6—THE EFFECT OF ALKALINE AND ACID SWELLING AGENTS ON THE MECHANICAL PROPERTIES OF COTTON FIBRES

A study of the changes in mechanical properties of cotton brought about by sodium hydroxide, an iron tartrate complex in caustic soda (EWNN), cuprammonium hydroxide, and sulphuric, phosphoric, nitric, and perchloric acids has been made. Instead of choosing the normal mercerizing conditions with sodium hydroxide, different temperatures of treatment and of washing were studied to see what effect the condition had on the subsequent mechanical properties of the fibres. The variable studied with the other reagents was that of concentration, so that a distinction between interfibrillar and intrafibrillar swelling could be made. The main effect of swelling is to alter the extensibility of the fibre, and this has been analysed at different stages of loading up to break.     

38—THE EFFECTS OF PLANAR CRIMP IN THE MEASUREMENT OF THE MECHANICAL PROPERTIES OF FIBRES,FILAMENTS, AND YARNS

A theoretical investigation of the tensile, flexural and torsional behaviour of crimped filaments has been made; the relationships describing the filament behaviour are presented in graphical and in analytical form, and are verified experimentally. Two results are of particular importance in routine textile testing: it is shown that the Young's modulus of staple fibres measured with a tensile-testing machine is not subject to significant error caused by crimp; and a new expression is proposed which enables the optimum tension for the routine yarn-crimp test to be calculated.     

13—AN INVESTIGATION OF THE TAPER OF COTTON FIBRES. PART III: VARIATION IN THE MECHANICAL PROPERTIES OF A COTTON FIBRE ALONG ITS LENGTH

The pattern of distribution of the mechanical properties and structural reversals along the fibre and their dependence on the fibre profile are reported in this paper. Experiments on twelve cottons showed that both the fibre tenacity and the percentage elongation increased steadily from the root part to the middle region and then decreased to a minimum value at the tip part of the fibre. The decrease in tenacity from the middle to the tip part of the fibre was found to be influenced by the fibre profile. The structural reversals increased from the root to the tip through the middle, and the maximum variation was observed in fibres having the highest uniformity in the cross-sectional shape of the fibre along its length. The variation in the structural reversals is shown to be a factor responsible for the observed distribution of tenacity along the fibre.     

37—THE PROPERTIES OF JUTE FIBRES AT DIFFERENT STAGES OF PLANT GROWTH

An investigation is described in which cell-wall thickness, linear density, and filament tenacity were studied for jute fibres of both the C. capsularis and C. olitorius species at different stages of growth of the jute plant. It is shown that the cell-wall thickness goes on increasing for 120 days and then levels off, whereas the linear density goes on increasing for only about 60 days and then falls and levels off after 80 days. The fact that, despite the increase in cell-wall thickness, the linear density does not increase afier 70–80 days indicates that filaments become split at some stage prior to ihe determination of linear density. Breaking strength at first increases rapidly and then levels off after 80 days and falls after 120 days. Variation in breaking strengih is consistent with the variation in multicellular character, cementing material, and fine structure of the fibre with the growth of the plant.     

25—THE STRUCTURAL DEPENDENCE OF SOME MECHANICAL PROPERTIES OF COTTON OF THE GOSSYPIUM HIRSUTUM SPECIES

The structure, physical characteristics, and mechanical properties of 24 varieties of the Gossypium hirsutum species are reported. It is shown that the average crystallite orientation is a good index of fibre properties. Analysis of the mechanical data in terms of two single-phase structural models indicates that the intrinsic stiffness of the crystallites in the longitudinal and lateral directions is different for different varieties.     

45—OBSERVATIONS ON THE TENSILE PROPERTIES OF ULTIMATE CELLS OF SOME PLANT FIBRES

The tensile stress-strain relations for nine types of vegetable fibre have been measured, with the fibres in the form of (a) the commercial fibres and (b) the ultimate cells extracted from the fibres. Spiral angles were obtained by an X-ray diffraction method. The experimental results are compared with theoretical predictions.     

