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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Fotosyntetická reakce autotrofních organismů v přítomnosti vybraného laktamu / Photosynthetic response of autotrophic organism in presence of selected lactam

NOVÁK, Jan January 2014 (has links)
The aim of this work is to evaluate the effect of caprolactam on the process of photosynthesis in model representatives of green algae (Scenedesmus quadricauda) through the dynamics of the release of oxygen into the solution of medium.
12

"Quat-Primer" Polymers as Dispersants for Nanoparticles

Beckmann, Ralph 14 December 2012 (has links)
Nanoparticles promise many interesting applications because of their exceptional chemical and physical properties. Therefore nanoparticles offer a pathway for the fabrication of new functional, smart materials. Since the primary particle strongly tends to strong agglomeration, and since the surface of nanoparticles is often not compatible with polymers, it is not possible to disperse single particles homogeneously in a polymer melt. Formations of agglomerates are responsible for strong differences in concentration of the nanoparticles in the material matrix and therefore impede a homogeneous property profile. Furthermore properties of compounds are not only determined by single components, but considerably by the interface between these single components. Hence, a strong chemical and physical adhesion between the constituents is required. Thus, surface modification of nanoparticles is a crucial issue. This work focuses on the control of the particle/polymer interface in composite materials which has a thickness of some nanometers. This interface regulates the compatibility of the surface of the nanoparticles and their environment. This interface is also the place where the transmission of energy between nanoparticle and polymer occurs. The interlayer of this boundary surface should be occupied with functional “primer”-macromolecules that provide at least two types of functional groups: one species of functional group should assure the bonding of the primer to the surface of the nanoparticle, and the second type enables the compatibilizing to the matrix, and when indicated also the covalent adhesion to the ambient polymer system. The macromolecular scaffold of the primer permits the selective adjustment of important interface properties as elasticity, durability and the surface energy of the particle – matrix interface. Within this thesis hyperbranched polyethylene (PEI) imine was used as starting platform for “Quat-Primer Polymers” bearing a multitude of functional moieties in form of primary, secondary and tertiary amino groups. Chapter 2 gives a literature – review on hyperbranched polymers – with focus on PEI, stabilization of colloids by polymers, as well as polymer – “nanocomposites”. In Chapter 3 the reaction of PEI with glycidyltrimethylammonium chloride will be described to obtain hyperbranched polymers that consist of (i) the hyperbranched PEI scaffold, (ii) primary, secondary and tertiary amino groups that can be used for further modification reactions with amino-reactive compounds, and (iii) ammonium moieties that can adsorb to negatively charged surfaces. It will be shown that these Quat-Primer polymers have the ability to stabilize several nanoparticles in water to form aqueous dispersions and that they are capable to partially deagglomerate nanoparticles leading to smaller diameters of the particles in the dispersion. Additionally the reaction of hyperbranched polyethylene imine with glycidol will be described displaying a possibility to change the reactivity of the functional groups and exhibiting that also the generated hydroxyl groups generated by the ring-opening reaction of epoxides with PEI react with epoxide rings to form ether linkages. In Chapter 4 the synthesis of several amino-reactive ATRP initiators will be described and two methods to graft PMMA arms to “Quat-Primer polymers” presented in the previous chapter including the “grafting from” and the “grafting to” technique. These synthesized Quat-Primer polymers bearing ammonium moieties, as well as PMMA arms can be used to fabricate PMMA nanocomposites with homogeneously distributed nanoparticles. The developed method allow for grafting monomers that can be used in ATRP polymerization, including acrylates, acrylonitriles and styrenes, to hyperbranched polyethylene imine. Chapter 5 will display pathways to graft caprolactam derivatives to hyperbranched polyethylene imine to generate Quat-Primer polymers bearing ammonium moieties, as well as caprolactam rings. These quat-primer polymers can be used for the fabrication of PA-6 nanocomposites by dispersing nanoparticles in presence of these Quat-Primer polymers and subsequent polymerization.
13

Potential Migration of ε-Caprolactam to Water and Wine As Affected by Transportation and Storage

