TBBPAER/DDM的固化反应动力学

用等温差示扫描量热法研究了4，4’-二氨基二苯甲烷固化四溴双酚-A环氧树脂的反应动力学，测定了固化反应热，得出了不同温度下固化反应速率与反应程度、固化反应程度与反应时间的关系曲线．结果表明等温固化反应按自催化反应机理进行，用Kamal方程较好地描述了不同温度下其固化反应的自催化反应过程，并反映出不同温度下扩散作用的差别，其动力学参数k1、k2、m、n由非线性回归法拟合而出，k1、k2对应的反应表现活化能分别为52．2kJ·mol-1和46．5kJ·mol-1。     

2－乙基－4－甲基咪唑固化环氧树脂的固化反应机理、动力学及其反应活性

本文应用ＤＳＣ和ＦＴＩＲ对２－乙基－４－甲基咪唑固化双酚Ａ二缩水甘油醚型环氧树脂体系的固化反应机理和２－乙基－４－甲基咪唑固化双酚Ａ二缩水甘油醚型、缩水甘油酯与脂环型环氧树脂体系的固化反应特征、动力学及其反应活性进行了研究．结果表明，双酚Ａ二缩水甘油醚型环氧树脂／咪唑体系的固化反应是分两步独立进行的，第一步是加成反应，第二步是催化聚合反应．缩水甘油酯与脂环型环氧树脂（ＴＤＥ－８５）／咪唑体系的固化反应过程也分两步进行，第一阶段反应主要是缩水甘油酯型环氧基进行的加成反应和催化聚合反应，第二阶段主要是脂环型环氧基进行的加成反应．各体系第一阶段的表现反应活化能均低于第二阶段活化能．当ＴＤＥ－８５型环氧树脂中引入缩水甘油醚型环氧树脂后，固化反应速率均较ＴＤＥ－８５环氧树脂单独固化时快．     

2－乙基－4－甲基咪唑固化环氧树脂的固化反应机理、动力学及其反应活性

 本文应用ＤＳＣ和ＦＴＩＲ对２－乙基－４－甲基咪唑固化双酚Ａ二缩水甘油醚型环氧树脂体系的固化反应机理和２－乙基－４－甲基咪唑固化双酚Ａ二缩水甘油醚型、缩水甘油酯与脂环型环氧树脂体系的固化反应特征、动力学及其反应活性进行了研究．结果表明，双酚Ａ二缩水甘油醚型环氧树脂／咪唑体系的固化反应是分两步独立进行的，第一步是加成反应，第二步是催化聚合反应．缩水甘油酯与脂环型环氧树脂（ＴＤＥ－８５）／咪唑体系的固化反应过程也分两步进行，第一阶段反应主要是缩水甘油酯型环氧基进行的加成反应和催化聚合反应，第二阶段主要是脂环型环氧基进行的加成反应．各体系第一阶段的表现反应活化能均低于第二阶段活化能．当ＴＤＥ－８５型环氧树脂中引入缩水甘油醚型环氧树脂后，固化反应速率均较ＴＤＥ－８５环氧树脂单独固化时快．     

纳米SiO2的修饰改性及其在紫外光固化涂料中的性能研究

以对-甲基苯磺酸为催化剂，用丙烯酸羟乙酯和纳米SiO2进行酯化反应制备改性纳米SiO2用红外光谱仪和热失重分析仪对产物分析表明：纳米SiO2中约70．5％的Si-OH基团和丙烯酸羟乙酯发生了酯化反应。将改性前后的纳米SiO2应用于紫外光固化涂料中，研究了对涂料黏度和固化速率、涂料固化膜的铅笔硬度和耐磨性能等的影响。结果...     

气氛条件对纳米Y-TZP浆料固化过程的影响

对纳米Y-TZP(氧化钇稳定)坯片在新型水基凝胶流延成型工艺中,气氛条件对浆料固化过程的影响进行了研究。结果表明,为了克服纳米Y-TZP浆料中有机单体在聚合反应过程中的氧阻聚效应,对成型坯体进行氮气等惰性气氛保护,可以有效地隔绝氧气,顺利完成浆料的固化过程。同时研究发现由于有机单体聚合反应中伴随着NH3分子生成,在一定真空度下,反应平衡有利于向气体生成的方向进行,有助于提高聚合反应速率,从而加快了浆料的固化进程。     

聚氨酯改性不饱和聚酯/色浆复合体系的固化特性

系统研究了聚氨酯改性不饱和聚酯/色浆复合体系的黏度与固化特性,发现随着色浆含量的增加,复合体系的黏度呈递增趋势,但明显低于理论加和值;而复合体系的凝胶时间、表观起始固化温度与表观峰值固化温度随着色浆含量的增加而增加,但表观终止固化温度与固化热焓却降低;随着升温速率的增大,复合体系的特征固化温度均向高温方向移动,但固化热焓基本不变.将升温速率外推至零,可计算出体系的起始固化温度、峰值固化温度以及终止固化温度,从而确定体系的固化工艺.同时基于不同升温速率下的表观峰值固化温度,通过Kissinger方程可计算得到聚氨酯改性不饱和聚酯/色浆复合体系的固化反应表观活化能以及固化反应动力学指前因子.在最佳固化工艺条件下,聚氨酯改性不饱和聚酯树脂/色浆复合涂层的黏附力均在一级以上.     

