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Morphological properties of poly (ethylene terephthalate) (PET) nanocomposites in relation to fracture toughness.Pendse, Siddhi 08 1900 (has links)
The effect of incorporation of montmorillonite layered silicate (MLS) on poly (ethylene terephthalate) (PET) matrix was investigated. MLS was added in varying concentration of 1 to 5 weight percent in the PET matrix. DSC and polarized optical microscopy were used to determine the crystallization effects of MLS addition. Non isothermal crystallization kinetics showed that the melting temperature and crystallization temperature decrease as the MLS percent increases. This delayed crystallization along with the irregular spherulitic shape indicates hindered crystallization in the presence of MLS platelets. The influence of this morphology was related with the fracture toughness of PET nanocomposites using essential work of fracture coupled with the infra red (IR) thermography. Both the essential as well as non essential work of fracture decreased on addition of MLS with nanocomposite showing reduced toughness.
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Prevalence of severe acute respiratory syndrome Coronavirus 2 antibodies among market and city bus depot workers in Lima, PeruTovar, Marco, Peinado, Jesús, Palomino, Santiago, Llanos, Fernando, Ramírez, Claudio, Valderrama, Gisella, Calderón, Roger I., Williams, Roger B., Velásquez, Gustavo E., Mitnick, Carole D., Franke, Molly F., Lecca, Leonid 29 January 2022 (has links)
We report severe acute respiratory syndrome coronavirus 2 antibody positivity among market and city bus depot workers in Lima, Peru. Among 1285 vendors from 8 markets, prevalence ranged from 27% to 73%. Among 488 workers from 3 city bus depots, prevalence ranged from 11% to 47%. Self-reported symptoms were infrequent. / National Institute of Allergy and Infectious Diseases / Revisión por pares
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A methodology for evaluating multiple mechanical properties of prototype microfibrillated cellulose/poly(lactic acid) film compositesDing, Jie 08 September 2011 (has links)
The context of this thesis is a research project focused on the investigation of a renewable biopolymer-poly(lactic acid) (PLA) as a potential replacement of petroleum-based polymers in advanced nanocomposites reinforced with Microfibrillated cellulose (MFC). MFC is extracted from wood, which is a renewable, sustainable, carbon neutral and recyclable material. This advanced MFC-PLA bio-
based composite material is expected to allow for the substitution of petroleum-based plastics in various markets and applications.
The specific objectives of the thesis are: 1) to describe the morphological characterization of MFC used for prototype MFC-PLA composites, and 2) to determine the mechanical properties of the prototype MFC-PLA nanocomposites formulation generated in form of thin transparent films.
In order to meet this objective it was necessary to: 2.1) develop a methodology for optical strain measurement in transparent thin films; and 2.2) develop an effective methodology for obtaining multiple mechanical properties from small number of specimens of prototype materials subjected to tensile tests.
Two types of MFC, one obtained by courtesy of University of Maine and the other purchased from Innventia AB company, were investigated under a field emission scanning electron microscopy (FESEM). The micrographs obtained from FESEM showed that both types of MFC were of complex hierarchical structures, which did not allow qualitative characterization of the morphological features in terms of particulate composites nor cellular solids.
Since prototype formulations of MFC-PLA composites were generated in small amounts (typically one Petri dish) in a form of thin transparent films, there was a need for quick and efficient assessment of their key mechanical properties that would provide feedback and guide further prototyping work. An optical measurement method based on digital image correlation (DIC) principle was developed to measure the deformation and strains of the tensile film samples. In our study, the accuracy and precision of the measurement of deformation were ±1.5 µm and 0.4 µm respectively. The corresponding accuracy and precision in terms of strains were ±30 µstrain and 75 µstrain respectively. This method can be successfully used to determine the critical mechanical properties, such as elastic modulus, toughness and Poisson's ratio, of transparent thin films by a single tensile test, all of which require precise strain measurement.
In addition, this optical measurement method makes it possible to significantly simplify the testing for measuring essential work of fracture (EWF), an important material property of thin transparent films. In traditional method, measurement of EWF requires large amount of notched specimens. However, our study showed that only a small amount of notched specimens were needed to measure the EWF of a material. This method could not be successfully used to determine EWF from un-notched tensile specimens. / Graduation date: 2012 / Folder labeled "UMaine MFC aerogel" contains SEM micrographs of MFC from University of Maine (referred as type A MFC in the thesis). Two pieces of leaf-like flakes at different locations were cut by Focused Ion Beam (FIB) in order to observe the internal structure of the flakes.
