Design and Performance of a High-Temperature X-Ray Diffractometer Furnace

A high-temperature X-ray diffractometer furnace that can be operated for extended periods at 2700°F in air has been constructed. The furnace has been operated successfully for shorter periods to 2800°F in air. Construction details are presented. This research tool has been used to follow the polymorphic inversions of silica from quartz in various high-purity silica materials. The rate of inversion from quartz to cristobalite and tridymite has been found to be a function of crystallite size rather than of particle size.     

Improvements in the Dyeing of Wool at Low Temperatures by the Use of Amine or Ammonia Pretreatments

Pretreatments of wool with strong solutions of amines and ammonia have been reported to increase dye adsorption rates in many cases. The effect has been ascribed to the formation of β-aminoalanine residues in the wool with a resultant increase in its electrical potential. The effect of more dilute solutions of ammonia and dimethylamine is reported here. The possibility that the amines act simply as alkaline hydrolysis promoters has been examined by taking into account internal pH effects. The addition of salt to the amine treatment solution has been shown to be very advantageous so that ‘low-temperature-dyeing’ wool may be readily prepared by a simple ammonia-salt pretreatment.     

Citrate gel processing of oxide superconductors

Citrate gel processing of superconducting oxides of both the La-Ba-Sr-Cu-O and Y-Ba-Cu-O types has been investigated because of the need to produce pure, homogeneous powders of a controlled quality. The production and decomposition of the gels has been studied using TGA, SEM and XRD. The sintering of the powders obtained from the gels has been investigated using dilatometry such that the densification kinetics may be related to initial powder particle size, temperature, time, cooling rate and atmosphere used for sintering. Sintered pellets have been characterised structurally using XRD and TEM. AC magnetic susceptibility measurements have been made on the pellets so that the value and width of the superconducting transition may be related to the conditions of sintering. It has been shown that although the products of low temperature decomposition are finer and sinter more readily, they do not make good superconductors.     

Evaluation of a multifunctional indicator for the electroanalytical determination of nitrite

The derivatisation of phloroglucinol by acidified nitrite has been investigated as a means through which the latter can be quantified within freshwater and saline samples. The resulting nitroso derivative is shown to provide a number of options through which an electroanalytical signal can be obtained. Three distinct species can be electrochemically addressed and their respective sensitivities and practical implementations have been evaluated. The technology has been successfully transferred from bulk electrode formats to a disposable screen-printed electrode platform that is more amenable to field analysis. The analytical viability of the resulting assay system has been critically assessed and validated through the determination of endogenous nitrite within lake water and through recovery experiments in seawater.     

Sensitivity of nitromethane for low velocity detonation

Recently the occurrence of a low velocity detonation (LVD) in nitromethane has been demonstrated. In the present study this phenomenon has been further investigated by mapping the shock loading regime in which a stable LVD can develop. A confinement geometry has been chosen that earlier appeared to be able to sustain the LVD. A calibrated shock donor system has been used, so that loading shock strengths were known. The critical shock strengths for the occurrence of both high and low velocity detonation could thus be determined. Including LVDs, nitromethane appears to have a sensitivity comparable to that of relatively sensitive high explosives. The results also indicate that the geometries of some standard shock sensitivity tests are not fully adequate to detect an LVD in nitromethane.     

Influence of interfacial resistance on kinetics of sorption

A model for sorption influenced by rate of transfer to the surface layer of polymeric sheets has been examined. The rate of uptake into the surface layer has been taken to be proportional to the degree of unsaturation of the surface layer. The predicted sorption behaviour has been compared with experimentally observed data which shows a reasonable agreement. A method for calculating diffusion coefficients has been demonstrated. It has been shown that sorption rates could be affected by factors like pressure of the penetrant in the vapour phase and the structure of the surface vis-á-vis that of the bulk. Extension of the model qualitatively, to systems with diffusion coefficients strongly dependent on concentration, indicates the possibility of larger uptake of the penetrant in thinner sheets in an initial time interval. This supports some experimental observations reported earlier. The model supports the experimental work of Long and Richman who observed the time dependence of surface concentrations during sorption.     

