Teses / dissertações sobre o tema "Yarns/fabrics"

The aim of the research was to produce hollow yarn knitted fabrics with improved thermal comfort properties. Thermal comfort properties and utility properties determine the wearing comfort of textiles and the suitability of a new textile product for a particular application. Both, Thermal comfort properties such as thermal absorptiveness, thermal conductivity, air permeability and utility properties like percent stretch, spirality, bursting strength of core yarn knitted fabrics and hollow yarn knitted fabrics were assessed. A new method was proposed and discussed for producing hollow yarns at fabric stage (in this case knitted fabric) which involved the following steps: - a) Production of ring spun yarns, comprising nylon as a core and cotton as a sheath, using Ring Spinning System. b) Production of knitted fabrics of different knit structures viz., single jersey, rib and interlock using above mentioned yarn. c) Dissolution of core element i.e. Nylon into formic acid to obtain hollow yarn knitted fabrics and this hollow yarn knitted fabrics can be tailored for specific end use. The study covers comparative analysis of thermal insulation properties like thermal absorptiveness, thermal conductivity and others for core yarn knitted fabrics and hollow yarn knitted fabrics and the influence of the count of core nylon filament and the type of knit structures on the thermal properties of the fabrics. Based on the results obtained from the work, it can be stated that hollow yarn knitted fabrics offer numerous possibilities for creating fabric properties which influence their comfort of use.

Not dyed wool yarns and fabrics were treated by ultraviolet radiations, using a medium pressure Hg lamp, in order to obtain a modification onto fibre surface. As consequence, UV treated wool showed increase in metal ions absorption and hydrophilicity, together with improved kinetics of dye absorption under the same dyeing conditions as untreated wool. The surface modification of wool due to UV radiations was confirmed by FTIR-ATR analysis, nevertheless the fibre morphology by SEM analysis was unaffected. Experimental results showed that different kind of dyes are able to give differential dyeing after irradiation, but not all members of the same dyeing class have similar behaviour. Then, a selection of 1:1 metal-complex dyes was chosen to evidence the maximum of difference between irradiated and not irradiated areas. The main interests on wool fabrics were focused on two effects: a) one shade, double face with different depth, higher on treated side; b) two shades, double face with different colour and depth. Moreover it was found that UV pretreatment can be useful to obtain the same dyeing with lower temperature conditions (85°C). Fastness evaluations towards dry rubbing and machine washing at 50°C were also carried out to confirm the feasibility of this alternative dyeing technique; in all experiments carried out with selected 1:1 metal-complex dyes the same score of conventional premetallized 1:1 dyeings was obtained. Dyed cotton yarns and fabrics were treated by ultraviolet radiations, using a medium pressure Hg lamp, in order to obtain a fading of coloured fibre surface. As consequence, UV-treated dyed cotton showed different resistances to discoloration as a function of the selections of reactive dyes used; a selection of cold-reactive dyes (applicable at 60 ° C on cellulosic fibers), having good contrast between UV treated part and untreated, was presented. Industrial applications for discontinuous and continuous treatments (yarns or fabrics) and new proposal are also presented, with an economical evaluation of the processes (feasibility, reliability and effective costs).

About a decade ago an attempt to build a viable wild silk industry, prompted by the discovery of the naturally available wild silk cocoons in the North West Province of South Africa, was made and a degumming plant was established in the Ganyesa village. The challenges faced in that establishment soon brought the developments to a standstill and cited among the problems was the lack of designer input in the production stages, which resulted in poor quality products. Focusing on the design problem the intention of this research is to explore a more effective design and production method for the wild silk fabrics. Through assessing the previously produced fabrics in order to identify their limitations, and by experimenting with innovative fabric production processes, a suitable aesthetic quality can be added to the final products. Starting with the investigation of current trends and choosing a design theme as a guide for the production process, fabric samples intended for use in upholstery of home furniture are developed. With the objective of successfully achieving a balance between aesthetic appeal and suitability for the intended end use, the fabrics are subjected to performance assessments based on internationally recognised standards. From the findings of this research it is therefore envisaged that, from the design aspect, proper redevelopment of the South African wild silk industry could encourage further involvement from textile designers. This would bring more improvement to the fabrics produced and encourage their use in different applications.

