPE预辐照接枝SSS与AA体系的反应动力学研究

采用电子束引发预辐照接枝方法在高密度聚乙烯(HDPE)上接枝丙烯酸(AA)与对苯乙烯磺酸钠(SSS)两种单体,以制备含磺酸和羧酸基团的双功能基阳离子交换膜。研究发现,接枝速率与辐照剂量、单体总浓度及反应温度密切相关。接枝反应的活化能为22．2kJ／mol。傅立叶变换红外光谱(FTIR)测试表明,接枝膜上引入了磺酸基团和羧酸基团。     

γ射线辐照聚偏氟乙烯接枝苯乙烯磺酸乙酯

以聚偏氟乙烯(Polyvinylidene fluoride,PVDF)树脂为基材,采用γ射线预辐射接枝法在PVDF树脂上接枝苯乙烯磺酸乙酯(Ethyl styrenesulfonate,ETSS),探讨吸收剂量、接枝温度、接枝反应时间及单体浓度对接枝率的影响。之后在95℃水解PVDF-g-PETSS聚合物得到PVDF接枝苯乙烯磺酸(PVDF-g-PSSA)离子交换树脂。红外光谱、X射线光电子能谱、热重分析证明PVDF-g-PETSS及PVDF-g-PSSA被成功制备。当接枝率为120%时,PVDF-g-PSSA的离子交换容量达到2.05 mmol/g。这种将带有磺酸基团的单体通过辐照接枝引入PVDF基材然后水解的方法简单、高效、污染小,有望在离子交换树脂及离子交换膜的制备中得到应用。     

聚乙烯辐照接枝体系改变pH对接枝率的影响

采用γ射线辐照引发接枝的方法，在高密度聚乙烯（HDPE）上接枝丙烯酸（AA）和对接枝苯乙烯磺酸钠（SSS），制备了一种含羧酸基团和磺酸基团的阳离子交换膜，详细研究了反应体系在不同pH值下的接枝率变化规律。实验表明，在共辐照接枝方法中，当AA与SSS一步法接枝HDPE或接枝上AA的HDPE膜再共辐照接枝SSS时，总接枝率（Gt）及对苯乙烯磺酸钠的接枝率（Gs）随体系的pH的降低而升高，在预辐照一步法接枝中，Gt与Gs随体系pH的降低先升高后又有所降低，综合分析认为，改变pH值使体系粘度发生变化，从而影响了单体向基体的扩散速率。     

电子束引发双功能基阳离子交换膜的制备研究

在所有的离子交换膜中,最引人注目的当数20世纪70年代已商品化的Nation系列膜。具有磺酸功能基的Nation膜电阻低,但用在氯碱工业时电流效率低。1974年Seko发明了全氟羧酸阳离子交换膜,使电流效率有实质性提高,并推动了复合膜的发展。复合膜具有磺酸膜的低电阻性能和羧酸膜的高电流效率。本工作采用辐射接枝法制备含羧酸基团和磺酸基团的双功能基阳离子交换膜,目的主要是以低成本且简单可行的辐射接枝法代替共聚法,制备稳定性好、低电阻、高电流效率的阳离子交换膜。     

HDPE膜电子束引发预辐照接枝甲基丙烯酸缩水甘油酯的研究

用电子束引发预辐照接枝的方法，在高密度聚乙烯（High density polyethylene，HDPE）薄膜上接枝甲基丙烯酸缩水甘油酯（Glycidyl methacrylate，GMA），制备了含有高活性环氧基团的聚合物膜。详细研究了单体浓度、反应温度和时间以及吸收剂量等因素对接枝率的影响规律。应用傅立叶变换红外光谱（FT-IR）、差示扫描量热仪（DSC）、原子力显微镜（AFM）研究了接枝物的组成、热性能和表面形貌。FT-IR测试表明接枝物为HDPE-g-GMA共聚物；接枝膜的熔融温度Tm以及修正后HDPE组分△Hf（HDPE）均随着接枝率的增大而降低，原因归结于HDPE接枝后结晶度降低。HDPE-g-GMA膜的AFM图像显示其表面粗糙度增加，进一步证明膜表面发生了接枝反应。     

HDPE膜预辐照接枝VBTAC制备阴离子交换膜

在氮气保护下,利用预辐照接枝技术在高密度聚乙烯(HDPE)膜上接枝苯乙烯三甲基氯化铵(VBTAC)单体,以甲基丙烯酸二甲氨基乙酯(DMAEMA)单体作为接枝辅助单体来提高VBTAC的接枝率,制备出阴离子交换膜,解决了在HDPE上难以直接接枝聚合VBTAC的问题.本文研究了接枝条件及接枝液的组分对接枝的影响,并用X射线显微分析方法研究了VBTAC的接枝进程和接枝分布.     

