Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Polymer fibre spinning.
Rozprawy doktorskie na temat „Polymer fibre spinning”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 30 najlepszych rozpraw doktorskich naukowych na temat „Polymer fibre spinning”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
1
Zhang, Siqi. "Functional polymer fibre spinning by infusion gyration". Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10052048/.
Pełny tekst źródłaStreszczenie:
Fibres show promising applications such as textiles, filtration, sensing and tissue engineering. In this study, an infusion gyration system to produce polymer micro and nano fibres with functions was introduced. By using this method, functional fibres can be formed from polymer solutions mixed with other functional materials. PEO or PVA water solution was used for making the spinning solutions. The fluorescence protein bound with gold nanoparticles was carried by the PEO water solution, from which the fibres assembled with protein were successfully generated through infusion gyration. A mixed molecular weight PVA combined water solution mixed with processed magnetic nanoparticles achieved fabrication of magnetically controllable fibres have the potential for drug release and its demonstration test showed a positive result. This spinning system provides control of the polymer solution flow rate during spinning which affects the fibre morphology such as average diameter and size distribution. The relationship between the spinning parameters and the product properties was studied for better understanding of the method. The analysis of infusion gyration and its fibre forming process was carried out. The fibres were characterised using several methods, such as optical microscopy, SEM, FTIR and UV-Vis, to establish the potential of infusion gyration and to confirm the functions of final fibre product. The infusion gyration system provides a simple micro and nano scale assembly approach to integrate different protein functionalities into nanofibres with potential applications. Magnetic PVA nanofibres are promising for drug delivery.
2
Razzaq, Wasif. "Microfluidic spinning of polymer microfibers : effect of operating parameters on morphology and properties towards the development of novel and smart materials". Thesis, Strasbourg, 2022. http://www.theses.fr/2022STRAE004.
Pełny tekst źródłaStreszczenie:
Le filage microfluidique est une technologie émergente pour la production de micro/nanofibres qui ont un fort potentiel pour des applications telles que l’ingénierie tissulaire, l’électronique portable, les systèmes de délivrance de principes actifs et la collecte des eaux. En filage microfluidique, des fibres de diamètres et morphologies contrôlée peuvent être obtenues en manipulant précisément le débit des fluides et la géométrie du dispositif microfluidique. Le but de ce projet doctoral est de développer une expertise et des compétences dans le domaine du filage microfluidique pour produire des fibres polymères par photopolymérisation sous irradiations UV à partir de monomères en utilisant un dispositif microfluidique à base de capillaires avec les objectifs suivants : (1) la mise en place d’une relation empirique pour prédire le diamètre des fibres en prenant en compte les différents paramètres opératoires et de matériaux, (2) la production de fibres Janus/Hecate à partir de monomères ayant différentes propriétés chimiques et physiques avec un contrôle des propriétés morphologiques et mécaniques qui ont été exploitées pour adsorber simultanément des colorants chargés positivement ou négativement, mais aussi pour préparer des actuateurs à partir de fibres Janus thermorépondantes, et (3) le développement d’une approche de modification de surface des fibres pendant leur productionMicrofluidic spinning is an emerging technology to produce micro/nanofibers which have a significant potential in advanced applications such as tissue engineering, wearable electronics, drug delivery, and water harvesting. In microfluidic spinning, fibers with controlled diameters and morphologies could be easily produced by precisely manipulating the fluids flow and the geometry of the microfluidic device. The purpose of this doctoral project was to develop expertise and skills in the field of microfluidic spinning to produce polymer fibers using UV photopolymerization of the monomers using a capillary-based microfluidic device with the following objectives : (1) the development of an empirical relationship to predict the fiber diameter considering the different operating and materials parameters, (2) the production of Janus/Hecate fibers from monomers with different chemical and physical properties with controllability of morphological and mechanical properties that were explored to remove simultaneously cationic and anionic dyes and to prepare thermoresponsive Janus fiber actuators, and (3) the development of an in-process rapid surface modification approach to modify the surface of fibers
3
Tajul, Islam Mollah Mohammad. "Experimental study on Temperature regulating bi-component fibres containing paraffin wax in the core". Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19749.