Ianneo, Joseph C 01 March 2009 (has links) (PDF)
Abstract: Under normal sealing and storage conditions, Nylon-6, poly-caprolactam-based plastic laminates may release impurities to packaged foods and liquids and the application of heat for cooking often increases the rate of migration. Epsilon-caprolactam is one of the main contaminates found to migrate from a Nylon-6 poly-caprolactam plastic film. The objectives of this study were to determine the effects of solvent, transportation and storage time on the migration of ε-caprolactam from a Nylon-6-based lidding material into water or a white wine substitute (12% ethanol). Polypropylene plastic cups were filled, sealed, packaged, stacked and exposed to a simulated 3-day cross-country shipment. Cups were sampled with or without simulated shipment after 0, 7, 14 and 28 days at 20.6°C. Epsilon-caprolactam was determined using a GC equipped with FID and a Restek Rtx 1301 megabore column. Results of the study indicated migration of ε-caprolactam into containers at the time of sealing with significantly higher levels (4.42 ppm average) occurring in cups containing 12% ethanol vs. water (0.01 ppm average). After the cups were sealed, neither simulated cross-country shipment nor storage increased levels of ε-caprolactam in either solvent. The results indicate that wine sealed in packages lined with Nylon-6-based plastic could contain significant amounts of ε-caprolactam. However, it is not understood how the alcohol, whether as liquid or vapor, interacted with the lidding material to increase migration at the time of sealing. No delamination of the polypropylene layer in the lidding material was observed after sealing. Future research needs to be conducted to study the effects of alcohol, alcohol vapor, sealing time and temperature on ε-caprolactam migration.
14

Enhancement of wood properties with EPSILON-Caprolactam, and development of an apparatus for continuous monitoring water vapor sorption and desorption and its resultant wood dimensional changes

Milsted, David 06 August 2021 (has links)
Lack of dimensional stability and susceptibility to the action of xylophagous organisms make wood a challenging material to work with. E-Caprolactam is a water-soluble cyclic amide chemical with low mammalian toxicity, that can be used as a bulking agent to improve the dimensional stability of wood and offers protection against subterranean termites and several wood degradant fungi. E-Caprolactam delivers a similar level of dimensional stability as that provided by PEG-1000, a chemical extensively studied in the past decades and a standard dimensional stabilizer agent for wood. Regarding wood protection, E-Caprolactam exhibits efficacy against wood decay fungi and termites at very low levels compared to PEG-1000. If water leaching can be inhibited for this product, e-Caprolactam can be considered as a strong candidate for the wood decking industry. In addition to the evaluation of E-Caprolactam for wood dimensional stabilization and preservation this dissertation covers the development of an apparatus developed to automate wood sorption and desorption studies, and their influence in the wood dimensional behavior. Product design techniques and prototyping studies were conducted, and calibration procedures were made. This apparatus is still in development, but it shows potential for increasing the accuracy of shrinking and swelling measurements and efficiency for dimensional stabilization studies.
15

Polyamide 6/silica hybrid materials by a coupled polymerization reaction

Kaßner, Lysann, Nagel, Kevin, Grützner, R.-E., Korb, Marcus, Rüffer, Tobias, Lang, Heinrich, Spange, Stefan 15 February 2016 (has links) (PDF)
Polyamide 6/SiO2 hybrid materials were produced by a coupled polymerization reaction of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)4), 6-aminocaproic acid (ε-ACA) and ε-caprolactam (ε-CL) within one process. Si(ε-CL)4 together with ε-ACA has been found suitable as a precursor monomer for the silica and PA6 components. The accurate adjustment of the molar ratio of both components, as well as the combination of the overall process for producing the polyamide 6/SiO2 hybrid material with the hydrolytic ring opening polymerization of ε-caprolactam is of great importance to achieve homogeneous products with a low extractable content. Water in comparison with ε-ACA has been found unsuitable as an oxygen source to produce uniformly distributed silica. The procedure was carried out in a commercial laboratory autoclave at 8 bar initial pressure. The molecular structure and morphology of the hybrid materials have been investigated by solid state 29Si and 13C NMR spectroscopy, DSC and FTIR spectroscopy and electron microscopy measurements. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
16

