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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. [ABSTRACT FROM AUTHOR]

Previous papers have described the use of the cloth-bending-hysteresis test in investigating the detailed bending behaviour of fabrics. An account is given in this paper of the use of the techniques of regression analysis to investigate the correlation between the results of this test and other mechanical tests with subjective assessments of cloth stiffness and liveliness for two groups of fabrics. The correlations are shown to be highly significant, and good estimates of these two subjective properties could be made from the laboratory tests. [ABSTRACT FROM AUTHOR]

It has been shown in the preceding paper how high-speed cam systems were desired to give substantial increases in the rate of fabric production of weft-knitting machinery. This paper provides a detailed analysis of the effect of cam shape on the knitting-yarn tensions, machine performance, and individual needle forces. It is explained that, although the yarn tensions developed within the knitting cycle are greater for high-speed cams than for conventional linear cams, these tensions do not affect the resulting fabric appearance or the machine performance. In addition, calculations of individual needle forces and high-speed trials indicate that speeds many times as great as commercial speeds may be achieved with the mathematically designed high-speed cams. [ABSTRACT FROM AUTHOR]

It has been shown that the conventional analysis of the capstan-friction behaviour of textile materials is innaccurate for two reasons: firstly, because it ignores the fact that such materials do not as a rule obey Amontons's Law, and. secondly, because the effect of the rigidity of the body passing round the capstan has been neglected. These effects have been analysed separately in a series of papers, but in this paper an attempt is made to take both effects into account. To do this it is necessary to obtain the relationship between the friction constants for localized- and distributed-force systems. This is done, and the resulting equations are shown to give predictions that are in agreement with experimental findings. [ABSTRACT FROM AUTHOR]

An account is given of an investigation of the effects of fibre type (rayon, acrylic fibre, wool, and cotton) and dimensions on the properties of needled fabrics, the test methods used being those described in a previous paper. Some fabrics show a stick-slip behaviour in extension; others deform smoothly. Rayon webs — consolidate more easily on needling than Courtelle or wool webs. Longer fibres give higher fabric strengths. Finer fibres also give higher strength, unless fibre damage occurs. The influence of fibre friction is discussed. [ABSTRACT FROM AUTHOR]

A critical assessment of the merits of core-spinning by means of comparisons of the strength and extension of core-spun yarns with all-staple-fibre yarns forms the basis of this paper. Core-spinning was done by introducing the filament under tension into the drafted strand as the latter entered the front rollers of the ring-frame. A 20-den (2.2-tex) nylon monofilament was used as core, and three types of staple-fibre covering were investigated. The effects of twist, pre-tension, and feeding arrangements on the geometrical disposition and tensile properties of the yarns were examined. Irnprovements in strength are, in general, realized at low twists by the incorporation of the filament and by further constraining it to occupy the core. The contribution of the components to the yarn strength and the process of breaking were also subjected to a detailed study. The studies reported provide an interesting insight into the extent of cohesion developed between the fibres during the straining of the yarn and its influence on the process of breaking and ultimately on yarn extension. [ABSTRACT FROM AUTHOR]

The relevance of the extensional recovery of single filaments to the resilience of textiles is discussed, and tests are described that yield information at three different effective rates of loading. The methods considered are: (i) cyclic measurements on an Instron Tensile Tester; (ii) recovery from a sustained extension; and (iii) recovery from impact. Applications of these methods will be discussed in two later papers. [ABSTRACT FROM AUTHOR]

Three empirical test methods of determining the extensional recovery of textile fibres have been reported in the previous paper. Data are now presented to demonstrate how recovery depends on the test material and its method of preparation, the strain, the rate of strain, the time under load, the number of times the load is applied, and the temperature at which testing is done. The importance is stressed of ensuring that test conditions cover the range of deformation experienced by the finished product. [ABSTRACT FROM AUTHOR]

Steely wool has a low crimp rate and low strength and doggy wool a low crimp rate but normal strength, so that both wools are exceptionally useful experimental materials. An account is given in this paper of a comparison of the processing behaviour of wools of the two types with that of matched normal wools from yarn to fabric. The tensile properties and abrasion-resistance of the anomalous wools were as expected, but an unusual effect of the steely wool in washing shrinkage was found. The presence of steely-wool yarn in one direction (e.g., warp) caused increased shrinkage of the yam in the cross direction. Thus, in a fabric with a steely-wool warp yarn and a normal-wool weft yarn, the shrinkage index of the weft yam increased from 1.8 to 3.0; when the normal-wool yarn was used as warp with a steely-wool weft, the increase was from 1.7 to 2.4, This co-operative shrinkage did not occur with the doggy wool; it is thought to be caused by the low tensile modulus of the steely wool. [ABSTRACT FROM AUTHOR]