Pełny tekst źródłaStreszczenie:
Putting on or taking off clothes helps the body to stay within the comfortable temperature range (toavoid shivering or sweating) at different activity levels and ambient conditions. Clothes with built-inthermo-regulating properties would mean maintained comfort without putting on or taking off clothesthat frequently. Integration of phase change materials (PCMs) in clothes is one way of achievingthermo-regulating properties. When the body temperature goes up, the PCM melts and absorbs theheat from the body in the form of latent heat (cooling effect). When the temperature drops, the PCMcrystallizes and the stored heat is released again (warming effect).Research on thermo regulating fibres of the bi-component type containing PCM in the core has beenconducted at Swerea IVF in Mölndal, Sweden, for some time. It has been found that high molecularweight HDPE is a suitable viscosity modifier for hydrocarbon waxes used as PCM. The preparation ofcore materials has so far been done in a batch wise fashion in the way that molten wax has beensoaked into pelletized HDPE at around 180°C during prolonged times followed by melt compoundingin a Brabender batch kneader (0.3 kg per batch). Besides being very impractical for larger productionvolumes the method involves long residence times at high temperatures which may induce thermaldegradation reactions. The objective of the present diploma (master’s thesis) work was to develop acontinuous mixing method to produce PCM/HDPE blends and to test the resulting material in bicomponentfibers with a Nylon (PA6) sheath and to characterize the resulting fiber properties in termsof strength and latent heat.It was proven possible to compound HDPE with large amounts (70%) of octadecane (PCM) on aBrabender twin screw extruder. HDPE was metered to the extruder hoper by means of a screw feederand wax was continuously fed to the hoper in the liquid state by means of a heated membrane pump.To facilitate mixing HDPE in form of powder instead of pellets was used. The extruded threads weresolidified in a water bath followed by granulation. Bi-component fibers were successfully producedfrom such materials. Fibers containing 15 to 42% Octadecane were produced showing heat of fusionsin the range 26 to 86 J/g and tenacities in the range 33 to 16 cN/tex. The heat of fusion of the fiberscompares favorable with existing commercial products showing values in the range 5-15 J/g (acrylicand cellulosic fibres containing microencapsulated hydrocarbon waxes). The peak melting point ofoctadecane measured by DSC was found to be depressed some 4-5°C in the fibers compared to pureoctadecane (28°C). Such a melting point depression is important to consider when choosing type ofhydrocarbon wax.Program: Magisterutbildning i textilteknologi
4
Jenkins, Shawn Eric. "Synthesis and spinning of a new thermotropic liquid crystallinepolymers : characterization of fiber morphology and mechanical properties". Thesis, Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/8557.
Pełny tekst źródła
5
Su, Yang. "Theoretical studies of hollow fiber spinning /". Connect to Online Resource-OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1180971638.
Pełny tekst źródłaStreszczenie:
Dissertation (Ph.D.)--University of Toledo, 2007.Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Engineering." Bibliography: leaves 200-218.
6
Khoury, Joe Farid. "Liquid Dispersions and Fiber Spinning of Boron Nitride Nanotubes Combined With Polyvinyl Alcohol". Cleveland State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=csu1623868708786823.
Pełny tekst źródła
7
Ramalingam, Suresh. "Fiber spinning and rheology of liquid-crystalline polymers". Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/33813.
Pełny tekst źródła
8
Gagov, Atanas. "INSTABILITIES IN ELONGATION FLOWS OF POLYMERS AT HIGH DEBORAH NUMBERS". University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1191895515.
Pełny tekst źródła
9
Hagen, Thomas Ch. "Elongational Flows in Polymer Processing". Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/29437.
Pełny tekst źródłaStreszczenie:
The production of long, thin polymeric fibers is a main objective of the textile industry. Melt-spinning is a particularly simple and effective technique. In this work, we shall discuss the equations of melt-spinning in viscous and viscoelastic flow. These quasilinear hyperbolic equations model the uniaxial extension of a fluid thread before its solidification.
We will address the following topics: first we shall prove existence, uniqueness, and regularity of solutions. Our solution strategy will be developed in detail for the viscous case. For non-Newtonian and isothermal flows, we shall outline the general ideas. Our solution technique consists of energy estimates and fixed-point arguments in appropriate Banach spaces. The existence result for a simple transport equation is the key to understanding the quasilinear case. The second issue of this exposition will be the stability of the unforced frost line formation. We will give a rigorous justification that, in the viscous regime, the linearized equations obey the ``Principle of Linear Stability''. As a consequence, we are allowed to relate the stability of the associated strongly continuous semigroup to the numerical resolution of the spectrum of its generator. By using a spectral collocation method, we shall derive numerical results on the eigenvalue distribution, thereby confirming prior results on the stability of the steady-state solution.Ph. D.
10
Pang, Kyeong. "NOVEL MANUFACTURING, SPINNING, AND CHARACTERIZATION OF POLYESTERS BASED ON 1,2-ETHANEDIOL AND 1,3-PROPANEDIOL". NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-12272004-133333/.