微波在高分子中的应用

作为一种新型高效的加热方式，微波技术为高分子合成及应用提供了一种新思路，它的应用可大大降低反应的时间与能耗，提高各种反应的速率、收率和选择性，正日渐成为人们关注的热点。本文综述了近年来微波技术在高分子材料，特别是功能高分子材料合成中的应用，以及微波固化与传统热固化的同异，指出微波固化高效均匀，可使固化反应加速，降低固化时间，产品的物理和机械性能优异，可在更广的范围内替代热固法。     

环氧基笼型倍半硅氧烷/4,4'-二氨基二苯砜体系的等温固化动力学

应用等温差示扫描量热法研究了4,4'-二氨基二苯砜(DDS)固化笼型倍半硅氧烷环氧树脂(POSSER)体系的反应动力学,测定了固化反应热,得出了不同温度下固化反应程度与反应时间、固化反应速率与反应时间的关系曲线,通过非线性拟合得到固化反应速率与反应程度的关系曲线.结果表明,固化反应在体系的玻璃化转变温度以上进行,等温固化反应遵从自催化反应机理,用Kamal方程可很好地描述不同温度下固化反应的自催化过程,拟合得到其反应动力学参数k1、k2、m、n,k1和k2对应的固化反应的表观活化能分别为79.67和59.84 kJ/mol.     

Pt/Al2O3蜂窝状催化剂上NO选择性催化还原反应动力学研究

采用多次涂层和浸渍法制备了蜂窝状Pt/Al2O3催化剂，并在高空速和大气体流量条件下对无梯度循环式反应器和积分反应器上催化剂的活性进行了比较。同时采用循环式反应器对动力学数据进行了测定。根据Langmuir-Hinshelwood模型和实验结果，推测了NO-C3H6-O2体系的SCR反应机理，并导出了NO和C3H6反应速率的数学表达式。据此所计算的理论模拟值能够与实验值很好地吻合。实验结果表明，氧气浓度对NO和C3H6的反应速率有明显的影响，二者均随着氧浓度c (O2)的增加达到峰值，再增加氧气浓度时，C3H6的反应速率r(C3H6)保持不变，而NO反应速率r (NO)却下降，而且下降的程度随着温度的升高而加剧。同时，随着氧气浓度增加，r (NO)达到最大值时的温度亦随之下降。     

松香改性酚醛环氧树脂的固化反应动力学研究

以自制的松香改性酚醛环氧树脂（RPAE）为对象,采用差示扫描量热法研究了其与4,4．二氨基二苯砜组成的体系（RPAE／DDS）的固化动力学,利用Kissinger方程计算得到体系的固化热约为109．29J／g,表观活化能为51．56kJ／mol,该体系反应级数为0．85,近似为1级反应,反应速率常数为2．69×10^4／s。采用Ozawa-Flynn-Wall方程分析,得到体系的表观活化能为70。1kJ／mol。     

Ultraviolet-induced responses in two species of climax tropical marine macrophytes.

In tropical regions nominal reductions in stratospheric ozone could be detrimental to marine organisms that live near their upper tolerance levels of ultraviolet (UV) radiation and temperature. Well-known plant responses to UV include inhibition of photosynthesis, reductions in chlorophyll content, morphological changes and production of UV absorbing compounds such as flavonoids. An assessment of the effects and responses of two tropical marine macrophytes to full solar radiation and solar radiation depleted of UV were conducted in southwestern Puerto Rico. Changes in concentration of photosynthetic and photoprotective pigments, and in leaf optical properties of the red mangrove Rhizophora mangle and the seagrass Thalassia testudinum, were evaluated in field exclusion experiments. Rhizophora mangle exposed to full solar radiation showed lower leaf reflectance and a shift of 5 nm in the inflection point of the red edge. Thalassia testudinum samples excluded from UV had significant increases in total chlorophyll and carotenoid concentrations. These marine macrophytes showed increments in their concentration of UV-B absorbing compounds with exposure to UV radiation. Results indicate that even minor increases in UV radiation at low latitudes could have significant effects on the pigment composition of these climax species.     

