乙炔氢氯化反应铜基催化剂研究进展

开发乙炔氢氯化无汞催化剂对我国聚氯乙烯(PVC)工业具有重要意义,目前以金为代表的贵金属催化剂已经接近工业化应用,但其生产成本高限制了其市场推广,因此相对价廉的铜基催化剂受到广泛关注。主要从配体和载体改性等方面综述了科研人员对金属铜基催化剂在乙炔氢氯化反应中性能提升所做的工作,并且总结了含铜多金属催化剂在乙炔氢氯化反应中的研究进展,最后对铜催化剂工业发展前景进行了展望。     

氯碱工业汞污染问题分析

由于汞的使用和管理不善,采用水银电解法生产烧碱过程中,大量的汞随废水和盐泥排到外环境中;采用乙炔法生产醋酸或氯乙烯时,因使用含汞催化剂,生产中也会有少量汞随废水排入到外环境,造成严重的汞污染.我国虽然于"十五"初期已彻底淘汰水银法烧碱,"十五"后期淘汰了汞法醋酸,但这两类装置遗留的汞污染问题依然十分严重,乙炔法氯乙烯生产排放的含汞废水问题也不应忽视,各级政府和管理部门对此要高度重视,争取早日解决现存的汞污染问题.     

Electrochemical corrosion behavior of 300M ultra high strength steel in chloride containing environment

The electrochemical corrosion behavior of 300M ultra high strength steel in chloride containing environment was investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results show that uniform corrosion occurs on 300M steel during the electrochemical measurements because no anodic passivation phenomenon is observed on polarization curves within the measurement range. The tests also show that 300M steel is highly susceptible to chloride containing solution, which is characterized by corrosion current density increasing with the addition of chlorides, and corrosion potential shifting towards positive direction and corrosion resistance decreasing, positively suggesting that chloride ions speed up the corrosion rate of 300M steel. Meanwhile corrosion products on the 300M steel surface formed during the salt spray test are too loose and porous to effectively slow down the corrosion rate. Additionally, a schematic structure of uniform corrosion mechanism can explain that 300M steel has better property of stress corrosion cracking (SCC) resistance than stainless steels.     

Irreversible dilation of NaCl contaminated lime-cement mortar due to crystallization cycles

The mechanism of damage occurring in NaCl contaminated materials has not been clarified yet. Apart from crystallization pressure, other hypotheses have been proposed to explain the cause of decay. Irreversible dilation has been observed in a few cases but has never been studied in a more systematic way. The aim of the research is to contribute to the modeling of this phenomenon.In the present paper the effect of NaCl on the hydric and hygric behavior of a lime-cement mortar is extensively studied. The results indicate that NaCl influences the hydric and hygric dilation behavior of the material. The material contaminated with NaCl shrinks during dissolution and dilates during crystallization of the salt. This dilation is irreversible and sufficient to damage the material after few dissolution/crystallization cycles. This behavior is not restricted to NaCl, but is observed in the presence of other salts as well (NaNO₃ and KCl). Outcomes of electron microscopy studies suggest that salts causing irreversible dilation tend to crystallize as layers on the pore wall.     

乙烯基橡胶增韧双马来酰亚胺树脂的研究

采用二烯丙基双酚A(DP)与乙烯基橡胶对两种结构类型双马树脂进行增韧。探讨了乙烯基橡胶用量对改性树脂的力学性能、耐热性能及玻璃化转变温度的影响,确定当乙烯基橡胶用量为5%(占双马树脂)时,改性树脂具有较好的综合性能,较未增韧前有大幅提高。此时,冲击强度为23.17kJ/m2,GIC值为338.5J·m-2,玻璃化转变温度为241℃,5%热失重温度约在420℃。同时,通过SEM观察其断面的微观形貌为典型的韧性破坏。     

VAc／BA／AA乳液共聚反应动力学研究

用丙烯酸丁酯（BA）和丙烯酸（AA）对醋酸乙烯酯（VAc）进行共聚改性,制备了稳定的VAc／BA／AA共聚乳液。研究了该聚合体系的动力学特征,讨论了乳化剂浓度（CE）、引发剂浓度（C1）和反应温度（T）对聚合速率和单体转化率的影响。实验结果表明,乳液聚合速率随着CE、C1和T的增加而增大;单体转化率随着CE和C1的增加而增大,在75℃时转化率有最大值;得到该共聚乳液体系的表观活化能Ea=64．4kJ·mol^-1;聚合反应速率Rp^∝CE^0.45C1^0．76该式与经典的乳液聚合动力学模型有较大偏差。     