Pełny tekst źródłaStreszczenie:
Poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), poly(ethylene isophthalate) (PEI), and poly(trimethylene isophthalate) (PTI) were synthesized in a Parr reactor and melt-spun. Thermal and physical properties of the as-synthesized polymers and melt-spun fibers were determined. As-synthesized PEI and PTI were amorphous polymers and did not show any melting peaks by DSC analysis. All the polymers were thermally stable (TGA analysis). Amorphous films were made by a melt-press method with PET and PEI for determination of CO2 gas barrier properties. PEI, which has the meta-linkage of ester groups on the phenyl ring, had much lower CO2 gas permeability around one tenth that of PET, which has the para-linkage of ester groups on the phenyl ring. This is because in PET the phenyl rings are substituted in the para (1,4) positions, which allows for their facile flipping, effectively permitting gases to pass through. However, the meta-substituted phenyl rings in PEI do not permit such ring flipping, and thus PEI may be more suitable for barrier applications. The coalesced PEI was prepared from the inclusion compound of PEI with ?×-cyclodextrin. The coalesced PEI may have retained partially highly extended and parallel chains from the narrow channels of the inclusion compound, resulting in better/tighter packing among the PEI chains and exhibited a higher glass-transition temperature. Cyclic oligoesters of PET, PTT, PEI, and PTI were prepared by cyclo-depolymerization of these polyesters. The cyclic oligoesters were mixtures of different sized cyclic oligomers. PET cyclic oligomers showed four melting peaks at 59, 122, 194, and 276 o C. The cyclic oligomers of PTT, PEI, and PTI showed single melting peaks at 241, 335o C and 147o C, respectively. The cyclic oligoesters could be converted to linear polyesters by ring-opening polymerization. PTT was also prepared by ring-opening polymerization of its cyclic dimer obtained as a by-product in the conventional manufacturing plant. Antimony, tin, and titanium catalysts were used with various concentrations. The highest molecular weight, 40,000 g/mol was obtained when 0.25 mol% of titanium(IV) butoxide was used.
11
Hsiao, Hsien-Fu. "Mechanical behavior and heat transfer in polymer fiber melt-spinning and drawing processes". Connect to resource, 1997. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osuosu1243349868.
Pełny tekst źródła
12
Oh, Kyung Hee. "Effect of shear, elongation and phase separation in hollow fiber membrane spinning". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53992.
Pełny tekst źródłaStreszczenie:
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.
13
GHOSH, MONOJ. "Fabrication of Inorganic Oxide Nanofibers Using Gas Jet Fiber Spinning Process and Their Applications in Photocatalytic Oxidation". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1478726324293037.
Pełny tekst źródła
14
Ma, Hongming. "Fiber spinning, structure and properties of poly(ethylene terephthalate-co-4,4' bibenzoate) copolyester fibers". Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/8607.
Pełny tekst źródła
15
McLeod, Michael Allen. "Injection Molding of Pregenerated Microcomposites". Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/28844.
Pełny tekst źródłaStreszczenie:
One portion of this work was concerned with injection molding pregenerated microcomposites composed primarily of poly(ethylene terephthalate) (PET) as the matrix and HX1000 as the thermotropic liquid crystalline polymer (TLCP). Several factors were examined to maximize the mechanical properties of these composites, including injection molding temperature, matrix viscosity, and nozzle tip exit diameter. In addition, concentrated strands of HX1000/PET (50/50 wt%) were diluted using both an injection molding grade of PET and an injection molding grade of PBT. From this work, it was determined that the best mechanical properties were produced when the microcomposites were processed at the lowest injection molding temperatures, diluted with PBT, and injection molded using a large nozzle tip exit diameter.
The pregenerated microcomposite properties were compared against theoretical predictions as well as glass-filled PET. It was found that the pregenerated microcomposites had tensile moduli of approximately 70% of theoretical expectations in the machine direction. Additionally, the comparisons against glass-filled PET revealed that at the same weight fraction of reinforcement, the pregenerated microcomposites had lower properties. Still, the composites were found to have smoother surfaces than glass-filled PET and at temperatures up to 150° C the storage and loss moduli of the pregenerated microcomposites were similar to those of glass filled PET. It was concluded that if the theoretically expected levels of reinforcement could be attained, the pregenerated microcomposites processing scheme would be a viable method of producing light weight, wholly thermoplastic composites with smoother surfaces than are obtained with glass reinforcement.
An additional focus of this research was to evaluate the ability to modify the crystallization behavior of a high melting TLCP (HX6000, Tm = 332° C) with a lower melting TLCP (HX8000, Tm = 272°C). It was found that it was possible to tailor the crystallization behavior of these TLCP/TLCP blends by varying the weight fraction of each component, as determined by rheological cooling scans and differential scanning calorimetric cooling tests. Based on the analysis of these TLCPs at the maximum injection molding temperature of 360° C, it was speculated that they had reacted with one another.Ph. D.
