Thèses sur le sujet « Elastomeric thermoplastic »
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1
Jindal, Aditya Jindal. « Electrospinning and Characterization of Polyisobutylene-based Thermoplastic Elastomeric Fiber Mats For Drug Release Application ». University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1512483246405986.
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RAJAN, GURU SANKAR. « PREPARATION AND CHARACTERIZATION OF SOME UNUSUAL ELASTOMERIC AND PLASTIC COMPOSITES ». University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1022871144.
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Asplund, Basse. « Biodegradable Thermoplastic Elastomers ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7434.
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Zhou, Ruijuan [Verfasser], et Martin [Akademischer Betreuer] Maier. « Nanoparticle-Filled Thermoplastics and Thermoplastic Elastomer : Structure-Property Relationships / Ruijuan Zhou ; Betreuer : Martin Maier ». Kaiserslautern : Technische Universität Kaiserslautern, 2017. http://d-nb.info/1138630527/34.
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Kumar, Nishant C. « Anionically Polymerized Supramolecular Thermoplastic Elastomers ». University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1427128414.
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Scetta, Giorgia. « Fatigue cracking of thermoplastic elastomers ». Electronic Thesis or Diss., Université Paris sciences et lettres, 2020. http://www.theses.fr/2020UPSLS022.
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Les élastomères thermoplastiques de polyuréthane (TPU) sont une classe de copolymères à blocs caractérisés par une élasticité réversible et une excellente résistance à l'abrasion. Ils sont déjà utilisés dans un certain nombre d’applications de type caoutchouc telles que semelles, roues, câbles flexibles, etc. Pourtant, le comportement en fatigue du TPU sous chargement cyclique n'a pas été étudié en détail, et plusieurs questions restent ouvertes sur la meilleure façon de prédire la durabilité à long terme des TPU. En l'absence de procédure établie pour évaluer la résistance à la fatigue dans les TPU, nous avons proposé une méthode basée sur la propagation de fissure qui permet des comparer la résistance a fatigue des TPU avec les élastomères vulcanisés. On a caractérisé les propriétés mécaniques en petites et grandes déformations de trois TPU avec modules linéaires similaires mais des comportements différents en grandes déformations : adoucissement, rhéodurcissement et cristallisation sous contrainte. Contrairement aux élastomères vulcanisés, tous ces TPU se rigidifient avec la déformation. La diffusion des rayons X a été utilisée pour caractériser les changements de structure à des échelles microscopique induits au fond de fissure pendant le chargement cyclique. La remarquable résistance à la fatigue cyclique du TPU a été expliquée comme une conséquence de la modification de la structure locale des TPU qui génère un durcissement en fond de fissure empêchant le transfert des contraintes pendant le chargement cyclique. On a enfin proposé que ce rhéodurcissement vient de la fragmentation des domaines rigides en domaines plus petits mais plus nombreux qui agissent comme des points de réticulation physiques additionnelsSoft thermoplastic polyurethane elastomers (TPU) are a class of block copolymers characterised by a low linear modulus (<10MPa), reversible elasticity and excellent abrasion resistance already used in several rubber‐like applications such as soles, wheels, flexible cables, etc. Yet, their fatigue behaviour under cyclic loading has not been fully investigated so far, leaving several open questions about how predicting long‐term durability of TPUs for a safe design. In this work we proposed a reproducible experimental protocol to assess and compare the resistance to crack propagation in cyclic conditions of TPU, with that of classical filled rubbers by using a fracture mechanics approach. Furthermore, we characterized the mechanical response under cyclic loading at large and small strain of three commercial TPUs with similar linear moduli and rheology but different large strain behaviours: extended softening, strain hardening and strain hardening enhanced by SIC. Irrespectively of their composition, all TPUs presented an unconventional strain induced stiffening in step‐cyclic experiment. Using DIC and X‐Ray in situ experiments we showed that, the strain gradient at the crack tip generates a spatial re‐organization of the TPU microstructure consistent with a volume locally stiffer than the bulk. This heterogeneity in the deformability reduces the strain intensification at the crack tip explaining the high fatigue resistance in TPU. The local stiffening was ultimately associated to the fragmentation of original hard domains in smaller but more numerous units increasing the degree of physical crosslinking
7
Firko, Megan (Megan Rose). « Hot micro-embossing of thermoplastic elastomers ». Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/54461.
Texte intégralRésumé :
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, September 2008."June 2008." Cataloged from PDF version of thesis.
Includes bibliographical references (p. 69-71).
Microfluidic devices have been a rapidly increasing area of study since the mid 1990s. Such devices are useful for a wide variety of biological applications and offer the possibility for large scale integration of fluidic chips, similar to that of electrical circuits. With this in mind, the future market for microfluidic devices will certainly thrive, and a means of mass production will be necessary. However PDMS, the current material used to fabricate the flexible active elements central to many microfluidic chips, imposes a limit to the production rate due to the curing process used to fabricate devices. Thermoplastic elastomers (TPEs) provide a potential alternative to PDMS. Soft and rubbery at room temperature, TPEs become molten when heated and can be processed using traditional thermoplastic fabrication techniques such as injection molding or casting. One promising fabrication technique for TPEs is hot micro-embossing (HME) in which a material is heated above its glass transition temperature and imprinted with a micromachined tool, replicating the negative of the tools features. Thus far, little research has been conducted on the topic of hot embossing TPEs, and investigations seeking to determine ideal processing conditions are non-existent. This investigation concerns the selection of a promising TPE for fabrication of flexible active elements, and the characterization of the processing window for hot embossing this TPE using a tool designed to form long winding channels, with feature heights of 66Cpm and widths of 80jpm. Ideal processing conditions for the tool were found to be pressures in the range of 1MPa-1.5MPa and temperatures above 1400.
(cont.) The best replication occurred at 1500 C and 1.5 MPa, and at these conditions channel depth was within 5% of the tool, and width was within 10%. For some processing conditions a smearing effect due to bulk material flow was observed. No upper limit on temperature was found, suggesting that fabrication processes in which the material is fully melted may also be suitable for fabrication of devices from TPEs.
by Megan Firko.
S.B.
8
Miller, Paul. « Sulfur Mustard penetration of thermoplastic elastomers ». Fishermans Bend Vic. : Defence Science and Technology Organisation, 2008. http://nla.gov.au/nla.arc-24764.
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Canevarolo, Sebastiao V. « Melt behaviour of thermoplastic rubbers ». Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/27871.
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Thermoplastic rubbers have been shown to have unusual solid state properties which must derive from the structure of the melt prior to solidification. The melt phase has been studied in some detail. The molecular architecture of these block copolymers comprises of hard segments (usually polystyrene) connected by a flexible rubbery chain (polybutadiene or polyisoprene) in a linear or radial structure. Their flow characteristics have been studied and the results correlated with measurements in the solid state. They have been modelled mathematically based on two particular theoretical models. A liquid phase transition was recorded for both models, with appreciable reduction in the apparent activation energy of flow above this temperature. The quality of the domain structure depends on the continuity of the polystyrene phase and has been measured by the stress at yield and by the optical birefringence. A change in response was associated with the liquid-liquid transition.
10
Pattern, Wayne Eric. « The synthesis and characterisation of novel thermoplastic elastomers ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0004/MQ30718.pdf.
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Kantor, Jozsef. « Synthesis and Electrospinning of Polyisobutylene-based Thermoplastic Elastomers ». University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1555509494206123.
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Li, Kai. « Thermoplastic Elastomers with Oligo (ß-Alanine) Hard Segments ». University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1404831585.
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CRISENZA, TOMMASO ULISSE FILIPPO. « Thermoplastic elastomers from chlorinated polyethylene/nylon terpolyamide blends ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28398.
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Blends of chlorinated polyethylene (CPE) and Nylon terpolyamide (PA) were
prepared with different ratios. It is generally known that CPE has intrinsic
properties of heat, oil and oxidation resistance, so the obtained materials are well
suitable in the hose, pipe and seal industry. CPE was strengthened by a 6,6-6,12
co-polyamide with the glass transition temperature slightly above room
temperature and a particularly low melting temperature, that allowed to obtain
the blends by typical industrial processes of mixing, milling and injection
molding. Mechanical and rheological properties were investigated both with
tensile tests and dynamic mechanical analysis: the results showed that CPE and
PA form phase separated systems with excellent compatibility as the strength and
modulus were improved. The thermal and mechanical behavior of the blends is
that typical of thermoplastic elastomers. The comparison of the FTIR spectra of
the blends in respect of linear combination of those of the component polymers
allowed the detection of differences attributed to the existence of interactions at
the interface responsible of the enhanced mechanical properties. These results
were corroborated by time-domain proton NMR experiments, with an improved
method for the measurement of the hard/soft ratio in phase separated systems.
