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.     

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.     

24—THE BENDING BEHAVIOUR OF PLAIN-WEAVE FABRICS WOVEN FROM SPUN YARNS

The bending behaviour of square plain-weave fabrics spun and woven from nineteen different fibres, each in a range of cover factors, has been studied. It is shown how this behaviour is determined by the mechanical properties of the fibre and the frictional and geometrical restraints within and between yams in the fabric. The effects on these restraints of cover factor and of relaxation in wet finishing and in heat-setting are examined. Factors affecting cloth stiffness are summarized, and it is shown that two quantities, an elastic component and a frictional component, are required to specify the bending behaviour with reasonable completeness.     

18—THE PREDICTION OF STRIPINESS DUE TO ROGUES IN KNITTED FABRICS

A group of adjacent rogue threadlines in a knitted fabric is likely to be visible as a stripe when the fabric is dyed. This paper provides theoretical results (which are also presented graphically) that give the probability of two or more, and of three or more, rogues occurring together in fabrics of various widths for varying proportions of rogues in the threadline population.     

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.     

6—THE RELATIONSHIP BETWEEN THE RESISTANCE TO COMPRESSION OF WOOL BULKS AND FOLLICLE CURVATURE

It is shown that there are strong relationships between the resistance to compression, the felt-ball diameter, and the curvature of the parent wool follicles. The relationship of these properties with follicle curvature is stronger than that with staple-crimp frequency.     

23—THE RELATION BETWEEN THE TWIST AND RESISTANCE TO REPEATED EXTENSIONS OF MAN-MADE-FIBRE ROTOR-SPUN YARNS

The relation existing between the twist and resistance to repeated extensions of man-made-fibre rotor-spun yarns is studied. Experiments on acrylic-fibre, polyester-fibre, and viscose staple-fibre rotor-spun yarns are reported, and it is shown that, for these fibres, the maximum resistance to repeated extension is consistent with generally low twist multipliers, although the level of the resistance is dependent on both the fibre type and the linear density of the yarns. Some complementary tests concerning the relation existing between twist and tensile strength for cotton, polyester-fibre, and acrylic-fibre rotor-spun yarns are also reported. It is shown that, whereas for cotton yarns the twist for maximum strength is found for a high twist multiplier, for man-made-fibre yarns the optimum twist occurs at low values of the twist multiplier.     

9—THE INFLUENCE OF RESISTANCE TO COMPRESSION ON THE PROCESSING PERFORMANCE OF SUPERFINE WOOLS PART I: TOPMAKING

Two series of experiments carried out to assess the rôole of resistance to compression in the topmaking performance of superfine wools are reported.

Wools of high resistance to compression gave lower scoured yields (by 4%) and top-and-noil yields (by 5%) and higher card wastes (by 2%) and noilages (by 3%) than wools of low resistance to compression. The tops produced from wools of high resistance to compression were shorter by 6 mm (Hauteur) than tops from wools of low resistance to compression. It is concluded that the differences are sufficiently large to be of commercial and technical significance.     

2—THE MOISTURE-VAPOUR PERMEABILITY OF TEXTILE FABRICS

The current ‘dish’ techniques for measuring the moisture-vapour permeability of textile fabrics are slow and tedious. A new approach, based on the measurement of the relative-humidity gradient in a closed linear system, is described. This Resistance Tube provides results that are equivalent to those of the dish techniques but requires less than one-third of the time for a determination and is much easier to accomplish. The sensitivity achieved is currently about one-half that of the dish method and is considered adequate for practical use. In addition, there is a potential for improving the Resistance Tube to the point where it has a sensitivity equal to, or greater than, that of the dish techniques. An important advantage of the new method is the fact that it can be used to investigate the permeability of composite specimens, as encountered in a practical clothing system.     

14—THE WET-RELAXED DIMENSIONS OF PLAIN-KNITTED FABRICS

Various states of relaxation of the plain weft-knitted structure are discussed in relation to fabric dimensions. An experimental investigation of dimensions in the wet-relaxed state shows that, in addition lo being dependent on the stitch length, these are also a function of the yarn diameter. A discussion of the possible causes of this effect concludes that it is the result of a combination of various yarn properties.     

39—THE FLEXURAL RIGIDITY OF THIN FABRICS

A simplified version of the Owen–Grosberg flexural-rigidity tester, of improved sensitivity, is described, and the theory of the instrument is presented.     

