32—THE SNARLING OF HIGHLY TWISTED MONOFILAMENTS. PART I: THE LOAD–ELONGATION BEHAVIOUR WITH NORMAL SNARLING

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 viscoelastic filaments, the theory still gives a good indication of the behaviour of these filaments under torsion.     

10—THE UNWINDING OF YARNS FROM PACKAGES PART II: UNWINDING FROM CYLINDRICAL PACKAGES

The particular case of unwinding from cylindrical packages is considered. Tables of balloon parameters are given for various unwinding conditions, and empirical formulae for estimating these parameters are presented.     

36—THE AGEING OF WOOL. PART II: THE AGEING OF DISORGANIZED FIBRES

Experiments are described in which the stress-relaxation and recovery behaviour in bending is determined during ageing for wool fibres previously disorganized by a treatment in boiling water and is shown to be generalized linearly viscoelastic. This behaviour is also shown to parallel that of the stress-relaxation and ageing behaviour of native fibres in torsion, which is known to reflect the behaviour of the matrix component of structure. The results are shown to be consistent with a hypothesis proposed by Rigby et al. It is also demonstrated that the microfibrillar regions of the fibre contribute a constant spring-like component to the modulus, which does not stress-relax or age but is destroyed when fibres are disorganized by a treatment in boiling water. It seems certain that the major mechanical effects observed during ageing result directly from processes occurring in the matrix.     

27—THE NORMAL FORCE BETWEEN TWISTED FILAMENTS: PART II: EXPERIMENTAL VERIFICATION

In a previous paper, the importance of lateral pressure in the tension and bending behaviour of yarns was discussed; a theoretical model, which included the effects of bending and torsional rigidities as well as the tensile, shear, and frictional forces, was proposed, and expressions for the lateral pressures were derived. In this sequel, the experimental verification of the previously derived expressions has been carried out on a very simple twisted structure, consisting of two rubber strands. The results obtained support the theoretical predictions of the lateral pressure for the experimental model and lead to the conclusion that, for filaments with significant torsional and bending rigidities, lateral pressures are obtained in the yarn even when there is no significant tension on the individual filaments. An approximate scheme for estimating the lateral pressures in an idealized, close-packed, multilayered continuous-filament yarn is proposed as an extension of the above results.     

4—THE FINITE-DEFORMATION THEORY OF PLAIN-WEAVE FABRICS. PART II: THE UNIAXIAL-DEFORMATION THEORY

The uniaxial tensile deformation of a fabric is analysed as a special case of the biaxial theory presented in Part I, and the bending rigidity of the yarn at right angles to the tensile direction is introduced.

The structural model presented in Part I is used again to solve the uniaxial case. The biaxial-deformation theory introduced in Part I can, however, be applied directly to solve the uniaxial case because no tension is applied to the yam in the transverse direction, that is, there is no resistance force preventing the straightening of the yarn in the transverse direction. There must, though, be some kind of force, and this resistance force. F ^c, is introduced in this paper and represented by two constants C ⁰ and C ¹. Theoretical considerations for introducing these constants are presented whereby the bending rigidity and the coefficient of friction of the fibre are used. An experimental method for obtaining the constants is also introduced, and the F ^c functions obtained by theoretical and experimental methods are compared.

Finally, the uniaxial load-extension curves of some fabrics are measured and compared with the theoretically calculated curves.     

70—THE MECHANICS OF SELF-PLYING STRUCTURES. PART II: MULTIFILAMENT STRANDS

Analyses of the mechanics of self-plying structures are presented for multi-filament component strands, and an account is given of the experimental verification of theoretical predictions, made by means of the use of nylon multifilament model yarns.     

19—THE MEASUREMENT OF TORQUE IN CONTINUOUS-FILAMENT YARNS. PART II: THE EFFECT OF YARN TENSION

The yarn torque developed by the applied tension in the torsion-balance apparatus described in Part 1 of this series is calculated by using an expression derived in an earlier paper. Differences in shape of net-torque–twist curves are studied for nylon monofilaments and model plied yarns; these differences in shape are related to friction effects and to the mechanical properties of the constituent filaments. The torsional rigidity of the yarns is evaluated from the initial slope of the torque–twist curves for a series of nylon monofilaments; the torsional rigidity and torsional modulus are also calculated from the load–extension curve of a closely wound helical spring by employing the classical theory of elasticity.     

33—THE DYNAMICS OF THE FALSE-TWIST PROCESS PART I: THE PROCESS SURVEYED

The changes experienced by a yarn during its progress through the falst-twist-texturing system are examined. The relations involved, between twist, tension, and torque, and the process parameters, are shown to be those of a feedback system, and the dynamic operation of the process is considered, in a general way, by using this concept.     

41—AN APPLICATION OF MINI-COMPUTERS TO THE OPTIMIZATION OF THE OPEN-END-SPINNING PROCESS. PART II: CONSIDERATION OF THE CASE OF THREE VARIABLES

The application of a mini-computer to the analysis of three-variable experimental designs (speed of opening cylinder, rotor speed, and twist multiplier) is studied with reference to the spinning of polyester-fibre-cotton blends. A technological interpretation of the results obtained is given, which generally confirms earlier work and also contributes new details of the phenomena determining the observed behaviour.     

