C. A. Lawrence

Effects of Machine Variables on the Structure and Properties of Air-Jet Fasciated Yarns

The structure of fasciated yams, spun from 2.4 dtex, 51 mm acrylic fibers on an air-jet experimental machine, consisted of an untwisted core of fibers and a surface layer of fibers wrapped around the greater part of the core length. The surface fiber wrapping varied markedly in appearance and gave distinctive, reoccurring features along the yam length. These features were grouped into three classes based on the presence and the orderliness of the wrapping fibers. The mean length and frequency per meter of yam were obtained for each class, and the effects of the machine variables on these structural parameters and the yam properties were determined. Statistical analysis showed that the changes in the structural parameters correlated significantly with changes in the measured yam properties.

A Study of the Fibre-transfer-channel Design in Rotor-spinning. Part I: The Fibre Trajectory

An investigation is described in which high-speed cinematography was used to study the removal of fibres from the opening roller and their passage through the transfer channel during rotor-spinning. From the results obtained, it was concluded that short fibres would escape the pin-clothing of the opening roller in the region of the trash box. These fibres pass over the knife edge of the transfer-channel interface and are then drawn back into the mass of flow down the channel. Longer fibres will remain with their leading ends hooked around the pin-clothing, while their trailing lengths are ejected from the opening roller and bend over the knife-edge before the fibres are pulled down into the channel. An analysis of the transfer-channel design showed that a narrow rectangular cross-section, as opposed to a circular one, was more conducive to fibre-straightening.

Advances in yarn spinning technology

Part 1 Introduction to yarn spinning and structure: Overview of developments in yarn spinning technology Fundamental principles of ring spinning of yarns Fundamental principles of open end spinning of yarns Blending and composite yarn spinning Yarn structure and properties from different spinning techniques Yarn structural requirements for knitted and woven fabrics. Part 2 Advances in particular yarn spinning technologies: Developments in ring spinning Siro and solo spinning of yarns Compact spinning technology for yarns Rotor spinning of yarns Friction spinning of yarns Air-jet spinning of yarns Hollow spindle spinning of yarns Self-twist spinning of yarns Minimizing fiber damage caused by spinning Spin finishes for textiles.

The Physical Properties of Composite Yarns Produced by an Electrostatic Filament-charging Method

A technique is described for the separation of the individual filaments of a continuous-filament yarn. This involves the yarns being treated with a small amount of Permalose TM anti-static agent and the induction of electrostatic charges onto the individual filaments. The separated filaments are intermingled with a drafted ribbon of fibres at the front-roller nip of a ring-spinning frame, to produce 20-tex 70/30 cotton/polyester-fibre filament-blended composite yarns in which a degree of mixing between Fibres and filaments was achieved. Cotton ring-spun and the equivalent core-spun yarns were also made to compare their physical properties with those of the composite yarns. Twist, fibre length, and the roving-feeding arrangement were varied to observe their influence on the yarn properties.

An interferometric prediction of the intrinsic optical properties for cold-drawn iPP, PTFE and PVDF fibres

Interference polarizing (Pluta and Interphako) microscopes have been used to measure the birefringence and refractive indices during the cold-drawing of isotactic poly(propylene) (iPP), poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF) fibres. The intrinsic birefringence (Δn0) and refractive indices (niso, and ) of iPP, PTFE and PVDF fibres were interferometrically predicted using affine and pseudo-affine models. In terms of these intrinsic values, a new way of calculating the orientation parameter is discussed. A selection of microinterferograms is given for illustration.

A Study of the Fibre-transfer-channel Design in Rotor-spinning. Part II: Optimization of the Transfer-channel Design

Empirical equations are determined that mathematically model the design of a fibre-transfer channel with a rectangular cross-section. These equations are used to find the optimum geometric-design parameters of the channel. Analysis of high-speed photographic observations indicates the optimum design to give a threefold improvement in the straightening of fibres when compared with a commonly used commercial design.

16—HIGH-SPEED PHOTOGRAPHIC STUDIES OF THE FIBRE CONFIGURATION DURING TRANSFER FROM THE OPENING ROLLER OF A ROTOR-SPINNING UNIT

A study is reported of the configurations fibres adopt in open-end spinning during their transfer from the opening roller down the transfer channel to the rotor. A technique was developed for quantifying the fibre configurations in three-dimensional (3-D) space. This involved taking high-speed (3-μs flash) photographs of the configurations, viewed from two vertical planes placed mutually at right angles. The photographic images were then digitized and fed into a micro-computer, and numerical values relating to the fibre configurations were calculated. The relationship between the numerical data and the changes in the ratio of the air-flow speed at the inlet of the transfer channel to the peripheral speed of the opening roller was examined. The results obtained showed that, as this ratio increased, the percentage of fibres with a near-straight configuration also increased. Increasing the ratio to the maximum for the machine design increased the number of near-straight fibres to only 28% of the total number...

Mechanisms of wrapper fibre formation in rotor spinning: An experimental approach

Abstract Open-end rotor-spun yarns, unlike ring-spun yarns, are basically of a three-part construction: a tensely packed core of (straight) fibres substantially aligned with the yarn axis, more loosely packed fibres twisted around the core and wrapper fibres on the outside. The presence of wrapper fibres on the yarn surface is a characteristic feature of open-end rotor-spun yarns. In this study, the mechanics of twist insertion and the possible causes and mechanisms of wrapper fibre formation in rotor spinning under different operating conditions have been investigated.

A novel non-crimped thermoplastic fabric prepreg from waste carbon and polyester fibres

A biaxial non-crimped fabric, 400 ± 10 g/m2, +45°/−45° lay-up protocol, was made from a unidirectional tape comprised of a 60/40 wt% carded blend of virgin waste carbon fibres, 60 mm chopped length, and polyester resin fibres, 60 mm staple length. The non-crimped fabric was used as a thermoplastic prepreg to produce laminated composite panels. The prepreg exhibited a high degree of drapeability. The physical and mechanical properties of composite samples were determined; the density, void contents, tensile and flexural strengths and moduli were found to be 1.5 g/cm3, 10%, 180.7 MPa, 260.5 MPa, 34.2 GPa and 30.4 GPa, respectively. Modification of the consolidation process and the use of finer polyester fibres should decrease the void content. It was concluded that waste carbon fibres can be converted into flexible/drapeable dry prepreg materials, potentially useful for the manufacturing of thermoplastic composite products by hot press compaction.

An Investigation into the Hydraulic Properties of Needle-punched Nonwovens for Application in Wet-press Concrete Casting Part II: Predictive Models for the Water Permeability of Needle-punched Nonwoven Fabrics

A review of various models for predicting the water permeability of fibrous structures is reported. Using the Hagen–Poiseuille formula, a modified form of the Kozeny–Carman equation was derived. An apparatus was constructed that enabled cross-plane and in-plane water permeabilities of various needle-punched nonwoven fabrics to be measured under a range of compressive loads applied to the fabrics. Fabrics were made from 3, 6, 10, and 17 denier polypropylene fibres and the measured permeability values were compared with predicted values obtained from the various models. Three of the models gave reasonable agreement with the experimental data for cross-plane water permeability. However, a suitable model has yet to be developed which gives adequate predictions of the in-plane water permeability of needle-punched nonwoven structures.