19—THE HIGH-CURVATURE CREASING BEHAVIOUR OF FABRICS

An alternative theoretical analysis is presented of an apparatus described by Skelton to measure the bending characteristics of fabrics by simultaneous rolling and compression of fabric loops between flat plates. At low values of θ, the angle between the direction of movement of the plates and the plate surfaces, the present analysis does not differ appreciably from that provided by Skelton. However, at higher values of θ, the differences are considerable. Other limitations of this method of obtaining bending parameters are discussed.     

27—THE CONVECTIVE DRYING OF SINGLE SHEETS OF FABRICS

Experiments are described in which the drying of single sheets of fabrics revealed two constant-rate periods when a specially designed continuous-recording balance was used for the measurement of the drying rate. In addition, it was found that a sudden increase in the drying rate occurred during the subsequent falling-rate period. Explanations are offered for these unexpected phenomena in terms of the change in fabric-surface roughness during drying and the shrinkage of the fabric during drying.     

34—THE CONTROL OF THE SHAPE AND DIMENSIONS OF KNITTED WOOL FABRICS

An account is given of an investigation of the use of steam treatments as a means of controlling the shape and dimensions of plain-knitted wool fabrics, firstly by allowing the fabric to relax towards its dimensionally stable state during steaming and secondly by steam-setting the fabric while it is held at a predetermined width. This steam-setting procedure is compared with two permanent-setting treatments for wool—a chemical-setting treatment and setting in boiling water.

Of the two methods of producing a dimensionally stable fabric, namely, by relaxation and by setting, the relaxation method is by far the more effective. The most important result of this work is that knitted wool fabrics—whether unset, steam-set, or permanently set—will always approach their completely relaxed shape and dimensions after only a couple of minutes' gentle agitation in water. It is concluded that conventional methods of shaping knitted wool fabrics and garments, which rely principally on steam-setting the fabric or garment to a size and shape different from its relaxed size and shape, are not likely to produce garments that have good dimensional stability and good shape-retention properties.

The ineffectiveness of permanent-setting agents in producing dimensionally stable knitted garments is contrasted with the relative effectiveness of these agents in producing pleats and permanent creases in wool cloths. This difference in behaviour is explained in terms of the different levels of individual fibre strains involved.     

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.     

31—EXPERIMENTAL STUDIES OF THE DIMENSIONAL PROPERTIES OF DOUBLE-KNIT FABRICS

An investigation is reported in which the dimensional properties of some double-jersey structures are compared under conditions whereby the run-in ratio, average loop length, cylinder-and-dial loop length, or dial-only loop length is maintained constant. It is concluded that, on the basis of the average loop length, K values, from which other dimensional parameters can be calculated, may be used to characterize the structures under investigation.     

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.     

37—THE WRINKLING AND BENDING OF FUSIBLE INTERLININGS

A series of apparel fabrics were bonded both to a cotton base cloth and to a worsted base cloth. The fabrics were then wrinkled by the AKU tester under wet and standard atmospheric conditions, and their wrinkle severity was determined by means of the Sivim Wrinklemeter. Buckling and cantilever tests were also made, and the wrinkling behaviour and bending performance were compared.     

15—A STUDY OF NEEDLED FABRICS. PART V: THE APPROACH TO THEORETICAL UNDERSTANDING

Needled fabrics are complicated structures, and an exact analysis of their mechanics is not yet possible. Understanding is approached through three routes. Firstly, the behaviour of a fully bonded web is used to predict the effects of orientation, and to estimate the upper limits of strength. These estimates may be reasonable if the network that actually exists at the breaking point is used in calculations. Needled fabrics can give a fairly high utilization of fibre strength. Secondly, the effects of slippage are discussed qualitatively, by analogy with the behaviour of spun yams. The influences of entanglement, fibre length, fibre fineness, and fibre friction are discussed. Thirdly, a quantitative analysis, with many approximations, of a much-simplified model is made. Despite the unsatisfactory nature of some of the assumptions, the predictions are in general accord with experimental results.     

23—THE SETTING OF KNITTED WOOL FABRICS IN THE EXTENDED STATE

Setting treatments known to be effective for woven wool fabrics were applied to pure-wool weft-knitted fabrics while they were held in the extended state. The fabrics, of plain, interlock, and bourrelet structures, were initially wet-relaxed and conditioned before treatment. The effectiveness of the treatments was assessed by steam- and wet-relaxation techniques. For the plain fabrics, even the most successful treatments were not capable of preventing most of the set from being lost during a single mild wash. On the other hand, about half the set imparted lo the double-jersey fabrics could be retained under the same conditions. A possible explanation for this difference is advanced, this being based upon the difference in the setting behaviour of fibres in torsion and in bending.