With the aim to resolve the morphology of the blends, samples were studied with
laser scanning confocal fluorescent microscopy (LSCFM). CPE rubber was
homogeneously labeled with a fluorescent dye by solution treatment and then
blended with PA in order to increase the contrast between phases in fluorescent
microscopy. Scanning Electron Microscopy and Atomic Force Microscopy
techniques were used to confirm the data collected with LSCFM. A continuous
and interpenetrating structure of the two phases is finally revealed for the blend
with the best mechanical properties.Blends with co-continuous structures may combine the properties of both
components in a favorable way. For example, a co-continuous structure leads to
the maximum contribution of the mechanical modulus from each component
simultaneously. Synergistic effects have also been shown in mechanical
properties. Constituting a stable co-continuous morphology just mixing two
polymers it is not that easy, and even more difficult is to detect such
microstructure within the bulk of the material. For these two reasons, cocontinuous
polymer blends are an interesting and challenging research topic. In
addition, these co-continuous structures offer promising opportunities for
improving properties and creating tailor-made materials.
For these reason, and also as very few examples of Thermoplastic elastomers
based on Chlorinated polyethylene and Nylon are present in the literature, the
project for this thesis came to life. This work is aimed at the achievement of a
material with thermoplastic elastomeric mechanical and processing properties,
for which the structure properties relationships would be completely understood
and explained as due to synergistic interfacial interaction between phases and cocontinuous
morphology within them.
14
Mace, Tamara Lee. « Phase segregation study of thermoplastic polyurethanes ». Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04072004-180051/unrestricted/mace%5ftamara%5fl%5f200312%5fms.pdf.
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Sykes, Paul A. « Structure-property relationships of chain-extended thermoplastic polyurethane elastomers ». Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/12451.
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The effect of chain extender chemical structure on the physical and mechanical properties of thermoplastic polyurethane/urethaneurea elastomers was systematically investigated. Several series of materials were synthesised using 4,4' -diphenylmethane diisocyanate (MDI) and poly(tetramethylene oxide) glycol (PTMG), each series incorporating a particular class of chain extender compound. Elucidation of the influence of chain extender structural variations within each series was the principal objective of the investigation…
16
Beckett, Laura. « Synthesis and characterisation of photoresponsive thermoplastic liquid crystal elastomers ». Thesis, University of Bristol, 2019. http://hdl.handle.net/1983/a7a2fec4-cb13-4bdb-bebf-8b97687d2050.
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Liquid crystal elastomers (LCEs) are polymeric materials capable of rapid, reversible shape change on application of an external stimulus. However, their application as soft actuators has, to date, been limited by the requirement to induce a liquid crystal monodomain, with common alignment methods restricting possible structures to thin films. Thermoplastic LCEs have the potential for processing through large-scale techniques such as extrusion or fibre spinning but have been relatively unexplored, with low-yielding synthetic methods preventing further investigation into their suitability for processing into alternative geometries to films. For this reason, photoresponsive thermoplastic side-chain LCEs based on a polystyrene-b-poly(methylvinylsiloxane)-b-polystyrene block copolymer backbone have been synthesised for processing into responsive fibres. A two-step post-polymerisation modification was used to first attach a linking group, followed by the mesogen. A yield of 85% was achieved in the final coupling stage, resulting in polymers with 65-85% of linking groups functionalised with mesogen. Through the choice of linking group or mesogen it was possible to tune the thermal properties of the LCEs to obtain useful transition temperatures for use as room temperature actuators. The presence of a nematic mesophase was shown to have a strong effect on the physical properties of the polymer, resulting in a microphase segregated morphology at temperatures far above the order-disorder transition temperature of the unfunctionalised triblock copolymer. This, combined with the relatively high molecular weight of 150,000 g mol-1, was demonstrated to limit the ability to process the LCE by melt extrusion, with gel-like behaviour observed at temperatures up to 200 °C. However, the high molecular weight of the polymer made it suitable for processing from solution, and preliminary experiments demonstrated for the first time that fibres of a thermoplastic LCE could be produced by electrospinning, with elongation of the jet resulting in the formation of an aligned nematic LC mesophase.
17
Pollock, Gregory S. « Synthesis and characterization of silk-inspired thermoplastic polyurethane elastomers ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33718.
Texte intégralRésumé :
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2005.Includes bibliographical references.
Segmented polyurethane elastomers containing additional ordered structures within the hard or soft domains were developed to mimic the hierarchical structure and superior properties observed in spider silk fibers. The silk's toughness is related to a fiber morphology that includes P-pleated crystalline sheets within an amorphous matrix, as well as an additional interphase with an orientation and mobility between that of the two microphases. In the polyurethane mimics, bulky aromatic diisocyanates were incorporated between aliphatic hexamethylene diisocyanate (HDI) hard segments and poly(tetramethylene oxide) (PTMO) soft segments, to enhance the size and orientation of the interphase. The mixture of diisocyanates reduces the crystallinity of the HDI hard segments, allowing the polyurethane to form more well-organized domains observed by AFM imaging. The more interconnected hard domains allow the elastomers to deform to higher elongations and absorb more energy without a decrease of initial modulus. Shearing of the hydrogen-bonded hard domains orients the hard blocks at a preferred tilt angle of ±20⁰ from the strain direction during tensile deformation.
(cont.) While the average spacing of hard domains increases during deformation, the spacing of hard domains aligned with the strain decreases, and the spacing of hard domains at the preferred tilt angle remains constant. Strain-induced crystallization of the PTMO soft segments was observed in all samples; however, hard segments with mixed diisocyanates exhibited non-crystalline alignment of the hard domains. Several polyurethane nanocomposite structures were also created using particles that preferentially associate with hard or soft segments. HDI-PTMO polyurethane/Laponite nanocomposites provided modest mechanical property improvements (80% increase in modulus and 15% increase in toughness) without any loss of extensibility. The Laponite discs exhibited an exfoliated structure, associating with and reinforcing the hydrophilic polyurethane hard segments. HDI-PTMO polyurethane/MQ siloxane resin nanocomposites also exhibited particle association with the hard segments, providing a 60% increase in modulus with a small loss of toughness.
(cont.) However, composites of isobutyl-POSS dispersed in polyurethanes with mixed hard segments exhibited formation of POSS crystals associated with the soft segments at all loadings, resulting in tensile failure at strains 80-100% lower than the pure polyurethane.
by Gregory Stewart Pollock.
Ph.D.
18
Rabani, Gouher. « Synthesis and characterisation of thermoplastic elastomers containing uniform aramid units ». Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/297.
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Ramezani, Kakroodi Adel. « Production and characterization of thermoplastic elastomers based on recycled rubber ». Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30327/30327.pdf.
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Ce travail de doctorat est consacré à la production et à la caractérisation de composés polymères à base de matrices thermoplastiques en mélange avec des particules de caoutchoucs recyclés. Les principales applications visées sont: (A) la production d’élastomères thermoplastiques (TPE) à haute teneur (50% et plus) en poudrette de caoutchouc de pneus usés (GTR); et (B) l’amélioration de la résistance à l’impact des composites thermoplastiques avec de faibles concentrations en GTR. Dans la première partie de ce travail, du polyéthylène maléaté (MAPE) a été utilisé comme matrice pour produire des mélanges MAPE/GTR présentant d'excellentes caractéristiques en tant qu’élastomère thermoplastique. Puis, les effets de différents mécanismes de dégradation (humidité, chaleur et recyclage) sur les propriétés des composites MAPE/GTR ont été largement examinés afin d’évaluer le potentiel de ces matériaux après plusieurs cycles d’utilisation. Enfin, le renforcement des TPE/GTR par différentes particules solides (poudre de bois et talc) a été étudié pour des applications plus exigeantes (caractéristiques mécaniques). Dans la seconde partie de ce travail, une nouvelle approche est proposée pour la modification de la résistance aux chocs des composites à base de polypropylène renforcé par des charges organique (chanvre) et inorganiques (talc, verre). L’amélioration des propriétés à l'impact de ces composites a été réalisée par l’addition d’un mélange à base de polypropylène maléaté (MAPP) et de poudrette de caoutchouc (GTR et déchets d’EPDM) contenant des concentrations élevées (jusqu’à 70% en poids) de déchets caoutchoutiques.This Ph.D. work is devoted to the production and characterization of polymer compounds based on thermoplastic matrix filled with waste rubber powder. The main applications include: (A) the production of thermoplastic elastomer (TPE) resins containing high ground tire rubber (GTR) contents (50% and higher), and (B) impact modification of thermoplastic composites using low concentrations of GTR. In the first part of the work, maleated polyethylene (MAPE) is proposed as a matrix to produce MAPE/GTR blends having excellent characteristics as thermoplastic elastomers. Then, the effects of different degradation mechanisms (weathering, thermal degradation and reprocessing) on the properties of MAPE/GTR compounds were extensively investigated to determine their potential for further recycling. Finally, the reinforcement of GTR filled TPE was investigated using different types of solid particles (wood flour and talc) for more demanding applications (mechanical characteristics). In the second part of the work, a new approach is proposed for impact modification of polypropylene based composites based on organic (hemp) and inorganic (talc and glass) reinforcements. The effective improvement of the impact properties of these composites is performed through the addition of a masterbatch based on maleated polypropylene (MAPP)/waste rubber powder (GTR or waste EPDM) containing high concentrations (70% by weight) of waste rubber.