29—THE INFLUENCE OF GRINDING ON THE STRUCTURE OF KERATIN

It is shown that cystine and to a less extent tyrosine residues may be destroyed when wool is ground. Although sulphate radicals, cysteic acid, and lanthionine residues have been identified in the product, the degradation produced by grinding is not confined to disulphide-bond fission. The mechanism of the disruption chemical bonds during the grinding process is discussed.     

31—THE EFFECT OF THE APPLICATION OF BATCHING OIL ON THE FINE STRUCTURE AND MECHANICAL PROPERTIES OF JUTE

An investigation is described in which jute filaments obtained from breaker-card sliver were subjected to the following treatments: (i) samples were made moisture-free but retained the batching oil; (ii) samples were made both moisture-free and oil-free; (iii) moisture-free and oil-free samples were soaked in water and again made moisture-free. Jute filaments were also obtained from raw fibre and from raw fibre from which natural fat and wax had been removed. The X-ray crystallinity was determined for all the samples in the moisture-free condition. The results obtained are explained on the basis of a paracrystalline structure of cellulosic fibre, some regions of which are capable of diffracting X-rays and at the same time are accessible to moisture. It has been proposed that, when the fibre is treated with an oil–water emulsion, water molecules penetrate into the amorphous regions and into portions of the region of intermediate order (paracrystalline), the resultant swelling then producing fissures that oil particles in the emulsion enter and in which they anchor themselves like wedges. These anchored oil particles are retained when the absorbed moisture (the water molecule) gradually evaporates to leave the structure in a less crystalline state. Rigidity values of the variously treated jute filaments support this view.     

18—A CONSIDERATION OF THE REAL MATURITY OF COTTON FIBRES

Maturity is an important fibre characteristic, which is related to the extent of development of the fibre wall Several methods exist to measure this characteristic, but all these methods are calibrated by starting from procedures that depend upon measurements made on swollen fibres, such as the ASTM or the BSI method.

In this paper the results of an investigation are given in which maturity was measured directly on cross-sections of unswollen fibres. The results are compared with those obtained by measurements on swollen fibres as well as with estimations of maturity made by two indirect instrumental methods (the Arealometer and the IlC-Shirley Fineness/Maturity Tester (FMT)), both of which use the double-compression air-flow technique.

It is concluded that microscopical measurements made on swollen fibres do not always adequately reflect the botanical maturity and that in any case the two instrumental methods are more reliable. Appropriate conversion formulae are given for estimating the true fibre maturity from both Arealometer and IlC-Shirley FMT readings.     

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.     

42—THE EFFECT OF DEAGEING ON SOME MECHANICAL PROPERTIES OF WOOL OUTERWEAR FABRICS

This paper describes an experimental investigation of fabric-wrinkling behaviour as measured on a Thermobench, fabric stress-relaxation measured under both constant and varying ambient conditions, and inter-fibre friction of a series of three wool fabrics tested in both their ‘aged’ and ‘deaged’ states. Deaging of these fabrics was achieved by four different methods. It is shown that simply soaking in water at room temperature is an effective and practical deageing procedure for wool fabrics.     

39—THE DETERMINATION OF THE LATERAL-COMPRESSION MODULUS OF FIBRES

An account is given of the measurement of the transverse deformation of fibres under various loads acting normal to the fibre longitudinal axis by a technique in which fibres are interleaved between glass plates in a vertical stack. Graphs of transverse load against compression are plotted for nylon, acrylic, and viscose rayon fibres under both air-dry and wet conditions.

An expression for the transverse deformation in terms of the applied load is proposed and used to calculate the lateral-compression moduli of the various fibres. The results show that, laterally, nylon fibres in both wet and dry states have the highest modulus and that acrylic fibres appear to be least affected by immersion in water. Viscose rayon fibres are most affected by water and experience a reduction in modulus by a factor of about 20.     