16
Riazi, Kamran [Verfasser], i M. [Akademischer Betreuer] Wilhelm. "Branched polystyrene model systems to investigate the rheology of polymer fiber spinning / Kamran Riazi ; Betreuer: M. Wilhelm". Karlsruhe : KIT-Bibliothek, 2018. http://d-nb.info/1162543973/34.
Pełny tekst źródła
17
Soroudi, Azadeh. "Melt Spun Electro-Conductive Polymer Composite Fibers". Doctoral thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-3590.
Pełny tekst źródłaStreszczenie:
One interesting approach is the development of conductive polymer composite fibers for innovative textile applications such as in sensors, actuators and electrostatic discharge. In this study, conductive polymer composite fibers were prepared using several different blends containing conductive components: a conjugated polymer (polyaniline-complex) and/or carbon nanotubes. Different factors such as processing parameters, the morphology of the initial blends and the final fibers, fiber draw ratio and material selection were studied separately to characterize their effects on the fiber properties. In binary blends of PP/polyaniline-complex, the processing conditions, the matrix viscosity and the fiber draw ratio had substantial effects on the electrical conductivity of the fibers and linearity of resistance-voltage dependence. These factors were associated with each other to create conductive pathways through maintaining an appropriate balance of fibril formation and breakage along the fiber. The blend morphology was defined as the initial size of the dispersed conductive phase (polyaniline-phase), which depended on the melt blending conditions as well as the PP matrix viscosity. Depending on the initial droplet phase size, an optimum draw ratio was necessary to obtain maximum conductivity by promoting fibril formation (sufficient stress) and preventing fibril breakage (no excess stress) to create continuous pathways of conductive phase. Ternary blend fibers of PP/PA6/polyaniline-complex illustrated at least three-phase morphology with matrix/core-shell dispersed phase style. When ternary fibers were compared to binary fibers, the former could combine better mechanical and electrical properties only at a specific draw ratio; this showed that draw ratio was a more determinant factor for the ternary fibers, as both conductivity and tensile strength depended on the formation of fibrils from the core-shell droplets of the PA6/polyaniline-complex through the polypropylene matrix. The achieved maximum conductivity so far was in the range of 10 S/cm to 10 S/cm, which for different samples were observed at different fiber draw ratios depending on the mixing conditions, the matrix viscosity or whether the fiber was a binary or ternary blend. To improve the properties, PP/polyaniline-complex blends were filled with CNTs. The CNTs and the polyaniline-complex both had an increasing effect on the crystallization temperature and the thermal stability of PP. Furthermore, the maximum conductivity was observed in samples containing both CNTs and polyaniline-complex rather than the PP with either one of the fillers. Although increasing the content of CNTs improved the conductivity in PP/CNT fibers, the ease of melt spinning, diameter uniformity and mechanical properties of fibers were adversely affected. Diameter variation of PP/CNT as-spun fibers was shown to be an indication of hidden melt-drawings that had occurred during the fiber extrusion; this could lead to variations in morphology such as increases in the insulating microcracks and the distance between the conductive agglomerates in the drawn parts of the fiber. Variations in morphology result in variations in the electrical conductivity; consequently, the conductivity of such inhomogeneous fiber is no longer its physical property, as this varies with varying size.Thesis to be defended in public on Friday, May 20, 2011 at 10.00 at KC-salen, Kemigården 4, Göteborg, for the degree of Doctor of Philosophy.
18
Hu, Xiaodong. "Synthesis, characterization, fiber spinning, and mechanical properties of poly(benzobisthiazole)s with substituted biphenyl moieties in the main chain". Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/10180.
Pełny tekst źródła
19
Chae, Han Gi. "Polyacrylonitrile/carbon nanotube composite fibers". Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/28125.
Pełny tekst źródłaStreszczenie:
Thesis (M. S.)--Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, 2008.Committee Chair: Satish Kumar; Committee Member: Anselm Griffin; Committee Member: Dong Yao; Committee Member: Naresh Thadhani; Committee Member: Samuel Graham
20
Choi, Young Ho. "Polyacrylonitrile / carbon nanotube composite fibers: effect of various processing parameters on fiber structure and properties". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42902.