20
Liff, Shawna M. (Shawna Marie). « Preferential nanoreinforcement of thermoplastic polyurethane elastomers with dispersed nano-clay ». Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32356.
Texte intégralRésumé :
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (p. 94-99).
It is difficult for scientists to engineer elastomeric materials that are both strong and tough like spider dragline silk. Inspired by the morphology of spider dragline silk and motivated to develop strong, tough, elastomeric polyurethanes to be used in soldier applications I have prepared polyurethane/clay nanocomposites. Polymer/clay nanocomposites have exhibited great potential for providing enhanced and possibly-tunable thermomechanical behavior. However, the biggest challenge facing advances in polymer/clay nanocomposites is the complete dispersion of nano- clay within the polymer matrix due to thermodynamic and kinetic limitations. A novel solvent exchange method to fully exfoliate and disperse discotic smectic clay, Laponite (diameter = 25 nm, thickness = 1 nm), in three thermoplastic polyurethane elastomers (TPUs) -- Elasthane 80A, HDI-PTMO PU, and PU-1-33 -- has been developed. This clay was selected because the diameter of one platelet is similar to the lateral dimension of a single hard-domain in block-polymeric TPU. WAXD, TEM, and AFM phase imaging of cast films following solvent exchange show that the nano-clay is well dispersed in the TPUs. Uniaxial mechanical testing showed that as much as a 23-fold increase in elastic modulus, 100% increase in toughness, and 50% increase in strength can be achieved without a reduction in extensibility when Laponite is added to Elasthane. Furthermore, the heat distortion temperature of the Elasthane can be increased from 101⁰C to more than 200⁰C, as measured by DMA, when 20 wt% Laponite is added.
(cont.) The HDI-PTMO PU/Laponite nanocomposites behave like the Elasthane/Laponite nanocomposites, exhibiting an increase in elastic modulus, strength, and toughness without a loss in extensibility. In contrast, a PU-1-33 thin film exhibits a significant decrease in extensibility, strength, and toughness with no significant change in elastic modulus when filled with Laponite. Characterization shows that the Laponite is preferentially embedded within the polar hard domains of the Elasthane and HDI-PTMO PU and embedded within the soft domain of PU-1-33. The Laponite is attracted to the polar, hydrophilic soft segment constituent, polyethylene oxide, in PU-1-33. Ultimately, Laponite can be used to strengthen and toughen TPUs and the location of Laponite reinforcement can be altered by adjusting the polarity and hydrophilicity of the soft segment.
by Shawna M. Liff.
S.M.
21
Bryant, Richard. « Phase separation in thermoplastic polyurethane elastomers : a structure-property investigation ». Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/33571.
Texte intégralRésumé :
The effect of soft segment, isocyanate and chain extender chemical structure on the physical and mechanical properties of thermoplastic polyurethane elastomers was systematically investigated. Several series of materials were produced with identical stoichiometry and under the same reaction conditions. The raw materials used to synthesise these materials were systematically altered to facilitate comment on the influence of molecular weight, cohesive energy density (CED) and molecular geometry on the phase separation phenomena observed in polyurethane elastomers.
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Gergely, Attila Levente. « Synthesis and Characterization of Poly(Alloocimene-b-Isobutylene) Thermoplastic Elastomers ». University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1404212407.
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Charif, Rodriguez Andrea Carolina. « New Applications for Linear and Arborescent Polyisobuylene-Based Thermoplastic Elastomers ». University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1425420506.
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Chen, Ming. « Electromagnetic radiation calorimetry of thermoplastics, elastomers and composites systems ». Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54780.
Texte intégralRésumé :
The application of microwave radiation for processing of glassy and semicrystalline thermoplastics, elastomeric polymers and composites was investigated. The goal of this research was to reveal the relationship between polymer structure and microwave absorptivity, and hence processability. The specimens were subjected to an electric field at 2.45 GHz either inside a rectangular waveguide or in a cylindrical resonant cavity applicator with less than 100 watts applied power. Both travelling wave modes and standing wave modes were examined. Temperatures, powers and times were recorded, leading to the concept of "microwave calorimetry." Low frequency dynamic mechanical and dielectric frequency-temperature spectra were obtained on the materials and combined to conveniently extrapolate structure-property relationships into the GHz region. A correlation was found between the dielectric properties of various polymers and the dipole moments of small molecule analogues. Evaluating heatability was most accurately found to be determined by the magnitude of (εS - ε∞), the oscillator strength. The value of (εS - ε∞) should be used together with the distribution of relaxation times and the activation energies of dipolar dispersion to predict heatability for microwave processing. The critical temperatures, TC, of dielectric loss were obtained from the intercepts of positive slope tangents of heating rate versus temperature plots at 2.45 GHz for polymers. Microwave processing was rapid above the critical temperature where the maximum dielectric loss fell in the 2.45 GHz frequency domain for efficient coupling of energy to the polymers. Shifting the dielectric relaxation spectrum into the microwave region by directly or indirectly increasing the temperature of each sample was unique and of key importance to processability. A schematic model was proposed to explain the behavior of two-phase materials subjected to microwave heating. Combining the heatability, (εS - ε∞), and the dielectric relaxation spectral response was found to be helpful in evaluating formulations of two-phase materials for electromagnetic radiation processing at high frequencies.Ph. D.
25
Brannigan, Ruairi. « Design of novel monomers for applications in hydrolytically degradable thermoplastic elastomers ». Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77250/.
Texte intégralRésumé :
This thesis explores the synthesis of novel monomers in the design of hydrolytically degradable materials with defined physical and chemical properties using a selection of coupling and polymerisation techniques. Chapter 1 introduces the concept of hydrolytically degradable polymers, namely polyesters, and exhibits the dynamic range of biomedical applications in which they might be utilised. In Chapter 2, the organocatalysed ROP of a previously synthesised spirocyclic carbonate monomer bearing pendant benzylacetal functionality (PTO) and a novel spirocyclic carbonate monomer bearing pendant norbornene-acetal functionality (NTC) are described. The successful post-polymerisation modification of the norbornene functionality is demonstrated utilising a variety of addition reactions; the 1,3-dipolar cycloaddition of azides,inverse electron demand Diels-Alder reaction with tetrazines and the radical thiolene addition. Furthermore, the synthesis, self-assembly and pH-triggered degradation of graft copolymers, prepared by the thiol-ene addition of a thiol-terminated hydrophilic polymer to the hydrophobic polycarbonate backbone, is also described. Chapter 3 describes the synthesis of A-B-A triblock copolyester-carbonates via the ROP of PTO (described in Chapter 2) initiated from an α,ω-dihydroxy poly(caprolactone) (PCL) macroinitiator, with varying molecular weights, yielding thermoplastic materials with superior tensile properties (elongation and Young’s modulus) to that of the PCL homopolymer. Furthermore, the alteration of PCLs thermal and degradation properties, as a consequence of the chain extension PTO, was also described. In Chapter 4, the utilisation of the diol precursors to PTO and NTC (described in Chapter 2) as chain extenders for the organocatalysed synthesis of novel PCL-based thermoplastic polyesterurethanes (TPEUs) is reported. The successful post-polymerisation modification of the norbornene functionality is demonstrated utilising addition reactions optimised from Chapter 2. Furthermore, the mechanical, surface hydrophilicity and degradation properties of the TPEUs, before and after modification, are also described. Chapter 5 describes the synthesis of novel diol chain extenders derived from natural amino acids, modified with carbamate and urea pendant groups, and their utilisation in the organocatalysed synthesis of novel PCL-based TPEUs. The modulation of physical and degradation properties by varying polymer composition and extender type were also described. Chapter 6 provides a summary of the key findings of Chapters 2 – 5 and Chapter 7 provides the experimental methods of this thesis.
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Paul, Steffen. « Spritzgußsimulation als Kopplungselement von CAD und CAE ». Universitätsbibliothek Chemnitz, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-142037.