Polyamide 6/silica hybrid materials by a coupled polymerization reaction

Kaßner, Lysann, Nagel, Kevin, Grützner, R.-E., Korb, Marcus, Rüffer, Tobias, Lang, Heinrich, Spange, Stefan 15 February 2016 (has links)
Polyamide 6/SiO2 hybrid materials were produced by a coupled polymerization reaction of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one) (Si(ε-CL)4), 6-aminocaproic acid (ε-ACA) and ε-caprolactam (ε-CL) within one process. Si(ε-CL)4 together with ε-ACA has been found suitable as a precursor monomer for the silica and PA6 components. The accurate adjustment of the molar ratio of both components, as well as the combination of the overall process for producing the polyamide 6/SiO2 hybrid material with the hydrolytic ring opening polymerization of ε-caprolactam is of great importance to achieve homogeneous products with a low extractable content. Water in comparison with ε-ACA has been found unsuitable as an oxygen source to produce uniformly distributed silica. The procedure was carried out in a commercial laboratory autoclave at 8 bar initial pressure. The molecular structure and morphology of the hybrid materials have been investigated by solid state 29Si and 13C NMR spectroscopy, DSC and FTIR spectroscopy and electron microscopy measurements. / Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
17

Synthesis of functionalized polyamide 6 by anionic ring-opening polymerization / Synthèse de polyamide 6 fonctionnalisés par polymérisation anionique par ouverture de cycle

Tunc, Deniz 30 October 2014 (has links)
Les études présentées dans le cadre de cette thèse visent à copolymériser l'ԑ-caprolactame (CL) avec différents dérivés de l'α-amino-ԑ-caprolactame (qui possèdent une amine primaire fonctionnalisable) par polymérisation anionique par ouverture de cycle. En utilisant cette stratégie, nous décrivons; (i) la préparation de polyamides 6 fluorés thermiquement plus stables, et ayant une surface hydrophobe; (ii) la synthèse de polyamides 6 portant des groupes pendants cinnamoyl thermo et photosensibles. Une réticulation réversible est observée ainsi que l'amélioration des propriétés thermo-mécaniques; (iii) la copolymérisation anionique par ouverture de cycle de CL avec un bis-monomère issu de l'α-amino-ԑ-caprolactame comme contrôle de la réticulation du polyamide 6. Enfin, dans le cadre de notre intérêt continu pour la chimie du polyamide 6, nous avons mis en évidence la possible combinaison de la polymérisation anionique par ouverture de cycle de CL avec la polycondensation en chaîne de l'éthyl-4-butylaminobenzoate pour obtenir en une étape un polyamide aliphatique/aromatique / The studies presented in this thesis aim to copolymerize ԑ-caprolactam (CL) with different derivatives of α-amino-ԑ-caprolactam (which has a functionalizable primary amine) via anionic ring-opening polymerization. By using this strategy, we describe: (i) the synthesis of thermally more stable fluorinated polyamide 6 having a hydrophobic surface; (ii) the synthesis of polyamides 6 bearing pendant cinnamoyl groups, which are thermo-and photoresponsivechromophore groups, and demonstrating their reversible crosslinking as well as improved thermo-mechanical properties; (iii) the copolymerization ofCL with a crosslinker (N-functionalized α-amino-ԑ-caprolactambis-monomers) into crosslinked polyamides 6.As part of our continuing interest in polyamide 6 chemistry, we developed the combination of anionic ring-opening polymerization of CL and chain-growth condensation polymerization of ethyl 4-butylaminobenzoate in order to obtain aliphatic/aromatic polyamides in one-step.
18

