Research Interests:
Research Interests: Art()
()
Research Interests:
Direct Digital Manufacturing (DDM) is often regarded as the future of manufacturing. Since the future will be governed by questions of sustainability (e. g. availability of resources, emission prevention and fair production standards) DDM... more
Direct Digital Manufacturing (DDM) is often regarded as the future of manufacturing. Since the future will be governed by questions of sustainability (e. g. availability of resources, emission prevention and fair production standards) DDM has to be analysed and optimised with respect to this. In this paper we will address sustainability aspects regarding two distinct development directions in DDM: the replacement of industrially established processes by additive manufacturing and the FabLab movement as an example of paradigm shift in consumer-producer-relationship.
What are additive manufacturing, 3D-printing and FabLabs? Additive manufacturing is a procedure in which an object is formed successively from layers of material following a computer model. 3D-printing is the most prominent example of... more
What are additive manufacturing, 3D-printing and FabLabs? Additive manufacturing is a procedure in which an object is formed successively from layers of material following a computer model. 3D-printing is the most prominent example of these techniques, which are the technological backbone of the FabLab movement. FabLabs are open high-tech workshops where individuals have the opportunity to develop and produce custom-made things which are not accessible by conventional industrial scale technologies. Furthermore, FabLabs are strongly connected to activities in social networks and the exchange of knowledge. Therefore they are based on the idea of collaboration, decentralization, participation and democratisation (Gershenfeld 2005). FabLabs and additive manufacturing could therefore be part of a new mode of innovation, production and consumption. The idea of FabLabs started in 2002 at the MIT. Small groups of people get involved in open and collaborative high-tech workshops to individua...
There is need for sealing applications in numerous fields of technology. Swellable polymers or hydrogels offer the change to develop tailor-made materials for specific sealing tasks. Based on the capability of swelling the materials are... more
There is need for sealing applications in numerous fields of technology. Swellable polymers or hydrogels offer the change to develop tailor-made materials for specific sealing tasks. Based on the capability of swelling the materials are able to realise self-healing sealing systems. When getting in contact with aqueous liquids the polymers swell and form hydrogels. The polymers can take up 1000 times of their dry weight, while storing the absorbed liquid in form of a hydrogel even under pressure. The objectives of using these materials are the design of user-oriented sealing solutions, which would provide a high degree of security even where unusual problems are concerned. For the development of sealing products based on swellable polymers, information about the swelling pressure is of essential significance. Up to now only few scientific studies have adressed the application of polymer hydrogels for sealing techniques. Such materials are mostly used empirically. Detailed analyses as...
Thermoplastic composition elastomer-modified powder with at least one material matriztermoplastico and at least one elastomer material thin, crosslinked particle and powder attached to materialde matrix by mixing of the melt, wherein the... more
Thermoplastic composition elastomer-modified powder with at least one material matriztermoplastico and at least one elastomer material thin, crosslinked particle and powder attached to materialde matrix by mixing of the melt, wherein the elastomeric material is selected theGroup elastomeric materials crosslinked with a hardness (X) similar or identical to the hardness (Y) of material lamatriz where the hardness (Y) of the elastomer material satisfying the following relation [X] - [Z] <= [Y ] <= [X] + [Z] (I) where- [Y] denotes the Shore hardness of the elastomer material according to DIN 53505, based on Shore A. [X] denotes the Shore hardness of the material of the matrix according to DIN 53505, based on Shore a hardness y- [Z] denotes the difference between the Shore hardness of the elastomer material and the Shore hardness of the material of lamatriz, referred each in Shore a, with [Z] < = 20and where the materials elast merely has a Shore hardness according to DIN 53505 ...
Probennahmevorrichtung (1) zur Entnahme einer Probenmenge aus einem Schmelzestrom (2), insbesondere aus einem Prozessschmelzestrom eines Extrusions- oder Compoundierprozesses, mit einem Schmelzekanal (3) fur den Schmelzestrom (2) und mit... more
Probennahmevorrichtung (1) zur Entnahme einer Probenmenge aus einem Schmelzestrom (2), insbesondere aus einem Prozessschmelzestrom eines Extrusions- oder Compoundierprozesses, mit einem Schmelzekanal (3) fur den Schmelzestrom (2) und mit einem Kolbenelement (8), wobei der Schmelzekanal (3) eine Eintrittsoffnung (4) und eine Austrittsoffnung (5) und eine zwischen der Eintrittsoffnung (4) und der Austrittsoffnung (5) angeordnete Zugangsoffnung fur das Kolbenelement (8) aufweist, wobei das Kolbenelement (8) in dem Schmelzekanal (3) quer oder geneigt zum Schmelzekanal (3) bewegbar angeordnet ist und bei einer Probennahme uber die Zugangsoffnung in den Schmelzekanal (3) eingreift, um eine bestimmte Menge des Schmelzestroms (2) aus einer Probennahmekavitat (15) der Probennahmevorrichtung (1) zu verdrangen und aus dem Schmelzekanal (3) abzufuhren, wobei das Kolbenelement (8) vor der Probennahme den Schmelzekanal (3) durchgreift und von dem Schmelzestrom (2) um- und/oder durchstro mt wird.