An account is given of an experimental investigation of the normal snarling of highly twisted monofilaments, those used being vulcanized rubber and nylon. An earlier theoretical analysis is corrected, and the experimental results show that, after this correction, the theory put forward for the mechanical properties of the snarling mechanism holds reasonably well for elastic filaments. Although, as would be expected, there are larger deviations from the theory for visccelastic filaments, the theory still gives a good indication of the behaviour of these filaments under torsion. [ABSTRACT FROM AUTHOR]

A reappraisal of previous work on the hairiness of ring-spun yarns that the conclusions reached regarding the effect of fibre characteristics on cotton-yarn hairiness need to be revised. The observed effects can be explained by a simple hypothesis that the mean weight and mean length are the only fibre characteristics that intrinsically affect yarn hairiness. Published data are shown to be inadequate for arriving at satisfactory explanations of the way in which the spinning parameters affect yarn hairiness. The need for the measurement of the hairiness of yarns from the spinning zone and from the instantaneous surface of the cop, in addition to that from the interior of the cop, is established. Methods for these measurements are proposed. The information obtained is shown to be useful in explaining the phenomenon of yarn hairiness and particularly in accounting for the observed differences between different yams. [ABSTRACT FROM AUTHOR]

An account is given of a study of the bending behaviour of three types of warp-knitted fabric with the aid of a cloth-bending-hysteresis tester. The stiffness, liveliness, and curling tendency of these fabrics, together with the effects of heat-setting on these properties, v/ere assessed, and the critical condition for rolling of the edge of a curly fabric is derived in a theoretical appendix. [ABSTRACT FROM AUTHOR]

A brief summary of the structure of keratin fibres is followed by a review of their mechanical and allied properties. Among these properties are tensile stress-strain properties, stress relaxation, and creep, and torsional stress-strain properties and stress relaxation. The mechanism of supercontraction, properties of set fibres and disulphide-reduced fibres, and thermal transitions in keratin are also discussed. Finally, the various theoretical attempts that have been made to explain these properties are critically reviewed. [ABSTRACT FROM AUTHOR]

The effect of previous alkali (sodium carbonate) treatments at different concentrations on the properties of wool bleached with solutions of hydrogen peroxide at different concentrations was evaluated. Optical, chemical and mechanical properties of bleached and unbleached unscoured wool and of pretreated and bleached wool were determined. Treatment with the sodium carbonate solutions leads to a decrease of both degree of whiteness and the Yellowness Index of the original wool; bleaching of pretreated wool yields a lower degree of whiteness than bleaching of wool pretreated with sodium carbonate. On the other hand, the Yellowness Index of bleached wools is not altered by the alkali pretreatment. The alkali solubility of pretreated, bleached wool is lower than that of untreated wool bleached at the same peroxide concentration. At a given concentration of hydrogen peroxide, the content of cysteic acid of pretreated, bleached wool is independent of the severity of the previous alkali treatment and lower than that of I wool not treated with alkali. The wet tensile strength is much more sensitive to the alkali and hydrogen peroxide treatments than the dry strength. [ABSTRACT FROM AUTHOR]

The effects on the conditions of flow of the surface and configurational properties of the fibres in a compressible porous layer are discussed. The characteristics of a layer of wool are evaluated, and its compressibility is determined. It is shown that, when a liquid of initial uniform pressure flows through a compressible porous medium, the pressure gradient within the medium increases with the distance of flow. The resulting pressure drop is found to depend on a function of the ratio of the downstream to the upstream porosity of the compressible medium. Experimental results are reported for permeable flow through various layers of loose wool; these indicate that, when the flow is disturbed turbulent, the pressure drop through the layers is proportional to the square of the filter velocity. This result is not readily apparent from the graphs of pressure drop against filter velocity because of the compressibility of the fibres. [ABSTRACT FROM AUTHOR]

An account is given of an experimental investigation of the cylindrical snarling of highly twisted monofilaments. The theory underlying cylindrical snarling is set out, and an expression is derived for calculating the critical twist level at which normal snarling will be replaced by cylindrical snarling. Experiments on rubber filaments are described, and it is shown that there is good agreement between the theoretical and experimental results. Further experiments, in which the specimen was allowed to contract freely or forced into other forms, are also described. It is shown from these experiments that it is difficult to establish the true equilibrium behaviour, since the situation appears to be dominated by frictional effects or by direct barriers to relative movement. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

