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Forced vibrational experiments and stress relaxation experiments have been performed on acetate rayon, viscose rayon, nylon, and polyethylene over a range of humidities at both 2°C and 25°C. Forced vibrational experiments have also been carried out on acetate rayon, viscose rayon, and raw silk over the temperature range -80°C to 0°C. Interpretation of previous experiments is discussed in terms of both Newtonian viscosity and Eyring viscosity. The apparatus employed is described and a method for calibrating the solenoid of the forced vibrator is outlined. An inverse relation has been found between ηω and the negative slope of the stress relaxation curve, E°. Since the equation ηω = π/(4.606) E° derived on the basis of Newtonian viscous units predicts a direct relation between ηω and the slope E°, it is assumed that the flow in stress relaxation must be non-Newtonian* Preliminary calculations indicate that a more satisfactory relation between ηω and E° may exist if the flow units involved in stress relaxation follow the Eyring law of viscous flow. An outline for determining such a relation is given. The experimental 1y observed increase with decreasing temperature of dynamic modulus, stress relaxation modulus, and energy loss, as measured by ηω, is interpreted in terms of increasing order of chain segments. A maximum found at -55°C in the ηω vs. temperature curve for viscose rayon is attributed to a "freezing in" of segment motions as the result of a second order transition. / Science, Faculty of / Chemistry, Department of / Graduate

This work investigates the tensile behaviour of non-uniform fibres and fibrous composites. Wool fibres are used as an example of non-uniform fibres because they're physical, morphological and geometrical properties vary greatly not only between fibres but also within a fibre. The focus of this work is on the effect of both between-fibre and within-fibre diameter variations on fibre tensile behaviour. In addition, fit to the Weibull distribution by the non-brittle and non-uniform visco-elastic wool fibres is examined, and the Weibull model is developed further for non-uniform fibres with diameter variation along the fibre length. A novel model fibre composite is introduced to facilitate the investigation into the tensile behaviour of fibre-reinforced composites. This work first confirms that for processed wool, its coefficient of variation in break force can be predicted from that of minimum fibre diameters, and the prediction is better for longer fibres. This implies that even for processed wool, fibre breakage is closely associated with the occurrence of thin sections along a fibre, and damage to fibres during processing is not the main cause of fibre breakage. The effect of along-fibre diameter variation on fibre tensile behaviour of scoured wool and mohair is examined next. Only wet wool samples were examined in the past. The extensions of individual segments of single non-uniform fibres are measured at different strain levels. An important finding is the maximum extension (%) (Normally at the thinnest section) equals the average fibre extension (%) plus the diameter variation (CV %) among the fibre segments. This relationship has not been reported before. During a tensile test, it is only the average fibre extension that is measured. The third part of this work is on the applicability of Weibull distribution to the strength of non-uniform visco-elastic wool fibres. Little work has been done for wool fibres in this area, even though the Weibull model has been widely applied to many brittle fibres. An improved Weibull model incorporating within-fibre diameter variations has been developed for non-uniform fibres. This model predicts the gauge length effect more accurately than the conventional Weibull model. In studies of fibre-reinforced composites, ideal composite specimens are usually prepared and used in the experiments. Sample preparation has been a tedious process. A novel fibre reinforced composite is developed and used in this work to investigate the tensile behaviour of fibre-reinforced composites. The results obtained from the novel composite specimen are consistent with that obtained from the normal specimens.

This work investigates the effect of fibre irregularities on the mechanical behaviour of the irregular fibres using the finite element method (FEM). The first part of this work examines that the effect of fibre dimensional irregularities on the linear and non-linear tensile behaviour of the fibres, using a two-dimensional (2D) finite element models. In the linear simulation, a concept of method Young’s modulus is introduced. The method Young’s modulus, breaking load and breaking extension are affected by the magnitude and frequency of diameter variation in the fibre specimen. Fibre dimensional variation and the gauge length effect are also simulated. In the non-linear analysis, some additional information is obtained on changes in the yield and post-yield regions, which are clearly shown in the load-extension curves. Further investigation is focused on the flexural buckling behaviour of fibres with dimensional irregularities. A three-dimensional (3D) finite element model is used to simulate the buckling deformation of dimensionally irregular fibres, and the critical buckling load of the simulated fibre is calculated. Two parameters, the effective length and the average diameter within the effective length of an irregular fibre, are considered to be the key factors that influence the buckling behaviour of the fibre. An important aspect of this work is the calculation of the effective length of an irregular fibre specimen during buckling. This method has not been reported before. The third part of this work is on the combined tensile and torsional behaviour of fibres with dimensional irregularities, using a three-dimensional (3D) finite element model. Two types of fibres, polyester and wool, are simulated with sine waves of different level (magnitude) and frequency at different twist levels. For the polyester fibre, experiment verification of the simulation results has been carried out, and the results indicate the FE model is well acceptable for the simulation. The final part of this work examines the combined effect of dimensional and structural irregularities on the fibre tensile behaviour. Three-dimensional (3D) finite element models are used to simulate the cracks (transverse, longitudinal, combined transverse and longitudinal cracks) and cavities distributed in uniform fibres and fibres with 30% level of diameter variation, respectively. One of important conclusions is that under the simulated conditions, the dimensional irregularity of fibre influences the tensile behaviour of fibres more than the fibre structural irregularity. The fibre dimensional irregularity affects not only the values of the breaking load and breaking extension, but also the shape of load-extension curves. However, the fibre structural irregularity simulated in the study appears to have little effect on the shape of the load-extension curves. In addition, the effect of crack or cavity size, type and distribution on fibre tensile properties is also investigated.

