OPTIMISING THE FIBRE-TO-YARN PRODUCTION PROCESS: FINDING A BLEND OF FIBRE QUALITIES TO CREATE AN OPTIMAL PRICE/QUALITY YARN

S. Sette, L. van Langenhove
Department of Textiles, Universiteit Gent
Technologiepark 9, 9052 Zwijnaarde, Belgium

An important aspect of the fibre-to-yarn production process is the quality and price of the resulting yarn. The yarn should have optimal product characteristics, while maintaining as low a price as possible. Early optimisation models of the fibre-to-yarn process, based on neural networks and genetic algorithms, were severely limited in their potential applications as they generated unrealistic (ideal) conditions for the process. In this paper, a method is presented to model and optimise the fibre-to-yarn production process which avoids the aforementioned problems. A neural network is used to model the process, with the machine settings and fibre quality parameters as input and yarn tenacity and elongation as output. A constrained optimisation algorithm is used afterwards to optimise the blend of fibre qualities to obtain the best yarns. This results in an optimal price-yarn quality surface where each point corresponds with a set of blend coefficients and machine settings. Furthermore, constraints can easily be adjusted to correspond to real-life production environments.

Date Added: 2002-06-28
Date Added: 2002-06-28

THE USE OF PLASMA AND NEURAL MODELLING TO OPTIMISE THE APPLICATION OF A REPELLENT COATING TO DISPOSABLE SURGICAL GARMENTS

G. Allan, A. Fotheringham, P. Weedall
School of Textiles
Heriot-Watt University
Galashiels, Scotland, UK.

The modification of the surface properties of and the application of coatings to textile materials by means of exposure to plasma has attracted much attention in recent years. The advantages of using excited gases include low process cost and duration, and the avoidance of effluents such as solvents or chlorine. Low-pressure plasma treatment with hexafluoroethane has been shown to create a hydrophobic surface on cotton, which would normally be hydrophilic. Cotton is a popular material for surgical garments and drapes because of its comfort and low cost. The acquisition of hydrophobic behaviour will provide haemo-repellancy and the prevention of bacterial attachment.
This paper describes a series of designed experiments to vary three parameters for the plasma process, gas concentration, power and duration, and to measure the resulting degrees of hydrophobic behaviour at the cotton surface by means of observing water droplets.
Neural networks can provide rapid development of simulation models of processes by adaptation to observed conditions as inputs and the results as outputs. The data from the plasma trials has been used to develop a neural model to predict surface hydrophobic behaviour. The model is itself optimised for interpolative ability, and allows a search to be made through the data space to find the best possible combination of the process parameters to encourage optimal surface treatment, and thus make the cotton most hydrophobic.
The work indicates how the environmentally-friendly approach of plasma treatment can be used to provide garments and drapes for surgery which are comfortable but also protective.

Date Added: 2002-06-28
Date Added: 2002-06-28

QUALITATIVE EVALUATION OF PROTECTIVE FABRICS

Maria Cybulska*, Marek Snycerski*, Marian Ornat**
*Faculty of Textile Engineering
Technical University of Lodz
ul. Stefanowskiego 1/15
90-924 Lodz, Poland
*Institute of the Material Engineering of Textiles
ul.Gdanska 118
90-520 Lodz, Poland

Protective garments are designed to meet the dual needs of product/process protection and workers' safety and comfort. In this paper, a qualitative evaluation of woven protective fabrics has been presented. The fabric parameters which are most important from the point of view of the user's needs have been selected and analysed. Basic mechanical parameters such as breaking load, elongation at break and tear resistance were determined in certain example fabrics before and after the washing and sterilisation processes. The worker comfort was analysed by determining air and water vapour permeability and surface resistance. The barrier properties of fabrics were analysed by determining the efficiency of filtration and fabric porosity. The durability of fabrics was evaluated in respect of their ability to stand up to the washing and sterilisation processes, and of the analysis of fabric structure deformation under external loading.