40—THE CONSTITUTION OF THE EPICUTICLE OF WOOL. PART II: THE PURIFICATION OF ALLWÖRDEN MEMBRANES BY PHYSICAL METHODS

Experiments are described in which concentrates of Allwörden membranes were fractionated by sedimentation and by electrophoresis. Both techniques yield two main fractions in about the same proportions. The more dense minor fraction, which also has the higher electrophoretic mobility, contains the membranes. Amino-acid compositions of the electrophoretic fractions are given.     

34—THE DYNAMICS OF THE FALSE-TWIST PROCESS PART II: A THEORETICAL MODEL

General equations of twist- and mass-balance for the process are derived, and a linearized theoretical model is developed. Its predicted dynamic behaviour, for the pin-spindle process, is shown to depend on steady-state characteristics in addition to machine transit times. The behaviour is discussed in terms of frequency response.     

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.     

42—THE RAPID MEASUREMENT OF THE TENSILE PROPERTIES OF FIBRE BUNDLES PART II: EXAMPLES OF EXPERIMENTAL RESULTS

An account is given of the use of the bundle tester described in Part I of this series to determine the breaking force, work of rupture, and elongation at break of various textile specimens. Typical results (which include tests on wool staples and semi-processed materials) are reported.     

38—THE INFLUENCE OF WIRE PROFILE ON THE QUALITY OF WOOL-TYPE CARDED WEBS. PART II: NON-CONVENTIONAL FLEXIBLE WIRE

This paper describes a series of carding experiments in which non-conventionally shaped flexible card teeth, with the leading edge of the tooth made narrower than the following edge, in contrast to conventionally shaped teeth, in which the leading edge is wider than the following edge, were used to assess the nep content and fibre breakage of webs made from 70s lamb's wool containing known amounts of cut woollen and worsted threads.

It is demonstrated, both theoretically and practically, that this new conception of card-wire profile will give less neppy webs for the same production rate than those produced by using conventionally shaped teeth. It is also shown that the new type of card wire leads to greater carding power, measured in terms of thread removal, with no increase in fibre breakage.     

61—AN INVESTIGATION OF THE TAPER OF COTTON FIBRES. PART II: THE LENGTHWISE VARIATION OF MOLECULAR ORIENTATION IN COTTON FIBRES

An investigation is described in which the variation in the orientation of the chain molecules and the crystallites along the length of the cotton fibre was studied by employing optical and X-ray techniques. Three distinct regions, namely, the root, middle, and tip, of the fibres belonging to the modal-length group of the cottons were scanned. Birefringence was determined by the Beckeline method and root-tip-aligned bundles mounted on special clamps were used for the X-ray studies. Cottons of widely varying fibre properties and belonging to different botanical species were investigated.

The data revealed that the birefringence of the fibres increased significantly from root to tip through the middle. The X-ray crystallite orientation at the root was also found to be significantly lower than that in the other regions. These observations lead to the inference that the molecular chains become progressively better aligned as one proceeds from the root to the tip of a fibre. Intra-fibre variation and the discrepancies between the optical and X-ray measurements are discussed in terms of the fibre profile.     

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.     

33—WITHDRAWAL FORCES IN THE PROCESSING OF WOOL SLIVERS: PART I: THE DETERMINATION OF WITHDRAWAL FORCE

Apparatus is described by means of which the force necessary to withdraw a tuft of fibres from a sliver inserted in pins can be measured. An account is given of the use of this apparatus in investigations of withdrawal-force variations for different sliver weights and withdrawal speeds.     

25—ANALYSIS OF THE DRY-RELAXED KNITTED-LOOP CONFIGURATION: PART II: THREE-DIMENSIONAL ANALYSIS

The two-dimensional analysis of the dry-relaxed knitted loop given in Part I of this series is extended to three dimensions by considering the couples acting on the loop at the points of interlocking. The fabric dimensional parameters and the knitted-fabric cover are evaluated for the three-dimensional structure, and the conditions of jamming are investigated. The distribution of curvature and torsion along the loop indicates that very high torsional strains are induced in the arms of the loop.

The order of magnitude of the applied forces and couples is evaluated, and the energy of the loop is obtained as a function of G/B, the ratio of the torsional rigidity of the yarn to its flexural rigidity. The significance of these results is discussed. Finally, there is a critical discussion of the assumptions made throughout the work.     

11—THE DRYING OF TEXTILE FABRICS. PART II: THE RELATIONSHIP BETWEEN AIR-MOISTURE CONTENT AND FABRIC TEMPERATURE

The measurement of fabric temperatures by contact methods during drying is shown to give an unreliable estimate of the moisture content of the air in equilibrium with the fabric because the contacting device behaves as an improperly wetted wet bulb. Automatic control systems depending on such measurement to regulate drying in a tenter are therefore unsatisfactory.     

41—THE CONSTITUTION OF THE EPICUTICLE OF WOOL. PART III: THE SURVIVAL OF AMINO-ACID RESIDUES IN CHLORINE-WATER

An account is given of the determination of the extent to which saturated chlorine-water destroys individual amino-acid residues in insulin, lysozyme, α-keratose, and wool. Survival factors for a 5-min treatment are given for sixteen amino acids in each protein.