The topic of 3D printing has attracted intense discussions, much of it highly enthusiastic and optimistic in nature. The technology surely offers numerous possibilities and opportunities for changing and influencing the future of... more
The topic of 3D printing has attracted intense discussions, much of it highly enthusiastic and optimistic in nature. The technology surely offers numerous possibilities and opportunities for changing and influencing the future of manufacturing on many, very different, levels—from the shop floor to impacts on the environment, future business models and even social aspects. In order to better prepare ourselves and possibly pave the way for these various impacts, it is important to recognize that 3D printing offers both advantages and disadvantages. The goal is to review some of these critically in order to not only moderate and inform expectations, but also maintain the momentum.
Research Interests:
Considerable research achievements were made to address the plastic crisis using biotechnology, but this is still limited to polyesters. This Comment aims to clarify important aspects related to myths and realities about plastic... more
Considerable research achievements were made to address the plastic crisis using biotechnology, but this is still limited to polyesters. This Comment aims to clarify important aspects related to myths and realities about plastic biodegradation and suggests distinct strategies for a bio-based circular plastic economy in the future.
Research Interests:
Research Interests:
Polymer based elements are frequently subject to high mechanical load. It is well known, that such components can spontaneously break although the mechanical stress has not reached the average maximum load. These fatigue fractures are... more
Polymer based elements are frequently subject to high mechanical load. It is well known, that such components can spontaneously break although the mechanical stress has not reached the average maximum load. These fatigue fractures are caused by micro-cracks. A smart approach would be to implement a self-healing function that is able to heal a crack in an early stage and thus avoid crack propagation. Fraunhofer UMSICHT and the Plant Biomechanics Group Freiburg together with co-operation partners develop biomimetic self-healing elastomers having the capability to repair micro-cracks automatically without any intervention from outside.
Research Interests:
During the past decades, research in self-healing materials has focused on the improvement in the mechanical properties, making stronger materials, able to bear increasing solicitations. This strategy proved to be costly and in some cases... more
During the past decades, research in self-healing materials has focused on the improvement in the mechanical properties, making stronger materials, able to bear increasing solicitations. This strategy proved to be costly and in some cases inefficient, since materials continue to fail, and maintenance costs remained high. Instead of preparing stronger materials, it is more efficient to prepare them to heal themselves, reducing repairing costs and prolonging their lifetime. Several different self-healing strategies, applied to different material classes, have been comprehensively studied. When new materials are subject of research, the attention is directed into the formulations, product processing and scale-up possibilities. Efforts to measure self-healing properties have been conducted considering the specific characteristics of each material class. The development of comprehensive service conditions allowing a unified discussion across different materials classes and the standardiz...
Research Interests:
Aufgabenstellung: Lösemittelfreie Beschichtungssysteme und Sinterbauteile auf Basis pulverförmiger Polymere gewinnen in der industriellen Praxis stetig an Bedeutung. Wichtige diesbezügliche Produktionstechniken sind Beschichtungsverfahren... more
Aufgabenstellung: Lösemittelfreie Beschichtungssysteme und Sinterbauteile auf Basis pulverförmiger Polymere gewinnen in der industriellen Praxis stetig an Bedeutung. Wichtige diesbezügliche Produktionstechniken sind Beschichtungsverfahren wie elektrostatisches bzw. thermisches Pulverbeschichten und Wirbelsintern, die Herstellung großer Bauteile durch Rotationssintern und prototypischer Funktionsmodelle durch Lasersintern (Rapid Prototyping). Anwendungsbeispiele sind Gleit- und Verschleißschutzschichten als Führungselemente für Sicherheitsgurte, Sitze, Sonnendächer und Schubfächer im Automobilbau, sowie lasergesinterte Funktionsmodelle oder Kleinserien für Saugrohre, Luft- und Klimasysteme, Pumpenlaufräder, Taster und Scharniere. Im Rahmen des Projekts "Verdichtetes Kohlendioxid als Prozessadditiv zur Herstellung polymerer und mikronisierter Nanokomposite" sollen tribologisch optimierte Nanokomposite in Form mikronisierter Beschichtungs- und Sinterpulver für diese Anwendung...