Folder "FIB_01 ": a series of SEM micrographs of FIB-cut flake at different magnification levels.
Folder "FIB_02 ": another series of SEM micrographs of FIB-cut flake at various magnification levels.
Folder labeled "Swedish MFC aerogel" contains SEM micrographs of MFC from Innventia AB company, Sweden (referred as type B MFC in the thesis). There is a series of SEM micrographs of type B MFC aerogel at various magnification levels in this folder.
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Métodos de mecânica da fratura aplicados a polietileno de média densidade destinado à extrusão de tubos. / Fracture mechanics methods applied to medium density polyethylene designed for extrusion of pipes.Peres, Fabiano Moreno 25 June 2009 (has links)
O polietileno de média densidade (PEMD) é um polímero termoplástico parcialmente cristalino, cujo uso tem crescido bastante em aplicações de engenharia, como em tubos plásticos para sistemas de distribuição de água e de gás. Sob carga constante, entretanto, este material pode eventualmente apresentar fratura por fluência, por meio de um mecanismo de crescimento lento de trincas, provocando acentuadas perdas por vazamento nos sistemas. Os métodos atuais empregados pela indústria para estimar a durabilidade dos tubos são caros, demorados, pouco práticos e imprecisos. Busca-se o desenvolvimento de técnicas mais eficientes, sendo que os métodos da mecânica da fratura são promissores no sentido de descrever a etapa de propagação da trinca. Ensaios de mecânica da fratura, entretanto, requerem a introdução de pré-trincas nos corpos de prova. Sabe-se que as técnicas artificiais de introdução de pré-trincas causam algum tipo de dano na matriz polimérica, que pode ou não afetar os resultados dos ensaios, dependendo dos eventos que ocorrerem após o carregamento inicial. A principal propriedade requerida de um método de introdução de pré-trinca, portanto, é reprodutibilidade. Neste estudo foram aplicados três importantes métodos de mecânica da fratura ao PEMD e investigados os efeitos de diferentes técnicas de introdução de pré-trincas sobre os resultados dos ensaios e sobre as estruturas de deformação na matriz do material na ponta da trinca. Os ensaios de tenacidade à fratura no estado plano de deformação - KIc - foram realizados em condições criogênicas, em vista do comportamento dúctil do material à temperatura ambiente, sendo que a estratégia mostrou-se satisfatória. Os resultados dos ensaios de Integral-J sugerem que o método pode não ser aplicável ao PEMD, devido ao peculiar mecanismo de fratura do material. O método do trabalho essencial de fratura - EWF - se aplica bem ao PEMD. Os resultados dos ensaios de KIc e EWF demonstraram que diferentes técnicas de introdução de pré-trincas provocam diferentes estruturas de deformação no material na ponta da trinca e afetam os resultados de ensaios de fratura no PEMD. Os resultados de EWF demonstraram ainda que o processamento também afeta as propriedades de fratura do material. É proposta uma nova técnica para a introdução de pré-trincas, com características mais naturais, a qual requer estudos complementares para seu aperfeiçoamento. / Medium density polyethylene (MDPE) is a semicrystalline thermoplastic polymer that has been increasingly used in engineering applications, as plastic pipes for water and gas distribution systems. Under constant load, however, this material may occasionally present creep failure, by means of a mechanism of slow crack growth, leading to leakage losses in the systems. Current methods used by industry to estimate durability of pipes are expensive, time consuming, non practical and inaccurate. The development of more efficient methods is a common target and fracture mechanics methods are promising in describing the crack propagation stage. Fracture mechanics testing methods, however, require the introduction of pre-cracks into the specimens. It is known that artificial methods of introducing pre-cracks produce some damage on the polymeric matrix, which may or not affect the results of tests, depending on the events that occur after the initial loading. Main propriety required of a pre-crack introducing method, therefore, is reproducibility. In this study three important fracture mechanics methods were applied to MDPE and the effects of different methods of pre-cracking over test results and over deformation structures of material matrix at the crack tip were investigated. Plane-strain fracture toughness - KIc tests were performed under cryogenic conditions, in view of the ductile behavior of material at room temperature and this strategy was well succeed. Results of Integral-J tests suggest that this method may not be applicable to MDPE, due to the peculiar fracture mechanism of the material. The essential work of fracture method EWF is well suited to study MDPE. The results of KIc and EWF tests showed that different pre-cracking methods cause different deformation structures in the material at the crack tip and affect the fracture tests with MDPE. EWF results showed also that the processing affect the fracture properties of materials too. It is proposed a new method for introducing pre-cracks, with more natural characteristics that requires complementary studies for its improving.