Cette thèse s’inscrit dans le cadre du projet européen 3D-LightTrans ayant pour objectifs la fabrication à grande à échelle et à bas coût de pièces composites. Pour parvenir à ces objectifs, des semi-produits sous forme de tissus 3D de mèches comélées ont été réalisés. Le but de ces travaux est de caractériser le comportement mécanique de ces tissus en vue d’analyser leur formabilité et d’être en mesure de prédire leur comportement pendant les processus de mise en forme utilisés lors de la fabrication des pièces composites. Le premier objectif de ces travaux était de caractériser expérimentalement le comportement mécanique des tissus 3D. Après avoir effectué un état de l’art ayant permis de définir les types et paramètres d’essais à utiliser pour la caractérisation du comportement des tissus, l’analyse des résultats de ces différents essais a permis de mettre en évidence les spécificités du comportement des tissus 3D. Le deuxième objectif des travaux était de modéliser le comportement des tissus par une approche numérique. Le choix s’étant porté sur une approche à l’échelle mésoscopique, le comportement mécanique des mèches comélées a été caractérisé expérimentalement. Les limitations du logiciel GeoFab quant à son utilisation pour la génération de modèles CAO de mailles élémentaires de tissus 3D ont été identifiées. Des améliorations permettant de répondre à ces limitations ont été proposées et leur faisabilité démontrée. Un modèle CAO d’une sous partie de la maille élémentaire d’un des tissus a alors été généré. Après avoir modélisé le comportement des mèches comélées en se basant sur les résultats de leur caractérisation expérimentale, des premières simulations éléments finis ayant permis d’obtenir des résultats encourageants ont été réalisés
This thesis is part of the European project 3D-LightTrans whose objectives are the large scale and low-cost manufacturing of composite parts. To achieve these goals, semi-finished products in the form of 3D fabrics of commingled yarns were produced. The purpose of this work is to characterize the mechanical behavior of these fabrics in order to investigate their formability and be able to predict their behavior during the forming processes used for the manufacturing of composite parts. The first objective of the work was to characterize experimentally the 3D fabrics mechanical behavior. A state of the art was realized in order to define the types and test parameters to use. The analysis of these test results allowed to highlight the specific 3D fabrics mechanical behaviour. The second objective of the work was to model the fabrics behavior using a numerical method. A mesoscopic scale approach having been selected, experimental characterization of the commingled yarns mechanical behavior was necessary. Then, GeoFab software limitations on its use for the generation of CAD models of 3D fabrics unit cells were identified. Improvements to address these limitations have been proposed and their feasibility was demonstrated. A CAD model of a sub part of one of the fabrics unit cell was then generated. After having modeled the commingled yarns behaviour using experimental results, finite element simulations were performed on fabric CAD model and first encouraging results were obtained