Pełny tekst źródłaStreszczenie:
This study elucidates the effect of various processing parameters on polyacrylonitrile (PAN) /carbon nanotube (CNT) composite fiber structure and properties. Interaction between PAN and MWNT enabled the gel-spun PAN/MWNT composite fiber to be drawn to a higher draw ratio, than the control PAN fiber, resulting in the composite fiber tensile strength value as high as 1.3 GPa. PAN/MWNT composite fibers were stabilized and carbonized, and the resulting fibers have been characterized for their structure and properties. The effect of precursor fiber shelf-time on the mechanical properties of the gel-spun PAN/MWNT composite fibers is also reported. A rheological study of PAN-co-MAA/few wall nanotube (FWNT) composite solution has been conducted. At low shear rates, the network of FWNTs contributes to elastic response, resulting in higher viscosity and storage modulus for the composite solution as compared to the control solution. On the other hand, at high shear rates, the network of FWNTs can be broken, resulting in lower viscosity for the composite solution than that for the control solution. Larger PAN crystal size (~16.2 nm) and enhanced mechanical properties are observed when the fiber was drawn at room temperature (cold-drawing) prior to being drawn at elevated temperature (~ 165 °C; hot-drawing). Azimuthal scan of wide angle X-ray diffraction (WAXD) and Raman G-band intensities were used for the evaluation of Herman's orientation factor for PAN crystal (fPAN) and FWNT (fFWNT), respectively. Significantly higher nanotube orientation was observed than PAN orientation at an early stage of fiber processing (i.e during spinning, cold-drawing). Differential scanning calorimetry (DSC) revealed that PAN-co-MAA fiber can be converted into cyclic structure at milder conditions than those for PAN. Continuous in-line stabilization, carbonization, and characterization of the resulting carbon fibers were carried out. Rheological and fiber spinning studies have also been carried out on PAN-co-MAA/VGCNF (vapor grown carbon nano fiber). The diameter of PAN-co-MAA/VGCNF composite fiber is smaller than that of the PAN-co-MAA control fiber with same draw ratio due to the suppressed die-swell in the presence of VGCNF. The mechanical properties of PAN-co-MAA control and PAN-co-MAA/VGCNF composite fibers were characterized. Crystalline structure and morphology of the solution-spun PAN-co-MAA/VGCNF fibers are characterized using WAXD and scanning electron microscopy (SEM), respectively. The volume fraction of PAN-CNT interphase in PAN matrix has been calculated to illustrate the impact of CNTs on structural change in PAN matrix, when ordered PAN molecules are developed in the vicinity of CNTs during fiber processing. The effect of PAN-CNT interphase thickness, CNT diameter, and mass density of CNT on volume fraction of PAN-CNT interphase has been explored.
21
Bessho, Naoki. "Advanced pressure swing adsorption system with fiber sorbents for hydrogen recovery". Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42822.
Pełny tekst źródłaStreszczenie:
A new concept of a "fiber sorbent" has been investigated. The fiber sorbent is produced as a pseudo-monolithic material comprising polymer (cellulose acetate, CA) and zeolite (NaY) by applying hollow fiber spinning technology. Phase separation of the polymer solution provides an appropriately porous structure throughout the fiber matrix. In addition, the zeolite crystals are homogeneously dispersed in the polymer matrix with high loading. The zeolite is the main contributor to sorption capacity of the fiber sorbent. Mass transfer processes in the fiber sorbent module are analyzed for hydrogen recovery and compared with results for an equivalent size packed bed with identical diameter and length. The model indicates advantageous cases for application of fiber sorbent module over packed bed technology that allows system downsizing and energy saving by changing the outer and bore diameters to maintain or even reduce the pressure drop. The CA-NaY fiber sorbent was spun successfully with highly porous structure and high CO2 sorption capacity. The fiber sorbent enables the shell-side void space for thermal moderation to heat of adsorption, while this cannot be applied to the packed bed. The poly(vinyl alcohol) coated CA-NaY demonstrated the thermal moderation with paraffin wax, which was carefully selected and melt at slightly above operating temperature, in the shell-side in a rapidly cycled pressure swing adsorption. So this new approach is attractive for some hydrogen recovery applications as an alternative to traditional zeolite pellets.
22
Yan, Xiang. "Design of biphasic polymeric fiber from melt-spinning charged with nanoparticles : effects of the formulation and the fillers localization, to obtain a functionalized fiber at surface level". Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1I084.