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The Essential Work of Fracture Method Applied to Mode II Interlaminar Fracture in Fiber Reinforced PolymersMcKinney, Scott D Unknown Date
No description available.
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Métodos de mecânica da fratura aplicados a polietileno de média densidade destinado à extrusão de tubos. / Fracture mechanics methods applied to medium density polyethylene designed for extrusion of pipes.Fabiano Moreno Peres 25 June 2009 (has links)
O polietileno de média densidade (PEMD) é um polímero termoplástico parcialmente cristalino, cujo uso tem crescido bastante em aplicações de engenharia, como em tubos plásticos para sistemas de distribuição de água e de gás. Sob carga constante, entretanto, este material pode eventualmente apresentar fratura por fluência, por meio de um mecanismo de crescimento lento de trincas, provocando acentuadas perdas por vazamento nos sistemas. Os métodos atuais empregados pela indústria para estimar a durabilidade dos tubos são caros, demorados, pouco práticos e imprecisos. Busca-se o desenvolvimento de técnicas mais eficientes, sendo que os métodos da mecânica da fratura são promissores no sentido de descrever a etapa de propagação da trinca. Ensaios de mecânica da fratura, entretanto, requerem a introdução de pré-trincas nos corpos de prova. Sabe-se que as técnicas artificiais de introdução de pré-trincas causam algum tipo de dano na matriz polimérica, que pode ou não afetar os resultados dos ensaios, dependendo dos eventos que ocorrerem após o carregamento inicial. A principal propriedade requerida de um método de introdução de pré-trinca, portanto, é reprodutibilidade. Neste estudo foram aplicados três importantes métodos de mecânica da fratura ao PEMD e investigados os efeitos de diferentes técnicas de introdução de pré-trincas sobre os resultados dos ensaios e sobre as estruturas de deformação na matriz do material na ponta da trinca. Os ensaios de tenacidade à fratura no estado plano de deformação - KIc - foram realizados em condições criogênicas, em vista do comportamento dúctil do material à temperatura ambiente, sendo que a estratégia mostrou-se satisfatória. Os resultados dos ensaios de Integral-J sugerem que o método pode não ser aplicável ao PEMD, devido ao peculiar mecanismo de fratura do material. O método do trabalho essencial de fratura - EWF - se aplica bem ao PEMD. Os resultados dos ensaios de KIc e EWF demonstraram que diferentes técnicas de introdução de pré-trincas provocam diferentes estruturas de deformação no material na ponta da trinca e afetam os resultados de ensaios de fratura no PEMD. Os resultados de EWF demonstraram ainda que o processamento também afeta as propriedades de fratura do material. É proposta uma nova técnica para a introdução de pré-trincas, com características mais naturais, a qual requer estudos complementares para seu aperfeiçoamento. / Medium density polyethylene (MDPE) is a semicrystalline thermoplastic polymer that has been increasingly used in engineering applications, as plastic pipes for water and gas distribution systems. Under constant load, however, this material may occasionally present creep failure, by means of a mechanism of slow crack growth, leading to leakage losses in the systems. Current methods used by industry to estimate durability of pipes are expensive, time consuming, non practical and inaccurate. The development of more efficient methods is a common target and fracture mechanics methods are promising in describing the crack propagation stage. Fracture mechanics testing methods, however, require the introduction of pre-cracks into the specimens. It is known that artificial methods of introducing pre-cracks produce some damage on the polymeric matrix, which may or not affect the results of tests, depending on the events that occur after the initial loading. Main propriety required of a pre-crack introducing method, therefore, is reproducibility. In this study three important fracture mechanics methods were applied to MDPE and the effects of different methods of pre-cracking over test results and over deformation structures of material matrix at the crack tip were investigated. Plane-strain fracture toughness - KIc tests were performed under cryogenic conditions, in view of the ductile behavior of material at room temperature and this strategy was well succeed. Results of Integral-J tests suggest that this method may not be applicable to MDPE, due to the peculiar fracture mechanism of the material. The essential work of fracture method EWF is well suited to study MDPE. The results of KIc and EWF tests showed that different pre-cracking methods cause different deformation structures in the material at the crack tip and affect the fracture tests with MDPE. EWF results showed also that the processing affect the fracture properties of materials too. It is proposed a new method for introducing pre-cracks, with more natural characteristics that requires complementary studies for its improving.