Um tipo de composto têxtil, comumente chamado de membrana têxtil, tem sido empregado, nas últimas décadas, como parte de um sistema arquitetônico usado para a cobertura, fechamento e/ou proteção de espaços públicos e privados em vários países do mundo. O termo membrana está relacionado com o fato de o material permanecer tensionado e separar dois ambientes que se interagem. Essa solução arquitetônica é comumente conhecida como arquitetura têxtil, especialmente quando se trata de estruturas tensionadas; o termo é usado por muitos profissionais em todo mundo, apesar de não existir uma unanimidade de opiniões sobre os conceitos envolvidos na definição do termo e o que ele abrange. Na maior parte dos casos, as obras geradas são muito atraentes, práticas e funcionais, com características, formas e tamanhos diversos, dependendo da necessidade a ser atendida. Quando bem projetadas, integram-se perfeitamente ao ambiente por terem formas orgânicas e passarem uma imagem de leveza, fluidez e modernidade. São dois os tipos de membranas têxteis mais usados: 1) um grupo de membranas cujo tecido estruturante é um tecido de poliéster recoberto em ambos os lados por uma camada de cloreto de polivinila (PVC), e 2) um grupo de membranas feitas com tecidos de vidro recobertos com politetraflúoretileno (PTFE). O foco principal deste trabalho são as membranas de poliéster/PVC usadas para estruturas tensionadas. Os tecidos usados nessa gama estão enquadrados na categoria denominada tecidos técnicos, e são formados por fios compostos por filamentos de poliéster de alta tenacidade de diferentes tipos, gerando vários artigos com características técnicas distintas e, consequentemente, membranas com diversas especificações e comportamentos diferentes na aplicação final.Este estudo traz uma visão geral sobre o assunto no mundo e um panorama mais detalhado para o Brasil, abordando definições, termos usados, materiais, fornecedores, especificações, tipos de produtos e acabamentos, normas, reciclagem e meio ambiente. A beleza e modernidade são apontadas como as principais qualidades desse tipo de cobertura. As expectativas são de crescimento dessa aplicação para os próximos anos. Porém a falta de conhecimento e a complexidade técnica desse tipo de solução é um problema a ser solucionado para que melhores resultados sejam atingidos e ela possa realmente ser considerada uma solução viável e adequada para o país.
The type of textile compound, commonly called textile membrane, has been employed in recent decades, as part of an architectural system used for covering, closing and/or protection of publics and private spaces in many countries around the world. The term membrane is related to the fact that the material remains tensioned and separating two interacting environments. This architectural solution is commonly known as \' textile architecture \', especially when tensile structures are involved; this term is used by many professionals worldwide, although it do not exist a unanimity of opinions regarding the concepts involved in the definition of the term and what it encompasses. In most cases, the structures generated are very attractive, practical and functional, with different characteristics, different shapes and sizes, depending on the requirements to be met. When well designed, they will be seamlessly integrated with the environment by having organic forms, giving a feeling of lightness, fluidity and modernity. The two types of textile membranes commonly used are: 1) a group whose structuring material of the membrane is a polyester fabric coated, on both sides, with a layer of polyvinyl chloride (PVC), and 2) a group of membranes made with glass filament fabrics coated with polytetrafluoretilene (PTFE). The focus of this work is the polyester/PVC membranes used for tensile structures. The fabric used in this range is framed within the category named \'technical fabrics\', and are composed by different kinds of high tenacity yarns of polyester filaments, generating several articles with different technical characteristics and consequently, membranes with different specifications and different behaviors in the final application. The study provides an overview of the subject in the world and a panorama slightly more detailed for Brazil, covering definitions, terms, used materials, suppliers, specifications, product types and finishes, recycling and environment issues. The \' beauty \' and \' modernity \' are cited as the main qualities of this type of covering. There are expectations of growing of this application for coming years. But the lack of knowledge and the technical complexity of this kind of solution is a problem to be solved, so that best results can are achieved and it can really be considered a viable and appropriate solution for the country.

Thermophysiological comfort is one of the most important factors for people to choose desirable gar-ments, which can be evaluated via measuring permeability of body heat and sweat. In this paper the water vapor permeability of nanocomposite nylon 6 fabrics produced from melt spun nanocomposite yarns with different TiO2 nanoparticle concentrations have been investigated. Results from measuring water vapor permeability at different environment temperatures for 4 h. indicated that sample with 0.4 wt% of TiO2 nanoparticle can provide fabric with maximum comfort properties. At low temperature 27.5% decline of permeability as compared to pure fabric causes this sample to protect body from cool weather through pre-venting loss of body heat. By increasing temperature from 12 to 35 oC water vapor permeability enhance-ment of nanocomposite improved about 99% as compared to pure one. Consequently nanocomposite with suitable nanoparticle content can provide more comfortable fabrics in different temperatures and applica-tions. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35603