In contrast to the precision requested in industrial processing, biological structures only seem to possess a perfect, uniform regularity. Within the recurring patterns and periodic self-similar structures a randomly acting variation... more
In contrast to the precision requested in industrial processing, biological structures only seem to possess a perfect, uniform regularity. Within the recurring patterns and periodic self-similar structures a randomly acting variation appears to be present. The main goal of this work is to elucidate whether these variations are irrelevant or related to the particular functionality of a surface or if they are just a result of stimulus- environmental interaction and genetical predisposition. The diversity within the entire structural system may have an equally large influence on the respective function as the structure itself.
DE 102008047976 A1 UPAB: 20100414 NOVELTY - Microcapsule (5) comprises at least one solid carrier material (1) for at least one auxiliary- and/or active-substance (2) and at least one wall material (4) encapsulating the carrier material,... more
DE 102008047976 A1 UPAB: 20100414 NOVELTY - Microcapsule (5) comprises at least one solid carrier material (1) for at least one auxiliary- and/or active-substance (2) and at least one wall material (4) encapsulating the carrier material, where the carrier material is loaded with the auxiliary- and/or active-substance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) a composite comprising a matrix material (preferably a thermoplastic polymer) and the above microcapsule, as additive, distributed in the matrix material; (2) a method for preparing the composite from a thermoplastic polymer and the microcapsule, as additive, comprising mixing the polymer with the microcapsule by melt mixing in a mixing and/or extruding device to form the composite; and (3) intermediate or final product obtained by extruding, injection molding, blow molding, calendering, deep-drawing and/or pressing the composite. USE - The microcapsule is useful as additive in a composite, which is useful...
Research Interests:
Research Interests:
Die Bionik ist eine seit langem bekannte und dennoch immer noch faszinierende Variante eines Innovationsprozesses. In ihm ist die Analogie zwischen einem naturlichen Vorbild und einem technischen Zielobjekt die grundlegende Basis fur die... more
Die Bionik ist eine seit langem bekannte und dennoch immer noch faszinierende Variante eines Innovationsprozesses. In ihm ist die Analogie zwischen einem naturlichen Vorbild und einem technischen Zielobjekt die grundlegende Basis fur die (in der Regel) technische Entwicklung. Im folgenden Kapitel wird dazu zunachst die historische Entwicklung der Bionik beschrieben, die gleichzeitig auch einen Einblick in die Vielfalt technischer Anwendungsgebiete gibt. Zur Abgrenzung von anderen Innovationsstrategien bzw. Wissenschaftsdisziplinen werden anschliesend die Definitionen der Bionik vorgestellt. Es folgt eine grundlegende Diskussion zur Bedeutung eines Bezugs auf biologische Vorbilder und darauf aufbauend eine detaillierte Darstellung des bionischen Arbeitsprozesses. Dem schliest sich eine Darstellung der Grunde fur bionisches Arbeiten an. Hier wird neben der Qualitat eines biologischen Vorbildes und der Bedeutung biologisch-technischer Interdisziplinaritat auch das Potenzial der Bionik fur die Nachhaltige Entwicklung erlautert. Das Kapitel schliest mit einigen aktuellen Beispielen bionischer Forschungsarbeiten.
Self‐healing is a basic and essential property of living organisms and a great challenge for materials sciences. Over the last decade self‐repair mechanisms found in plants have proved to be promising role models for the development of... more
Self‐healing is a basic and essential property of living organisms and a great challenge for materials sciences. Over the last decade self‐repair mechanisms found in plants have proved to be promising role models for the development of bio‐inspired self‐healing materials. Biological self‐repair processes typically can be divided in a fast self‐sealing and a slower self‐healing phase. The potential of biomimetic approaches for the development of bio‐inspired self‐healing materials is exemplified by three current R&D projects. The first example deals with the development of self‐repairing closed‐cell foam coatings for pneumatic structures inspired by lianas of the genus Aristolochia in which internal fissures are repaired by pressurized (turgescent) cortex cells that swell in the newly formed (micro‐)cracks and seal them. In the second example self‐sealing mechanisms found in succulent leaves of Delosperma cooperi were analysed which may serve as concept generator for self‐sealing membranes In the third project self‐healing elastomers for sealings and dampers have been developed inspired by self‐healing processes found in rubber plants. These plants contain latex emulsions in micro‐tubes which are released after injury and seal the fissures by coagulation. Inspired by these models, new types of self‐healing elastomers based e.g. on ionomers and on micro‐phase separation, respectively, have been developed.