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Avaliação do mecanismo de fratura dos compósitos de polipropileno/talco através do método EWF (Trabalho Essencial de Fratura) / Fracture mechanism evaluation of polypropylene/talco composites by the EWF method (Essential Work of Fracture)Campos, Diego Adalberto Teles 29 February 2016 (has links)
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The use of talco as a dispersive phase in thermoplastic composites has strategic
and economic functions in the polymer industry, propitiating advances in properties
such as rigidity, thermal and dimensional stability, amongst others; seeing that this
mineral filler presents a lamellar geometry. The objective of the present dissertation was
to evaluate the effect of varied amounts of talco on the fracture mechanisms of
polypropylene/talco composites applying the EWF method (Essential Work of
Fracture). Composites of 5, 10 & 15 wt% of talco were prepared by extrusion then
injected into mold plates, subsequently, the specimens were cut in DDENT geometry
(deeply double edge-notched type). Six varied ligament lengths of 6 to 16mm were
prepared for evaluation. The data used to determine the EWF parameters were obtained
by unidirectional tensile tests. The results show that the specific essential work fracture
(we) of the composites was considerably lower than that of the pure polypropylene
specimen, which indicates that talco produced modifications in the composite’s
structure, reducing the capacity to absorb energy. An increment in the specific nonessential
work fracture (βwp) was observed with increasing amounts of talco, due to
structural alterations which raise the amount of energy needed for plastic zone
deformation. Based on the results of this study, the EWF method proves efficient in the
fracture tenacity evaluation of these composites. / O uso do talco como fase dispersa em compósitos de matriz polimérica
termoplástica tem funções estratégicas e econômicas na indústria de polímeros,
propiciando melhoria nas propriedades como: rigidez, estabilidade térmica e
dimensional, dentre outras propriedades, visto que este mineral apresenta geometria
lamelar. Diante disto o objetivo do presente trabalho foi avaliar o efeito de diferentes
teores de talco sobre os mecanismos de fratura dos compósitos de polipropileno/talco
aplicando o método Trabalho Essencial de Fratura (EWF). Neste estudo, compósitos
contendo 5, 10 e 20 % (em peso) de talco foram preparados através do processo de
extrusão, em seguida os compósitos foram submetidos ao processo de injeção para
obtenção de placas das quais foram retiradas os corpos de prova do tipo DENT
(entalhados duplamente nas faces opostas). O duplo entalhe foi inserido nos corpos de
prova com objetivo de produzir diferentes comprimentos de ligamentos, na faixa de 6 a
16 mm. Os dados usados para determinar os parâmetros do método EWF foram obtidos
do ensaio de tração unidirecional. Os resultados mostraram que o trabalho essencial
específico de fratura, we, dos compósitos apresentaram uma redução em relação ao PP
puro, indicando que o talco produziu modificações na estrutura do compósito que
acarretaram a diminuição da capacidade de absorção de energia. Houve um incremento
do trabalho não-essencial específico de fratura, βwp, com o aumento do teor de talco,
devido às alterações estruturais terem induzido ao aumento da energia necessária para a
deformar a zona plástica. Os resultados obtidos permitiram concluir que o método EWF
se mostrou eficiente para avaliar a tenacidade à fratura destes compósitos.
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Development of High Toughness Bioactive Composites Using Electrospinning TechniquesBaji, Avinash 17 December 2008 (has links)
No description available.