An account is given of experiments made with an apparatus constructed for recording, simultaneously and continuously, weight and length changes during the drying and steaming of fabrics. Hot air at a temperature of 100 or 115°C was used in the drying experiments. Steaming was done under the same conditions. The maximum level to which the moisture regain could be increased with steam varied with the fabric construction. Below this maximum level, absorption and desorption experiments with relaxed fabrics gave reproducible and identical hygral-expansion curves. Moisture-regain changes below saturation caused by steaming and drying did not completely release the strain in fabrics cohesively set. The difference resulting from the use of saturated and superheated steam was negligible. The lower the temperature during cohesive setting, the less resistant was the set towards moisture-regain changes. [ABSTRACT FROM AUTHOR]

A study is made of the effect of uniplanar crimps on the resistance of filaments to bending, both in the plane and perpendicular to the plane of the crimps. Results are verified by bending steel wires, and some attention is paid to the bending of wool staples. [ABSTRACT FROM AUTHOR]

A study of the recovery of single fibres from bending is reported for nylon, polypropylene fibre, Courtelle, and some carpet fibres. Most of the recovery takes place during the first hour, with further small increases for up to seven days. The effects of heat treatments both before and during bending are examined. Poor correlation between bending and tensile recoveries leads to a consideration of tensile and axial compressive effects. Further work is desirable on the latter aspect. [ABSTRACT FROM AUTHOR]

Treatments designed to increase and decrease friction were applied to rayon staple fibre before processing, as card web, and after needling. Basic frictional properties of the fibres were examined. The first two groups were processed into needled fabrics, and it is shown that considerable damage occurs with high-friction fibres: this results in a deterioration in mechanical properties. Even a wet process without additive causes some loss of strength. However, treatment with a high-friction additive after needling results in increased strength in the fabric. [ABSTRACT FROM AUTHOR]

An account is given of an investigation of the effectiveness of steaming on the longitudinal stabilization of wool yarn. Specially prepared worsted yarns were used to study the effects of initial regain and of time and temperature of steaming. Of the several different mechanisms proposed for the longitudinal stabilization of yarn by steaming, only permanent setting is demonstrated directly, and the effects of temperature, initial regain, and time of treatment are established. Two threshold values were observed below which no permanent setting took place—an Initial-regain threshold of 7-8 % and a temperature threshold of about 88 °C. It is considered possible that the threshold temperature is a function of the particular release treatment used and that it would increase with increasing severity of the conditions of release. The contribution of permanent setting to the over-all longitudinal stabilization was apparently small, but this may have been a result of using a rather severe release treatment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

An account is given of a study of the changes in fabric properties caused by setting with steam in autoclaves. Dimensional stability, shear angles, thickness, and breaking strength were measured, and the influence of variations in setting conditions, such as humidity, temperature, time, pH, and mechanical pressure, was investigated. The controls necessary for eliminating end-to-end effects in whole pieces are discussed. [ABSTRACT FROM AUTHOR]

The STT system is one in which unidirectional twist is added to self-twist yarns to produce two-ply weaving yarns. The added twist required for the elimination of fabric patterning due to cyclic twist variation in the yarn has been determined and has been expressed in terms of the amount of self-twist in the yarn. Fabrics woven from STT yarns have been evaluated, and the dependence of fabric properties on initial self-twist and on added-twist levels has been investigated. This has resulted in recommendations for the spinning and twisting of STT yarns for use in making high-quality worsted fabrics. [ABSTRACT FROM AUTHOR]

Cotton fabric has been methylated under a variety of conditions. The extent of methylation has been shown to be dependent on the time of methylation and on the degree of swelling or disruption of structure. The latter is caused by the alkali pretreatment or by the swelling of the partly methylated cellulose. Fabric physical properties have been measured and the influence of the methylation treatment has been examined. [ABSTRACT FROM AUTHOR]