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Mahallati, Paridokht. « Optimization of thermoplastic elastomer foams based on PP and recycled rubber ». Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25551.
Texte intégralRésumé :
Cette étude porte sur la production et la caractérisation d’élastomères thermoplastiques (TPE) à base de polypropylène et de caoutchouc vulcanisé recyclé, ainsi que leurs mousses. La première partie de cette étude est liée à la caractérisation de mélanges polypropylène/éthylène-propylène-diène monomère recyclé (PP/r-EPDM) (50/50) avec du polypropylène greffé d'anhydride maléique (PP-g-MA) (0 à 8% en poids). En particulier, l’effet de l'ordre d'alimentation dans une extrudeuse bi-vis et la composition sont étudiées. À partir des échantillons obtenus par moulage en injection, une comparaison est effectuée sur la morphologie et les propriétés mécaniques (impact, tension et flexion), ainsi que la densité et la dureté. Dans la deuxième étape du travail, les mélanges PP/r-EPDM ont été produits par extrusion bi-vis, suivi par un moulage en injection. Dans ce cas, l'effet de la concentration de r-EPDM (jusqu'à 65% en poids), ainsi que la position et l’ordre d'alimentation le long de la vis d'extrusion ont été étudiées pour comparer la morphologie et les propriétés mécaniques. Enfin, les conditions de mise en œuvre optimales obtenues dans les deux premières parties du travail ont été utilisées pour produire des mousses de PP/r-EPDM par moulage en injection. Pour ces échantillons, l'effet de la concentration de r-EPDM (0 à 65% en poids) et de l’agent gonflant chimique (azodicarbonamide) (jusqu'à 1,5% en poids), ainsi que les conditions d'injection (température du moule (30 et 70 °C) et la quantité de matière injectée) ont été étudiées pour la morphologie (taille des cellules, densité cellulaire, et l'épaisseur de la peau), les propriétés mécaniques (impact, tension et flexion), ainsi que la densité et la dureté. Les résultats montrent que l'incorporation de r-EPDM conduit à une amélioration substantielle de la résistance aux chocs du PP (jusqu'à 329%), tandis que l'addition de PP-g-MA comme agent de couplage n'est pas nécessaire dans ce système à cause de la bonne adhésion entre le PP et les particules de r-EPDM. Il a été constaté que l'ordre d’introduction de chacun des composants dans l'extrudeuse a un effet direct sur les propriétés du mélange. Par conséquent, l'alimentation de r-EPDM dans la première zone et du PP dans la quatrième zone de l'extrudeuse conduit à des particules plus petites de r-EPDM en raison du plus long temps de séjour et des contraintes appliquées sur les particules de r-EPDM dans la première section de l'extrudeuse. Enfin, les résultats montrent qu'il est plus difficile de réaliser une bonne structure de mousse avec une teneur élevée en r-EPDM.This investigation focuses on the production and characterization of thermoplastic elastomers (TPE) based on polypropylene and recycled vulcanized rubber, as well as their foams. The first part of this study is related to the characterization of polypropylene/recycled ethylene-propylene-diene monomer (PP/r-EPDM) (50/50) blends modified with polypropylene-graft-maleic anhydride (PP-g-MA) (0 to 8% wt.). In particular, the effect of feeding order in a twin-screw extruder and blend composition are investigated. From the samples produced via injection molding, a comparison is made based on blend morphology and mechanical properties (impact, tension, and flexion), as well as density and hardness. In the second step of the work, PP/r-EPDM blends are produced through twin-screw extrusion followed by injection molding. In this case, the effect of r-EPDM concentration (up to 65% wt.), feeding order and feeding position along the extruder screw are studied and the blends are compared in terms of morphology and mechanical properties. Finally, the optimum processing conditions obtained in the first two parts are used to produce PP/r-EPDM foams via injection molding. For these samples, the effect of r-EPDM (0 to 65% wt.) and chemical foaming agent (azodicarbonamide) (up to 1.5% wt.) contents, as well as injection conditions (mold temperature (30 and 70 °C) and shot size) are studied with respect to morphology (cell size, cell density, and skin thickness) and mechanical properties (impact, tension, and flexion), as well as density and hardness. The results show that incorporation of r-EPDM leads to a substantial improvement of PP impact strength (up to 329%), while the addition of PP-g-MA as a coupling agent is not necessary in this system due to good adhesion between the PP matrix and dispersed r-EPDM particles. In addition, it is found that the feeding order of each component in the extruder has a direct effect on blend properties. Consequently, feeding the r-EPDM in the first zone and PP in the fourth zone of the extruder leads to smaller r-EPDM particles because of the longer residence time and direct shear/elongational stresses applied on the r-EPDM particles in the first section of the extruder. Finally, the results show that it is more difficult to produce a good foam structure with increasing r-EPDM content.
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Pedroni, Lucas Gomes. « Nanocompositos elastomericos baseados em MWCNTs : preparação, caracterização, e aplicações ». [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248452.
Texte intégralRésumé :
Orientadores: Ana Flavia Nogueira, Maria Isabel FelisbertiDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Nanocompósitos poliméricos baseados em nanotubos de carbono possuem um dos mais elevados potenciais tecnológicos devido à possibilidade de produção de materiais com destacadas propriedades mecânicas, alta condutividade elétrica em baixos teores (baixos limites de percolação), e boa processabilidade. São sistemas versáteis que podem apresentar propriedades excepcionais, as quais podem ser controladas pela alteração na proporção de seus componentes, permitindo que sejam moldados para atender à aplicação exigida. Nesse trabalho, nanocompósitos de nanotubos de carbono de paredes múltiplas (MWCNTs) e um elastômero comercial (Kraton-D®), que é um copolímero em bloco de estireno-butadieno-estireno (SBS), foram preparados por extrusão e pela técnica de evaporação de solvente (casting). As propriedades térmicas, mecânicas, e elétricas desses materiais foram comparadas. A caracterização foi realizada através de medidas de condutividade elétrica (método de Coleman), microscopias eletrônicas de varredura e de transmissão (caracterização morfológica), termogravimetria (determinação do teor de cargas e estabilidade térmica), ensaios de tração e análise dinâmico-mecânica (propriedades mecânicas). Além disso, o potencial de aplicação dos compósitos em células solares de TiO2/corante (DSSC) e como materiais absorvedores de radiação (MAR) foi avaliado. Os resultados evidenciaram uma forte influência da metodologia de preparo nas propriedades finais dos compósitos, a qual é creditada a mudanças de morfologia do sistema em função das condições de preparação utilizadas. As amostras preparadas por casting apresentaram condutividades elétricas mais elevadas, enquanto as propriedades mecânicas foram superiores para os filmes extrudados, e ambas tiveram melhoria da estabilidade térmica. Os compósitos se mostraram promissores quanto ao uso em DSSC e como MAR, mas muitos estudos ainda são necessários para aprimorar sua eficiência nesses campos
Abstract: Polymeric nanocomposites based on carbon nanotubes (CNTs) have one of the highest technological potential due to the possibility of produce materials with improved mechanical properties, high electrical conductivity at low loadings (low percolation threshold), and good processability. These systems are versatile, may present astonishing properties, and are allowed to control them by changing the proportion of their components, being able to tailor these materials to suit a desired application. In this work, nanocomposites of multiwalled carbon nanotubes (MWCNTs) and a commercial elastomer (Kraton-D®), which is a block copolymer of styrenebutadiene- styrene (SBS), were prepared by extrusion and by casting. The thermal, mechanical, and electrical properties presented by these materials were compared. The characterization was performed by measurement of the electrical conductivity (Coleman¿s method), scanning and transmission electron microscopy (for morphologic characterization), thermogravimetry (for thermal stability and determination of the loading of filler), stress-strain tests and dynamic mechanical analysis (for the mechanical properties). Furthermore, the potential of application of the extruded composites in dye-sensitized solar cells (DSSC) and as radiation absorbing materials (RAM) was tested. The results showed a strong influence of the methodology of preparation upon the final properties of composites, which was attributed to changes in the morphology of the system with conditions used to prepare the samples. Composites made by casting showed a higher electrical conductivity than the extruded ones, although the latter presented better mechanical properties than the former ones. Despite the requirement of further studies to improve their efficiency in DSSC and as RAM, the composites were promising for these applications
Mestrado
Quimica Inorganica
Mestre em Química
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Pavka, Paul. « Effect of Network Structure on the Quasi-Static, Fatigue, Creep, Thermal, and Fiber Properties of Polyisobutylene-based Thermoplastic Elastomers ». University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1377014416.