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Aplicación del método del trabajo esencial de fractura al estudio de films de polipropileno y de copolímeros propileno-etileno en bloquesFerrer Balas, Dídac 06 July 2001 (has links)
En aquest treball, es presenta l'estudi de les propietats de fractura de films de polipropilè (PP) i copolímers etilè-propilè en blocs (EPBC) per mitjà de la tècnica del Treball Essencial de Fractura (EWF). Aquesta tècnica es mostra com una alternativa molt adapatada per a l'aplicació de la Mecànica de la Fractura a films dúctils, i permet separar l'energia total de fractura en un terme essencial, que fa referència al treball real de fractura, i un terme no essencial, relatiu a la dissipació d'energia de deformació plàstica al voltant del camí de fractura.En una primera part, s'estudien les condicions òptimes d'assaig de la técnica EWF per aplicar-la a films de polímers dúctils, analitzant la influència de variables d'assaig com són les dimensions de la proveta, la velocitat d'assaig o el mode de fractura.En una segona part, s'ha estudiat la relació entre els paràmetres de fractura obtinguts mitjançant la tècnica EWF i diferents propietats referents a l'estructura del material. Entre aquestes, s'ha analitzat la influència de les característiques cristal·lines, modificades per un procés de recuit previ als assajos, i del contingut d'etilè a diferents temperatures d'assaig. S'han aplicat nombroses tècniques de caracterització tant mecàniques i de fractura com físico-químiques.Els resultats mostren que el mètode EWF s'adapta bé a la necessitat de caracteritzar la fractura de films polimèrics, i permet estudiar la relació entre la seva estructura i les propietats de fractura que presenten. Alhora, es plantegen diferents modificacions del mètode que permeten potenciar les seves possibilitats. S'observa que al millorar la perfecció cristalina dels materials estudiats, el terme essencial augmenta en detriment del terme no essencial. També es demostra que la presència d'etilè en els EPBC minimitza la gran dependència que presenten les propietats de fractura del PP homopolímer en variar la temperatura, i es relaciona aquest comportament amb els canvis dels mecanismes de deformació predominants en el material. / En este trabajo, se presenta el estudio de las propiedades de fractura de films de polipropileno (PP) y copolímeros etileno-propileno (EPBC) por medio de la técnica del Trabajo Esencial de Fractura (EWF). Esta técnica se muestra como una alternativa muy adaptada para la aplicación de la Mecánica de la Fractura en films dúctiles, y permite separar la energía total de fractura en un término esencial, que hace referencia al trabajo real de fractura, y un término no esencial, relativo a la disipación de energía de deformación plástica alrededor del camino de fractura.En una primera parte, se estudian las condiciones óptimas de ensayo de la técnica WF para aplicarla a films de polímeros dúctiles, estudiando la influencia de variables de ensayo como son las dimensiones de probeta, la velocidad de ensayo o el modo de fractura.En una segunda parte, se ha estudiado la relación entre los parámetros de fractura obtenidos mediante la técnica EWF y distintas propiedades referentes a la estructura del material. Entre éstas, se ha analizado la influencia de las características cristalinas, modificadas por un proceso de recocido previo a los ensayos, y del contenido de etileno a diferentes temperaturas de ensayo. Se han aplicado numerosas técnicas de caracterización, tanto mecánicas y de fractura como físico-químicas.Los resultados muestran que el método EWF se adapta bien a la necesidad de caracterizar la fractura de films poliméricos, y permite estudiar la relación entre su estructura y las propiedades de fractura que presentan. También se plantean diferentes modificaciones del método que permiten potenciar sus posibilidades. Se observa que al mejorar la perfección cristalina de los materiales estudiados, el término esencial aumenta en detrimento del término no esencial. También se demuestra que la presencia de etileno en los EPBC minimiza la gran dependencia que presentan las propiedades de fractura del PP homopolímero