Date Added: 2002-06-28
Date Added: 2002-06-28

FIBROUS SYSTEMS WITH PROGRAMMED BIOLOGICAL-ACTIVITY AND THEIR APPLICATION IN MEDICAL PRACTICE

Petar Skundric, Adela Medovic1, Mirjana Kostic
Department of Textile Engineering, Faculty of Technology and Metallurgy,
University of Belgrade
Karnegijeva 4, 11000 Belgrade, Yugoslavia
01 Junior College for Textiles
0Starine Novaka 24, 11000 Belgrade, Yugoslavia

An effective two-stage method for obtaining both biologically activated fibres with antibacterial and anaesthetic activity and biologically activated complex fibres -insulin as an artificial store of insulin has been developed. The first stage involves the formation of reactive functional groups by chemical modification, followed by the second stage where the fibres are modified with chemotherapeutic agent solutions.
This paper presents the results of obtaining biologically activated fibres with antibacterial and anaesthetic activity as well as an artificial store of insulin in the form of complex ion-exchanged fibre-insulin. The level of immobilisation of the drug in the antibacterial fibre amounts to 140 mg of gentamicin sulphate per 1 g of fibres, in the anaesthetic fibre 180 mg of procaine hydrochloride per 1 g of fibres, and in the fibrous store of insulin 800 mg of insulin per 1 g of fibres.

Date Added: 2002-06-28
Date Added: 2002-06-28

EFFECT OF LAUNDERING ON THE DIMENSIONAL STABILITY AND DISTORTION OF KNITTED FABRICS

S. C. Anand, K. S. M. Brown, L. G. Higgins, D. A. Holmes, M. E. Hall and D. Conrad
Faculty of Technology,
Bolton Institute,
Deane Road,
Bolton, U.K. BL3 5AB

Three popular 100% cotton knitted fabrics, (plain single-jersey, 1x1 rib and interlock) were subjected to five cycles of four different washing and drying regimes. This was in order to investigate the effect of laundering with detergent as opposed to water, and tumble drying against line drying. The main aim of this work was to systematically investigate the effect of the principal washing and drying variables on the dimensional stability and distortion of knitted fabrics. The work demonstrated that changes occurring after laundering were largely due to alterations in the loop shape, rather than yarn or loop length shrinkage. The fabrics had taken up their fully relaxed dimensions after five wash and dry cycles and appropriate conditions for laundering had been applied, as no significant yarn stitch length or linear density changes occurred.
Further research work was conducted to investigate and thus isolate the area of the laundering cycle causing the most dimensional changes and distortion in knitted fabrics. Three 100% cotton knitted fabrics, plain single-jersey, lacoste and interlock, were investigated during this stage of research. These fabrics were subjected to five cycles of different washing and drying regimes which isolated the wash, rinse, spin, agitation during drying and the effect of heat during drying. The work demonstrated that changes occurring after laundering were largely caused due to the agitation during tumble drying. The agitation was found to have caused 34% of the changes during laundering, followed by the spin cycle during washing, which caused 24% of the dimensional changes and distortion.

Date Added: 2002-06-28
Date Added: 2002-06-28

MORPHOLOGICAL STRUCTURE OF POLYETHERKETONE MEMBRANES FOR GAS SEPARATION PREPARED BY PHASE INVERSION

PJ Brown*, S Ying** and J Yang**
*School of Materials Science and Engineering
Clemson University
South Carolina, USA 29634
**Department of Textile Industries
University of Leeds
Leeds LS2 9JT, UK

There has been increasing worldwide interest in the field of technical textile materials. Within this context the use of membranes for industrial separation processes has developed, and they can now compete effectively with conventional processes in terms of energy and capital costs. Membranes for gas separation have developed significantly in the last twenty years; however, there is still a need for high-temperature and chemically resistant membranes that exhibit good selectivity and gas permeability. In spite of the developments in gas separation membranes, only a few types of hollow-fibre membranes are still commercially available. Our study examines the fundamental properties of polyetherketone (PEK, a thermally stable and chemically resistant polymer) membranes prepared using concentrated sulphuric acid (98% H2SO4) as a solvent and dilute sulphuric acid (30%-60% H2SO4) as a non-solvent. Other non-solvents included acetic acid, ethanol, methanol, glycerol, and water. The concentration of the polymer-casting solutions was between 15% and 20%. The membrane structure was examined using SEM, and the gas separation properties were measured using a lab-scale test rig. The results show that formation and control of membrane structure are complicated, and that many preparation parameters affect membrane morphology and performance. Polymer concentration is a particularly important parameter. At each individual polymer concentration, the precipitant plays a crucial role, and has a determining influence on membrane structure. Membranes cast using 30-40% glycerol and 50-60% H2SO4 or 70-90% acetic acid as precipitants possessed sponge-type structures, and as such have an acceptable permeation rate. However, membranes cast into water display finger-like structures even at a low coagulation temperature of 3?C, and also exhibit lower permeation rates. It has also been shown that precipitated structures of PEK membranes are highly dependent upon the heat of mixing of the solvent with non-solvent, and that a reduction in this heat of mixing leads to sponge-like structures that are preferential for gas separation membranes.

Date Added: 2002-06-28
Date Added: 2002-06-28
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