UV/H2O2工艺湿法脱除燃煤烟气中NO的研究

在自行设计的内置紫外光-鼓泡器中，利用UV/H₂O₂高级氧化工艺湿法脱除燃煤烟气中的NO气体。主要对紫外光强度、H₂O₂初始浓度、NO初始浓度以及烟气总流量对NO脱除效率的影响进行了考察。研究结果表明，在实验范围内，NO脱除效率随着紫外光强度和H₂O₂初始浓度的增加而增加，但当达到一定值后，NO脱除效率的增加幅度均变得相对平缓；NO脱除效率随着NO初始浓度以及烟气总流量的增加呈近似线性减小。通过离子色谱对液相离子产物进行了定性与定量检测，并对NO中的氮元素进行了物料平衡计算，在此基础上对NO脱除路径与产物形态进行了理论分析。
     

Temperature dependence of ESR spectra of methyl methacrylate radicals from 77 K to 300 K

The radicals formed in poly(methyl methacrylate) (PMMA) under vacuum by UV irradiation at room temperature were carefully examined from 77 K to 300 K by electron spin resonance (ESR). The conventional nine-line spectrum was observed with significant overall intensity changes in contrast to previous reports. The intensity decreases greatly as the temperature increases from 77 K to 100 K. The intensity of the ESR spectrum increases as the temperature increases gradually from 100 K to 260 K. The spectral changes were reversible at all temperatures. Three different models are considered to interpret the temperature dependence of the intensity of the ESR spectrum. The results indicate that the ESR spectrum depends on (1) the steady-state concentration of the propagating radical in the polymer, (2) the conformational distributions of the radicals, and (3) the environmental structures of the polymer matrix.     

ULTRAVIOLET ACTION SPECTRUM FOR FLUOROGEN PRODUCTION IN THE OCULAR LENS

Abstract— …Previous work has demonstrated that fluorescent material (360nm excitation, 440nm emission), whose concentration normally increases with age in human lenses, can be generated artificially by exposing cultured human or animal lenses to UV radiation. In the present paper we report measurements of the rate of production of this fluorescent material in rat lenses in vitro as a function of UV irradiation wavelength. A plot of the observed rate of fluorogen production normalized to constant photon flux vs irradiation wavelength shows little action at 360 or 320nm, increases sharply at 300nm, remains relatively constant in the range 300–280nm, and then exhibits a further gradual rise from 270–250nm. The results on rat lenses are compared with results reported elsewhere for tryptophan in aqueous solution. The action spectrum for photochemical destruction of tryptophan in solution closely parallels that for fluorogen production in rat lenses. This result and other evidence suggest that photochemical destruction of tryptophan might be the initial event in UV-induced fluorogen production in the ocular lens.     

Inhibition of mild steel corrosion in HCl solution using chitosan

The efficiency of chitosan (a naturally occurring polymer) as a corrosion inhibitor for mild steel in 0.1 M HCl was investigated by gravimetric, potentiodynamic polarization, electrochemical impedance spectroscopy measurements, scanning electron microscopy, and UV–visible analysis. The polymer was found to inhibit corrosion even at a very low concentration. Inhibition efficiency increases with a rise in temperature up to 96 % at 60 °C and then drops to 93 % at 70 °C, while it slightly increases with an increase in chitosan concentration. Polarization curves indicate that chitosan functions as a mixed inhibitor, affecting both cathodic and anodic partial reactions. Impedance results indicate that chitosan was adsorbed on the metal/solution interface. Adsorption of chitosan at the mild steel surface is found to be in agreement with Langmuir adsorption isotherm model. Chemical adsorption is the proposed mechanism for corrosion inhibition considering the trend of protection efficiency with temperature. Calculated kinetic and thermodynamic parameters corroborate the proposed mechanism.     

Effects of UV-B on secondary metabolites of St. John's Wort (Hypericum perforatum L.) grown in controlled environments

The medicinal plant industry is under increasing scrutiny due to wide variance in active ingredient (AI) concentration from values claimed on labels. Reasons for this disparity include environmental and genotypic variation which influence AI concentration. St. John's wort (Hypericum perforatum) is a popular herbal remedy which also exhibits marked variance in AI concentration among products. This study evaluated concentration changes of three biologically active metabolites of H. perforatum after exposure to UV light while plants were still vegetative. Treatments were performed with 55-day-old plants grown under 400 μmol m(-2) s(-1) PAR for 16 h a day. Three UV light treatments were evaluated: a single dose, a daily dose and an increasing daily dose. Concentrations of hyperforin, pseudohypericin and hypericin were monitored for 7 days after each treatment. A daily dose and an increasing daily dose did not produce significantly greater increases in secondary metabolites compared to single dose treatments. These results suggest the small but significant transient metabolite concentration increases in H. perforatum can be induced by UV light exposure. Information from this study can be useful in optimizing total biomass and metabolite production in controlled environments.     