al variar la temperatura, y se relaciona este comportamiento con los cambios de los mecanismos de deformación predominantes en el material. / In this work, the study of the fracture properties of polypropylene (PP) and ethylene-propylene block copolymers (EPBC) films by means of the Essential Work of Fracture (EWF) method is presented. This method is considered as a suitable alternative for applying Fracture Mechanics to ductile films, allowing the separation of the total fracture energy into two different items: an essential term, related to the actual fracture work, and a non essential term, related to the plastic deformation energy dissipation occurring in the region surrounding the fracture path.In a first part, the optimal EWF method test conditions for ductile plastic films are studied, by analysing the influence of such test variables as the specimen dimensions, the test rate or the fracture mode.In a second part, the relationship between the fracture parameters obtained by applying the EWF method and different materials structural properties are studied. Among these properties, the influence of the crystalline characteristics, modified by an annealing process before the tests, and that of the ethylene content at different test temperatures have been analysed.Various mechanical, fracture and physico-chemical characterisation techniques have been applied.The results show that the EWF method is very suitable to assess the fracture of polymeric films, and therefore to study the relationship between their structure and the fracture properties that they present. In addition, various modifications of the method are proposed in order to improve its possibilities.It is observed that as the crystalline perfection grows, the essential term increases but the non-essential term decreases. It is also shown that the ethylene presence in the EPBC minimises the strong temperature dependence shown by the fracture properties of the PP homopolymer. This behaviour is related to the predominant deformation mechanisms in the material. / Cet ouvrage présente l'étude des propriétés de rupture de films de polypropylène (PP) et de copolymères éthylène-propylène en blocs (EPBC) par moyen de la methode du Travail Essentiel de Rupture (EWF). Cette technique se révèle comme une alternative très adaptée à l'application de la Mécanique de la Rupture aux films ductiles, et permet la séparation de l'énergie totale de rupture en un terme essentiel, qui fait référence au travail réel de rupture, et en un terme non essentiel, relatif à la dissipation d'énergie de déformation plastique autour du chemin de rupture.Dans une première partie, les conditions optimales d'essai de la technique EWF pour l'application aux polymères ductiles sont étudiées, tout en analysant l'influence de variables d'essai telles que les dimensions de l'éprouvette, la vitesse de l'essai, ou le mode de rupture. La deuxième partie est consacrée à l'étude de la relation entre les paramètres de rupture obtenus par la méthode EWF et différentes propriétés de la structure du matériau. Parmis celles-ci, nous avons analysé l'influence des caractéristiques cristallines, modifiées par un processus de recuit préalable aux essais, et de l'effet du contenu en éthylène à différentes températures d'essai. Plusieurs techniques de caractérisation, aussi bien mécaniques, que de rupture, que physico-chimiques ont été utilisées.Les résultats montrent que la méthode EWF est très adaptée à la caractérisation de la rupture de films de polymères, et permet d'étudier la relation entre leur structure et leurs propriétés de rupture. Nous présentons, aussi, différentes approches modifiées de la technique EWF qui permettent d'accroître son potentiel. Il est observé que, quand la perfection cristalline des matériaux étudiés augmente, le terme essentiel augmente lui aussi, mais le terme non essentiel présente une tendance opposée. De même, il est démontré que la présence d'ethylène dans les EPBC a un effet de minimisation de l'importante dépendence que le PP homopolymère présente vis-à-vis de la température, et ce comportement est relié aux changements des mécanismes de déformation prédominants dans le matériau.
