Freudenberg Forschungsdienste Kg

Weinheim, Germany

Freudenberg Forschungsdienste Kg

Weinheim, Germany

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Patent
Freudenberg Forschungsdienste KG and Basf | Date: 2014-02-03

The present invention concerns stable aqueous protein dispersions comprising in an aqueous phase at least one self-assembling protein in dispersed form and also at least one specific dispersant for the self-assembling protein; processes for producing such stable aqueous dispersions; processes for electrospinning self-assembling proteins using such stable aqueous dispersions; processes for producing fibrous sheet bodies or fibers from such aqueous dispersions; the use of such aqueous dispersions for coating surfaces; the use of the materials produced by electrospinning in the manufacture of medical devices, hygiene articles and textiles; and also fibrous or fibrous sheet bodies produced by an electrospinning process of the present invention.


Patent
Freudenberg Forschungsdienste KG and Basf | Date: 2011-08-25

The present invention concerns stable aqueous protein dispersions comprising in an aqueous phase at least one self-assembling protein in dispersed form and also at least one specific dispersant for the self-assembling protein; processes for producing such stable aqueous dispersions; processes for electrospinning self-assembling proteins using such stable aqueous dispersions; processes for producing fibrous sheet bodies or fibers from such aqueous dispersions; the use of such aqueous dispersions for coating surfaces; the use of the materials produced by electrospinning in the manufacture of medical devices, hygiene articles and textiles; and also fibrous or fibrous sheet bodies produced by an electrospinning process of the present invention.


Schock-Kusch D.,University of Heidelberg | Schock-Kusch D.,Heidelberg University of Applied Sciences | Xie Q.,University of Heidelberg | Xie Q.,Heidelberg University of Applied Sciences | And 11 more authors.
Kidney International | Year: 2011

Determination of the urinary or plasma clearance of exogenous renal markers, such as inulin or iohexol, is considered to be the gold standard for glomerular filtration rate (GFR) measurement. Here, we describe a technique allowing determination of renal function based on transcutaneously measured elimination kinetics of fluorescein isothiocyanate (FITC)-sinistrin, the FITC-labeled active pharmaceutical ingredient of a commercially available marker of GFR. A low cost device transcutaneously excites FITC-sinistrin at 480 nm and detects the emitted light through the skin at 520 nm. A radio-frequency transmission allows remote monitoring and real-time analysis of FITC-sinistrin excretion as a marker of renal function. Due to miniaturization, the whole device fits on the back of freely moving rats, and requires neither blood sampling nor laboratory assays. As proof of principle, comparative measurements of transcutaneous and plasma elimination kinetics of FITC-sinistrin were compared in freely moving healthy rats, rats showing reduced kidney function due to unilateral nephrectomy and PKD/Mhm rats with cystic kidney disease. Results show highly comparable elimination half-lives and GFR values in all animal groups. Bland-Altman analysis of enzymatically compared with transcutaneously measured GFR found a mean difference (bias) of 0.01 and a 0.30 to 0.33 ml/min per 100 g body weight with 95% limit of agreement. Thus, with this device, renal function can be reliably measured in freely moving rats eliminating the need for and influence of anesthesia on renal function. © 2011 International Society of Nephrology.


Baaser H.,Freudenberg Forschungsdienste KG | Schobel A.,RWTH Aachen | Michaeli W.,RWTH Aachen | Masberg U.,RWTH Aachen
KGK Kautschuk Gummi Kunststoffe | Year: 2011

For the efficient dimensioning of elastomer parts the structural simulation by means of Finite Element Analysis (FEA) has developed to be an indispensable tool. For the calibration of these models often only uniaxial tensile tests are conducted to estimate the material parameters. However since technical elastomer parts are usually multiaxially loaded, the accomplishment of multiaxial material testing for a precise structural simulation is essential. Different approaches for the testing of the equibiaxial tensile load condition, which can be easily converted into a pressure load condition, exist at Freudenberg Forschungsdienste (FFD) as well as at the Institute of Plastics Processing (IKV). Despite the differences at (FFD) and at the IKV in the basic principles and the mechanical set-up of both methods, comparable material answers for this load condition can be determined.


