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Polyacrylonitrile (PAN) fiber is one of the most important synthetic fibers in the world because it is a precursor to carbon fiber. Compared to the traditional solution spinning process, the melting spinning process of PAN is less costly and can further reduce the price of PAN fiber. This dissertation is concerned with the objective of establishment of conditions (temperature, plasticizer type, and plasticizer composition) that a PAN copolymer is able to be stable melt spun with water based plasticizers. More specifically, PAN/water/acetonitrile (70/15/15) mixture is considered as reference sample in this study because it was proposed in a BASF patent in which it was claimed it could be stably melt spun. We are looking for a more benign plasticizer so that the use of acetonitrile can be avoided and PAN can still be stably melt spun. To achieve this objective, the first step is to measure the melting point (Tm) of PAN copolymer with various plasticizers and compositions by using differential scanning calorimetry (DSC). The results indicate the Tm of PAN copolymer can be reduced to around 160 oC with water only as a plasticizer, which is lower than the degradation temperature of PAN (180 oC). Moreover, using a water/ethanol mixture and water/acetonitrile as plasticizers can further reduce the melting point of PAN to 150 oC and 135 oC, respectively. The second step is conducting rheological measurements on the PAN/plasticizers mixture. A pressure chamber was designed and attached to the capillary rheometer in order to prevent the foaming and evaporation of plasticizers during the viscosity experiments. Both steady-shear and time-dependent viscosity measurements were conducted. The rheological measurement results indicate that PAN can keep stable for more than 120 minutes with all plasticizers under 170 oC, and it starts to degrade in 60 minutes at 180 oC, except samples plasticized with 30 wt% of water (which keep stable for 120 minutes as well). The steady-shear viscosity results indicate the shear-thinning behavior is observed for the PAN/plasticizer mixtures at a temperature ranging from 170 oC to 190 oC and provide the fundamental viscosity data which can be applied to the extrusion process. In conclusion, the rheological measurements show PAN/Water (70/30 wt%) at 180 oC and PAN/EtOH/Water (70/15/15) at 170 oC are two potential systems for carrying out the PAN melt spinning process. Scanning electron microscopy (SEM) images were taken for the reference state and potential conditions. These images show that the copolymer strands have more and larger voids when plasticized with water only compared to those plasticized with water/acetonitrile and water/ethanol mixture. In this case, PAN/EtOH/Water (70/15/15) at 170 oC is considered to be the most benign system for that PAN melt spinning. / Doctor of Philosophy / The melt spinning process of polyacrylonitrile (PAN) has been studied in the past few decades. Compared to the traditional solution spinning process, it does not require toxic organic solvents. The major problem of the PAN melt spinning process is the melting point (Tm) of PAN is much higher than its degradation temperature. However, by adding plasticizers the Tm of PAN can be significantly reduced, which makes PAN melt spinning feasible. In this work we discuss the feasibility of the melt spinning process of polyacrylonitrile (PAN) copolymer plasticized with water based plasticizers by using differential scanning calorimetry (DSC) and rheological methods. The objective is to use water only as a plasticizer to melt spin PAN under specific conditions (composition, temperature etc). The melting point and rheological measurements have been conducted by DSC and a modified capillary rheometer, respectively, for this plasticized system. The DSC results show that the melting point of the PAN copolymer can be reduced below the degradation temperature of PAN, and the rheological results show that the PAN copolymer can be extruded with a reasonable viscosity at 15-20 o v above its melting point, and also the stability and viscosity are strongly dependent on temperature and the plasticizer type and content. Furthermore, the Scanning electron microscopy (SEM) images show the copolymer strands extruded from PAN/H2O mixture have many more and larger voids than PAN/H2O/EtOH mixture. In conclusion, the results indicate that the most appropriate condition for PAN melt spinning is PAN/H2O/EtOH mixture of 70/15/15 wt% ratio at a temperature of 170 oC