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Knox, John Graeme. « The engineering development of power transmission belts based on thermoplastic polyurethane elastomers ». Thesis, University of Ulster, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270457.
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Moghaddamzadeh, Siavosh. « Thermoplastic elastomers based on polyester recycled tire fibers and ground tire rubber ». Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/30261.
Texte intégralRésumé :
Ce projet porte sur la production et la caractérisation de composites hybrides basés sur un polymère thermoplastique (polyéthylène linéaire de basse densité, LLDPE) avec des fibres de polyester de pneus recyclés (RTF) mélangées avec le caoutchouc des pneus usés (GTR) avec et sans styrène-éthylène-butylène-styrène greffé d’anhydride maléique (SEBS-g-MA) comme compatibilisant. L'étude vise à améliorer les propriétés du LLDPE avec le RTF, GTR et SEBS-g-MA. La première étape de l'étude est composée de deux parties principales. La première partie porte sur la caractérisation des RTF par spectroscopie infrarouge à transformée de Fourier (FTIR), spectroscopie des photoélectrons X (XPS), analyse thermogravimétrique (TGA), calorimétrie différentielle à balayage (DSC), microscopie électronique (SEM) et densité; tandis que la deuxième partie rapporte la morphologie des composites fabriqués à partir de différentes conditions. En particulier, l'effet de la concentration de RTF (10, 25 et 50% en poids) avec et sans 10% poids de SEBS-g-MA à différentes vitesses de vis (110, 180 et 250 rpm) en-dessous (LT) et au-dessus (HT) de la température de fusion du RTF (253°C) est étudié par extrusion double-vis suivie du moulage par injection. Les résultats montrent une meilleure distribution des particules GTR (intégrées au RTF) dans la matrice (LLDPE) avec l'augmentation du contenu en RTF dans les mélanges compatibilisés. En outre, l’augmentation de la vitesse des vis entraîne une réduction de la longueur des RTF et de la taille des GTR. Cependant, un profil HT mène à la dégradation de la matrice et du GTR. Dans la deuxième étape du travail, une série complète de caractérisation physique (densité et dureté) et mécanique (tension, flexion et impact) des échantillons produits dans la première partie est présentée. Malgré la diminution des modules et des contraintes maximales, la résistance au choc Charpy augmente de 50% avec 50% de FTR compatibilisées et une amélioration supplémentaire de 56% à haute vitesse de rotation des vis (250 rpm). Cependant, le profil HT diminue toutes les propriétés physico-mécaniques des mélanges. Finalement, les propriétés rhéologiques des échantillons produits lors de la première partie ont été rhéologiquement caractérisés à l’état fondu (cisaillement oscillatoire de faible amplitude, SAOS) et solide (analyse mécanique dynamique, DMA) afin de déterminer les relations entre la mise en œuvre, la morphologie et les propriétés macroscopiques. Les résultats montrent une augmentation de l'élasticité des mélanges avec l’augmentation du contenu en RTF en présence de SEBS-g-MA surtout à des vitesses de vis élevées. Néanmoins, le profil HT présente une diminution de l'élasticité à l’état fondu, tandis que la DMA montre une augmentation de l’élasticité pour le profil LT.This project focuses on the production and characterization of hybrid composites based on a thermoplastic polymer (linear low-density polyethylene, LLDPE) and polyester recycled tire fibers (RTF) mixed with ground tire rubber (GTR) with and without styrene-ethylenebutylene-styrene grafted maleic anhydride (SEBS-g-MA) as a compatibilizer. The study aims at improving the properties of LLDPE using RTF, GTR and SEBS-g-MA. The first step is composed of two main parts. The first part is the characterization of RTF via Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and density; while the second part is to report on the morphology from different processing parameters. In particular, the effect of RTF concentration (10, 25 and 50 wt.%) with and without 10 wt.% SEBS-g-MA at different screw speeds (110, 180 and 250 rpm) processed below (LT) and above (HT) the RTF melting temperature (253°C) are investigated for samples produced via twin-screw extrusion followed by injection molding. The results show better GTR particles distribution (imbedded in RTF) in the matrix (LLDPE) with increasing RTF content in the compatibilized compounds. Also, increasing the screw speed leads to a reduction of RTF length and GTR sizes. However, HT profiles produced degradation of the matrix and GTR particles. In the second step, a complete series of physical (density and hardness) and mechanical (tension, flexion and impact) characterization was performed on the samples produced in the first step. Despite lower moduli and strength, Charpy impact strength increases by 50% for compatibilized 50% RTF compounds with an additional 56% improvement at higher screw speed (250 rpm). However, HT profiles decrease all physico-mechanical properties of the samples. Finally, the rheological properties of the samples produced in the first step are investigated in both the melt (small amplitude oscillatory shear, SAOS) and solid (dynamic mechanical analysis, DMA) states to understand the relations between processing, morphology and macroscopic properties. The results show increased elasticity with increasing RTF content with SEBS-g-MA, especially at higher extrusion screw speeds. HT profiles lead to lower elasticity in the melt state, while DMA results show higher elasticity for LT profiles.
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Munoz, Robledo Lyn G. « Attachment and Growth of Aortic Adventitial Fibroblasts on Polyisobutylene-based Thermoplastic Elastomers ». University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1208204988.
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Zicheng, Wang, et Mohammad Nouri. « Investigation on Filament Extrusion of Thermoplastic Elastomer (TPE) for Fused Deposition Modeling ». Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-40778.
Texte intégralRésumé :
This thesis is an investigation of the TPE filament for Fused Deposition Modelling (FDM) manufacturing method. All the investigations aim to optimize the quality of the filament in order to make Thermoplastic Elastomer (TPE) material possible for FDM manufacturing method. Optimization experiments were made to find out key parameters in the extrusion process that determine the quality of the filament. With the optimal parameters, further investigation of the additive content in the TPE granulate was made to solve the current problem of the filament in practical 3D printing, which the high surface friction massively affects the FDM manufacturing feasibility. The filaments were manufactured by the desktop extruder 3devo filament extruder and the surface friction tests were performed on TribotesterTM. Additionally, discussion was made to summarize the pros and cons of TPE material as well as the significance of 3D printing TPE. Potential application and benefits are mentioned for combining the property of TPE and the advantage of FDM manufacturing. Current state-of-art extrusion equipment and FDM technology are also summarized.
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Choi, Wonsook. « Mechanistic studies of the metal catalyzed formation of polycarbonates and their thermoplastic elastomers ». [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1433.
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Verdugo, Fernández Pedro Manuel. « Stimuli cleavable ABA block copolymers : Synthesis of degradable thermoplastic elastomers from renewable resources ». Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/671470.
Texte intégralRésumé :
Actualment, un dels majors reptes que afronta la societat es el de adaptar la nostra forma de viure de tal manera que
el nostre impacte en el medi ambient sigui el mínim possible. Aquest objectiu s’ha d’abordar des de diferents àmbits,
entre ells de la ciència de materials. Per a un futur sostenible, en la fabricació de polímers cal substituir els compostos
petroquímics, com a font de matèries primeres, per altres d’origen renovable (p. ex. olis vegetals). Però, al mateix
temps, els polímers han de ser capaços de ser fàcilment degradables o reciclables un cop acabada la seva vida útil.
En aquesta tesis s’han preparat polímers fent servir monòmers d’origen renovable. La -decalactona, que pot ser
obtinguda a partir d’àcids grassos presents a l’oli de gira-sol o mitjançant la fermentació del bagàs de canya de sucre y la -metilen- -butirolactona (o tulipalina A), que està present en certes flors com les tulipes. Aquest monòmers han
estat polimeritzats de forma controlada mitjançant les tècniques de polimerització per apertura d’anell (ROP) i
polimerització radical per transferència atòmica (ATRP) respectivament. La combinació de ambdues tècniques ha
permès obtenir copolímers de bloc ABA amb propietats d’elastòmer termoplàstic.
En el disseny d’aquests materials, s’han incorporat grups sensibles al punt mig del copolímer que puguin respondre a
estímuls externs. Sota determinades condicions (p. ex. àcid, redox., etc.) és produeix el trencament del grup sensible,
obtenint copolímers AB.Actualmente, uno de los mayores retos a los que se enfrenta nuestra sociedad es el de adaptar nuestra forma de vida de tal manera que nuestro impacto en el medio ambiente sea el mínimo posible. Este objetivo debe afrontarse des de diferentes ámbitos, entre ellos el de la ciencia de materiales. Para un futuro sostenible, en la fabricación de polímeros hay que sustituir los compuestos petroquímicos, como fuente de materias primas, por otros de origen renovable (p. ej. aceites vegetales). Pero, al mismo tiempo, los polímeros han de ser capaces de ser fácilmente degradables o reciclables una vez acabada su vida útil. En esta tesis se han preparado polímeros utilizando monómeros de origen renovable. La -decalactona, que puede ser obtenida a partir de ácidos grasos presentes en el aceite de girasol o mediante fermentación del bagazo de la caña de azúcar y la -metilen- -butirolactona (o tulipalina A), que se encuentra en ciertas flores como los tulipanes. Estos monómeros han sido polimerizados de forma controlada mediante las técnicas de polimerización por apertura de anillo (ROP) y polimerización radical por transferencia atómica (ATRP) respectivamente. La combinación de las dos técnicas ha permitido obtener copolímeros de bloque ABA con propiedades de elastómero termoplástico. En el diseño de estos materiales, se han incorporado grupos sensibles en el punto medio del copolímero que puedan responder a estímulos externos.
