聚(N-异丙基丙烯酰胺-co-丙烯酸)水凝胶对铜离子的体积响应动力学

采用微波辐射法制备了N-异丙基丙烯酰胺-co-丙烯酸共聚水凝胶,探讨了该水凝胶对Cu²⁺的响应动力学,并估算出此过程中水凝胶的体积收缩速率常数及其反应活化能,同时建立了Cu²⁺浓度对水凝胶体积收缩响应速率常数影响的数学关系模型。实验结果表明,水凝胶对Cu²⁺所产生的体积收缩响应符合拟一级动力学反应。在40～60℃水溶液中,水凝胶的收缩速率随溶液中Cu²⁺浓度的增高而加快,其反应活化能在36～42 kJ•mol^-1之间,且随着溶液中Cu²⁺浓度的增大而逐渐减小。重复性实验表明,该共聚水凝胶经过3次体积收缩(50.0℃溶液)/溶胀(6.0℃溶液)的循环实验,它在含Cu²⁺水溶液中对温度变化仍能保持高灵敏度的体积收缩/溶胀响应,而且其3次体积收缩/溶胀响应值几乎一样,有很好的重现性。     

厌氧氨氧化固定床反应器脱氮性能和过程动力学特性

进行了厌氧氨氧化固定床反应器的运行性能试验,分析了其过程动力学特性。接种反硝化污泥,用模拟废水可成功启动该反应器。当进水总氮浓度为608 mg·L^-1,水力停留时间为2 h,总氮负荷为7.34 kg·m^-3·d^-1时,反应器获得最大基质去除速率6.11 kg·m^-3·d^-1。二级动力学模型和改进的Stover Kincannon模型均适用于非基质抑制状态下的厌氧氨氧化反应器过程模拟。Stover Kincannon模型动力学分析表明,这种反应器的最大基质去除速率可达12.4 kg·m^-3·d^-1,具有较大的脱氮潜能。     

聚丙烯固相接枝丙烯酸聚合动力学及其接枝聚合速率模型

基于自由基固相接枝聚合的终止反应主要是自由基单基终止反应的假设提出了相应的聚合机理,并建立了聚合速率模型,聚合速率与引发剂浓度呈1次方、与单体浓度呈小于1次方关系,与聚合温度服从Arrhenius关系.实验考察了聚丙烯固相接枝丙烯酸体系聚合温度、引发剂浓度、单体浓度与初始接枝聚合速率的依赖关系,这一关系与上述速率模型十分吻合.采用无约束非线性优化方法得到了各参数的全局最优解：频率因子为6.868×10⁹,表观活化能为58.89 kJ•mol^-1,单体浓度的幂为0.78.     

不同金属离子掺杂TiO2薄膜的制备及光催化活性的研究

以溶胶-凝胶法制备了分别用Ag^+、Cu²⁺、Fe³⁺、La³⁺、Ce³⁺和Eu³⁺等离子掺杂的纳米TiO₂薄膜，经XRD和UV-Vis对薄膜样品进行表征并研究了其光催化活性。XRD结果证明，掺镧TiO₂薄膜与未掺杂薄膜的X射线衍射图基本一致，实验条件下主要为锐钛矿型，且掺入La^3+离子使得TiO₂薄膜的晶粒变小。UV-Vis吸收光谱说明当λ＞380 nm时，其吸光度低于0.15。薄膜光催化降解亚甲基蓝的实验表明,La³⁺或Fe^3+掺杂薄膜的光催化降解率远高于未掺杂TiO₂薄膜，而Ce^3+或Cu^2+离子掺杂薄膜与未掺杂薄膜的光催化活性相似，掺Ag⁺或Eu³⁺离子则降低了活性。当最佳掺杂量La³⁺为0.6%或Fe³⁺为1.5%时，光催化降解率分别高达92%和82%。     