Dans le processus de fabrication des renforts textiles, la friction entre les fils torsadés joue un rôle clé dans les propriétés mécaniques des composites renforcés de fibres, une friction excessive pouvant les détériorer. Cette étude développe un cadre analytique pour comprendre ce comportement frictionnel. Deux modèles analytiques ont été introduits pour décrire la friction des fils, prenant en compte la dynamique de contact à grande échelle. Les validations expérimentales confirment l'efficacité des modèles, offrant une caractérisation détaillée de la friction dans différentes conditions et révélant l'influence de paramètres critiques sur le comportement des architectures textiles. En outre, un modèle numérique innovant a été développé pour prédire la friction et l'usure des fils, en intégrant des composantes géométriques et mécaniques. Ce modèle prend en compte l'endommagement des fibres selon la théorie de la poutre de Timoshenko et aborde les problèmes de pénétration via un auto-codage. Il a été validé par des résultats expérimentaux et une imagerie micro-CT, confirmant sa précision. Cette méthode fournit des informations précieuses sur la réponse mécanique des fils pendant la fabrication des renforts, permettant une compréhension approfondie des effets des paramètres géométriques et mécaniques sur la friction et l'usure. Des améliorations futures de ce modèle pourront affiner la caractérisation du comportement frictionnel lors de la formation des composites et ainsi optimiser les processus de fabrication pour prolonger la durée de vie des produits tout en réduisant les déchets
In the manufacturing process of textile reinforcements, friction between twisted yarns is a critical factor that significantly influences the mechanical properties of fiber-reinforced composites. Excessive friction can deteriorate these properties. This study develops a comprehensive analytical framework to understand the friction behavior in the manufacturing of textile reinforcements. Two novel analytical models were introduced to describe friction behaviorof yarns. The models account for the full-scale contact dynamics influenced. Experimental validations confirm the model's efficacy by providing a detailed characterization of friction under various conditions, which reveal the influence of critical parameters on friction behavior of fabric architectures. Additionally, an innovative numerical model for predicting yarn friction and wear behavior was introduced, incorporating both geometric and mechanical components. A yarn model,considering fiber damage behavior based on the Timoshenko beam, was developed to explore friction and wear during reinforcement manufacturing. The model effectively addresses penetration problems through self-coding and was validated by experimental results and microCT imaging, confirming its accuracy. This method provides valuable insights into the mechanical response of yarns during reinforcement manufacturing, allowing for an in-depth understanding of the effect of yarn geometrical and mechanical parameters on friction and wear behavior. Future improvements can further characterize friction behavior during composite forming and optimize the manufacturing process, promoting longer product lifespans and reduced waste

During the last decade medical applications of textile sensors have been growing rapidly and textile sensors are the focal research point for many sensor projects. Textile sensors are still not available as a mainstream product to replace conventional electric sensors and electrodes. Textile sensors can be integrated in a textile garment to measure vital signs of a human being. In this regard stretch sensors are able to measure breathing rate of a person. In this project we use seamless knitting technique to make stretch sensors using conductive fibers. The resistance difference between stretching and relaxing of these sensors gives a pattern for human breathing. Four knitting structures with different conductive fibers are made and tested with cyclic tester to construct a graph between resistance and time to find the knitting structure which gives the best results. Tests are also done to check the results after washing. These sensors can be used in breathing monitoring of patients during daily life.
Program: Master programme in Textile Technology

During the last decade medical applications of textile sensors have been growing rapidly and textile sensors are the focal research point for many sensor projects. Textile sensors are still not available as a mainstream product to replace conventional electric sensors and electrodes. Textile sensors can be integrated in a textile garment to measure vital signs of a human being. In this regard stretch sensors are able to measure breathing rate of a person. In this project we use seamless knitting technique to make stretch sensors using conductive fibers. The resistance difference between stretching and relaxing of these sensors gives a pattern for human breathing. Four knitting structures with different conductive fibers are made and tested with cyclic tester to construct a graph between resistance and time to find the knitting structure which gives the best results. Tests are also done to check the results after washing. These sensors can be used in breathing monitoring of patients during daily life.
Program: Master Programme in Textile Technology