偕胺肟功能化水热碳微球对铀的吸附性能

为在碳微球表面引入偕胺肟基团,采用丙烯腈接枝淀粉为原料,通过水热法成功制备偕胺肟功能化水热碳微球(HTC-AO),并研究了HTC-AO对水溶液中铀的吸附性能,HTC-AO对铀吸附的最佳pH=6.0,吸附量最大为455.6mg/g,吸附过程符合Langmuir等温方程和准二级动力学方程。热力学研究表明,吸附过程为自发吸热过程。选择性研究结果表明,在多种离子共存的情况下HTC-AO对铀具有很高的选择性。     

辐射法制备含氟磺酸型质子交换膜

含氟磺酸型质子交换膜是一类具有高热稳定性、化学稳定性及良好机械性能的离子交换膜，具有极其广阔的应用前景。采用辐射法制备了一种含氟磺酸型质子交换膜，分别测试了该膜的抗拉强度、面电阻、吸碱率等物理化学性能，通过扫描电镜观察了其表面形貌并对其在质子交换膜燃料电池中的应用进行了初步研究。     

预辐射接枝法制备FEP-g-PSSA/AA膜

采用γ射线预辐射接枝方法制备了FEP—g—PSSA／AA膜，反应制得的接枝膜是一种含氟磺酸型质子交换膜。系统研究了影响接枝反应的阻聚剂用量、膜的厚度、单体摩尔比及总摩尔浓度变化等因素。结果表明，丙烯酸（Acrylic acid，AA）与苯乙烯磺酸钠（Sodium styrene sulfonate，SSS）对全氟乙丙烯（Polytetranuoroethyleneco-hexanuoropropylene，FEP）的接枝率几乎不受膜厚度变化的影响，而且全氟乙丙烯（FEP）辐照后放置三个月再进行接枝反应，接枝率也几乎没有变化。     

用辐射接枝法对HDPE膜进行功能化改性

利用预辐射接枝技术,在聚乙烯膜上接枝苯乙烯磺酸钠（ＳＳＳ）、苯乙烯三甲基氯化铵（ＶＢＴＡＣ）等具有离子交换性能的单体,研制出具有抗菌性能的离子交换膜,并且使得原先增水性的基膜转变为亲水性较好的膜。通过实验,掌握了膜的接枝工艺,并对膜接枝过程、结构特征、经性能有较多的了解。从各个角度对膜的亲水性能作了定量研究,提出了水合数与表面自由能的计算方法。对几种膜的抗菌性能进行了评价。确定了ＶＢＴＡＣ膜作为抗     

Time dependence of linear stability parameters of a BWR

In this work we present several tools to study the time dependence of the linear stability parameters of a BWR using neutron noise analysis. Particularly, we have studied the variation in time of the fundamental frequency of a signal using the short-time Fourier transform and we have compared this method with the calculation of a time dependent Power Spectral Density (PSD) function. The temporal variation of the decay ratio is analysed using a method based on an autoregressive model to fit the different blocks of the signal. The performance of the tools presented is compared analysing analytic signals and a real signal of Forsmark 1&2 Stability Benchmark.     

Semi-physical identification of dynamic properties in a thermohydraulic channel

The aim of this work is to investigate whether it is possible to extract information from process noise measurements by combining physical knowledge with system identification methods. This could be used for implicit measurements of process variables, tuning the model in a multidimensional parameter space, or simply for increasing our knowledge of the dynamical process, for example BWR stability.     