Pełny tekst źródłaStreszczenie:
Le but de ce travail est de développer des filaments fonctionnels de polypropylène (PP) poreuses mais aussi des microfibres de PP par filage voie fondu de mélange de polymères immiscibles PP/Poly(vinyl-alcool) (PVA) après extraction sélective de la phase de PVA. Le premier objectif est de déterminer le ratio optimal entre le PP et le PVA afin d’obtenir la filabilité du mélange et de localiser les charges à l’interface du mélange biphasique. Les charges utilisées sont à la fois des nanoparticules de silices modifiées ainsi que des particules Janus à base de kaolinite, favorisant la localisation à l’interface. Les morphologies et les localisations des charges ont été analysées à la fois sur des joncs extrudés ainsi que sur des fibres. Le travail s’est concentré principalement sur des ratios de polymères permettant d’obtenir des fibres de PP poreuses, mais un travail exploratoire a permis de déterminer les conditions d’obtention de microfibres de PP. Le ratio PP/PVA avec 70 % de PP et 30 % de PVA en masse est la formulation idéale pour fabriquer ces fibres poreuses. La localisation des nanocharges de silice dans le mélange biphasique est principalement contrôlée par la thermodynamique du mélange, et en fonction des tensions de surface des nanosilices, la localisation à l’interface a pu être obtenue. De plus, les particules Janus permettent une voie alternative afin d’obtenir une localisation à l’interface, qui apportent un renforcement mécanique de la formulation. La faisabilité de la production de microfibres via l’inversion de phase PVA/PP avec l’ajout de nanocharges a été démontréeThe work aims to make the functional porous polypropylene (PP) fibers as well as PP microfibers, by the melt spinning of PP-poly(vinyl alcohol) (PVA) blends followed with the selective phase extraction of PVA. The objective is to first find out the optimal ratio of PP and PVA for fabrication of multifilament yarns by melt spinning, and to localize the filler at the biphasic interface. The fillers include not only the homogenously modified silica nanoparticles, but also the kaolinite Janus particles. The concomitant morphology evolution of the extrudates and fibers were observed. The work mainly discusses about the fabrication of porous fibers, but also makes an exploratory experiment to reverse the ratio to fabricate the microfibers. It was found that the ratio of two polymers as 70 wt.%/30 wt.% is an ideal formula for fabricating the porous fibers. Both of the two fillers are successfully tailored at the biphasic interface. The localization of silica nanoparticles within the biphasic can be fixed by the thermodynamic control, and one of the sorts has been dominantly localized at the biphasic interface. In addition, the Janus particles provide an alternative way to have the interface localization, which even helps the mechanical enhancement. The feasibility of microfiber production with the embedment of the fillers was also demonstrated
23
Blachot, Jean-François. "Étude des propriétés rhéologiques des solutions cellulose/monohydrate de N-oxyde de N-méthylmorpholine (NMMO) : filage de cellulose extraite de paille de blé : structure et fibrillation des fils obtenus". Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10189.
Pełny tekst źródłaStreszczenie:
Une etude originale des proprietes rheologiques de solutions de cellulose dissoute dans du monohydrate de n-oxyde de n-methylmorpholine (nmmo) nous a permis de determiner l'influence de la concentration et de la masse molaire de la cellulose sur les valeurs de la viscosite newtonienne et du temps d'ecoulement qui evoluent respectivement comme c#4#,#6m#5 et c#2#,#7m#5. D'autre part, des mesures effectuees en spectrometrie mecanique a differentes temperatures ont permis d'elaborer une courbe maitresse decrivant le comportement de ces solutions depuis l'etat visqueux jusqu'a l'etat vitreux. Nous avons aussi file par voie humide des solutions contenant 10% de pates cellulosiques, plus ou moins raffinees, qui ont ete extraites de la paille de ble grace a un traitement par explosion a la vapeur. Les fils d'un diametre de 13 micrometres presentent une structure fibrillaire tres orientee pouvant conduire a des delaminations de surface. Ce phenomene designe sous le nom de fibrillation est fonction de la nature et de la concentration en lignines. L'analyse de la structure, et plus particulierement, de la dechirure longitudinale des fils montre que la fibrillation est reliee a la cohesion laterale des fibrilles. Par ailleurs, dans une application de type materiaux composites, cette fibrillation augmente le renfort produit par les fibres dans les matrices de polymeres
24
Aussawasathien, Darunee. "ELECTROSPUN CONDUCTING NANOFIBER-BASED MATERIALS AND THEIR CHARACTERIZATIONS: EFFECTS OF FIBER CHARACTERISTICS ON PROPERTIES AND APPLICATIONS". Akron, OH : University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1145050541.
Pełny tekst źródłaStreszczenie:
Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2006."May, 2006." Title from electronic dissertation title page (viewed 10/11/2006) Advisor, Erol Sancaktar; Committee members, James L. White, Kyonsuku Min, Darrell H. Reneker, Wieslaw Binienda; Department Chair, Sadhan C. Jana; Dean of the College, Frank N. Kelley; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
25
Edrington, Sarah. "THE LIMITS & EFFECTS OF DRAW ON PROPERTIES AND MORPHOLOGY OF PAN-BASED PRECURSOR AND THE RESULTANT CARBON FIBERS". UKnowledge, 2017. http://uknowledge.uky.edu/me_etds/89.
Pełny tekst źródłaStreszczenie:
The process, structure, and property relationship of PAN fiber as a precursor to carbon fiber was studied. The limitations of stable spinning and property improvement associated with hot draw in solution spinning were found and quantified. Conditions were varied to generated precursor fiber up to the limit of draw, from which actual samples were collected for thermal conversion to carbon fiber. Samples of PAN and subsequent carbon fiber were characterized using tensile testing and x-ray analysis. The effects of draw on modulus and break stress, as well as the orientation of the crystalline structure of both parent precursor and resultant carbon fiber were found and related back to the quantified draw limit.