碩士
輔仁大學
織品服裝學系碩士班
106
In recent years, there have been many studies on the development of profiled fiber sections, but there is almost non 4T Profiled Fiber research. Therefore, this study will discuss the basic properties of 4T Profiled Fiber yarns and compare them with 4T Profiled Fiber/flax blended yarn. In addition, we also weave them into Plain Fabric and Quadrangle pique Fabric. At last, we carry out moisture management test of all fabrics to analyze and compare its moisture absorption performance. The results show that compared them with different tissues, the Plain Fabric is similar to the Quadrangle pique Fabric. Overall, the higher the ratio of the flax blended fabric, the better the value of the fabric, especially when the flax blended come to 20% is much better, but if it is graded, it is within the same rating range. Besides, the Plain Fabric and the Quadrangle pique Fabric all have 4 to 5 grades at wetting time, absorption rate, maximum wetted radius and spreading speed, which are in excellent categories. In the one-way transportation capacity, it ranks as Level 2 (Ordinary). If the design of the fabric is a Plain Fabric, the ability to conduct moisture in one direction is not significant. However, it can be seen from the moisture profile of the fabric that the moisture of the skin layer is outwardly transmitted to the outer fabric. In terms of comfort, there is still the effect of achieving a comfortable and dry inner layer.

Dissertação de mestrado integrado em Engenharia Têxtil
O crescente interesse dos consumidores por produtos têxteis funcionais que transmitam uma sensação de conforto e bem-estar tem conduzido ao desenvolvimento de tecidos que promovem liberdade de movimentos, ao mesmo tempo que apresentam elasticidade para se conformarem ao corpo. O processo de produção destes tecidos, designados de elásticos, envolve normalmente a integração de filamentos de elastano ou fios contendo elastanos na direção da trama ou em ambas as direções-tecidos bi-elásticos. Contudo, a obtenção de determinadas funcionalidades, designadamente elasticidade bidirecional, não é trivial e pressupõe um controlo efetivo de todas as variáveis e parâmetros dos processos que tornam o fabrico de tecidos bi-elásticos complexo e desafiador. Por este motivo e face à emergência de tecidos bi-elásticos (bistretch),tornou-se pertinente analisar e caraterizar os processos envolvidos no fabrico de tecidos bi-elásticos e avaliar as propriedades dos tecidos obtidos, por forma a estabelecer as condições de processo que conduzem ao comportamento elástico requerido- Comfort stretch. O trabalho apresentado nesta dissertação de mestrado em Engenharia Têxtil teve como principal objetivo o estudo de tecidos bi-elásticos finos de elevada qualidade e alto valor acrescentado, integrando fios elásticos core-spun. Este estudo envolveu a caraterização de todo o processo – desde a receção do fio até ao acabamento do tecido-, a análise de todos os parâmetros e variáveis utilizados no seu fabrico e a caraterização das propriedades dos tecidos bi-elásticos resultantes, designadamente propriedades elásticas e térmicas. Este estudo permitiu identificar os parâmetros e variáveis dos processos com maior influência nas propriedades dos tecidos bi-elásticos, em particular nas propriedades elásticas. Permitiu ainda verificar que o processo de termofixação, apesar de fundamental na estabilização dimensional dos tecidos, pode ter um efeito negativo nas suas propriedades elásticas.
The growing increase of consumers’ demand for functional textile products that impart comfort and well-being sensations, is leading to the development of fabrics which promote freedom of movements, simultaneously providing elasticity to conform to the body. The production process of these fabrics, called elastic or stretchable fabrics, typically involves the integration of elastane filaments or yarns containing elastane in the weft direction or in both directions- bi-stretch fabrics. Nevertheless, the promotion of certain functionalities, namely bidirectional stretchability is not trivial and involves the effective control of all processes’ variables and parameters, making the production of bi-stretch fabrics complex and challenging. For that reason and due to the emergence of bi-stretch fabrics it was considered of utmost importance to characterize and analyse the processes involved in the production of bi-stretch fabrics and evaluate the properties of the fabrics obtained, to enable the specification of processes’ conditions that lead to the required elastic behaviour –Comfort stretch . The main objective of the work presented in this Master dissertation in Textile Engineering is the study of high quality, high added-value and thin bi-stretch fabrics integrating core-spun elastic yarns. This study involved the characterization of the whole production process- from yarn reception to fabric finishing- , the analysis of all parameters and variables used and the characterization of the resulting bi-stretch fabrics, namely elastic and thermal properties. This study allowed identifying processes’ parameters and variables that most influence the properties of bi-stretch fabrics, in particular elastic properties. It also enabled verifying that the thermosetting process, although fundamental to fabrics’ dimensional stability, may have a negative effect on fabrics’ elastic properties.