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Morphologie und Bruchverhalten von Block- und Multipfropfcopolymeren / Morphology and Fracture Behaviour of Block and Multigraft CopolymersStaudinger, Ulrike 16 August 2007 (has links) (PDF)
Ziel der vorliegenden Arbeit war es, die Zusammenhänge zwischen der molekularen Architektur, Morphologie und den mechanischen bzw. bruchmechanischen Eigenschaften in S-SB-S-Triblockcopolymeren und deren Blends und in PI-PS-Multipfropfcopolymeren herauszuarbeiten und damit einerseits einen Beitrag für das Verständnis der Struktur-Eigenschaftsbeziehungen in Block- und Pfropfcopolymeren zu leisten und andererseits Möglichkeiten zur Entwicklung neuer Materialien aufzuzeigen, welche besondere Eigenschaftskombinationen aufweisen und damit ein bedeutendes Interesse für industrielle Anwendungen hervorrufen. Für die Untersuchungen wurde dabei der PS-Außenblockanteil und das S/B-Verhältnis im SB-Mittelblock in S-SB-S-Triblockcopolymeren, die Thermoplast/Thermoplastisches Elastomer (TP/TPE) -Zusammensetzung in S-SB-S-Triblockcopolymer-Blends sowie die Funktionalität und die Anzahl der Verknüpfungspunkte in PI-PS-Multipfropfcopolymeren variiert. Zur Charakterisierung der Phasenmischbarkeit und der Morphologie wurden die dynamisch mechanische Analyse (DMA), die Transmissionselektronenmikroskopie (TEM) und die Röntgenkleinwinkelstreuung (SAXS) angewandt. Die mechanischen Eigenschaften wurden mit dem einachsigen Zugversuch untersucht. Bruchmechanische Untersuchungen erfolgten unter Anwendung der „Essential Work of Fracture“- (EWF-) Methode, welche als Konzept der „Post-Yield“-Bruchmechanik innerhalb der Fließbruchmechanik für duktile nanostrukturierte polymere Materialien sehr gut anwendbar ist und Aussagen zur Bruchzähigkeit der Materialien liefert. Zur näheren Charakterisierung des zeitaufgelösten Deformationsverhaltens sowie der Rissausbreitungskinetik wurden die Dehnungsfeldanalyse, eine Bruchflächenanalyse mittels Rasterelektronenmikroskopie (REM) sowie das Risswiderstandskurven-Konzept angewandt. Die Untersuchungen der S-SB-S-Triblockcopolymersysteme und der PI-PS-Multipfropfcopolymere konnten den signifikanten Einfluss der molekularen Architektur, der Blockzusammensetzung und des PS-Gehaltes auf das Phasenverhalten, die Morphologie und die Eigenschaften klar herausstellen. Durch die Variation dieser Parameter kann das Eigenschaftsspektrum von thermoplastisch zu elastomer eingestellt und somit sowohl TPs oder TPEs mit hoher Steifigkeit und Zähigkeit als auch TPEs mit superelastischem Charakter erzeugt werden. Daraus eröffnet sich ein breiter Anwendungsbereich dieser Materialien, welche aufgrund ihrer Transparenz und physiologischen Verträglichkeit auch interessante optische und gesundheitliche Vorteile mitbringen. Es konnte gezeigt werden, dass durch die systematische Variation der Architektur die gezielte Einstellung gewünschter Eigenschaftsprofile möglich ist. Die Arbeit leistet somit einen Beitrag zur Entwicklung anwendungsorientierter Materialkonzepte, welche ingenieurwissenschaftlich interessant sind. / The aim of this thesis was to study the relation between molecular architecture, morphology and (fracture) mechanical properties of S-SB-S triblock copolymers and PI-PS multigraft copolymers. Hence, this work should contribute to the understanding of structure-property-relationship in block and multigraft copolymers and thus offer possibilities for the development of novel materials with special properties interesting for industrial application. Within this study in the case of S-SB-S triblock copolymers the PS outer block content and the S/B ratio of the middle block, in the case of S-SB-S triblock copolymer blends the thermoplast/thermoplastic elastomer (TP/TPE) composition and in case of PI-PS multigraft copolymers the functionality and number of branch points were varied. For the characterisation of morphology and phase miscibility dynamic mechanical analysis (DMA), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) were applied. Uniaxial tensile tests were carried out to investigate the mechanical properties. The fracture mechanical behaviour was studied using essential work of fracture (EWF) concept based on the post yield fracture mechanic principles, which is suitable to characterise fracture toughness of ductile nanostructured materials. The time resolved analysis of deformation and fracture behaviour was characterised qualitatively by strain field analysis, scanning electron microscopy (SEM) of the fractured surfaces and quantitatively by evaluation of the crack propagation kinetics and construction of R-curves. This study clearly highlights the significant influence of molecular architecture block composition and PS content on the phase behaviour, morphology and properties of S-SB-S triblock copolymers and PI-PS multigraft copolymers. By varying these parameters the property profile can be adjusted diversifying from thermoplastic to elastomeric and both TP or TPE materials with high stiffness and toughness and TPEs with super-elastic characteristics can be designed. Hence, fundamentally it offers a broad scope of application of these materials, in which physiological compatibility and transparency are added advantages. Thus, conceptually it could be shown, that by systematic variation of the architecture desired property profiles can be adjusted. Therefore the present work contributes to the development of application-oriented material concepts, which are interesting in engineering terms.
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