10—THE FRICTION OF COTTON FIBRES

An account is given of an investigation in which the variation in the frictional forces developed along the surface of some Egyptian cotton fibres was measured over a range of the recorded normal-load values developed under the point–point conditions of contact with a straight-edge probe. It is evident from the video-tape recordings made that the frequency of convolutions in cotton fibres is primarily responsible for determining their frictional behaviour. Under the experimental conditions used, the frictional force varies linearly with the normal load, and no evidence of plastic deformation was observed within the limit of resolution of the scanning electron microscope.     

31—OBSERVATIONS ON THE MECHANICAL BEHAVIOUR OF LINCOLN-WOOL FIBRES SUPERCONTRACTED IN LITHIUM BROMIDE SOLUTION

A brief summary of certain phenomena associated with the two stages of supercontraction in aqueous lithium bromide solution is given; in particular, the mechanical properties, in the cold solution, of wool fibres at the end of each stage are discussed. Results previously obtained by Feughelman and Haly are reinterpreted in terms of the simple two-phase model of crystalline microfibril embedded in a less ordered matrix. On the basis of certain assumptions, it is possible to obtain an estimate of the Stress–Strain curve of the matrix in LiBr solution. The matrix Stress–Strain curve so obtained compares well with the theoretical inverse Langevin rubber-elasticity curve up to a certain strain level.

A value for the number of random links between cross-links is obtained.     

30—A NEW TEST FOR THE DETERMINATION OF THE MILLING PROPERTIES OF WOOL

A new milling test using felt balls is described. With the new laboratory milling machine that has been developed, it is possible to determine the milling properties of wools and blends in addition to the rate of felting (already measured by means of the Aachener Filztest). The nature and amount of mechanical energy on the specimen are similar to those in normal industrial milling machines. The test procedure may be varied. It is possible to use milling agents that foam with as low a wool/liquor ratio as 1:1. A comparative trial between the new milling test and the Aachener Filztest has brought to light some apparent discrepancies, which are discussed.     

18—THE EFFECT OF HUMIDITY ON THE PHOTOTENDERING OF UNDYED FIBRES

Various undyed textile fibres exposed to the Light-fastness Tester under different humidity conditions are shown to lose tensile strength to different degrees; poly(vinyl alcohol) fibre, viscose, nylon, and cotton are found to be very sensitive to changes in humidity, whereas Orion acrylic fibre and Terylene polyester fibre are the least sensitive materials among those tested.     

49—SOME ASPECTS OF WORSTED-YARN STRUCTURE. PART II: THE MECHANICAL STATE OF SINGLE FIBRES LEAVING THE DRAFTING ZONE

An investigation is described in which a novel method of constraining drafted material between transparent adhesive tapes was used to show that, whereas the main single-fibre strain-inducing parameter is the insertion of twist into a yarn, a significant amount of this strain occurs as a result of the drafting process. The differences in behaviour during drafting of the leading and trailing ends of fibres are also demonstrated.     

37—THE OPTICAL INVESTIGATION OF TWISTED FIBRES

Considerable attention has recently been paid to the investigation of the optical properties of twisted fibres. It has been shown that, if the ratio of the total twist angle to the total phase retardation is small, the rotation of the plane of polarization equals the twist angle. However, no effective method has been proposed for the experimental determination of the twist angle and of the total phase retardation in the general case, although the problem has been theoretically considered by Desai and Patel. It is the aini of this paper to show that some results gained in photoelasticity for the uniform rotation of principal axes are directly applicable to the investigation of twisted fibres. A method for the determination of the twist angle and of the total phase retardation of a twisted fibre in the general case is presented.     

21—THE SOILING BEHAVIOUR OF MAN-MADE FIBRES

An account is given of a study of the soil pick-up and retention of eight common man-made fibres. The fibres (all of which were of 3 den (3.3 dtex) and 1 7/16 in staple) were spun into yarns of a common linear density, which were woven onto a common cotton warp in an identical sateen construction. The fabrics were soiled by the felt-block method, and the results are interpreted in terms of the absorbing and scattering powers of the fabrics as calculated from the Kubelka-Munk equations. It is shown that the most important parameter governing the appearance of white fabrics after soiling is the scattering power, although differences in soil pick-up are also observed.