Analysis of Core Stability Measurement Data of Advanced 9×9 Fuel Assembly in a BWR Core

The core stability measurements were taken during the cycle-9 startup of the 1,300MWe BWR, Kernkraftwerk Kruemmel (KKK). The core contained advanced 9×9 type high burn-up design reload fuel with a higher enrichment than current 8x8 fuel. A design feature of the advanced 9x9 fuel assembly (FA) is a large square water channel for enhanced neutron moderation. The measurement data as a function of core flow and power showed almost the same stability characteristics as those of the past measurement during the cycle-3 startup of the KKK core with the 8×8 FA. The local power range monitors (LPRM) detected neutron flux oscillations in both core-wide in-phase and half-core out-of-phase modes.

The frequency-domain stability analysis using the STAIF-PK code well reproduced the measurement result that the onset of unstable operation in KKK first occurs when about half of the reactor internal pumps are operating and the other half are stopped. The stability performance of the advanced 9×9 FA in the core was compared with the 8×8 FA by a design parameter analysis with respect to thermal-hydraulic and neutronic design. It has been demonstrated by the analysis that the stability performance of the advanced 9×9 FA is comparable with current 8×8 FA.     

Design of Balanced Reactor Welded with Water-Cooled Aluminum Busbars

A new process of welding aluminum water-cooled busbars is proposed. It can not only reduce the weight and cost, but also improve the dynamic and thermal stability. Furthermore, both finite element method analysis and a prototype test testify the advantages of the design which is not limited by load current and provides a new approach for water-cooled reactors.     

装有稳压仪的电子静电加速器运行情况

随着辐射加工技术的发展,在国内,小功率的电子静电加速器也越来越多地用于工业生产,并要求加速器长期稳定运行。为此,于85年初,在我们的加速器上装上了由上海原子核所研制成功的稳压仪,到目前为止,加速器运行稳定。     

Preliminary Design and Analysis of the DC Reactor for the ITER Converter

The DC reactor is an important piece of equipment for restraining loop and ripple currents in the international thermonuclear experimental reactor （ITER） converter power supply system. As the reactor is operated at a steady state of 27.5 kA and needs to withstand a peak current of 175 kA, so the design of the DC reactor used in the ITER converter power supply system is necessary. A new water-cooling dry-type air-core reactor is designed in this work. The detailed structural parameters are calculated by theoretical formulas, and then the structure is optimized by electromagnetic simulation with ANSYS. Finally, thermal and dynamic stability analyses are performed to verify the temperature and stress at a rated current of 27.5 kA and pulsed current of 175 kA. The analysis results show that the temperature and stress meet the requirements of the ITER converter power supply system.     

Dynamic Stability Study of Static Gas Bearing for Small Cryogenic Turbo-Expander

An experimental method is presented to analyze the dynamic stability of the gas bearing for small cryogenic turbo-expanders. The rotation imbalance response and...     

低压流气系统稳定度研究

一、前言低压流气系统在平行板雪崩室、低压正比室以及基于气体电离室、正比室的焦面探测器和重粒子探测器中被广泛地应用,同时在一些化工及其他现代工业中要求高稳定流气气氛的工艺中也有很大用途。基于浮子稳压器的低压流气系统有制作简单,使用方便等优点,本文通过一些实验以及实验和理论估计的对比找出了提高流气系统工作气压稳定度的一些条件,为制造高稳定度流气系统提供了一点经验。     

基于Nyquist准则的超临界水冷堆热工水力系统稳定性分析

针对超临界水冷堆热工水力系统简化模型,采用微扰动线性化及Laplace变换的方法,对热工水力系统的非线性守恒方程进行线性化处理,推导出闭环系统传递函数。用Matlab软件对闭环系统进行了分析和仿真,得到模型闭环系统的稳定边界图,并分析了堆芯入口流速、加热段长度、重力加速度、入口节流系数对系统稳定边界的影响。结果表明,增大堆芯入口流速、加热段长度、重力加速度有利于系统的稳定,而入口节流系数对稳定性边界影响不大。     

高分辨率HPGe探测器及其稳定性

半导体探测器具有良好的能量分辨率,在能谱分析中已引起人们广泛的兴趣。Si材料原子序数(Z=14)较小,探测能量大于30keV的射线时,其效率迅速下降,因此人们选用Ge(Li)探测器。但它在制造和使用中存在两个主要的问题,一是必需用Li离子补偿Ge材料,二是Li在Ge中固有的不稳定性,使器件严禁升高到室温,即使是偶然的一次,也会导致器件的补偿度毁坏。这两个缺点,在用高纯Ge材料制备的探测器(HPGe探测器)中是不存在的,