Stickstoffhaltige Monomere zur Herstellung von Hybridmaterialien

Kaßner, Lysann 24 June 2015 (has links) (PDF)
In der vorliegenden Arbeit wurden stickstoffhaltige Monomere ausgehend von aromatischen Aminen oder Lactamen durch Umsetzung mit Chlorsilanen synthetisiert. Die so erhaltenen Derivate wurden mit Hilfe spektroskopischer und thermischer Analysenmethoden umfassend charakterisiert. Auf Basis der stickstoffhaltigen Monomere wurden über unterschiedliche Synthesestrategien organisch-anorganische, nanostrukturierte Hybridmaterialien hergestellt. Durch die thermisch induzierte Zwillingspolymerisation der Monomere 2,2‘-Spirobi[3,4-dihydro-1H-1,3,2-benzodiazasilin] und 1,1’,4,4‘-Tetrahydro-2,2‘-spirobi[benzo[d][1,3,2]-oxazasilin] gelang es, Hybridmaterialien bestehend aus Polyanilin-Formaldehyd-Harzen und Polysilazanen bzw. Siliciumdioxid unter Variation der Reaktionstemperatur herzustellen. Die Untersuchung der entstandenen Materialien erfolgte mittels spektroskopischer Methoden. Die Lactam-Monomere wurden durch die Zugabe von Aminocarbonsäuren zu Polyamid 6/SiO2- bzw. Polysiloxan-Kompositen umgesetzt. Hier stand die Ermittlung der molekularen Struktur, wie auch die Bestimmung des thermischen Verhaltens und der Homogenität der Materialien im Vordergrund. Es konnte gezeigt werden, dass die Synthese der thermoplastischen Kompositmaterialien auch in vergrößertem Maßstab reproduzierbar ist und die Produkte zudem zu Folien extrudierbar sind. / In the present work nitrogen-containing monomers have been synthesized by reactions of silicon tetrachloride with amines or lactames and were characterized by different spectroscopic and thermal analysis methods. The twin monomers 2,2‘-spirobi[3,4-dihydro-1H-1,3,2-benzodiazasiline] and 1,1’,4,4‘-tetrahydro-2,2‘-spirobi[benzo[d][1,3,2]¬oxazasiline] can be converted to hybrid materials containing polyaniline-formaldehyde resins and polysilazane or SiO2 by thermal induced twin polymerization under variation of the reaction temperature. The obtained nano composites were investigated by spectroscopic methods and electron microscopy. The lactam containing monomers were polymerized to polyamide 6/SiO2-composites by addition of aminocarbonic acids and -caprolactam. The analysis of the molecular structure as well as the investigation of the thermal behavior and the homogeneity of materials was emphasized. It could be shown, that the synthesis can be performed reproducible. Furthermore, it is possible to extrude the thermoplastic composite materials to films.
19

Stickstoffhaltige Monomere zur Herstellung von Hybridmaterialien

Kaßner, Lysann 05 June 2015 (has links)
In der vorliegenden Arbeit wurden stickstoffhaltige Monomere ausgehend von aromatischen Aminen oder Lactamen durch Umsetzung mit Chlorsilanen synthetisiert. Die so erhaltenen Derivate wurden mit Hilfe spektroskopischer und thermischer Analysenmethoden umfassend charakterisiert. Auf Basis der stickstoffhaltigen Monomere wurden über unterschiedliche Synthesestrategien organisch-anorganische, nanostrukturierte Hybridmaterialien hergestellt. Durch die thermisch induzierte Zwillingspolymerisation der Monomere 2,2‘-Spirobi[3,4-dihydro-1H-1,3,2-benzodiazasilin] und 1,1’,4,4‘-Tetrahydro-2,2‘-spirobi[benzo[d][1,3,2]-oxazasilin] gelang es, Hybridmaterialien bestehend aus Polyanilin-Formaldehyd-Harzen und Polysilazanen bzw. Siliciumdioxid unter Variation der Reaktionstemperatur herzustellen. Die Untersuchung der entstandenen Materialien erfolgte mittels spektroskopischer Methoden. Die Lactam-Monomere wurden durch die Zugabe von Aminocarbonsäuren zu Polyamid 6/SiO2- bzw. Polysiloxan-Kompositen umgesetzt. Hier stand die Ermittlung der molekularen Struktur, wie auch die Bestimmung des thermischen Verhaltens und der Homogenität der Materialien im Vordergrund. Es konnte gezeigt werden, dass die Synthese der thermoplastischen Kompositmaterialien auch in vergrößertem Maßstab reproduzierbar ist und die Produkte zudem zu Folien extrudierbar sind. / In the present work nitrogen-containing monomers have been synthesized by reactions of silicon tetrachloride with amines or lactames and were characterized by different spectroscopic and thermal analysis methods. The twin monomers 2,2‘-spirobi[3,4-dihydro-1H-1,3,2-benzodiazasiline] and 1,1’,4,4‘-tetrahydro-2,2‘-spirobi[benzo[d][1,3,2]¬oxazasiline] can be converted to hybrid materials containing polyaniline-formaldehyde resins and polysilazane or SiO2 by thermal induced twin polymerization under variation of the reaction temperature. The obtained nano composites were investigated by spectroscopic methods and electron microscopy. The lactam containing monomers were polymerized to polyamide 6/SiO2-composites by addition of aminocarbonic acids and -caprolactam. The analysis of the molecular structure as well as the investigation of the thermal behavior and the homogeneity of materials was emphasized. It could be shown, that the synthesis can be performed reproducible. Furthermore, it is possible to extrude the thermoplastic composite materials to films.
20