电沉积铁氰化镍薄膜的电控离子交换性能

采用电沉积方法在不同导电基体上制备出具有电化学控制离子交换(ESIX)性能的电活性NiHCF(nickel hexacyanoferrate)薄膜.在1 mol•L^-1 KNO₃溶液中采用电势循环可逆地置入与释放碱金属离子,比较了铂、铝和石墨基体上薄膜的电活性、离子交换容量及再生能力;在1 mol•L^-1(KNO₃+CsNO₃)混合溶液中测定了不同浓度下薄膜的伏安特性曲线和电化学交流阻抗谱,分析了薄膜对Cs/K离子的选择性.重点考察了制膜液组成对薄膜电化学性能的影响,通过EDS测定薄膜组成并结合循环伏安曲线分析了薄膜组成和结构与其电化学特性之间的关系.实验表明,3种基体材料上均能制得性能稳定的NiHCF膜,铝和石墨基体上的NiHCF薄膜同样具有良好的ESIX性能;控制制膜液组成可得到不同组分占优的膜,由此可筛选较为理想的ESIX膜材料.     

负载型二氧化钛光电催化降解苯酚废水的反应动力学

采用浸渍提拉法制备发泡镍载二氧化钛薄膜电极,并以其为工作电极,建立三电极光电催化体系,对该体系降解苯酚的动力学进行了研究.考察了反应液初始pH值、反应物初始浓度、催化剂用量、光辐照强度、外加直流偏压值对光电催化反应速率的影响,采用幂指数方程描述反应动力学,得到方程C=C₀exp(-0.5430 C ^-0.4241 ₀ E ^0.2968 Q ^0.5418 I ^0.5877 t).方程计算值与实验值吻合较好,误差基本在15％以内.     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明,NO与Co(NH₃)²⁺₆的反应为瞬间反应,当Co(NH₃)²⁺₆浓度低于20mmol•L^-1时过程为双膜控制,当Co(NH₃)²⁺₆浓度大于20mmol•L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低,气相中氧的存在有利于NO的吸收,但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.     

亚硫酸盐强制氧化传递与化学反应动力学

在湿法烟气脱硫的过程中,吸收塔底部发生的反应主要是亚硫酸钙和空气或氧气之间的气液传递与化学反应过程,根据双膜理论模型,分析了该反应的吸收机理,用一种图像边界识别的方法分析亚硫酸盐强制氧化气液反应.在没有催化剂或固定钴离子催化剂浓度时,SO^2-₃存在临界浓度0.328 mol•L^-1.当SO^2-₃的浓度低于0.328 mol•L^-1时,过程为双膜控制,SO^2-₃的反应级数为1;当SO^2-₃的浓度大于0.328 mol•L^-1时,过程逐渐变为气膜控制,SO^2-₃反应级数为0.当固定SO^2-₃浓度时,催化剂钴离子的反应级数则受到气液传质的影响,分为几个阶段,且反应级数不同.     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明，NO与Co(NH₃)²⁺₆的反应为瞬间反应，当Co(NH₃)²⁺₆浓度低于20mmol•L^-1时过程为双膜控制，当Co(NH₃)²⁺₆浓度大于20mmol•L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低，气相中氧的存在有利于NO的吸收，但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.     

双搅拌釜中半胱氨酸亚铁溶液吸收NO的传质-反应动力学

以半胱氨酸亚铁络合物Fe(Ⅱ)(CyS)₂作为吸收剂,在双搅拌釜内探讨了NO吸收反应动力学.实验结果表明：在pH=8.0,T=323 K实验条件下,半胱氨酸亚铁溶液吸收NO气体为快速拟一级反应,得到二级反应速率常数k₂=1.18×10⁵ m³•mol^-1•s^-1.3种理论模型即膜模型、Danckwerts表面更新模型、Higbie渗透模型应用于该拟一级反应,增强因子的计算结果是相同的.实验获得的增强因子与模型计算值吻合较好,最大相对偏差不超过13％.     