26
Grillard, Fabienne. "Structure et propriétés de fibres composites polymère-nanotubes de carbone obtenues par voie fondu". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14577/document.
Pełny tekst źródłaStreszczenie:
Cette thèse rapporte l’étude des propriétés de fibres composites polymère/nanotubes de carbone obtenues par voie fondu. Contrairement aux fibres produites jusqu’à présent par cette technologie, les fibres réalisées dans cette thèse sont conductrices. Les propriétés électriques sont étudiées en fonction de différents paramètres dont la température et les contraintes mécaniques. Par un modèle analytique, il est montré que l’étirement induit par leprocédé entraine une translation relative des nanotubes et une perte de contacts électriques.Ces fibres possèdent aussi des propriétés thermomécaniques originales comme des effets à mémoire de forme et à mémoire de température. Cette dernière est reflétée par un pic de contrainte générée à la température de déformation du matériau. Ces effets ont pu être mis en évidence sur des déformations de type traction et torsion. Même si ces effets sont gouvernés par le polymère, l’introduction des nanotubes apporte des améliorations des propriétésThis thesis reports the study of the properties and structure of carbon nanotube / polymercomposite fibers obtained by melt spinning. By contrast to most fibers produced by thistechnology, the fibers produced in this thesis are electrically conductive. The conductivityproperties are studied as a function of various parameters including temperature andmechanical stress. It is shown that fiber drawing induced by the process leads to a relativetranslation of the nanotubes relative to each other and to a loss of electrical contacts. Ananalytical model accounts for this phenomenon and reproduces the experimental results.Polymer-nanotube fibers exhibit also particularly original thermomechanical properties suchas shape memory effects that are controllable by the programming process. Surprisingly, thefibers have a temperature memory reflected by a peak of the generated stress at thetemperature at which the materials has been programmed. These effects have beendemonstrated for various types of deformations including elongation and torsion. Althoughthese effects are governed by the properties of the polymer, it is shown that the introductionof nanotubes provides significant improvements of the thermomechanical properties
27
Mortimer, Simon. "Etude de la structuration des fibres Lyocell". Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10033.
Pełny tekst źródłaStreszczenie:
Le but de cette these est d'etudier la formation des fibres produites a partir des solutions de cellulose dans le n-oxyde de n-methylmorpholine et de trouver des moyens pour modifier les proprietes de ces fibres, notamment leur tendance a fibriller. Dans une premiere partie, le systeme de filage de ces fibres est introduit, suivi par une explication des methodes de mesure en-ligne du developpement du diametre et de la birefringence des fibres. Ensuite, on utilise ces techniques pour suivre l'evolution de la structure d'une fibre des la filiere jusqu'a la fibre sechee. La structure finale est comparee avec celles d'autres fibres cellulosiques. Dans les quatrieme et cinquieme chapitres l'influence sur la formation de la fibre de plusieurs parametres du procede est etudie, tels que le taux d'etirage, la vitesse de filage, le diametre de la filiere et l'air entre la filiere et le bain de precipitation. Finalement, on developpe des methodes pour le filage des fibres ayant une faible tendance a fibriller, utilisant les parametres de filage, dont les plus importants sont l'air et le taux d'etirage
28
Martínez, Sanz Marta. "Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging". Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/30312.
Pełny tekst źródłaStreszczenie:
El presente trabajo tiene por objetivo estudiar las aplicaciones de los nanocristales o ¿nanowhiskers¿ extraídos mediante hidrólisis ácida de celulosa bacteriana (BCNW) para el desarrollo de materiales poliméricos y biopoliméricos con propiedades mejoradas para su uso en aplicaciones de envasado de alimentos.
En primer lugar se estudió y optimizó el proceso de extracción de BCNW. Se desarrolló un procedimiento de extracción con ácido sulfúrico, que permitió obtener nanocristales con elevada relación de aspecto y cristalinidad y al mismo tiempo, un elevado rendimiento de extracción. Este procedimiento comprende una posterior etapa de neutralización que resultó ser necesaria para garantizar la estabilidad térmica de los nanocristales.