Nowadays, one of the most important issues of our society is to adapt our lifestyle in a way that our impact to the environment was as minimum as possible. This purpose must be addressed from different fields, material science among them. For a sustainable future, petrochemicals as raw materials, must be substituted by other from renewable sources (e. g. vegetable oils). However, at the same time, the polymers must be able to be easily degraded or recycled once finished their useful life. In this thesis polymers using monomers obtained from renewable resources have been synthesized. -Decalactone, which can be obtained from fatty acids present on sunflower oil or through the sugarcane bagasse fermentation and - methylene- -butyrolactone (or tulipalin A), which is present in some flowers such as tulips. These monomers have been polymerized in a controlled manner through the Ring-Opening Polymerization (ROP) and Atom Transfer Radical Polymerization (ATRP) mechanisms respectively. The combination of these two techniques allows the obtention of ABA block copolymers with thermoplastic elastomer properties. In the materials design, sensitive groups which can respond to external stimuli, have been incorporated at the mid-point of the copolymer. The cleavage of the sensitive group can be done under certain conditions (e. g. acid, redox., etc.), obtaining AB copolymers
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Uddin, Md Salah. « Enhanced Coarse-Graining for Multiscale Modeling of Elastomers ». Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc955108/.
Texte intégralRésumé :
One of the major goal of the researchers is to reduce energy loss including nanoscale to the structural level. For instance, around 65% of fuel energy is lost during the propulsion of the automobiles, where 11% of the loss happens at tires due to rolling friction. Out of that tire loss, 90 to 95% loss happens due to hysteresis of tire materials. This dissertation focuses on multiscale modeling techniques in order to facilitate the discovery new rubber materials. Enhanced coarse-grained models of elastomers (thermoplastic polyurethane elastomer and natural rubber) are constructed from full-atomic models with reasonable repeat units/beads associated with pressure-correction for non-bonded interactions of the beads using inverse Boltzmann method (IBM). Equivalent continuum modeling is performed with volumetric/isochoric loading to predict macroscopic mechanical properties using molecular mechanics (MM) and molecular dynamics (MD). Glass-transition and rate-dependent mechanical properties along with hysteresis loss under uniaxial deformation is predicted with varying composition of the material. A statistical non-Gaussian treatment of a rubber chain is performed and linked with molecular dynamics in order predict hyperelastic material constants without fitting with any experimental data.
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Giese, Dagmar. « Recycling über Lösen von Elastomeren und faserverstärkten Thermoplasten : Konzeption einer Technikumsversuchsanlage / ». Berlin : TU, Univ.-Bibliothek, Abt. Publ, 1998. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=008141406&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Gordons, Temofebi G. « Stress relaxation behaviour in compression and some other mechanical properties of thermoplastic-elastomer ». Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/6942.
Texte intégralRésumé :
Thermoplastic elastomers have been found to have unsual properties, a consequence of composition and structure. The molecular composition comprises hard thermoplastic blocks which aggregate into domains, and flexible elastomer blocks in a linear or inter-penetrating structure. The mechanical properties such as stress relaxation, tensile strength, elongation, recovery and hardness of some thermopastic elatomers have been studied in some detail. The stress relaxation studies have been made possible with the development of the stress relaxation measuring equipment at the Institute of Polymer Technology. Highly accurate and reproducible results were obtained from the "ideal curve" measurements taken with the equipment, which permits continuous measurements of residual force and instantaneous modulus. It was noted that stress relaxation, while not only dependent on thermoplastic type and/or formulation (as expected) but also depended on the measuring technique (e.g. the strain rate, continuous loading, interrupted loading etc.) which have significant effects on subsequent stress relaxation. Temperature and environment also affect the results. The effect of thermal treatment, lubrication of surfaces and interrupted loading were investigated. An attempt was made to relate the modulus enhancement factor "MEF" to Hysteresis. An attempt was also made to relate the change in "MEF" to the continuous structural re-organization in the material and finally to stress relaxation.The commercial significance of stress relaxation and "MEF" in the performance of seals and gaskets is also explored. Some of the material supplied by industry for this project was prepared by "dynamic vulcanization". Attempt has been made using peroxide cross-linking agent to prepare EPDM/PP blends by this technique to explore structure-property relationship. As expected, the cured samples out-performed the uncured samples. Long term stress relaxation measurement (up to 10,000 hours) revealed the low premanent set and modest stress relaxation associated with thermoplastic elastomers in general.
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Fu, Lin. « SYNTHESIS AND CHARACTERIZATION OF OLIGO(¿-ALANINE) GRAFTED STYRENEBUTADIENE RUBBER ». University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491521308494791.
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Quaiatti, Marcelo Antonio. « Utilização de elastomeros termoplasticos no segmento de adesivos sensiveis a pressão (PSA) ». [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266211.
Texte intégralRésumé :
Orientador: João Sinezio de Carvalho CamposDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Os elastômeros termoplásticos do tipo SBC são copolímeros em bloco de estireno que possuem uma alta tecnologia e que possibilitam um vasto campo de aplicações. Trata-se na verdade da união das vantagens da borracha natural e do plástico, e justamente pelas inúmeras vantagens que ele apresenta, sua atuação no mercado tem se tornado crescente, justificando grandes investimentos realizados para desenvolvimentos de mercado, dentre os quais podemos destacar o mercado de adesivos que engloba aplicações bastante diversificadas, como por exemplo fitas adesivas, adesivos para industrias de móveis, adesivos para fraldas descartáveis e higiênicos, etiquetas, etc. Neste trabalho apresenta-se a utilização destes elastômeros em formulações adesivas destinadas à aplicações em adesivos sensíveis à pressão (PSA) e tem por objetivo auxiliar as pesquisas e desenvolvimentos voltados para este segmento, uma vez' que os resultados abordados neste trabalho podem auxiliar no direcionamento correto de formulações adesivas juntamente com os respectivos processos produtivos, bem como eleger o tipo correto de matéria prima ou componente a ser utilizado, dependendo do tipo de aplicação final
Abstract: The SBC thermoplastic elastomers are styrene block copolymers and combine the advantages of Natural Rubber and Plastics. Not only have a high technology, but also allow a large variety of applications and due to the mentioned advantages, its market share has been growing and justifying strong investment to be developed, and adhesives can be highlighted as it conglomerates diversified applications, as for instance adhesives tapes, adhesives to forniture ind,ustries diapers, labels, etc. This study shows the thermoplastic elastomers in adhesives formulations with the main focus on pressure sensitive adhesives (PSA), and can help future research and developments over this segment, as the results can help to achieve the right choice of the formulations and the respective malilufacturing process, and also elect the correct type of raw material to be considered, always based on the final application
Mestrado
Ciencia e Tecnologia de Materiais
Mestre em Engenharia Química
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Chen, Ying. « PATTERNING ELASTOMER, THERMOPLASTICS AND SHAPE MEMORYMATERIAL BY UVO LITHOGRAPHY AND SOFT LITHOGRAPHY ». University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491264216402058.
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Allen, Michael H. Jr. « Imidazole-Containing Polymerized Ionic Liquids for Emerging Applications : From Gene Delivery to Thermoplastic Elastomers ». Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/49593.
Texte intégralRésumé :
Novel imidazole-containing polyelectrolytes based on poly(1-vinylimidazole) (poly(1VIM)) were functionalized with various hydroxyalkyl-substituents to investigate the influence of charge density and hydrogen bonding on nonviral DNA delivery. Copolymers with higher charge densities exhibited increased cytotoxicity, whereas increased hydroxyl concentrations remained nontoxic. DNA binding affinity increased with increased charge densities and increased hydroxyl content. Dynamic light scattering determined the copolymers which delivered DNA most effectively maintained an intermediate binding affinity between copolymer and DNA. Copolymers containing higher charge densities or hydroxyl concentrations bound DNA too tightly, preventing its release inside the cell. Copolymers with lower charge densities failed to protect the DNA from enzymatic degradation. Tuning hydrogen bonding concentration allowed for a less toxic and more effective alternative to conventional, highly charged polymers for the development of nonviral DNA delivery vehicles. The synthesis of amine-containing imidazolium copolymers functionalized with low concentrations of folic acid enabled the investigation of additional polymer modifications on nonviral gene delivery.