PE—LD吸氧薄膜的研制

采用铁系脱氧剂、乙烯-乙烯醇共聚物(EVOH)、相容剂和PE-LD,通过双螺杆挤出机制备吸氧母料,将其与适量PE-LD混合经单螺杆挤出机吹塑成吸氧薄膜。考察了吸氧薄膜配方、温度和湿度对吸氧性能的影响。结果表明,随着铁系脱氧剂和EVOH含量的增加、环境温度的提高以及环境湿度的变大,薄膜吸氧量会随之增加;随着薄膜厚度的增加,薄膜吸氧量减少。     

HEAT AND MASS TRANSFER WITH POLYCONDENSATION IN RESIN FILM DURING DRYING

ABSTRACT

In a drying process of dielectric resin films coated on electric conductive substances, phenomena such as polymerization of monomers, by-products yield, shrinkage and stress generation lake place simultaneously in addition to heat and mass transfer. For the enhancement of the drying with high efficiency and high quality, it is important to understand the drying mechanism. In this paper, the characteristics of heat and mass transfer in the resin film including polycondensation reaction are presented. The apparent drying rate of polyamideimide varnish films was measured in two different heating modes of radiation and convection. The reaction rate of polycondensation was analyzed both by the thermogravimetry and the differential scanning calorimetry. The apparent drying rate began to drop remarkably when the reaction rate became significant. It implies that the diffusion of the solvent is inhibited by skinning at the surface. Applying the Vrentas/Duda free-volume diffusion model to the prediction of diffusivity, the heat and mass transfer in the resin film were analyzed theoretically with a reasonable accuracy.     

Barrier property and morphology of polypropylene/polyamide blend film

The barrier property of polypropylene (PP)/polyamide (PA) blend film produced by the extrusion casting film process was studied by investigating the effects of rheological properties of each components, compatibilizer content, screw rpm, and the absorbed moisture, and by performing morphological analysis and permeability modeling. The oxygen barrier property of blend film with ellipsoidal structure of PA dispersed phase was significantly improved by a factor of 5.4 with the addition of only 20 wt% PA, when compatibilizer was added by the content of 7 phr and the PP matrix resin and process condition was selected to induce lower viscosity ratio less than unity. Using Fricke’s model with the value of 19.6 of aspect ratio of the ellipsoid, the permeabilities of blend films as a function of PA content could be predicted and exhibited a good agreement with the experimental results. The absorbed moisture had a significant influence on the barrier property of the PP/PA blend system, suggesting that the hygroscopic PA resin should be incorporated with the high water barrier PP resin by the amount below about 20 wt% to minimize the deterioration of the barrier property in the humid atmosphere.     

Electrocatalytic reduction of oxygen at electropolymerized films of metalloporphyrins deposited onto multi-walled carbon nanotubes

The electrocatalytic reduction of oxygen at electropolymerized films of a number of different manganese, iron and cobalt porphyrins supported on multi-walled carbon nanotubes (MW-CNTs) which have been pre-stabilized with ultra-thin layers of organic 4-(pyrrole-1-yl) benzoic acid (PyBA) is reported. Special emphasis has been on the multiple oxidation states of manganese as central metal ion and its potential advantages for the electron transfer process during the reduction of molecular oxygen in a 0.1 M phosphate buffer solution. Electropolymerization of metal porphyrins leads to catalytically active films on the electrode. The incorporation of MW-CNTs in the film leads to a significant decrease in the hydrogen peroxide produced during the oxygen reduction reaction (ORR) and a significant positive shift of the oxygen reduction potential. Of the complexes studied, manganese tetratolyl porphyrin (MnTTP) has shown the best activity and stability towards oxygen reduction.     

米格列醇在大孔D001树脂上的离子交换性研究

为掌握米格列醇在离子交换树脂上的吸附行为,采用改变恒温振荡器的温度、震荡速率和溶液pH值来研究固定浓度的米格列醇溶液在定量树脂上的离子交换吸附行为,并结合热力学和动边界模型对交换过程进行分析.结果表明:吸附温度增大,分配系数KD变小,吉布斯函数值△G变大,不利于离子交换吸附,离子交换过程为放热过程;米格列醇溶液在中性条...     

Reactive sputter-deposition of oxygenated amorphous carbon thin films in Ar/O2

Oxygenated amorphous carbon thin films were deposited by DC magnetron sputtering using various argon and oxygen process gas mixtures. The X-ray diffraction data indicated that the predominantly amorphous films had more defined peaks with a higher partial pressure of oxygen. Results indicated that use of oxygen in the working gas enhanced the crystalline nature of the films. Scanning electron and atomic force microscopy revealed that the surface roughness and film topography differed with the oxygen process gas variations. X-ray photoelectron spectroscopy revealed increased surface oxygen content with higher oxygen concentration in the working gas. Raman spectroscopy results suggested that the increased oxygen in the films may have led to a higher percentage of sp³-bonded carbon atoms. The growth rate (deposition rate) of the films decreased as the amount of oxygen increased. This decreased deposition rate was associated with an oxygen etching of the film.     

