Gegenstand der Arbeit ist die Erarbeitung und Umsetzung eines reaktiven Aufbereitungsverfahrens im Doppelschneckenextruder zur kontinuierlichen Herstellung von gummimehlbasierten Elastomerlegierungen mit Polypropylenmatrix. Es wird eine Übersicht über den technischen Stand der Polymeraufbereitung in Doppelschneckenmaschinen sowie den Einsatz von Gummimehlen als funktionellem Füllstoff in Thermoplastmatrices gegeben, wobei neben verfahrenstechnischen Aspekten besonders auf die Möglichkeiten der Phasenkompatibilisierung in gummimehlhaltigen Polyolefincompounds zur Herstellung Thermoplastischer Elastomere eingegangen wird. Den Ausgangspunkt für die Verfahrensentwicklung bildet ein reaktiver Schmelzemischprozess in einem Innenmischer, auf dessen Basis die Auswahl der Rezepturkomponenten erfolgte. Gestützt auf eine Modellrezeptur erfolgte in diskontinuierlichen Voruntersuchungen im Labormesskneter eine Anpassung des Werkstoffsystems sowie die experimentelle Verifizierung möglicher Verfahrenskonzepte für die kontinuierliche reaktive Aufbereitung im Doppelschneckenextruder. Für die ausgewählten Verfahrenskonzepte wurden konkrete Extruderaufbauten konzipiert, deren stoff- und prozessgrößenabhängiges Betriebsverhalten auf Basis eines analytischen Prozessmodells abgeschätzt wurde. Nach vergleichenden experimentellen Untersuchungen der kontinuierlichen Verfahrensaufbauten, die auch Verweilzeitmessungen und Rezepturanpassungen einschlossen, wurde eine praxistaugliche Extruderkonfiguration ausgewählt und der Einfluss der technologischen Prozessgrößen auf die Werkstoffeigenschaften der Elastomerlegierungen untersucht. Mit optimierten Prozessparametern erfolgte die kontinuierliche reaktive Aufbereitung von Elastomerlegierungen mit variablen Gummimehlgehalten, deren Werkstoffverhalten umfassend charakterisiert wird / The present thesis deals with the development and implementation of a reactive compounding procedure in a co-rotating twin-screw extruder for the continuous preparation of ground rubber based Elastomeric Alloys with a polypropylene matrix. An overview about the state of the art of polymer compounding in twin-screw devices as well as of the utilisation of rubber powders as functional fillers in thermoplastic matrices is given. Beside process related aspects especially the methods of phase compatibilisation in ground rubber containing polyolefinic compounds for the preparation of Thermoplastic Elastomers are addressed. A reactive melt-mixing procedure in an internal mixer served as the base for the development of the continuous process as well as for the materials and formulations used. Preliminary experiments with a model formulation were carried out in a laboratory batch kneader to adapt the material system onto the requirements of the continuous process as well as to verify and select promising process concepts for the continuous reactive compounding in the twin-screw extruder. The selected concepts were transformed into extruder configurations followed by a simulation of their operating characteristics based on an analytical process model. The performance of the extruder configurations was verified by experiments that included also residence time investigations and further adaption of the formulation. The most suitable extruder setup was chosen for the investigation of the influence of the technological process parameters on the material properties of the Elastomeric Alloy model formulation. Using optimised technological parameters a familiy of Elastomeric Alloys with variable rubber powder content was prepared by continuous reactive compounding in the twin-screw extruder and followed by a comprehensive characterisation of their material performance and properties.

Polymers possess bulk elastic properties due to entanglement of the polymer chains, not due to an inherit elasticity found within the monomers. An appropriately disubstituted bicyclo[8.8.8]hexacosane monomer should impart inherit elasticity when utilized in a polymer. A stochastic search of disubstituted bicyclo[m.m.m]alkanes demonstrated that these systems will adopt an out,out configuration and bicycles with medium and large values of m possess variable bridgehead-bridgehead distances. A stochastic search of disubstituted bicyclo[8.8.n]alkanes demonstrated an even-odd effect within the bite-angle of the bicycle. Two model compounds with methyl and hydroxyl groups at the bridgehead carbons were synthesized that demonstrated solid-state structures that correlated extremely well with the computational search. The solid-state structures were observed with both an out,out configuration and variable bridgehead-bridgehead distances. To investigate this hypothesis, polyurethanes will be made from the following diol monomers: 1,10-decanediol, a monocyclic diol, and a bicyclo[8.8.8]hexacosane diol.

No description available.

No description available.

<p>A variety of intriguing surface patterns have been observed on developing natural systems, ranging from corrugated surface of white blood cells at nanometer scales to wrinkled dog skins at millimeter scales. To mimetically harness functionalities of natural morphologies, artificial transformative skin systems by using soft active materials have been rationally designed to generate versatile patterns for a variety of engineering applications. The study of the mechanics and design of these dynamic surface patterns on soft active materials are both physically interesting and technologically important. </p><p>This dissertation starts with studying abundant surface patterns in Nature by constructing a unified phase diagram of surface instabilities on soft materials with minimum numbers of physical parameters. Guided by this integrated phase diagram, an electroactive system is designed to investigate a variety of electrically-induced surface instabilities of elastomers, including electro-creasing, electro-cratering, electro-wrinkling and electro-cavitation. Combing experimental, theoretical and computational methods, the initiation, evolution and transition of these instabilities are analyzed. To apply these dynamic surface instabilities to serving engineering and biology, new techniques of Dynamic Electrostatic Lithography and electroactive anti-biofouling are demonstrated.</p> / Dissertation

No description available.

Polymeric composites are any of the combinations or compositions that comprise two or more materials as separate phases, at least one of which is a polymer. By mixing a polymer with another material, such as glass, carbon, or another polymer, it is often possible to improve the desired properties of the polymer. In this study, ternary composites were prepared by using recycled poly(ethylene terephthalate), PET as the matrix material, short glass fiber (SGF) as the reinforcing filler and thermoplastic elastomer as the impact modifier. Bottle grade recycled PET was mixed in a twin screw extruder with a thermoplastic elastomer which is a terpolymer of ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA), and E type short glass fiber is fed to the extruder from a side feeder. During this study, recycled PET was mixed with from 10 to 50 wt. % elastomer, and SGF was added to the system in the range from 10 to 40 % by weight. Processing parameters were kept constant during extrusion. The composites were then compression molded for characterization experiments. The produced composites were characterized in terms of their mechanical and thermal properties and morphologies. Melt behavior and fiber length distribution of the composites were also determined for selected composites. In ternary systems with 10 % elastomer, highest tensile strength values were observed. High tensile and flexural moduli values were obtained for the composites containing 20 % elastomer. Results of impact tests designated that impact strength increased significantly after 30 % elastomer content. Thermal analyses of the composites were done by using a DSC (Differential Scanning Calorimeter). Degree of crystallinity of ternary system decreased with increasing elastomer content, but melting points of the composites were not affected significantly. SEM micrographs showed that the adhesion between the matrix and fiber increased considerably with elastomer addition.

Techn. Hochsch., Diss., 2006--Aachen.

Zugl.: Stuttgart, Univ., Diss., 2003. / Print-Ausg. bei Shaker, Aachen erschienen.

Techn. Hochsch., Diss., 2000--Aachen.