26—THE WRINKLING OF WOOL WORSTED FABRICS. PART II: BENDING SET IN SINGLE FIBRES AND FABRIC AND THE EFFECT OF AGEING

An account is given of an investigation in which the recovery from bending of isolated wool fibres subjected to strains similar to those found in a wool fabric during bending in the multiple-pleat tester was measured. Fabric recovery and fibre recovery differ by a small amount that is probably produced by friction hindering relative movement. The improvement of fabric recovery with ageing is shown to be a single-fibre property, the friction being apparently unchanged.     

25—THE WRINKLING OF WOOL WORSTED FABRICS. PART I: FIBRE AND YARN DEFORMATION IN BENDING

Experiments are described in which the extensional, bending, and twisting strains of seven fibres were measured in a wool worsted fabric deformed in a multiple-pleat tester. The only significant strain appeared to be the bending strain.     

10—THE WRINKLING BEHAVIOUR OF WOOL FABRICS: THE EFFECT OF ANNEALING AND CROSS-LINKING

An investigation is described in which various polyfunctional compounds were applied to wool in attempts to stabilize the temporary improvements in wrinkle-recovery brought about by ‘annealing’. Several reactive systems involving formaldehyde were found to produce the desired permanently improved wrinkle-recovery.     

31—THE HANDLE AND BENDING BEHAVIOUR OF FABRIC LAMINATES

Certain aspects of the handle of fabric laminates are related to properties of the component fabrics. Particular attention is paid to a theoretical prediction of the bending stiffness of a laminate from the bending and tensile properties of its components. This theoretical stiffness is a minimum value; if, in practice, the observed stiffness is much greater than this, it may generally be assumed that excess of adhesive or of melted foam is the cause. The paper also reports work on other features of the bending behaviour, such as the degree of recovery from bending, and on the shearing behaviour. The work is concluded by a brief study of some faulty laminates.     

24—THE BENDING STRESS-STRAIN PROPERTIES OF SINGLE FIBRES AND THE EFFECT OF TEMPERATURE AND RELATIVE HUMIDITY

An investigation is described in which bending stress–strain curves of several keratin and synthetic fibres were obtained up to bending strains as high as 20%. These results suggest that low-stress compressive yielding is occurring at the intrados of the synthetic fibres during bending. The keratin fibres, on the other hand, do not appear to yield in compression, if at all, until much higher stresses are reached. The variations in nominal bending moduli of wool, nylon, and Terylene fibres with changes in temperature and relative humidity were also investigated.     

43—THE WRINKLING BEHAVIOUR OF WOOL FABRICS: THE EFFECT OF METAL SALTS ON DRY AND WET WRINKLE-RECOVERY

The dry and wet wrinkle-recovery of wool fabrics can be improved by reaction with metal salts in the anionic or cationic form. Small amounts of substantive metals are shown to have produced significant improvements in wet wrinkle-recovery, but, with the exception of chromium, only relatively large amounts of metals such as mercury, uranium, tungsten, and molybdenum improved dry wrinkle-recovery.

The mechanism by which mercuric acetate improves dry wrinkling does not appear to involve sulphur, despite extensive reaction between mercury salts and sulphur-containing residues, such as cysteine, cystine, and cysteic acid.     

31—THE WRINKLING BEHAVIOUR OF WOOL FABRICS: THE EFFECT OF ANNEALING PARAMETERS

An investigation is described in which conditions suitable for the rapid ‘ageing’ or ‘annealing’ of wool fabrics were assessed by measurement of the resultant wrinkle-recovery properties. Maximum annealing is shown to be obtained when the fabric is heated at 15% regain (the time taken depending on the temperature of heating) and then slowly cooled. The annealing mechanism is believed to involve molecular rearrangements via labile hydrogen bonds to give a lower energy network. Wetting out of the sample changes this arrangement and results in a lower recovery on subsequent wrinkling.     

26—THE BENDING ELASTIC RECOVERY OF NATIVE AND CHEMICALLY MODIFIED COTTON FIBRES

Measurements of the bending elastic recovery of native and chemically modified cotton fibres are described; the results are used to estimate the degree of cross-linking in the treated fibres, and to predict the crease-recovery behaviour of fabrics made from the fibres.     

37—THE HISTOLOGICAL STRUCTURE OF WOOL FIBRES AND THEIR PLASTICITY

The relation between the creep behaviour (plasticity) and the proportion of the orthocortical material (expressed as ortho/para ratio) in five lambs' wools has been examined by means of electron-microscope techniques, in conjunction with thin sectioning. No correlation was found between the amount of orthocortical material, on the one hand, and either plasticity or helical conformation (the latter estimated by other workers) on the other. These results are supported by the observation of the structural differences, greater than hitherto thought, within both cortical segments (as indicated by the considerable variation in metal absorption—‘staining’), and it is believed that these have the primary effect on the plasticity. The cells of intermediate morphological appearance and reactivity (between those of the two bilateral segments and referred to as as meso-type) have a secondary influence in this respect.     

40—THE BENDING OF A HELICAL WOOL FIBRE

The bending of a helical wool fibre having an elliptical cross-section is considered. It is shown that, at low helical angles (<20°), the fibre's bending rigidity decreases with increasing ellipticity, but this trend is reversed at high helical angles (>50°). For a merino fibre subjected to moderate bending, the maximum error involved in assuming a circular cross-section is less than 5%. Maximum stress does not occur at the inside or the outside of the bend but is found midway them.     