五层共挤阻隔膜的制备与性能研究

选用乙烯?乙烯醇共聚物(EVOH)为阻隔层原料,采用5层共挤薄膜吹塑机制备了5层共挤阻隔膜,并对其力学性能和阻氧性能进行了研究.结果表明,制备的阻隔膜各层厚度较均匀,拉伸强度可达30 MPa,热合强度超过35 N/15 mm,氧气透过量可达0.4 cm3/(m2·d·0.1 MPa);随着阻隔层厚度的增加,阻隔膜的阻氧...     

新型紫外线固化环氧树脂/丙烯酸酯改性水性聚氨酯的合成与性能

合成了一种新型的具有高交联密度和优异涂膜性能的环氧树脂和丙烯酸酯同时改性的紫外线（UV）固化水性聚氨酯（UV-EP-AC-WPUD）。通过环氧基团与以异氰酸酯基团（-N=C=O）封端的聚氨酯预聚体之间的反应引入质量分数为4%的环氧树脂E-20。同时,通过聚氨酯链的-N=C=O与二元丙烯酸酯（PEDA）以及季戊四醇三丙烯酸酯（PETA）的羟基之间的反应引入碳碳双键（C=C）,C=C的含量达到4.65 meq·g-1。 质量分数为3%的光引发剂Irgacure 2959被用于引发涂膜中C=C的聚合,涂膜的凝胶含量在12 s UV辐射之后达到91%,意味着C=C的聚合和交联速度快,同时所得到的涂膜的交联度非常高,不溶于溶剂丙酮,测试表明环氧树脂和两种丙烯酸酯单体已经成功嵌入聚氨酯链中,涂膜具有优异的力学性能和化学性能。     

Planarizing CVD diamond films by using hydrogen plasma etching enhanced carbon diffusion process

Polycrystalline diamond films, deposited by microwave plasma chemical vapor deposition (MPCVD), were planarized in hydrogen plasma under the graphitization of iron film obtained by reduction of iron chloride under hydrogen plasma ambient. For this process, the free-standing diamond films were dipped in a saturated iron chloride solution and dried horizontally in atmospheric ambient. Then the diamond samples were heated by hydrogen plasma in the same MPCVD reactor. Under the effect of hydrogen reduction, iron thin film was formed on the surface of diamond films. Under ca. 800 °C, the carbon diffusion process was carried out under the graphitization effect of iron thin film. Since the iron film used in this process is very thin, the diffused carbon will diffuse from the diamond side to the hydrogen plasma side and then etched away by the plasma. Therefore, the etching rate of diamond film can be kept consistent. After etching the growth surface of a free-standing diamond film, we investigated the surface morphologies and the carbon phases on the etched surfaces of diamond films. Finally, compared with the result of mechanical lapping experiments, we suggest that the hydrogen plasma etching enhanced carbon diffusion process can serve as a new planarization method for rough diamond film surface. A mechanism for this enhanced etching effect is also presented and discussed.     

Preparation and characterization of polysiloxane‐modified epoxy resin aqueous dispersions and their films

Polysiloxane‐modified epoxy resin aqueous dispersions were prepared by the reaction of amino‐polysiloxane (APS) with a graft epoxy resin that was synthesized with a diglycidyl ether of bisphenol A type epoxy resin and styrene/acrylic acid. The measurements of the epoxy values and FTIR spectra confirmed that this reaction really took place. The modified aqueous dispersion exhibits high viscosity, small particle size, and nearly the same surface tension as the unmodified one. Therefore, this indicates that the siloxane segments could be encapsulated into graft epoxy resin particles during the water dispersion process. For APS‐modified films, the thermal stability and water resistance are remarkably enhanced. Furthermore, lowering of the hardness and surface tension for these films was also observed and the surface composition was measured by X‐ray photoelectron spectroscopy. The experimental data indicate that the siloxane segments easily migrate onto the surface during the film formation process and finally enrich on the surface of the APS‐modified film. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 880–885, 2005