published_or_final_version / Economics / Master / Master of Arts

The spinning process of hollow fiber membranes was investigated with regards to two fundamental phenomena: flow (shear and elongation) and phase separation. Quantitative analysis of phase separation kinetics of binary (polymer/solvent) and ternary (polymer/solvent/volatile co-solvent) polymer solution was carried out with a newly developed microfluidic device. The device enables visualization of in situ phase separation and structure formation in controlled vapor and liquid environments. Results from these studies indicated that there was a weak correlation between phase separation kinetics and macroscopic defect (macrovoid) formation. In addition, the effect of shear and elongation on membrane morphology was tested by performing fiber extrusion through microfluidic channels. It was found that the membrane morphology is dominated by different factors depending on the rate of deformation. At high shear rates typical of spinning processes, shear was found to induce macrovoid formation through normal stresses, while elongation suppressed macroscopic defect formation. Furthermore, draw resonance, one of the key instabilities that can occur during fiber spinning, was investigated. It was found that draw resonance occurs at aggressive elongation condition, and could be suppressed by enhanced phase separation kinetics. These results can be used as guidelines for predicting hollow fiber membrane spinnability.

Made available in DSpace on 2015-05-08T14:59:46Z (GMT). No. of bitstreams: 1 parte1.pdf: 1839351 bytes, checksum: 34e86046fc8cf8f52125675d2e7267f6 (MD5) Previous issue date: 2009-03-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Melt spinnng processing is one of the most common processes to obtaining quasicrystaline structures. This is because of the fast cooling rate it imposes on the system, favoring such type of structure. This work deals with the production of quasycristaline phases (Al60Cu27,5Fe12,5 e Al57Cu27,5Fe12,5B3) via melt-spinning. The alloys were initially cast via induction melting under atmospheric air, with the designed chemical composition of the quasicrystals. Hence, the ribbons were produce by melt-spinning were characterized by means of x-ray diffraction and scanning electron microscopy. The results indicate that the icosahedral ψ - Al65Cu20Fe15 phase formed in both types of starting compositions. It seams that the boron contributes to stabilize the icosahedral phase. / O processo melt-spinning por imprimir altas taxas de resfriamento, é um dos principais meios para a obtenção de ligas com estrutura quasicristalinas, sendo o primeiro método utilizado para produzir materiais quasicristalinos. Neste trabalho utilizou-se este processo para a elaboração das ligas quasicristalinas Al(60-x)Cu25Fe15Bx, Al(60-x)Cu27,5Fe12,5Bx e Al(65-x)Cu20Fe15Bx (x=0 e x=3%at de boro). As ligas foram previamente fabricadas, por fusão, em atmosfera de argônio, em forno à indução, para em seguida serem submetidas ao processo melt-spinning , onde se obteve o material na forma de fita. As amostras foram caracterizadas por difração de raios-x e microscopia eletrônica de varredura. Os resultados indicaram a formação da fase icosaedral ψ - Al65Cu20Fe15 nas composições estudadas e uma provável contribuição do boro na produção dessa fase icosaedral

