Photoresponsive polymers having pendant chlorocinnamoyl moieties: synthesis, reactivity ratios and photochemical properties

New photoreactive homo- and copolymers containing pendant chlorocinnamoyl moieties were respectively synthesized by homopolymerization of corresponding acrylic monomer and copolymerization with glycidyl methacrylate. The diverse structures were characterized by different spectroscopic techniques. The thermal properties of the photosensitive polymers were investigated by thermogravimetric analysis in air and differential scanning calorimetry under nitrogen atmosphere. The compositions of polymers were determined by ¹H-NMR analysis. The reactivity ratios of both comonomers were calculated using the conventional linearization methods such as Fineman-Ross, Kelen-Tudos, extended Kelen-Tudos and a non-linear error-in-variables model (EVM) method using a computer program, RREVM, in order to optimize the reaction conditions for industrial applications. The photoreactivity of newly synthesized homo- and copolymers containing pendant chlorocinnamoyl moieties was investigated in solution as well as in thin films. The effects of solvent nature, concentration, temperature, copolymer compositions and photosensitizers on the rate of photocrosslinking of these new photoresponsive polymers were evaluated. Suitable conditions were discussed for using as negative photoresists in industries.     

Hydration of fly ash cement

It is necessary to establish the material design system for the utilization of large amounts of fly ash as blended cement instead of disposing of it as a waste. Cement blended with fly ash is also required as a countermeasure to reduce the amount of CO₂ generation. In this study, the influences of the glass content and the basicity of glass phase on the hydration of fly ash cement were clarified and hydration over a long curing time was characterized. Two kinds of fly ash with different glass content, one with 38.2% and another with 76.6%, were used. The hydration ratio of fly ash was increased by increasing the glass content in fly ash in the specimens cured for 270 days. When the glass content of fly ash is low, the basicity of glass phase tends to decrease. Reactivity of fly ash is controlled by the basicity of the glass phase in fly ash during a period from 28 to 270 days. However, at an age of 360 days, the reaction ratios of fly ash show almost identical values with different glass contents. Fly ash also affected the hydration of cement clinker minerals in fly ash cement. While the hydration of alite was accelerated, that of belite was retarded at a late stage.     

Investigation of the void reactivity effect in large-size Lead Fast Reactors

An aspect of great relevance in Lead Fast Reactors (LFRs) is the actual void reactivity evaluation. The purpose of this work is double: to inquire into the physical problem, and to evaluate the impact of different approaches and numerical methods on the calculation of the critical reactor parameters involved. Thus, results concerning void effect contributors have been evaluated through a cross-checked analysis performed by means of both a deterministic and a stochastic code. The field of investigation that has been assumed consists in the reference configuration of the 600 MW_e European Lead-cooled SYstem (ELSY), under development within the 6th and 7th EURATOM Framework Programmes. Calculations have been carried out on a 1500 MW_th MOX-fuelled core, composed by wrapper-less square Fuel Assemblies (FAs) with pins on a square lattice. The ERANOS (European Reactor Analysis Optimized System) deterministic code ver. 2.1 and the MCNP Monte Carlo code ver. 4c have been employed in conjunction with the JEFF-3.1 nuclear data library to assess the void reactivity variation and its breakdown into the most relevant nuclides, using both the neutron balance equation method and perturbation theory. Results have shown a very good agreement between ERANOS and MCNP outcomes: the huge reactivity worth determined by the core active region voiding (approximately 5000 pcm) is due to the predominant contributions of even isotopes – among which ²³⁸U plays a major role, being responsible for roughly 4300 pcm – as a consequence of their fission cross-section high sensitivity to spectral hardening (threshold reactions), despite their modest contribution to the total fissions.     

Reactivity between La(Sr)FeO3 cathode,doped CeO2 interlayer and yttria-stabilized zirconia electrolyte for solid oxide fuel cell applications

Detailed X-ray diffraction (XRD) analysis of two different Sr-doped LaFeO₃ cathodes, YSZ electrolyte and two Sm/Gd-doped CeO₂ interlayer and their mixtures were used to evaluate the formation of undesired secondary reaction compounds. The analysis of room temperature X-ray diffraction data of the mixtures indicates the crystallization of strontium and/or lanthanum zirconates between the cathode and the electrolyte materials and no detected reaction between the cathode and the interlayer materials.     

煅烧高岭土粒料的结构与酸溶反应速率的关系研究

在轻度润湿状态下制备的高岭石团粒,经煅烧后,仍具有发达的粒内大孔结构。在用盐酸加热浸取时,该类球粒内的铝质组分表现出高酸溶反应活性,不同粒级的该类球粒有相似的浸出率—时间曲线,且大部分铝能被迅速浸出。将传统的球粒—颗粒模型加以修改,即以两个尺寸相差悬殊的孔结构层次表达该类球粒内的离子运移通道,能圆满解释这类球粒的反应曲线的特征。该研究结果表明,避免高岭土球粒在煅烧时被“烧死”,能使粗粒煅烧高岭土的酸溶反应易于进行     