An account is given of an investigation in which gross particles consisting of either jute or viscose rayon fibres of different lengths and diameters were spun in both secondary cellulose acetate filaments and a polyurethane elastomer in order to verify whether a significant degree of reinforcement was possible with a composite material of this type. The mechanical properties of the composite cellulose acetate fibres were studied, and it is shown that both types of filler produced a decrease in breaking extension and an increase in initial modulus with increasing filler content. The strength of the jute-filled material is also shown to increase. Similar effects on the breaking extension and initial modulus of the rayon-filled polyurethane filaments were observed, and here there was also a decrease in strength that arose from the difference in extensibility between the rayon and the polyurethane filament. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Stress-strain data for wool fibres of different origin are presented, the tests having been made under different moisture conditions. Small differences exist between wool fibres from primary and secondary follicles from the same animal, the secondary being easier to stretch both initially and finally under wet conditions. However, the relative yield slope is markedly higher for secondary than for primary fibres. Differences exist between and within breeds in the initial modulus, the stress at 15% extension, and the slopes of the curves in the yield and post-yield regions. [ABSTRACT FROM AUTHOR]

A processing programme is outlined in which yarn pre-twist, applied air-pressure, and supply-yarn overfeed are systematically varied in the air-jet bulking process to investigate their effects on air-textured nylon 6.6 continuous-filament yarns. Optical magnification of the air-textured yarns enables the average loop sizes and frequencies to be measured. The experimental results are shown to be in general agreement with a suggested mechanism of the process, which argues that the initial filament twist in the parent yarn redistributes itself as snarled loops and that the overfed yarn contributes to the size of such loops; the deflexion of filaments by air-drag forces is also shown to make a contribution to a looping effect, which can be estimated theoretically. Increasing the yam overfeed increases both the loop size and the loop frequency. Increasing the yam pre-twist decreases the loop size and increases the loop frequency. Increasing the air-pressure also decreases the loop size and increases the loop frequency. Experimental and theoretical results are in general agreement. As would be expected, the only processing condition that effects a change in linear density is the overfeed, but all the processing conditions that have an effect on loop dimensions also have an effect on the change in volume, i.e., on the physical bulk. Overfeed is the greatest single contributor to physical bulk, since both loop size and loop frequency increase with overfeed, occluded air spaces being thereby created in yarn and fabric form; conversely, with varying twists and air-pressures, the effects of decreasing loop size and increasing loop frequency are to some extent self-balancing in their contribution to physical bulk. It is shown how the various processing parameters affect the stability of air-textured yarns. Textured yams produced from parent yarns possessing small amounts of pre-twist have a high instability because of the lack of binding twist for securing the entangled structure. Increasing the overfeed greatly increases the number and size of loops, and this causes greater instability. Increases in the applied air-pressure also increase the yarn instability. Two new mechanical techniques have been devised to measure the yarn instability, and these have been found to be greatly superior to the stability-testing apparatus normally used, which has serious defects from the viewpoint of accuracy. The tenacity of the air-textured yarns tends to decrease for increasing values of all the main processing variables considered. Increasing the yarn pre-twist tends to reduce the percentage elongation at break, but independent increases in the supply-yarn overfeed and the applied air-pressure both tend to increase this characteristic. These results are interpreted in the light of the bulking mechanism previously postulated. [ABSTRACT FROM AUTHOR]

The theory of the extension of continuous-filament yarns is re-examined by means of energy methods and presented in much simpler terms than those previously given. The essential statement of the theory is contained in four equations, which can be used as a basis for numerical computation. The limitations and possible generalizations of the theory are discussed. [ABSTRACT FROM AUTHOR]

An account is given of a study of the wearing properties of woven and tufted carpets made from wool, nylon, viscose rayon, and an acrylic fibre and from various blends of these fibres. The carpets were subjected to trials on two staircases and to laboratory tests for resistance to abrasion. It is shown that nylon resisted abrasion in use better than the other fibres studied, and the advantages of introducing nylon into a blend with one of the other fibres are demonstrated by comparison with the results obtained on carpets made entirely from the other fibres. It is also shown that, in general, the laboratory abrasion tests confirm the ranking of the carpets in the service trials on a staircase, although the advantages of introducing nylon appear to be greater in the laboratory tests than in use. [ABSTRACT FROM AUTHOR]

The effects of benzoquinone treatment on the frictional properties of wool fibres against a variety of surfaces are reported. The principal variations observed are explained in terms of ‘ploughing’ effects by scale tips and support the theory that the shrinkproofing properties of benzoquinone are not attributable to changes in frictional properties. The loose-wool-felting behaviour of short fibres emphasizes the importance of fibre-bending in felting and suggests that modification of this latter property may be the manner by which benzoquinone produces shrinkproofing effects. [ABSTRACT FROM AUTHOR]