A steam press has been modified in order to control independently the steam temperature and humidity and the rate of steam flow. The changes in temperature and moisture regain in wool fabrics have been studied in relation to these variables. A method of measuring the degree of setting has been established, and optimum conditions for steam-pressing of wool fabrics have been determined.
The sorption isotherms of several fibres, of different types and structures, have been determined by a gravinietric method. The experiniental results obtained can be used in the confirmation of the equations of Hailwood and Horrobin, which were obtained by considering fibre–water systems as solutions of water in the disordered regions of the polymer, the ordered regions being regarded as inert elements dispersed throughout the polymer. A study of the variation in moisture regain as a function of time has been made over very long periods for cellulosic, polyamide, and polyester fibres. This has allowed a determination to be made of the accuracy that one can attribute to the parameters of the equation when account is taken of supplementary information from a knowledge of the hysteresis. On the other hand, measurements of the heat of wetting of fibres previously conditioned at different relative humidities have shown that the heats depend only on the actual value of the moisture content and not on the route by which the moisture content has been reached: this confirms results obtained by other authors. This consideration of collected results suggests that there exists a considerable internal pressure in the fibre that may be described in terms of entropy.
A comparison is reported of the performance of the Noble and French combs in the recombing of oil-combed wool tops. The tops were spun into worsted yarns and the yarns were woven into fabrics, which were made up into garments. The products of the two types of comb were compared at each stage, and it is shown that, in almost every instance, the Noble comb gave more satisfactory results.
Conventional autolevelling is a radicai process in the sense that the mass per unit length of the product is determined by the setting of the autoleveller itself. This fact tends to limit the application of autolevelling to an early high-production process because, althougn there is a great deal of interest in the elimination of local variations introduced in subsequent processes, it is appreciated that the maintenance of a high standard of long-term uniformity is even more important than the removal of local irregularities. An attractive solution, which may well permit the employment of autolevellers at later processes than is at present economically and technically practicable, is conservative autolevelling. By this is meant autolevelling by devices which, although able to correct local variations, cannot exercise radical control of the mean level of the product. Part I of this paper considers the principles involved in the methods at present available for conservative autolevelling. Part II gives a theoretical treatment based on Unear-control-theory techniques. ln this part, transfer functions are derived to show how the response of the conventional system is modified and characterized in terms of machine parameters.
A theoretical expression is derived for the variation of the crease-recovery angle of a plain-weave monofilament fabric with orientation of the crease to the thread directions; it involves the constructional parameters of the fabric, the flexural and torsional rigidities of the monofilaments, and their elastic recoveries from flexural and torsional strains. This expression has been checked for two nylon fabrics, and, with one adjustable parameter, good agreement is obtained between the theoretical and observed polar variations. The variation of the fiexural rigidity of these fabrics with orientation is shown to be in agreement with the theoretical predictions of Cooper.
An account is given of measurements of fibre characteristics of wool from merino and longwool sheep bred in Australia in the early nineteenth century. The results are compared with those obtained on wool from several Spanish merinos that were reared in France in the eighteenth century. Although it was possible to make only a few tests, the results are considered to provide further evidence of the remarkable constancy of fibre diameter in merino wool over a long period.
Wool has been shown to absorb sulphuric acid from the vapour phase. The rate of absorption increases with acid concentrations of up to 99·5% by weight and decreases with the pressure of inert molecules present in the system. Uptakes in excess of 200% on the original weight of wool have been observed at temperatures close to ambient. The observed weight increase due to absorbed acid is dependent on exposure time because degradation of the wool results in loss of material. A proposed mechanism for the absorption of H2SO4, molecules includes steps involving the effect of inert-gas molecules adsorbed onto the fibre surface, immobilization of absorbed acid by chemicai reaction with the wool, and barrier effects due to packing densities and the formation of a boundary layer in the presence of appreciable pressures of inert-gas molecules. The presence of absorbed H2SO4 has been shown to modify the subsequent water-sorption properties of the wool owing to reaction of acid with hydrophilic groups and also because of the affinity between H2SO4 and water. The use of sulphuric acid as a desiccant or conditioning agent for wool has been shown to be an intrinsic source of error.
A comprehensive survey of the literature on the hairiness of yarns is presented. The techniques used in the measurement of hairiness are classified and discussed in detail. The parameters used to express hairiness and to derive the theory of hairiness are considered. The effects on hairiness are discussed of fibre and yarn characteristics, different spinning processes, and processes subsequent to spinning (winding, singeing, bleaching, dyeing, and sizing).
As a result of electron-microscope studies on a selection of mammalian hairs, evidence is presented of the existence of an interlinking mechanism between the cortex and the cuticle. The occurrence of these interpenetrating devices is greater in vicuna hair and guanaco hair than in wool, and it is suggested that the mechanism of phagocytosis may be involved in their formation.
Processing and product comparisons of sweated and sulphide-painted wools with shorn wools from the same flocks of sheep show top-yield advantages for the fellmongered wools. There was, however, a tendency for the tearing strength and abrasion-resistance of fabrics made from the fellniongered wools to be lower and for the colour to deteriorate, and, though the fabrics dyed very evenly, colour intensity after dyeing was different. This suggests that careful fibre-mixing is necessary in blends of skin and shorn wools. Fellmongered-wool fabrics were appreciably more yellow than shom-wool fabrics, but, after irradiation with imitation sunlight, differences between fabrics were very much less. Skin-digested wools could be processed satisfactorily, but the yams and fabrics showed appreciable loss of strength, extensibility, and colour compared with the shorn wools. Top yield was also less.
The action of soap and alkali and of alkali alone in removing dirt from naturally soiled fibres has been studied microscopically. The concentrations usually employed were those commonly used in laundering. Cinematography facilitated the observation of some of the effects. The most common methods of fatty-dirt removal involved emulsification and rolling up: complex-formation was less common. Most of the phenomena originally observed with artificial systems also occurred with these natural ones.
The effect of temperature on the stress–strain diagram and elastic recovery has been investigated for single fibres of Courtelle acrylic fibre. Most of the measurements were made in the wet state at temperatures of up to 80°C. Results show the presence of a glass-transition region at about 6O°C, and this has been confirmed by differential thermal analysis.