Research Interests:
Titanium dioxide is a ceramic material which is widely used as a white pigment and catalyst. In the present work the precipitation of TiO2 by the thermal hydrolysis of titanium oxysulphate was studied in terms of the homogeneous... more
Titanium dioxide is a ceramic material which is widely used as a white pigment and catalyst. In the present work the precipitation of TiO2 by the thermal hydrolysis of titanium oxysulphate was studied in terms of the homogeneous precipitation and the coating of capsules. Experimental work and simulations have been done to describe the precipitation in 0.1M aqueous solutions while in some experiments sulphuric acid was added to increase the reaction time. In the experimental part of this work, gravimetric and spectroscopic measurements were performed to determine the time-dependent precipitation of the material and particle size measurements to characterize the time-dependent size distribution of the precipitated particles. In the theoretical part different mechanisms of the precipitation process like nucleation, growth and agglomeration were considered using semi-empirical equations. For the transfer of the effects of the individual particle scale to the whole population of particle...
Research Interests:
Research Interests:
Microcapsules containing tetradecane as core and an amino resin as wall material were synthesised and used as templates for the production of micro hollow spheres. That way, the prepared microcapsules have been mineralised with titania by... more
Microcapsules containing tetradecane as core and an amino resin as wall material were synthesised and used as templates for the production of micro hollow spheres. That way, the prepared microcapsules have been mineralised with titania by thermal hydrolysis of titanyl sulphate and subsequently transformed into inorganic and organic/inorganic hybrid hollow spheres. Laser diffraction studies after the different process steps show
Research Interests:
ABSTRACT When exposed to a surface fire, the probability of a tree to survive widely varies, depending on its capability to protect the cambium from lethal temperatures above 60°C. Thereby, the bark, the entirety of all tissues outside... more
ABSTRACT When exposed to a surface fire, the probability of a tree to survive widely varies, depending on its capability to protect the cambium from lethal temperatures above 60°C. Thereby, the bark, the entirety of all tissues outside the cambium, serves as an insulation layer. In laboratory experiments, the heat production of a surface fire was simulated and the time span τ60 until the temperature of 60°C is reached in the inner bark surface was measured. Thereby, τ60—as a measure of the fire resistance—was quantitatively determined for seven tree species. In addition, the influence of bark thickness and moisture content on bark heat insulation capacities was examined. Independent of the tree species and bark moisture content a power function correlation between bark thickness and τ60 was found. Our results also show that fire resistance increases with decreasing bark density. The seven tree species examined can be classified in two groups differing highly significant in their bark structure: (1) tree species with a faintly structured bark, which show a low fire resistance, and (2) tree species with an intensely structured bark, showing a high fire resistance. Furthermore a mathematical model simulating heat conduction was applied to describe the experimental results, and some ideas for a transfer into biomimetic materials are presented.
Research Interests:
Research Interests:
Research Interests:
Microcapsules containing tetradecane as core and an amino resin as wall material were synthesised and used as templates for the production of micro hollow spheres. That way, the prepared microcapsules have been mineralised with titania by... more
Microcapsules containing tetradecane as core and an amino resin as wall material were synthesised and used as templates for the production of micro hollow spheres. That way, the prepared microcapsules have been mineralised with titania by thermal hydrolysis of titanyl sulphate and subsequently transformed into inorganic and organic/inorganic hybrid hollow spheres. Laser diffraction studies after the different process steps show
Research Interests:
ABSTRACT There have been several efforts to simulate the physical processes in a single droplet during spray drying in the last several years, but most of the models do not describe the solid formation in detail. In this work, the... more
ABSTRACT There have been several efforts to simulate the physical processes in a single droplet during spray drying in the last several years, but most of the models do not describe the solid formation in detail. In this work, the development of the microscopic solid structure in a droplet during spray drying is simulated. A radial-symmetric model of the droplet is used to simulate the mass and heat transport. The solid formation at every radial discretization point is obtained by the solution of population balances. This way, the distribution of the particle number density in the droplet depending on the macroscopic process parameters can be predicted. The model equations are solved in a normalized coordinate system to be able to describe the shrinkage of the droplet. The suitability of these population balances will also be discussed. For the validation, monodisperse single droplets consisting of a solution or suspension are dried with constant boundary conditions.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT Deutschland präsentiert sich auf der Expo 2005 in Japan mit einem Bionik-Pavillon und dem Thema „Lernen von der Natur” in Anlehnung an das ExpoMotto „Nature&#39;s Wisdom”. In diesem Beitrag wird das Potenzial biologischer... more
ABSTRACT Deutschland präsentiert sich auf der Expo 2005 in Japan mit einem Bionik-Pavillon und dem Thema „Lernen von der Natur” in Anlehnung an das ExpoMotto „Nature&#39;s Wisdom”. In diesem Beitrag wird das Potenzial biologischer Vorbilder für die Optimierung verfahrenstechnischer Prozesse diskutiert. Am Beispiel der Zerkleinerungstechnik wird die Möglichkeit zur Übertragung selbst schärfender Mechanismen von Säugetierzähnen in verfahrenstechnische Schneidprozesse dargestellt.