Cette recherche s’inscrit dans un contexte d’amélioration des performances et du confort des vêtements textiles d’intervention contre le feu et la chaleur. L’objectif est de réduire le poids total des équipements de protection individuelle (EPI), en remplaçant leur structure actuelle par un tissu complexe de type « Spacer Fabric », qui résulte de l’assemblage de deux couches, aux propriétés différentes, par un fil de liage. Ces travaux de thèse se concentrent sur le développement du fil de liage et peuvent se définir comme une étude de faisabilité visant à prouver la possibilité de filer des monofilaments de « gros » diamètre (200 – 300 μm) à partir d’une solution de polyamide-imide Kermel®. Pour mener ce projet à terme, un dispositif expérimental de filage par coagulation a été développé. Entièrement automatisé, il permet aussi bien l’étude de l’influence des paramètres de filage sur la qualité des monofilaments obtenus, que la simulation d’une production de type industriel. Pour répondre à notre problématique, cet outil de prototypage a été appliqué au développement des monofilaments souhaités. Un plan d’expériences a été construit, comprenant quatre facteurs : le diamètre d’extrusion, la concentration en solvant du bain de coagulation et les taux d’étirage appliqués dans le bain et dans l’air. Cette étude expérimentale a mis en évidence l’importance de la maîtrise de la cinétique de coagulation, avec une influence hautement significative des facteurs diamètre d’extrusion et concentration du bain de coagulation, notamment sur l’évolution du taux de vide des monofilaments obtenus. / This research aims to improve the performance and the comfort requirements of textile protective clothing against heat and flames. The main purpose is to reduce the weight of such personal equipment by replacing their current structure with complex woven “Spacer Fabric”, composed of an assembly of two textile layers, having different properties, and linked by a binder yarn. These works particularly focus on the development of this binder yarn and consist in a feasibility study to demonstrate the possibility to demonstrate the possibility to spun monofilaments having a large diameter (200 – 300 μm) from a polyamide-imide solution (Kermel®). A dedicated experimental wet-spinning device has been designed to carry out this project. Such fully automated machine enables to conduct detailed studies concerning the influence of multiple spinning parameters on the physical properties of the manufactured monofilaments, therefore providing a simulation of an industrial production of such fibers. Hence, this prototyping tool has been used to develop monofilaments addressing the initially stated issue. A four factor Design of Experiments has been built to investigate the effects and combinations between the following parameters: extrusion diameter, concentration of the coagulation bath, drawing rates applied in the bath and in the air. The derived results mainly showed the importance of controlling the coagulation kinetic. Moreover, highly significant influences of both extrusion diameter and concentration of coagulation bath factors have been highlighted, especially concerning the evolution of the void fraction of the monofilaments.

Bakgrund: Spinning Babies beskrivs som ett verktyg för att främja normal fysiologisk förlossning genom smärtlindring, avslappning och positioner som främjar optimal passage av barnet genom förlossningskanalen. Syfte: Att belysa barnmorskors erfarenheter av att tillämpa Spinning Babies vid förlossning. Metod: Studien genomfördes med en kvalitativ design. Datainsamlingen genomfördes genom tre fokusgruppsintervjuer med totalt 12 barnmorskor. Datamaterialet analyserades med kvalitativ innehållsanalys. Resultat: Resultatet presenteras i tre huvudkategorier med underkategorier: Ett verktyg för att främja det normala, Tillfredsställelse med att utöva och utvecklas i sin barnmorskekonst, Ett nytt perspektiv på födandet. Barnmorskornas erfarenhet är att Spinning Babies ger förutsättningar för att främja normal förlossning, att utövandet upplevs som stimulerande samt att tillämpningen av Spinning Babies ger upphov till ny förståelse. Slutsats: Barnmorskors förutsättningar att främja normal förlossning kan underlättas om de har konkreta verktyg. Spinning Babies kan användas för att förbättra förlossningsutfall och bidra till en positiv förlossningsupplevelse. När barnmorskor arbetar tillsammans för att stödja den födande kvinnan och partnern upplevs förlossningsarbetet även mer stimulerande. / Background: Spinning Babies is described as a tool to promote physiological birth process through pain relief, relaxation and positioning for optimal passage of the baby through the birth canal. Aim: To describe midwives experiences of applying Spinning Babies during childbirth. Method: The study was conducted with a qualitative design with three focus group interviews. 12 midwives participated. The data was systematically analysed with qualitative content analysis. Result: The result was presented in three main categories with subcategories: A tool for promoting the normal, Satisfaction with exercising and developing in one's midwifery art, A new perspective on childbirth. The midwives' experience that Spinning Babies provide conditions for promoting normal childbirth. The practice is viewed as stimulating and generates a new understanding of child birth. Conclusion: Midwives' ability to promote normal childbirth can be facilitated if they have concrete tools. Spinning Babies can be used to improve childbirth outcomes and contribute to a positive childbirth experience. When midwives work together to support the woman giving birth and her partner, their work is also experienced as more stimulating.