Functionalization of 1VIM with various hydroxyalkyl and alkyl groups and subsequent conventional free radical polymerization afforded a series of imidazolium-containing polyelectrolytes. Hydroxyl-containing homopolymers exhibited higher thermal stabilities and lower Tg's compared to the respective alkyl-analog. X-ray scattering demonstrated the polarity of the hydroxyl group facilitated solvation of the electrostatic interactions disrupting the
nanophase-separated morphology observed in the alkylated systems. Impedance spectroscopy determined hydroxyl-containing imidazolium homopolymers displayed higher ionic conductivities compared to the alkyl-containing analogs which was attributed to increased solvation of electrostatic interactions in the hydroxyl analogs.
Beyond functionalizing 1VIM monomers and homopolymers to tailor various properties, the synthesis of novel architectures in a controlled fashion remains difficult due to the radically unstable N-vinyl propagating radical. The regioisomer 4-vinylimidazole (4VIM) contains two resonance structures affording increased radical stability of the propagating radical. Nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) failed to control 4VIM homopolymerizations; however, reversible addition-fragmentation chain transfer (RAFT) demonstrated unprecedented control. Linear pseudo-first order kinetics were observed and successful chain extension with additional 4VIM suggested preservation of the trithiocarbonate functionality.
Effectively controlling the polymerization of 4VIM enabled the design of amphoteric block copolymers for emerging applications. The design of ABA triblock copolymers with 4VIM as a high Tg supporting outer block and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) as a low Tg, inner block, required the development of a new difunctional RAFT chain transfer agent (CTA). The difunctional CTA successfully mediated the synthesis of the ABA triblock copolymer, poly(4VIM-b-DEGMEMA-b-4VIM), which exhibited microphase separated morphologies. The amphoteric nature of the imidazole ring required substantially lower concentrations of outer block incorporation compared to traditional triblock copolymers to achieve similar mechanical properties and microphase separated morphologies.Ph. D.
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AllenJr, Michael Harry. « Imidazole-Containing Polymerized Ionic Liquids for Emerging Applications : From Gene Delivery to Thermoplastic Elastomers ». Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/49593.
Texte intégralRésumé :
Novel imidazole-containing polyelectrolytes based on poly(1-vinylimidazole) (poly(1VIM)) were functionalized with various hydroxyalkyl-substituents to investigate the influence of charge density and hydrogen bonding on nonviral DNA delivery. Copolymers with higher charge densities exhibited increased cytotoxicity, whereas increased hydroxyl concentrations remained nontoxic. DNA binding affinity increased with increased charge densities and increased hydroxyl content. Dynamic light scattering determined the copolymers which delivered DNA most effectively maintained an intermediate binding affinity between copolymer and DNA. Copolymers containing higher charge densities or hydroxyl concentrations bound DNA too tightly, preventing its release inside the cell. Copolymers with lower charge densities failed to protect the DNA from enzymatic degradation. Tuning hydrogen bonding concentration allowed for a less toxic and more effective alternative to conventional, highly charged polymers for the development of nonviral DNA delivery vehicles. The synthesis of amine-containing imidazolium copolymers functionalized with low concentrations of folic acid enabled the investigation of additional polymer modifications on nonviral gene delivery. Functionalization of 1VIM with various hydroxyalkyl and alkyl groups and subsequent conventional free radical polymerization afforded a series of imidazolium-containing polyelectrolytes. Hydroxyl-containing homopolymers exhibited higher thermal stabilities and lower Tg\'s compared to the respective alkyl-analog. X-ray scattering demonstrated the polarity of the hydroxyl group facilitated solvation of the electrostatic interactions disrupting the
nanophase-separated morphology observed in the alkylated systems. Impedance spectroscopy determined hydroxyl-containing imidazolium homopolymers displayed higher ionic conductivities compared to the alkyl-containing analogs which was attributed to increased solvation of electrostatic interactions in the hydroxyl analogs.
Beyond functionalizing 1VIM monomers and homopolymers to tailor various properties, the synthesis of novel architectures in a controlled fashion remains difficult due to the radically unstable N-vinyl propagating radical. The regioisomer 4-vinylimidazole (4VIM) contains two resonance structures affording increased radical stability of the propagating radical. Nitroxide-mediated polymerization (NMP) and atom transfer radical polymerization (ATRP) failed to control 4VIM homopolymerizations; however, reversible addition-fragmentation chain transfer (RAFT) demonstrated unprecedented control. Linear pseudo-first order kinetics were observed and successful chain extension with additional 4VIM suggested preservation of the trithiocarbonate functionality.
Effectively controlling the polymerization of 4VIM enabled the design of amphoteric block copolymers for emerging applications. The design of ABA triblock copolymers with 4VIM as a high Tg supporting outer block and di(ethylene glycol) methyl ether methacrylate (DEGMEMA) as a low Tg, inner block, required the development of a new difunctional RAFT chain transfer agent (CTA). The difunctional CTA successfully mediated the synthesis of the ABA triblock copolymer, poly(4VIM-b-DEGMEMA-b-4VIM), which exhibited microphase separated morphologies. The amphoteric nature of the imidazole ring required substantially lower concentrations of outer block incorporation compared to traditional triblock copolymers to achieve similar mechanical properties and microphase separated morphologies.
Ph. D.
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Liu, Jieruo. « Manufacturing of Polypropylene (PP)/ Ground Tire Rubber (GTR) Thermoplastic Elastomers Using Ultrasonically Aided Extrusion ». University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1375290253.
Texte intégral
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Ziegelmeier, Stefan. « Process analysis and material behavior of thermoplastic elastomers throughout the laser sintering processing chain ». Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/31532/.
Texte intégralRésumé :
Laser sintering (LS), an additive manufacturing (AM) technology, allows for the production of 3-dimensional parts by fusing together successive layers of polymer powder without the need for tooling. Its potential and applicability, however, is still constrained due to the limited repertoire of materials available and the lack of detail in understanding both the important process-material interactions and consequently the requirements for the development of new materials. Past research has mainly focused on polyamide 12 (PA12) as the standard material, hence most of the empirically grown or theoretical, often idealized, process models are based on this polymer. As a result, it was shown that there are strong interactions between the material and the process leading to an undesired deviation of part properties. Thermoplastic elastomers (TPEs) for LS have gained more and more popularity for the production of, for example flexible parts in the recent past but they are a group of polymers that is neither well studied nor understood regarding their use in LS. Therefore, this PhD investigation has focused on TPEs in order to reveal their process specifics throughout the processing chain in LS. As the properties of parts manufactured by LS are, amongst others, influenced by the packing and flow efficiencies of the powders, the bulk (static) and flow (dynamic) characteristics of the observed TPEs were examined on the powder scale as well as their effects on the process and parts. The resulting part properties were evaluated in terms of their tensile properties, surface roughness and density. In contrast to previous studies which have rarely taken into account the characteristics of the un-sintered particles, this work provided a novel approach quantifying and describing the interconnection between the powder characteristics as well as its performance and the part properties, thus providing valuable input on future material design. As mentioned before, for typical semi-crystalline thermoplastics such as PA12, different idealized process models describing the Pre-Process specifics exist, but they might not necessarily be applicable for thermoplastic elastomers with significantly different thermal characteristics. Consequently, the important interactions during processing of TPEs have been studied by high speed and high resolution thermography helping to indicate the most important material properties in combination with calorimetric analysis. The resulting understanding of crystallization and melting behaviour helped to derive a design of experiments revealing the possible range for the process management in terms of temperature control as well as energy input and the resulting part properties. Moreover, it is known that polymers used in LS change their intrinsic properties due to processing conditions that are close to the crystalline melting temperature. As a result, within this PhD investigation the ageing behaviour of TPEs was studied. Both the powder and the sintered parts were examined for chemical and physical ageing effects. The results showed that the materials observed could be used without refreshing throughout the applied ageing cycles, however, changes in the processing behaviour as well as in the parts’ mechanical properties were evident. These changes were due to the differing ageing states of the LS-powder showing an increase in the particle size affecting the bulk materials packing density. In the literature, modifications in the rheological properties due to thermal loads during LS are already known on basis of PA12. It was shown that they tend to experience an increase in molecular weight with increasing processing cycles. In this work it was found that TPEs exhibit the exact opposite trend in a slight decrease of molecular weight likely to reduce the mechanical strength of tensile specimens. By using novel process adapted methods in order to reveal vital interactions of TPE powders for LS, this thesis makes a significant contribution to an AM database. In addition, the comprehensive observation and applications of these methods over the whole processing chain helped expanding the understanding of important requirements for the development of new polymers for LS and builds a substantial basis for future work and quality assurance.