27—THE BENDING AND CREASING OF MULTICOMPONENT VISCOELASTIC FIBRE ASSEMBLIES. PART I: GENERAL CONSIDERATION OF THE PROBLEM

The problems involved in making a mechanical analysis of bending deformations in textile fabrics are discussed. It is suggested that progress can be made by making simplifying assumptions concerning the geometry of fabric structure and deformation and using energy considerations to calculate forces and moments. Certain simple examples are given of the usefulness of this approach. A foundation is laid for the construction of a computer model that will, it is hoped, simulate the viscoelastic bending and creasing behaviour of textile fabrics from a knowledge of the bending and torsional viscoelastic properties of the constituent fibre(s) and their relative geometrical arrangement.     

56—THE WRINKLING BEHAVIOUR OF WOOL FABRICS: THE EFFECT OF THE STRUCTURE OF FORMALDEHYDE CONDENSATION POLYMERS ON THE STABILIZATION OF ANNEALED WOOL

An investigation is reported of the use of formaldehyde condensation polymers of aromatic amines, heterocyclic amines, and phenols to stabilize the improved wrinkle-recovery of annealed wool. These polymers were formed in situ during the annealing process.

The most effective polymer networks were those obtained from the reaction of formaldehyde with multifunctional compounds such as (i) 2,4,6-triaminopyrimidine, (ii) 2,6-diaminopyridine, (iii) 3,5-diamino-1,2,4-triazole, (iv) 1,3,5-trihydroxybenzene, (v) 1,3-dihydroxybenzene, and (vi) 2,4,6-triamino-s-triazine.     

28—THE BENDING BEHAVIOUR OF A HELICAL FILAMENT PART I: THE RIGIDITY OF THE HELIX

The large-scale bending of a helical filament is considered. It is shown that, in many cases likely to be of interest in textile applications, the bending rigidity of the helix calculated from small-deflexion theory provides a good approximation to the large-deflexion case. The cross-section of the deformed helix and the position of the neutral axis are also discussed.     

13—A STUDY OF THE PARAMETERS MEASURED IN THE WRINKLING OF WOOL IN A FIXED-DEFORMATION TEST

In wrinkling tests based on angular recovery from a fixed deformation, constraints imposed on the fibres by virtue of yarn or fabric construction are of secondary importance. When ageing effects have been eliminated, this results in similar wrinkle-ratings for all fabrics. Any performance differences subjectively assessed during wear arise from either fabric deformability or optical effects caused by differences in curvature.     

26—THE ELASTIC RESISTANCE TO BENDING OF PLAIN-WOVEN FABRICS

The elastic resistance to bending of woven fabrics has previously been considered in terms of the existence in the yarns of rigid and elastic sections. The difficulties inherent in such a model and the noticeable differences between the predicted and experimental findings are examined in this paper. Two models of a plain-woven fabric in which the yarn cross-sections are incompressible are then analysed theoretically to obtain the predicted relationship between the applied couple and the curvature of the fabric.

In the first model, the yarns are considered to be unset, i.e., if released from the fabric, they would be uncrimped, and in the second model they are considered to be completely set, i.e., if released from the fabric, they would retain all their crimp. The predicted bending resistance does not agree with the behaviour of actual fabrics owing to the difficulty of defining the ‘radius’ of the yarn in the fabric, but many puzzling qualitative aspects of the bending behaviour of woven fabrics are, as a result of the analysis given, satisfactorily explained.     

37—THE ULTRAFILTRATION OF WOOL-SCOURING EFFLUENTS

It is shown that ultrafiltration is a feasible technique for producing an effluent completely free from suspended solids and wool grease together with a concentrated sludge from a strong wool-scouring liquor at a moderate cost. The process would be particularly applicable in areas where there are stringent effluent standards.     

21—THE NATURE OF INTER-FIBRE FRICTIONAL EFFECTS IN WOVEN-FABRIC BENDING

Inter-fibre friction in woven-fabric bending is discussed in terms of the fibre and fabric characteristics that influence its effect on a fabric's bending resistance. A model of the contribution of inter-fibre friction to fabric bending is developed. This model is combined with an existing model of the contribution of fibre bending to produce a new three-element model of a woven fabric in bending. The behaviour of this model is compared with experimental measurements on real fabrics in cyclic bending.     

60—THE BENDING BEHAVIOUR OF PLAIN-WEAVE FABRICS AT MEDIUM CURVATURES

The modification of the Shirley Bending-hysteresis Tester for low curvature (0.5 mm^?1) for use at higher curvatures (5 mm^?1) is described, and with its aid the contributions made by the frictional and fibre-viscoelastic deformations to non-recovery of a bent woven fabric are separated quantitatively. A study of the bending behaviour of component yarns is also reported.     

33—THE STRENGTH OF COTTON FIBRES AND THE DEGREE OF DEVELOPMENT OF THE SECONDARY WALL

A comparative analysis of two methods of determination of the maturity of cotton fibre is reported. One consisted in comparing fibres with reference drawings and the other in using the polarizing microscope. The relationship between the degree of development of the secondary wall determined by these methods and the strength of cotton as one of its most important physical properties was also taken into consideration.

The degree of correlation between the methods discussed and between the results obtained with them and the breaking load was found.

It was also ascertained that the degree of maturity was not the same throughout the length of the fibre. It increased from the base to the tip of the fibre.     

17—THE ORIENTATION AND MOTION OF THE WEAVING REED

Reed motion is discussed in terms of the orientation at which the reed is mounted on the sley. Looms examined suggest that normally this orientation is determined primarily by whether or not the weft-insertion element is guided within the working width and by the alignment with the warp required of any such guides during weft insertion. Reed-orientation angles are given for three looms with very different weft-insertion systems, and the method of measurement is outlined.

The relationship between the extreme reed positions is discussed, together with the reed-displacement components parallel and perpendicular to the reed face in its furthest-forward position. The orientation angle is shown to have only a modest effect on the perpendicular component and hence on the size of shed available for weft insertion.