Varje år kasserar Försvarets materielverk (FMV) en stor mängd av soldatutrustning av textil. Den textila soldatutrustningen kasseras med anledning att den inte längre går att laga eller har förlorat sin funktion och skickas därmed till förbränning. I enlighet med FMV:s miljöpolicy 2020 vägs ekonomiska och tekniska krav mot mer hållbara alternativ för att bli en mer miljömässigt hållbar verksamhet. Med avsikt att ytterligare utveckla sitt hållbarhetsarbete vill FMV utreda möjligheterna till textilåtervinning för att förlänga livslängd av textila material ytterligare. Därav har denna rapport behandlat mekanisk återvinning av textila soldatutrustningar samt garnspinning av återvunna fibrer. Arbetets bedrivs med syfte att redogöra en studie på uppdrag av FMV med fokus på möjligheter till hur mekanisk återvinning genomförs av textila soldatutrustning och hur garn kan spinnas av fibrer från återvunna fibrer. Genom en litteraturstudie har faktorer som påverkar mekanisk återvinning av textila material samt lämpliga garnspinningsmetoder för återvunna fibrer undersökts i detta arbete. En analys har även genomförts med fokus på fyra klädesplagg fån FMV: skjorta, t-tröja, långkalsong, och stickad tröja. De parametrar som i högsta grad behöver tas hänsyn till för att uppnå så hög garnkvalité är fiberblandning, samt inställningar för spinning, sträckning och kardning. Vid garnspinning är fiberlängden av stor betydelse och därav behöver den mekaniska återvinningen utföras på ett så skonsamt sätt som möjligt för att minska fiberslitaget. För att spinna garn av återvunna fibrer är rotorspinning och friktionsspinning de mest lämpliga metoder, men garnet som produceras har en hög grovlek. För en högre garnkvalité behövs en blandning av jungfruliga fibrer med återvunna fibrer för ett mer tillfredsställande resultat. / Each year, Försvarets Materielverk (FMV) discards a massive amount of textile soldier equipment no longer possible to repair and unqualified to use and are therefore incinerated. In accordance with FMV:s policy for environmental sustainability 2020, economic and technical requirements have to be considered in relation to more sustainable alternatives in order to become a more environmentally sustainable organization. With the purpose to further develop towards more sustainable practices, FMV are interested in investigating the possibilities for mechanical textile recycling and yarn spinning of the re-cycled fibers to extend the life cycle of textile materials. The report’s goal was to focus on possibilities and challenges considering the following garments assigned by FMV: t-shirt, knitted sweater, shirt and thermal underwear. The method is based on a literature study and examination of the garments.Conclusions drawn from the study are that fiber blend and settings for carding, drawing and spinning are crucial to produce yarn of high quality. Especially the fiber length has an impact on the possibilities of yarn spinning since it needs to be long enough. To spin yarns from recycled fibers, open-end spinning methods such as rotor spinning and friction spinning are the most suitable. Furthermore, recycled fibers need to be blended with virgin fibers to enable spinning.

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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / Designed for unattended 24 hours-a-day operation in automatic system environments, the 3801 TT&C Digital Processor Unit is the key communication unit for ground stations operating spacecraft, from integration to positioning phase and in-orbit operation. Its architecture and technology concept combine high performance, compactness and modularity. The 3801 TT&C Digital Processor Unit supports multiple formats in a single stand-alone chassis, and incorporates extensive interfacing and functional provisions to maximize effectiveness, reliability and dependability. It supports a number of configurations for satellite control applications and performs :* • Telemetry IF demodulation and transmission of data to a high-level communication interface, with time tagging and display of decommutated parameters, • Command generation, with FSK or PSK and FM or PM modulation at 70 MHz, • Ranging measurements and calibration using ESA, INTELSAT and major standards (tones and codes). In addition, the 3801 TT&C Digital Processor supports a Synchronous Command Generator for spinning satellite in a single stand-alone chassis and includes : • FM signal discrimination, for satellite spin reference information coming from the Telemetry Reception channel, • Synchronization Controller for providing the reference « top » for the transmission of the synchronous tones, • Tones Generation of frequency tones towards the PM/FM Modulator.