Please read the abstract in the section 00front of this document Copyright 2000, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bisschoff, J 2000, Oxygenated hydrocarbon compounds as flame retardants for polyester fabric, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-01122007-112752 / > H 81/th / Dissertation (M Eng (Chemical Engineering))--University of Pretoria, 2007. / Chemical Engineering / unrestricted

Th. doct.-ing.--Lille 1, 1977. N°: 205.

This paper studies the current cotton market situation. The situation is a recent vast increase in cotton fibre price, mainly due to tight supply and demand circumstances. Focus is on two issues; how the fibre price affect companies cost wise and the likely future development of the cotton market. The cotton market has been studied by hard facts and contemporary views from industry people and companies. Factors influencing the cotton market such as economical growth, population and substitute textile fibres are taken into consideration. Besides how companies themselves claim to respond to the cotton price increase cost calculations approximated by thumb rules of the industry are performed. The result is a higher cost, derived from higher cotton price, at the finish garment stage. The magnitude depend on if one sees it relative to retail price or manufacturing cost along with how the participant in the value chain react. The future cotton market is evaluated by what might effect cotton supply and cotton demand and how the market mechanism is likely to answer. Short term the high prices seem to lower the demand and along with a larger harvest next season prices should be lowered. Long term the price is suggested to remain high because of a larger grow in demand then supply. / Program: Magisterutbildning i Applied Textile Management

This paper studies the current cotton market situation. The situation is a recent vast increase in cotton fibre price, mainly due to tight supply and demand circumstances. Focus is on two issues; how the fibre price affect companies cost wise and the likely future development of the cotton market. The cotton market has been studied by hard facts and contemporary views from industry people and companies. Factors influencing the cotton market such as economical growth, population and substitute textile fibres are taken into consideration. Besides how companies themselves claim to respond to the cotton price increase cost calculations approximated by thumb rules of the industry are performed. The result is a higher cost, derived from higher cotton price, at the finish garment stage. The magnitude depend on if one sees it relative to retail price or manufacturing cost along with how the participant in the value chain react. The future cotton market is evaluated by what might effect cotton supply and cotton demand and how the market mechanism is likely to answer. Short term the high prices seem to lower the demand and along with a larger harvest next season prices should be lowered. Long term the price is suggested to remain high because of a larger grow in demand then supply. / Program: Applied Textile Management

This thesis forms part of a project with the objective of developing and implementing a novel, wood-based, process for the industrial production of cellulose textile fibres. This new process should not only be cost effective but also have far less environmental impact then current processes. Natural and man-made fibres are usually plagued with problems (e.g. economic and environmental) and are unsuitable in meeting growing demands. The focus of this thesis was therefore to investigate the dissolution of cellulose derived from various pulps in novel aqueous solvent systems.             It was shown that cellulose could be dissolved in a NaOH/H2O solvent at low temperatures (&lt;0°C) and that such an alkaline solvent can be improved regarding the solubility, stability and rheological properties of the cellulose dopes formed if different additives (salts or amphiphilic molecules) are used. The effect of different kinds of pretreatment (individually and combined) and the influence of pulp properties on cellulose accessibility and dissolution were also evaluated. These pretreatments affected, as expected, some characteristic properties of the pulps mainly by reducing the DP but also, for example, changing the composition of the carbohydrates. Not only did the pretreatment affect the solubility it also increased the stability of the cellulose dopes, resembling the effect of chemical additives to the NaOH system. According to multivariate data analysis it was established that, of the pulp properties analyzed, only the composition of carbohydrates and the DP had a significant influence on the solubility of the pulps used in this study. Finally, it was emphasized that the dissolution of cellulose pulps seemed to be controlled by a very complex interaction between both kinetic and thermodynamic parameters. / CelluNova

Il presente lavoro propone un percorso terminologico inteso a tracciare l’evoluzione generale della terminologia delle fibre tessili in francese dal Settecento in avanti, con un’attenzione particolare alle neoformazioni nel dominio delle fibre tessili chimiche. In linea con i principi fondamentali degli studi più avanzati nel campo della terminologia diacronica, il lavoro si propone di rendere conto dell’evoluzione terminologica nel dominio oggetto di studio, mettendo in evidenza il valore culturale dei termini e il legame con lo sviluppo tecnologico e il contesto socioeconomico. Lo studio è articolato in cinque capitoli aventi per oggetto, rispettivamente: la descrizione del quadro teorico di riferimento, l’analisi dei principali studi sui tessili e le fibre tessili pubblicati in francese in due periodi - dal XVIII al XIX secolo e dal XX secolo fino ad oggi - , la costruzione del corpus di dominio e l’analisi linguistico-terminologica, focalizzata sui processi di formazione dei nomi delle fibre. In chiusura è presente un glossario contenente le schede terminologiche che analizzano i termini delle fibre tessili chimiche in francese e forniscono gli equivalenti in italiano e in inglese. / The thesis proposes a terminological path aimed at tracing the general evolution of French terminology relating to textile fibres from the 18th century onwards, with a specific focus on the formation of new terms in the domain of chemical textile fibres. In line with the fundamental principles of the most advanced studies in the field of diachronic terminology, the work aims to account for the evolution of terminology in the domain under study, highlighting the cultural value of the terms and the link with technological development and the socio-economic context. The study is divided into five chapters. The first chapter provides a description of the theoretical framework, while the second and third present analyses of the main French-published studies on textiles and textile fibres during two periods – from the 18th to 19th centuries and from the 20th century to the present, respectively. Chapter four presents a construction of the domain corpus, while the fifth chapter engages in a linguistic-terminological analysis, focused on the process of the formation of fibre names. At the end of the study is a glossary containing terminology sheets analysing the French terms given to chemical textile fibres, alongside equivalents in Italian and English.