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Armstrong, Daniel Pierce. « Responsive Thermoplastic Elastomer Gels| Applications in Electroactive, Shape-Memory and Thermal Energy Management Materials ». Thesis, North Carolina State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10970021.
Texte intégralRésumé :
Thermoplastic elastomers are a class of rubbery polymeric materials that exhibit solidlike properties due to physically associating moieties. Block copolymers are often used as the network forming component of thermoplastic elastomers. Additionally, block copolymers can be modified with block selective solvents that contribute a specific functionality to the system; these solvent modified systems will be referred to throughout as thermoplastic elastomer gels. Thermoplastic elastomers and their gels have a long history of applications as specialty materials for passive systems where traditional rubbers cannot meet the required design criteria—often properties of softness, toughness and low hysteresis are of interest. Herein, we discuss the use of thermoplastic elastomer gels as active materials that respond to external stimuli to change their mechanical and thermal properties.
First, the text will introduce concepts of phase behavior and resultant physical behavior of block copolymers in the presence of a selective solvent. Included are specific details pertinent to materials used in experimental discussions presented in this work. Following this broad discussion, the introduction of a specific class of smart and responsive materials, known as dielectric elastomer actuators, is detailed in a survey of recent technological developments in the field.
The main body of the text describes multiple applications of thermoplastic elastomer gels. It begins with an entirely novel use of a semi-crystalline olefin block polymer gel as a dielectric elastomer actuator exhibiting programmable anisotropy and promising actuation behavior. The subsequent study uses specific control over the architecture of a polydimethylsiloxane elastomer to make ultra-soft films for exceptional dielectric elastomers. These so-called bottlebrush elastomers are formed from heavily grafted polymer backbones that reduce entanglements resulting in incredibly soft elastomers. As dielectric elastomers, these materials operate with no mechanical prestrain and achieve strains greater than 300% by area. This is followed by the use of a traditional ABA triblock copolymer (poly[styrene-bethylene- co-butylene-b-styrene]) with a crystallizing selective solvent to impart shape memory behavior. This is the first demonstration of a dielectric elastomer utilizing crystallization for electroactive strain fixation. Finally, we conclude with the discussion of thermoplastic copolyester based gels as form-stable phase change materials. These phase change gels have applications in passive thermal energy management systems and compete with existing commercial technologies.
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Lee, Bin. « Synthesis and characterization of high performance polytetrahydrofuran based polyurethane-urea and ionene elastomers ». Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/80277.
Texte intégralRésumé :
In this thesis, the effect of interphase bonding on the cohesiveness of domain structure was addressed. The interchain attractive forces between rigid segments and the phase separation between hard and soft segments have been improved by introducing either urea groups or ionic units. The urea linkages have the possibility of extensive hydrogen bonding while ionic units interact with each other by coulombic interactions, which provide even stronger interchain associations than the hydrogen bonding effects.
This thesis addressed the preparation and characterization of polytetrahydrofuran based segmented polyurethane-urea and ionene elastomers. The urea linkages were effectively introduced to the polyurethane elastomers through an unconventional route which was based on carbamate-isocyanate interactions. The carbamates were generated principally from isocyanate functional prepolymers and tertiary alcohols. The carbamates were rearranged thermally and/or catalytically to produce amines which were rapidly converted to ureas. The effects of varying the size of the rigid and flexible segments in polyurethane elastomers on physical behavior were investigated. The importance of hydrogen bonding interactions in promoting phase separation of hard and soft segments and the cohesiveness of hard segment domain structure was demonstrated. Living, difunctional polytetrahydrofuran dioxonium ions were prepared via triflic anhydride initiation. The direct coupling of these "living" polytetrahydrofuran dioxonium ions with a ditertiary amine was used to produce a novel segmented ionene elastomer. The ionenes thus synthesized displayed interesting solution behavior and could be molded, or cast to produce good physical properties. Photochromic as well as thermochromic phenomena were also noticed in these systems.Ph. D.
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Kavan, David. « Návrh technologie výroby dveřní průchodky z elastomeru ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241681.
Texte intégralRésumé :
The goal of this project is design of manufacturing technology for door elastomer grommet in a series of 400 000 units per year. As a proposed solution of manufacturing technology has been chosen multicomponent injection moulding. Appropriate thermoplastic elastomer and polyamide was chosen based on the knowledge gained in theoretical study of materials and technologies elaborated in the second part of the project. Moreover, the shape of the door grommnet was redesigned in accordance with the chosen technology. Working machine was chosen from manufacturer Arburg, model Allrounder 630S in a two-shot design, complemented by the index unit. A cost of production of one piece of the door grommet was determined in an economic evaluation. This cost was compared with current cost of production and new technology reducing manufacturing costs of one series by 25%.
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Lara, Garcia Alejandra. « Optimisation de l'adhésion interfaciale dans l'impression 3D multi-polymère pour améliorer les propriétés mécaniques des structures spatialement amorties ». Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0340.
Texte intégralRésumé :
Au cours de cette thèse, des solutions innovantes ont été étudiées afin d'améliorer l'adhésion interfaciale entre du PLA et un TPC lors du procédé d'impression par dépôt de fil fondu. Deux solutions ont été proposées : (i) l'utilisation d'additifs promoteurs d'adhésion et (ii) la synthèse de copolymères incorporant des blocs PLA comme éléments constitutifs. Dans le premier cas, différents additifs issus de la biomasse ont été incorporés individuellement dans la formulation du PTC. Des conditions de fabrication des filaments ont été optimisées pour obtenir des filaments sans défaut et de diamètre constant. L'évaluation de l'adhésion a été faite en utilisant une version modifiée du test T Peel de pelage. L'amidon 2-hydroxyéthyle a présenté la plus forte amélioration de l'adhésion avec de faibles variabilités des résultats. Elle prouve que les additifs peuvent être utilisés comme promoteurs d'adhésion dans des systèmes où l'adhésion est faible, par exemple entre des polymères incompatibles comme un PLA et un TPC. De plus, cette formulation n'a pas modifié le comportement d'amortissement et de filtrage des vibrations du TPC. Par conséquent, il a été possible d'imprimer à l'aide d'un FFF multi-polymère un prototype d'équipement de protection combinant un PLA et le TPC formulé, comme une genouillère. En parallèle, la deuxième solution testée consiste à synthétiser par extrusion réactive de nouveaux copolymères multiblocs via des réactions de transestérification entre le PLA et le PBT. Différentes expériences ont été réalisées pour optimiser les conditions de la réaction de transestérification. Bien que les résultats obtenus par FTIR, RMN 1H, DSC et DMA confirme la formation du copolymère en petites quantités, le matériau présentait une faible imprimabilité et une délamination des couches. Par conséquent, l'évaluation de l'adhésion n'a pas été réalisée avec ce matériauSolutions for improving multi-polymer FFF interlayer adhesion between PLA and a TPC were studied. Two solutions were proposed: (i) the use of adhesion promoter additives and (ii) the synthesis of copolymers incorporating PLA as building blocks. In the first one, different biosourced additives were individually incorporated into the formulation of the TPC. Filament fabrication conditions were optimized to achieve filaments with no defects and a constant diameter. Evaluation of adhesion was done using a modified version of the T-peel test. Only 2-hydroxyethyl starch presented the highest adhesion enhancement with low variabilities. Findings demonstrate the strategic potential of using modified biosourced additives to boost interfacial adhesion between two incompatible polymers. Furthermore, this formulation did not change the vibration-damping and filtering behavior of the TPC. Therefore, it was possible to print a prototype of protective equipment combining a PLA and the formulated TPC, such as a knee pad, using a multi-polymer FFF. The second solution refers to the synthesis through transesterification reactions of PLA and PBT new multiblock copolymers with a reactive extrusion process. Different experiments were done to optimize the transesterification's conditions. Although FTIR, 1H NMR, DSC and DMA results evidence the presence of the copolymer in small amounts, material had low printability presenting layer delamination. Therefore, the evaluation of adhesion was not achieved with this material
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VU, YEN THI. « SYNTHESIS AND CHARACTERIZATION OF ELASTOMER-BASED COMPOSITES AND POLYMER-IMMOBILIZED COLLOIDAL TRANSITION METAL NANOPARTICLES : CATALYTIC SELECTIVITY AND MORPHOLOGY ». University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1004541836.
Texte intégral