Studies related to the structure and reactivity of coals : 18. The chemical structures of products from reactions of a suite of higher rank Australian coals

The structure of the oils, asphaltenes and residues obtained by the thermal reactions of a suite of Australian higher rank coals under hydrogen or nitrogen have been studied by chemical and spectroscopic methods. The host-guest model that has been used to describe the structure of Australian brown coals cannot be applied directly to the higher rank coals. Evidence is provided that suggests that a modified version of the model may be of use in describing the structure of some subbituminous coals. The methodology has proved to be useful in the understanding of structural features of coals which are often not rank dependent, e.g. Callide coal (ABL2), a subbituminous coal, has been shown to have characteristics of both very high and also low rank coals.     

Electrodeposition of polyaniline and polyaniline composites from colloidal dispersions

The voltammetric properties of colloid dispersions of polyaniline have been studied. It has been found that with the use of appropriate oxidants, spherical polyaniline colloids with well defined voltammetric characteristics can be obtained. It has also been found that these colloids can be electrocoagulated to form coatings by imposition of a negative potential. Novel ‘Composite films’ can also be deposited from mixtures of colloids and show unique properties.     

Economy and Effectiveness of Post-bleaching Reactive Dyeings

The reduction in cost obtained by the alteration of the sequence of operations in wet processing, namely when bleaching is carried out after dyeing with reactive dyes instead of before, has been determined. The contribution to the reduction in cost by post-bleaching fabrics in a jig, as compared with the classical processing sequence involving bleaching in yarn form in a package dyeing machine has been included in the calculation. The effect of post-bleaching conditions on different reactive dyes has been assessed, and it has been found to be possible to choose a wide range of dyes that resist these conditions. The dyeings were observed to be brighter and the undyed yarn was of satisfactory whiteness.     

Equilibrium studies of the direct reduction of sulphur dioxide by coal

The direct reduction of sulphur dioxide to elemental sulphur using coal has been studied utilizing models that simulate thermodynamic equilibrium. Comparison has been made between the computer models and process results. The results of the analysis indicate a discrepancy which may be attributable to the manner in which samples are taken for analysis. The actual process may be in thermodynamic equilibrium.     

Flow behaviour of oil-in-water emulsions

The rheological behaviour of concentrated oil-in-water emulsions has been investigated using the Weissenberg Rheogoniometer. The oil concentration has been varied from 40 to 95 volume percent. The effects of shear rate and oil concentration on the viscosity have been determined. From the rheological data, the maximum attainable oil concentration in the emulsion has been estimated and is introduced as a parameter in the relationship between relative viscosity and oil concentration to account for certain variations in the emulsion characteristics. Empirical equations have been obtained which correlate zero shear rate viscosity and infinite shear viscosity as a function of reduced oil concentration. Comparison has been made between the emulsion viscosity and the solid-liquid suspension viscosity at high dispersed phase concentration. Estimated maximum attainable oil concentration is found to be in close agreement with the actual maximum concentration that could be achieved experimentally.     

Phase diagram of poly(vinyl chloride) and solution chlorinated polyethylene

The behaviour of mixtures of poly(vinyl chloride) (PVC) and solution chlorinated polyethylene (SCPE) has been investigated as a function of temperature. These polymers have been found to be compatible over some ranges of composition and exhibit the phenomenon of a lower critical solution temperature (LCST). The thermally-induced phase separation has been investigated by optical, dynamic mechanical, and electron microscope techniques. The single phase mixture has been investigated by scanning analytical electron microscopy. Some investigation of the thermodynamics of the mixture has been made and the heat of mixing term has been found to be negative and small, i.e. favouring mixing. It has been shown that the technique of in situ polymerization overcomes many of the problems of preparing these polymer mixtures in the solid state.     

Desorption of rhenium from weakly basic anion exchangers

The desorption of rhenium from an A172 anion exchanger with an ammonia solution has been studied. A172 and A170 anion exchangers have been investigated with infrared spectroscopy. The difference in their structures has been revealed so that A172 can be assigned to a medium basic anion exchanger type. The reason for the low desorption of rhenium from the A172 anion exchanger has been determined.     

