Re-equipping a dyehouse for maximum productivity — the factors involved

Before an existing dyehouse can be re-equipped for maximum productivity, substantial changes in machinery, techniques and in personnel attitudes are needed. These are described, along with an outline of further work that will be undertaken when suitable equipment becomes available.     

Synthetic fibres in the dyehouse — the manufacturers' role

This paper briefly outlines two recent examples of how Courtaulds' research programmes have led to fibre innovations designed to assist the dyer in his trade. Tencel is the world's first commercially available solvent-spun cellulose fibre, possessing extremely good dyeing characteristics. The yield of reactive dyes is exceptional, particularly in printing, where causticisation or mercerisation is no longer necessary to improve dye yields as with conventional viscose or cotton. Xtol is a new diacetate fibre. Its ability to be processed at higher temperatures than conventional diacetate without delustring brings improved fastness and higher dye yields.     

Heat and mass transfer from cylinders to a turbulent fluid stream — A critical review

A review is made of recent experimental and theoretical work on the transfer of heat and mass between a circular cylinder and a turbulent fluid stream in cross flow. Special attention has been given to the transport mechanism over the wake region and the different approaches used to model it. The overall and boundary layer transport characteristics are briefly discussed. The review is limited to investigations under subcritical flow conditions over the Reynolds number range from 10³ to 10⁵.     

Bubble emissions from submerged orifices – a critical review

A comparative study of reported theoretical and experimental investigations evaluating the numbers and sizes of bubbles emerging from submerged orifices reveals that the lack of consistency can be attributed largely to faulty experimental techniques. Errors are attributed to an inadequate knowledge of the influence of the surface properties of the solid and liquid media on the emission process and to the lack of standardization of the equipment geometries especially regarding the pressure chambers and orifice plates. The analyses provide guidance to designing standardized equipment to produce reproducible bubbles.     

Nanocomposite fire retardants — a review

Most fire retardant nanocomposites are made from layered silicates and organic polymers, a variety of methods are used in their synthesis. The mechanism for the fire retardancy of these composites is generally considered to be due to the structure of the char formed during combustion, which enables the char to thermally insulate the polymer and inhibit the formation and escape of volatiles during combustion. Fire retardant nanocomposites require relatively low concentrations of silicates for activity, resulting in low additional costs and weight. Improvements in the bulk physical properties of the polymer can be additional advantages over traditional fire retardants. Copyright © 2000 John Wiley & Sons, Ltd.     

Mass transfer between solid spheres and oscillating fluids — A critical review

Relative oscillatory motion between solid particles and a fluid increases the rate of interphase mass transfer due to the establishment of secondary flows (acoustic streaming). A critical survey of published data shows that mass transfer is well correlated by a theoretically founded dimensionless relation of the form where K, a, b and d depend on the Schmidt number. The equation successfully correlates experimental data for both gases and liquids over a range of frequencies F < 1 Hz to F ～ 10⁶ Hz, provided the amplitude to diameter ratio A/D is below 0.75. At higher values of this parameter, \documentclass{article}\pagestyle{empty}\begin{document}$ \bar N_{Sh} $\end{document} is better predicted by a quasi-steady model which no longer depends on A/D.     

Mass transfer between solid spheres and oscillating fluids — A critical review

Relative oscillatory motion between solid particles and a fluid increases the rate of interphase mass transfer due to the establishment of secondary flows (acoustic streaming). A critical survey of published data shows that mass transfer is well correlated by a theoretically founded dimensionless relation of the form where K, a, b and d depend on the Schmidt number. The equation successfully correlates experimental data for both gases and liquids over a range of frequencies F < 1 Hz to F ? 10⁶ Hz, provided the amplitude to diameter ratio A/D is below 0.75. At higher values of this parameter, N_Sh is better predicted by a quasi-steady model which no longer depends on A/D. Based on a paper presented at the 26th Canadian Chemical Engineering Conference, Montreal, Quebec, November 2–5, 1975.     

Throughput of rotating disc contactors — a review

Published procedures for calculating the maximum throughput of mutually saturated phases in rotating disc contactors, based on the slip-velocity concept, are compared against a set of experimental data from two sources. The results of the comparison are expressed as the standard relative deviation of the calculated and experimental continuous phase velocities.     

Thermal polymerisation of styrene—A critical review

Past work on the thermal polymerisation of styrene is critically reviewed. Particular attention is paid to the various initiation theories which have been proposed. Suggestions are made of areas where future studies could be most usefully directed.     

Measurement of smoke in fires—a review. I —characteristics of smoke

The Complexity of the behavior of smoke at fires can lead to great difficulties in obtaining measurements from instruments which are both reliable and correlatable with human observations. The first article in this two-part review considers the principal characteristics of smoke, the factors which influence its behaviour at fires, the basic theory of light transmission through smoke, and the behaviour of the eye in smoky conditions. This information will be used in the second article to assess the performance and limitations of various types of smoke measuring instruments.     

Comparison of instrumental methods for assessing colour fastness. Part 1 — Change in colour

Different instrumental methods for assessing change in colour are described. A set of experimental results were used to test the performance of the various formulae and to illustrate the lack of agreement between them and visual results. Each method is based on a different colour-difference formulae. The differences between the formulae are illustrated by plotting constant AE contours for each of the formulae for various colour centres. The areas of colour where the formulae differ most from each other have been identified. The differences between the methods in some areas were very large, up to a factor of five in terms of ΔE, or two full grades of fastness.     