El siguiente paso consistió en la formulación de materiales nanocompuestos con propiedades mejoradas incorporando BCNW en diferentes matrices plásticas, en concreto copolímeros de etileno-alcohol vinílico (EVOH), ácido poliláctico (PLA) y polihidroxialcanoatos (PHAs). Mediante las técnicas de electroestirado y estirado por soplado se generaron fibras híbridas de EVOH y PLA con BCNW. La incorporación de BCNW en las disoluciones empleadas para producir fibras modificó significativamente sus propiedades (viscosidad, tensión superficial y conductividad) y por tanto, la morfología de las fibras se vio afectada. Además, se generaron fibras con propiedades antimicrobianas mediante la incorporación de aditivos, maximizando el efecto antimicrobiano con la adición de sustancias de carácter hidrofílico. Seguidamente, se produjeron nanocompuestos por mezclado en fundido y se desarrollaron técnicas de pre-incorporación de BCNW para evitar la aglomeración de los mismos no sólo en matrices hidrofílicas como el EVOH, sino también en matrices hidrofóbicas como el PLA. La dispersión óptima de BCNW resultó en una mejora de las propiedades mecánicas y de barrera de los nanocompuestos. También se estudió la modificación de la superficie de los nanocristales mediante copolimerización con poli(glicidil metacrilato) para mejorar la compatibilidad de BCNW con una matriz hidrofóbica como el PLA. Se incluyen además los primeros resultados obtenidos en cuanto a la producción de nanobiocompuestos sintetizados por microorganismos, que consisten en PHAs con diferentes contenidos de hidroxivalerato reforzados con BCNW.
Por último, se desarrollaron películas con propiedades de alta barrera basadas en películas de BCNW recubiertas con capas hidrofóbicas. El recubrimiento mediante la deposición de fibras por electrospinning seguido de homogeneización por calentamiento garantizó una buena adhesión entre las diferentes capas, protegiendo así las películas de BCNW del efecto negativo de la humedad.Martínez Sanz, M. (2013). Bacterial cellulose nanowhiskers to enhance the properties of plastics and bioplastics of interest in food packaging [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/30312
TESIS
Premiado
29
Gulgunje, Prabhakar. "Investigation of the Processing, Structure and Properties of Poly(phenylene sulfide) (PPS) Melt Spun Fibers". 2010. http://trace.tennessee.edu/utk_graddiss/693.
Pełny tekst źródłaStreszczenie:
Numerous publications are available on the structure and properties correlation of fibers spun from polymers with flexible chains such as polyethylene terephthalate (PET), nylon, polypropylene. Also considerable amount of work is reported in fibers spun from rigid rod polymers like poly(p-phenylene terephthalamide) due to their value in high performance fibers category. However, very limited literature is available on the structure-properties relationship in fibers manufactured from poly(phenylene sulfide) (PPS), a high performance polymer which possesses chain flexibility between above two classes of polymers. A few researchers have studied crystallization kinetics and the fibers by extruding the polymer using capillary rheometers. However, there is a lack of in-depth study of conversion of PPS into fibers through melt spinning and further enhancement of properties by drawing and annealing experiments.
The purpose of the present research was to fill this void by systematically studying the fiber manufacture from PPS polymers. Four variances of proprietary Fortron® linear PPS resins differing in MW were analyzed for their characteristics such as molecular weight (MW) and MW distribution (MWD) using gel permeation chromatography (GPC), rheological properties using melt flow indexer (MFI) and capillary extrusion rheometer, and crystallization kinetics using differential scanning calorimetry (DSC). The fibers were spun on a pilot melt spinning facility, using a multi-hole spinneret, under different processing conditions. As-spun fibers were drawn and annealed subsequently by varying draw-annealing conditions. Thorough characterization of the as-spun and drawn-annealed fibers was carried out using various analytical techniques such as tensile testing, DSC, polarized light optical microscopy (POM), wide angle X-ray scattering (WAXS), and small angle X-ray scattering (SAXS). Relationship between polymer characteristics, process conditions and structure-properties in the fibers was analysed statistically.
A strong correlationship between polymer molecular weight, processing conditions during melt spinning and draw-annealing, processing behavior during melt spinning and drawing, fiber tensile properties and fiber morphology is reported herein. Interaction effects of material and process variables in evolving fiber structure and properties are also discussed. Through optimal combination of material and process variables, PPS fibers of tenacity close to six gpd were obtained. With the help of several characterization tools listed earlier, melting behavior of PPS polymers and fibers is decoded, and probable structural model of high tenacity PPS fibers is proposed.
30
(8774828), Caitlyn Michelle Clarkson. "Processing and Characterization of Nanocellulose Composites: The Leap from Poly(lactic acid) to Polyamide 6". Thesis, 2020.
Znajdź pełny tekst źródłaStreszczenie:
This disseration covers the processing and characterization of nanocellulose polymer composites. In this disseration, two fiber spinning methods were developed to create high stiffness nanocomposite fibers from renewably-sourced materials and the properties of these nanocomposites were evaluated. Additionally, bulk nanocomposites were created and some of the properties of these materials, for different types of nanoparticles, are also discussed. Evaluation of nanocellulose as a nucleation agent in poly(lactic acid) is also presented for very small concentrations of nanocelluloses in a plasticized polymer.