Drilling in mudrocks: rock behavior issues

Borehole stability analyses use different analytical models to evaluate stresses, pressures, and temperatures around boreholes. Mudrocks do not possess spatio-temporally constant material properties: mechanical properties are time-dependent because of the continuous change in pore pressure, moisture content, and temperature near the borehole. Mudrocks with high specific surface areas also exhibit high sensitivity to changes in physical and chemical properties of their pore fluids. Pressure and concentration diffusion during drilling continuously change the ionic composition of pore fluids and, accordingly, the engineering properties of those fine-grained argillaceous materials. Such fine-grained materials are considered “reactive”; it is shown that a “reactivity coefficient” can be used to assess the physico-chemical sensitivity of mudrocks. Coupling between chemical and mechanical properties may develop in reactive mudrocks, leading to further changes in their mechanical parameters. Experimental data from triaxial and oedometer tests are presented for several materials to illustrate their time-dependent mechano-chemical properties in borehole environments. A discussion of coupled diffusivity processes in mudrocks is included, and the concept of large micro-scale strains that can lead to deterioration of properties is introduced.Finally, we speculate on the degree of complexity required for constitutive modeling of borehole stability analysis of shales in practical situations.     

用堆振荡法测样品的反应性效率

一、引言在特定栅格上某材料样品的反应性效率是一项重要的物理量。我们在氢化锆-水-铀栅格的临界装置上测量了~(164)Dy,~(151)Eu,~(176)Lu和~(115)In等样品的反应性效率,由此确定了这些材料的单位质量所相当的反应性,也称材料价值。实验中为了消除样品对中子场的扰     

Catalytic gasification of coal using eutectic salts: identification of eutectics

Different eutectic salt mixture catalysts for the gasification of Illinois No. 6 coal were identified and various impregnation or catalyst addition methods to improve catalyst dispersion were evaluated in this study. In addition, the effects of major process variables such as temperature, pressure, and steam/carbon ratio were investigated in a thermogravimetric analyzer (TGA) and fixed-bed bench scale reactor systems. The TGA studies showed that the eutectic catalysts increased CO₂ gasification rate significantly. The methods of catalyst preparation and addition had significant effect on the catalytic activity and coal gasification. Based on the TGA studies of several eutectic systems, the 43.5% Li₂CO₃-31.5% Na₂CO₃-25% K₂CO₃ and 39% Li₂CO₃-38.5% Na₂CO₃-22.5% Rb₂CO₃ ternary eutectics, the 29% Na₂CO₃-71% K₂CO₃ binary eutectic and the K₂CO₃ single salt catalysts were selected for the fixed-bed studies. The catalyst loading increased the gasification rate and almost complete conversion of carbon was observed when 10 wt.% of catalyst was added to the coal. Upon further increasing the catalyst amount to 20 wt.% and above, there was no significant rise in gasification rate.     

The influence of primary QI on the oxidation behaviour of pitch-based C/C composites

Three unidirectional C/C composites were prepared from PAN-based carbon fibres and three coal-tar pitches obtained from the same parent coal-tar pitch but differing in their primary QI content. The effect of the amount of primary QI present in pitches on the air reactivity of pitch-cokes and C/C composites was studied by thermogravimetric analysis. The oxidation of pitch-cokes was performed at 10°C min⁻¹ up to 1000°C. The air reactivity of C/C composites was assessed from the weight loss curves obtained under isothermal conditions in the temperature range of 500 to 575°C for 4 h. The topography of the oxidized composites was examined by scanning electron microscopy. The results showed that pitch-cokes were more reactive than carbon fibres because the presence of QI particles increased their reactivity. With the increase of primary QI content in the pitches, C/C composites showed a higher percentage of carbon matrix, with a finer optical texture, fewer microcracks and less closed porosity. The air reactivity of the composites was affected by both chemical and physical factors, the extent of oxidation determining which of these exerted the greater influence. At low conversions the reactivity was decided by both QI content and the optical texture of the matrix. At high conversions the porosity of the composite was the determining factor.     

Strength and hydration products of reactive MgO–silica pastes

The reaction between MgO and microsilica has been studied by many researchers, who confirmed the formation of magnesium silicate hydrate. The blend was reported to have the potential as a novel material for construction and environment purposes. However, the characteristics of MgO vary significantly, e.g., reactivity and purity, which would have an effect on the hydration process of MgO–silica blend. This paper investigated the strength and hydration products of reactive MgO and silica blend at room temperature up to 90 days. The existence of magnesium silicate hydrate after 7 days’ curing was confirmed with the help of infrared spectroscopy, thermogravimetric analysis and X-ray diffraction. The microstructural and elemental analysis of the resulting magnesium silicate hydrate was conducted using scanning electron microscopy and energy dispersive spectroscopy. In addition, the effect of characteristics of MgO on the hydration process was discussed. It was found that the synthesis of magnesium silicate hydrate was highly dependent on the reactivity of the precursors. MgO and silica with higher reactivity resulted in higher formation rate of magnesium silicate hydrate. In addition, the impurity in the MgO affects the pH value of the blends, which in turn determines the solubility of silica and the formation of magnesium silicate hydrate.