The Interaction of solute transfer,contaminants and dro break-up in rotating disc contactors: Part II. The coupling of the mass transfer and breakage processes via interfacial tension

In order to investigate the influence of solute transfer and of surface active agents on the drop breakage process in liquih liquid extraction columns, their effect on the interfacial tension has to be studied in detail. The difficulty encountered is that the interfacial tension during solute transfer continuously changes and that no simple apparatus is commercially available which can measure these varying interfacial tension values. An attempt has been made here to theoretically predict them. The equations developed to predict the interfacial tension variation can be combined with a model for the breakage process and hence drop size distributions can be calculated from stage to stage. Applying a new combined film mass transfer coefficient model which takes into account the effect of contaminants, single drop extraction performance has been calculated for simplified conditions of constant bulk concentration in the continuous phase. Calculated efficiencies have been compared with experimental data and a good simulation of contaminant effects and dependency on drop size has been found. The calculations were restricted to low dispersed phase hold-up values, so that coalescence effects could be ignored. This work provides the required support for a procedure to be applied to counter-current flow extraction columns.     

Electrochemical polymerization of thionaphthene-indole

The polymer deriving from thionaphthene-indole has been prepared by electrochemical oxidation of the monomer in methylene chloride on platinum electrode. The oxidized polymer so obtained has been reduced on the same electrode to a neutral polymer, which is processable and soluble in several solvents. Both oxidized and neutral polymers have been characterized by UV, IR and mass spectrometry. The electrical conductivity of the oxidized material has been found to be nine orders of magnitude greater than that of the reduced product.     

高效载体催化剂下改性HDPE的合成

研究了TiCl_4/SiO_2—MgCl_2载体高效催化剂作用下的乙烯/己烯共聚,发现共聚合的催化效率高于乙烯均聚,从非均相Ziegler—Natta催化聚合的非稳态扩散动力学观点解释了这一现象。研究了所合成的改性HDPE范围的共聚物样品的热性能和拉伸性能,结果表明其性能与商品牌号样品性能相近。     

Template synthesis of CMK-3 nanostructured carbon material and study of its properties

Mesostructured carbon has been obtained by template synthesis. SBA-15 mesostructured silicate has been used as a template. The effect of the properties of a template on the ordering of a replica has been studied. It has been shown with the use of X-ray diffraction, gas adsorption, and electron microscopy that there are evident correlations of the conditions of synthesis of a template with the ordering of a carbon replica, which can be guided by the synthesis of materials. The ordering of a replica significantly depends on the mesopore volume of the initial template and thickness of the pore wall. One should use templates with the highest possible mesopore volume and minimal wall thickness to obtain highly ordered replicas. These templates can be prepared during the treatment of synthesized materials at temperatures close to 100°C. It has been determined that, when there is SBA-15, the presence of micropores is a necessary condition for the preparation of carbon replicas that retain the structure of the template.     

The anodic dissolution of uranium dioxide—II. In carbonate solutions

The anodic dissolution of uranium dioxide in alkaline carbonate solutions has been studied. Steady-state potentiostatic and cyclic voltammetric measurements have been shown to be consistent with a mechanism that involves a rate-determining two-electron transfer reaction. The presence of insulating uranium(VI) films on the surface at high anodic potentials has been confirmed by the use of ring-disc electrode measurements and characterized by X-ray-diffraction analyses. The dissolution behaviour of the films has been characterized and compared with that of samples of synthetic uranium trioxide and uranyl carbonate.     

Optimization of the polycondensation stage of poly(ethylene terephthalate) reactors

A general kinetic scheme for the polycondensation step of the PET formation has been used to establish the mole balance equations of various functional groups in batch reactors. An objective function has been defined which aims to attain a desired degree of polymerization in the shortest time, has a specified level of diethylene glycol group content, and minimizes the other side products. Using the control vector iteration procedure, an optimum temperature profile has been calculated. The computations suggest that a high temperature should be used initially which must be lowered as the time of reaction increases for limiting the formation of side products.     

Mechanical behaviour of bituminous waterproofing membrane systems

The mechanical behaviour of waterproofing membrane systems composed of one or more layers of bituminous sheeting fully bonded together to form an integral layer has been studied and a theory has been evolved which allows membrane stresses and strains to be calculated as a function of the mechanical properties of the constituent materials and of the associated substrate movement. Allowance is made for the visco-elastic effects of bitumen. It is concluded that the ability of membranes to accommodate substrate movement largely depends on the mechanical properties of the base fabrics used to reinforce bituminous sheetings, and this has been confirmed in controlled experimental work. The order of substrate movement that may be tolerated by a single-layer fully bonded system was calculated for a number of conditions. The improved mechanical performance afforded by partial bonding was considered to be worthwhile.