Solvent extraction — the challenges of a “mature” technology

The solvent extraction area is perceived by some chemical engineers as being mature and fully developed. The present review shows that this is not the case. Many chemical engineering problems must be solved before equipment can be confidently designed from first principles. The review also outlines progress in extraction process chemistry, and in new techniques such as membrane extraction.     

Improving γ-radiation stability of pvc—a review

PVC has a significant tendency to degrade under γ irradiation. Therefore, considerable efforts have been made to improve its γ-radiation stability. The purpose of this review is to summarize recent results in this area, with a special emphasis on the improvement of color stability of PVC-based materials used in medical applications.     

Instrumental methods for assessing colour fastness. Part 2 — Staining

In Part 1 of this paper, different fastness formulae for change in colour were compared. In the present report, the same methodology was used to compare different staining formulae. A set of experimental results was used to test the performance of various staining formulae. The constant grade contours for each formula were also calculated. Their patterns were compared and their differences were identified.     

Solidification and phase transformation behaviour of food fats — a review

Recent studies on physical behaviour of food fats have been reviewed, with an emphasis on solidification properties in bulk and emulsion states. It was shown that the use of synchrotron radiation X-ray beam highlighted the solidification behaviour of polymorphic fats, which was not unveiled by traditional X-ray beams on a laboratory scale as summarised in the following: (a) kinetic processes of molecular ordering of lamella-structured fat crystals, (b) mixing behaviour of different triacylglycerols forming miscible, eutectic, and molecular compound crystals, and (c) remarkable influences of shearing forces on the rapid solidification of the more stable forms of cocoa butter. These results have given some indications to the physical control of fat solidification, and the blending and fractionation of solid fats. The influences of hydrophobic emulsifiers on the solidification of fat crystals in O/W emulsions, which were in-situ monitored by an ultrasound velocity technique, have shown that the addition of highly hydrophobic emulsifiers having long-saturated acid moieties accelerated the nucleation of the fats at the interface areas of the emulsions. These effects are also indicative for the selection of the emulsifier for the control of the fat solidification in the emulsion phases.     

Structural properties of packed beds — A review

Some structural properties of packed bed systems on both the local and overall scales which are available in the literature and of interest in chemical engineering applications are discussed. Regular and random packings of uniformly sized spheres are initially analyzed as a basis for the later examination of the more general case of random packed beds containing particles of various sizes and shapes, with or without restraining surfaces.     

Dietary fat in the prevention of cardiovascular disease — a review

In developed countries atherosclerotic cardiovascular disease is the reason for about 50% of all deaths. With growing prosperity coronary heart disease (CHD) is becoming the major cause of premature death. Most complications of atherosclerosis occur unexpectedly and more than 50% of the patients developing a myocardial infarction do not survive more than one year. Because of the severe morbidity and high mortality primary prevention is likely to be the only solution. Epidemiological studies show a strong, positive relationship between plasma cholesterol concentrations and the incidence of CHD. People who immigrate from low‐risk to high‐risk areas usually acquire similar plasma cholesterol levels as the native population and a similar CHD risk. This demonstrates that environmental rather than genetic factors lead to the differences in cardiovascular risk and supports the notion that nutrition and lifestyle play a major role. The association between dietary intake of fat and cholesterol and the extent of atherosclerosis and CHD has been recognized in previous studies. The amount of saturated fat in the diet correlates stronger with the incidence of CHD than with total fat intake. The consumption of unsaturated fatty acids, however, appears to be beneficial, since it is inversely correlated with the plasma cholesterol concentration and risk of myocardial infarction. Lately additional nutritional factors like trans fatty acids with a negative influence on risk as well as positive factors like linolenic acid have attracted much attention. In conclusion, as a challenge to public health, preventive medicine needs to focus on changes in dietary habits with priority, particularly fat modification. A nutrition low in total fat primarily avoiding saturated and trans fatty acids, but rich in fruit and vegetables should be recommended.     

Passivation of metal alloys using sol–gel-derived materials — a review

The sol–gel method is being investigated as an environmentally compliant alternative for chromate-based conversion coatings currently in use. An overview of recent advances in the use of sol–gel derived coatings for improved corrosion resistance of aluminum and steel metal surfaces is given.     

Synthesis and Electronic Spectra of Some Disperse Dyes Derived from N—2—Cyanoethyl—1,2,3,4—tetrahydroquinoline

Various monoazo dyes suitable for transfer printing have been prepared from N—2cyanoethyl—1, 2, 3, 4—tetrahydroquinoline and compared with the corresponding N—methyl (kairoline) derivatives. The presence of a β—cyanoethyl group brings about significant hypsochromic shifts of the first absorption band and leads to some improvement in light—fastness properties on polyester fibre.     

Quantitative determination of the vinylacetate content in ethylene vinyl-acetate copolymers—a critical review

The various methods for the determination of the vinylacetate (VA) content in any ethylene vinylacetate copolymer are examined critically. Each available method is described briefly, together with its relative accuracy. All methods give comparable results and are equally valid, but IR spectrometry can be considered the most flexible and accurate VA content measuring technique.