The influence of indoxyl sulfate and ammonium on the autofluorescence of human urine

Despite biological variability the spectral characteristics of undiluted human urine show relatively low autofluorescence at short UV (250-300 nm) excitation. However with dilution the fluorescence intensity remarkably increases. This paper examines the mechanisms behind this effect, by using excitation-emission matrices. Corrections for the inner filter effect were made for improved understanding of the spectral patterns. We focused on three major fluorophores (tryptophan, indoxyl sulfate and 5-hydroxyindole-3-acetate) that are excited at these wavelengths, and whose content in urine is strongly linked with various health conditions. Their fluorescence was studied both individually and in combinations. We also examined the effect of ammonium on the fluorescence of these major fluorophores individually and in combinations. Through these studies we have identified the leading effects that reduce the UV fluorescence, namely higher concentration of indoxyl sulfate producing the inner filter effect and concentration quenching and quenching of fluorophores by ammonium. This result will assist in broader utilisation of UV fluorescence in medical diagnostics.     

A Simulation Study on the Effect of Cross-Linking Agent Concentration for Defect Tolerant Demolding in UV Nanoimprint Lithography

The chemistry and composition of UV-sensitive resists are key factors determining the stress in the molded resist structure in UV nanoimprint lithography (UV-NIL) and thus the success of the process. The stress in the molded structure is mainly generated due to shrinkage of the resist in the UV curing step and also adhesion and friction at the stamp/resist interface in the subsequent demolding step. Thus, understanding of the stress generated in these steps is critical to the improvement of the process as well as the development of new UV resists. In this paper the effect of resist composition on the stress generation was studied by numerical simulations of the curing and demolding steps in UV-NIL. Parameters required for the simulation, such as resist shrinkage, Young's modulus, fracture strength, friction coefficient, crack initiation stress, and debonding energy, were determined experimentally for different resist compositions. As the cross-linking agent concentration increases the fracture strength also improves. In addition, as more cross-linking agent is added to the resist composition, both shrinkage stress due to the curing and also adhesion at the stamp/resist interface increase resulting in a larger maximum local stress experienced by the resist on demolding. By normalizing the overall maximum local stress by the fracture stress of the resist, we found that there is an optimum for the cross-linking agent concentration that leads to the most successful imprinting. Our finding is also corroborated by qualitative experimentations performed for UV-NIL with various resist compositions.     

Combustion synthesis of calcium doped ZnO nanoparticles for the photocatalytic degradation of methylene blue dye

ZnO nanoparticles are one of the prominent photocatalysts for environmental applications due to its high redox ability, nontoxic and higher stability. This report explains the synthesis of ZnO nanoparticles by a simple solution combustion method using zinc nitrate hexahydrate as an oxidizing agent and incense stick powder as fuel at 400 °C. Several techniques were adopted for the characterization of the obtained product. X-ray diffraction (XRD) pattern shows that a lower concentration of fuel gives pure ZnO and a higher concentration of fuel results in calcium doped ZnO with a cubic phase having a crystallite size of 32–28 nm. UV–vis spectrum shows that as the fuel concentration increases, band gap decreases and reaches to 3.33 eV for 3 g of fuel. Spongy networks with many pores wereobserved in the scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed the average particle size of Ca doped ZnO NPs is about 20 nm. Pure and Ca doped ZnO nanoparticles were examined for photocatalytic degradation of methylene blue (MB) dye under UV light irradiation. The results prove that Ca doped ZnO nanoparticles show good photocatalytic activity.     

UV光引发的丙烯酰胺反相乳液聚合

报道了不透明丙烯酰胺反相乳液体系的UV光引发聚合新方法 .使用普通中压汞灯并辅以适当搅拌 ,UV光引发丙烯酰胺 水 煤油 Span80 +OP 10反相乳液聚合可在 2 0min左右完成 ,所得聚合物分子量达千万 ;聚合过程中不存在恒速期 ,扫描电镜未观察到聚合前后乳胶粒径有数量级的变化 ,表明聚合反应以单体液滴成核为主 .此外 ,考察了光引发剂类型及浓度、单体浓度、乳化剂用量、反应温度等对聚合反应的影响 ,结果表明不同光引发剂的引发活性为Irgacure 2 95 9>(ITX +EDAB) >BDK ,引发剂浓度增加 ,反应速度先增加而后降低 ,存在一最大值 ;单体浓度增加 ,反应速度加快 ,聚合物分子量提高 ;乳化剂用量增加 ,反应速度加快而分子量变化不明显 ;聚合表观活化能为 13 34kJ mol.