Evaluation of chloride penetration in high performance concrete using neural network algorithm and micro pore structure

Chloride attack is one of the major causes of deterioration of reinforced concrete structures. In order to evaluate the chloride behavior in concrete, a reasonable prediction for the diffusion coefficient of chloride ion, which governs mechanism of chloride diffusion inside concrete, is basically required. However, it is difficult to obtain chloride diffusion coefficients from experiments due to time and cost limitations.In this study, a numerical technique for chloride diffusion in high performance concrete (HPC) using a neural network algorithm is proposed. In order to collect comparative data on diffusion coefficients in concrete with various mineral admixtures such as ground granulated blast-furnace slag (GGBFS), fly ash (FA), and silica fume (SF), a series of electrically driven chloride penetration tests was performed. Seven material components in various mix designs and duration time are selected as neurons in a back-propagation algorithm, and associated learning of the neural network is carried out. An evaluation technique for chloride behavior in HPC using the obtained diffusion coefficients from the neural network algorithm is developed based on, so-called, Multi-Component Hydration Heat Model (MCHHM) and Micro Pore Structure Formation Model (MPSFM). The applicability of the developed technique is verified by comparing the analytical simulation results and the experimental results obtained in this study. Furthermore, this proposed technique using the neural network algorithm and micro modeling is applied to available experimental data for verification of its applicability.     

Effects of chloride and sulfate on the rate of oxidation of ferrous ion by H2O2

The rates of oxidation of Fe(II) by H(2)O(2) in the presence of sodium perchlorate, sodium nitrate, sodium chloride and sodium sulfate salts (0-1M) have been compared in the study. Experiments were carried out in a batch reactor, in the dark, at pH <3, 25+/-0.5 degrees C and at controlled ionic strength (< or =1M). The experimental results showed that the rates of oxidation of Fe(II) in the presence of chloride, nitrate and perchlorate were identical. In the presence of sulfate, the rate of oxidation of Fe(II) was faster and depended on the pH and the concentration of sulfate. The pseudo second-order rate constants for the reaction of H(2)O(2) with Fe(2+), FeCl(+) and FeSO(4) were determined as 55+/-1, 55+/-1 and 78+/-3 M(-1) s(-1), respectively.     

硅烷膏体浸渍剂在保护混凝土中的实际应用

渗透型有机硅成功用于保护混凝土在国外已有数十年的历史。用于保护钢筋混凝土，它可防止水分及氯离子的渗透，从而对于防止混凝土的腐蚀与破坏起到关键的作用。这种浸渍剂一般都由硅烷或硅氧烷组成。通常情况下，由于这些低粘度的液体非常容易挥发。尤其在桥梁底面及立面施工时，有效成分大量流失。为了避免出现这种情况，德国瓦克化学有限公司成功开发了一种新型的硅烷乳膏状产品。这种材料施工简单，只需一步完成，具有很高的遮盖率，由于不流淌，活性组分不会损失。与混凝土表面接触时间长，保证了在高等级混凝土中的渗透深度，而且在其表面不会残留任何痕迹。     

Experimental investigation and numerical modeling of chloride penetration and calcium dissolution in saturated concrete

Chloride penetration and calcium dissolution have been investigated for a saturated concrete after exposure to a 0.5 mol/L NaCl solution for a period of up to 3150 days. Simultaneous ion transport model (SiTraM) that allows the transport of chloride and calcium ions to be simultaneously simulated in a hydrated cement system has been used to verify the experimental results.Self-compacting concrete (SCC) with a water to cement ratio of 0.3 resulted in a limited chloride penetration depth while the calcium dissolution was also reduced within the near surface zone. Increased unit water content for normal concrete resulted in higher chloride penetration depth and larger dissolution front of Ca(OH)₂ regardless of having the same water to cement ratio.It was revealed that the SiTraM can predict the profiles of chloride and calcium for self-compacting concrete. It was also found that the primary factor to control chloride penetration front and the dissolution front of Ca(OH)₂ was the pore structure characteristic of concrete.