Elaboration et mise en forme de matériaux polymères à base de l’ε-caprolactame (PA6) par le procédé de rotomoulage réactif / Synthesis and processing of polymeric materials based on the ε-caprolactam (PA6) by reactive rotational molding process

Barhoumi, Najoua 09 December 2013 (has links)
Cette thèse porte sur le rotomoulage réactif de polyamide 6. Ce procédé a la particularité de présenter des cycles thermiques relativement réduit et de fabriquer des polymères sur mesure contrairement à son homologue conventionnelle. La voie envisagée pour la synthèse in situ de PA6 est la polymérisation anionique de l’ε-caprolactame par ouverture de cycle. Le Caprolactamate de sodium et le bromure de caprolactame-magnésium ont été utilisés comme catalyseurs, et l’hexaméthylène dicarbamoyl dicaprolactame a été employé comme activateur. L’étude rhéocinétique de deux systèmes réactifs lactames qui ont été utilisé à différentes compositions et températures a permis de déterminer une formulation appropriée aux exigences du procédé (faible viscosité initiale du système réactif, temps de polymérisation court...). La simultanéité des phénomènes de polymérisation et de cristallisation aux faibles températures à été observé à l’aide des résultats du suivi cinétique par DSC. La mise en forme par la technique de rotomoulage a été réalisée sur une installation pilote de rotomoulage associée à un système d’acquisition de température par télémesure radio. La comparaison des propriétés des articles en PA 6 obtenus par voie réactive par rapport a ceux obtenus par voie fondue, a montré un gain au niveau du temps de cycle et une amélioration des propriétés mécaniques du matériau notamment dans le domaine des faibles déformations. Le rotomoulage de la bicouche PA6/PE-GMA a été ainsi étudié, le contrôle des mécanismes réactionnels mis en jeu à l’interface par rhéologie, durant la formation de la couche de polymère PA6 par voie anionique sur une couche de PE-GMA a été effectué dans un rhéomètre, une bonne adhésion à l’interface a été observé. La faisabilité d’élaboration de nanocomposite PA 6/argile par le procède de rotomoulage réactif a été testé, les caractérisations physico-chimiques et les observations morphologiques ont été étudiés afin d’évaluer l’état de dispersion et la nature des interactions. Durant cette étude, nous avons mesurés la faisabilité de l’intercalation et le gonflement de l’argile dans le monomère ε- caprolactame et estimer la possibilité d’avoir une morphologie exfolié des nanocomposites élaborés par le procédé de rotomoulage réactif. / A reactive rotational molding (RRM) process was developed to obtain a PA6 by activated anionic ring-opening polymerization of epsilon-caprolactam (APA6). Sodium caprolactamate (C10) and caprolactam magnesium bromide (C1) were employed as catalysts, and difunctional hexamethylene-1,6-dicarbamoylcaprolactam (C20) was used as an activator. The kinetics of the anionic polymerization of ε-caprolactam into polyamide 6 was monitored through dynamic rheology and differential scanning calorimetry measurements. The effect of the processing parameters, such as the polymerization temperature, different catalyst/activator combinations and concentrations, on the kinetics of polymerization is discussed. A temperature of 150°C was demonstrated to be the most appropriate. It was also found that crystallization may occur during PA6 polymerization and that the combination C1/C20 was well suited as it permitted a suitable induction time. Isoviscosity curves were drawn in order to determine the available processing window for RRM. The properties of the obtained APA6 were compared with those of a conventionally rotomolded PA6. Results pointed at lower cycle times and increased tensile properties at weak deformation. Additionally, rotational molding of the bilayer PA6/PE-GMA has been studied, the control of the reactions mechanisms involved in the interface by rheology , during formation of the anionically PA6 polymer layer on a PE- GMA layer was carried out in a rheometer , a good adhesion at the interface was observed. The feasibility of developing nanocomposite PA 6/clay by reactive rotational molding process has been tested; the physico-chemical characterization and morphological observations were studied to assess the state of dispersion and the nature of interactions. During this study, we measured the feasibility of intercalation and swelling the clay in the ε-caprolactam monomer and estimate the possibility of having morphology of exfoliated nanocomposites prepared by reactive rotational molding process.

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