Pazur R.J.,Freudenberg Nok General Partnership FNGP | Pazur R.J.,Quality Engineering Test Establishment | Lee D.,Freudenberg Nok General Partnership FNGP | Walker F.J.,Freudenberg Nok General Partnership FNGP | Kasai M.,Freudenberg Forschungsdienste Kg
Rubber Chemistry and Technology | Year: 2012

A series of compounds based on peroxide-cured EPDM were prepared with varying amounts of paraffinic plasticizer and carbon black. Modeling of the NMR relaxation signal was successfully carried out by either a biexponential or triexponential fitting procedure. It was found the degree of plasticization correlated directly with the average molar mass between chain entanglements (M e) calculated from the short decay constant T 21. Values of M e correlated to the dynamic properties (storage modulus and tan δ) in the unvulcanized state, thus providing a measure of processability. An increase in carbon black concentration brought about a decrease in M e because of increased interactions between the filler and the polymer chain. A new parameter M chain-filler is introduced to estimate the average molar mass between polymer chains and fillers. Compared with the chain entanglement density, the overall magnitude of this interaction appears to be weak in the mobile zone of the compound matrix. As in the case of plasticization, a relatively good correlation is obtained betweenMe and the dynamical properties in the unvulcanized state. Compression-set resistance is shown to directly follow the average molar mass between cross-links (M c) before and after aging. The carbon black study results can be understood within the context of a morphological model containing different zones of chain mobility-a thin shell of immobilized chains, an intermediate zone of limited mobility, and a dominant mobile phase consisting mainly of entangled and cross-linked polymer chains.


Baaser H.,Freudenberg Forschungsdienste KG | Hopmann C.,RWTH Aachen | Schobel A.,RWTH Aachen
Archive of Applied Mechanics | Year: 2013

The description of (quasi-)incompressible materials such as elastomers is well established in modern continuum mechanics for many years now as well as from a theoretical background as in the numerical implementation in commercial software packages in the context of finite elements. Nevertheless, some questions arise in the practical application of that matter describing technical components, e.g., in the discussion What are valid equivalent measures in order to compare different deformations? Here, one could request for expressions that arise in a deformation intensity and an indication of the deformation mode locally at each material point. We propose an extension of the well-known description of incompressible kinematics. We reformulate the strain invariants at incompressibility in terms of (I 1, I 2) leading to an equivalent pair (λ, m) in order to determine a distance of an arbitrary deformation state, e.g., to its equivalent shearing state. Therefore, we postulate and define an associated deformation state and give the mathematical derivation of quite nice relationships, which we demonstrate on a shear example using the finite elements method to visualize the "new" measure quantity. © 2012 The Author(s).


Losel R.,RWTH Aachen | Grafahrend D.,Freudenberg Forschungsdienste KG | Moller M.,RWTH Aachen | Klee D.,RWTH Aachen
Macromolecular Bioscience | Year: 2010

For the reconstruction of functional tissue, biodegradable scaffolds providing specific surface functionality and a three-dimensional structure matching that of the damaged tissue are needed. Fibers capable of controlling cell-fiber interaction were produced by electrospinning of PDLLA-block-PEG with thiol-reactive end groups from a solvent mixture. The hydrophilic fibers uniquely combine minimized non-specific protein adsorption and well-defined surface reactivity allowing controlled immobilization of peptides and proteins. Human dermal fibroblasts show adherence and proliferation on the surface of RGDC-functionalized electrospun PDLLA-block-PEG fibers.Human dermal fibroblasts show adherence and proliferation on the surface of RGDC-functionalized electrospun PDLLA-block-PEG fibers. Electrospinning of PDLLA-block-PEG with thiol-reactive end groups from a suitable solvent mixture results in formation of fibers that are resistant towards protein adsorption and that can be functionalized with bioactive compounds taking advantage of their well-defined surface reactivity. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Mehling V.,Freudenberg Forschungsdienste KG | Baaser H.,Freudenberg Forschungsdienste KG | Hans T.,TU Munich
Constitutive Models for Rubber VII - Proceedings of the 7th European Conference on Constitutive Models for Rubber, ECCMR | Year: 2012

Shortening product life-cycle times, the demand for more intense loading and at the same time for more reliable operation call for generally applicable tools for the evaluation of the life-time of dynamically loaded rubber products. Today, engineers apply more or less sophisticated procedures to estimate the life-time of components. All of these procedures rely on an initial choice of a measure of fatigue loading, the so-called damage variable. This choice may be as simple as the global deformation of a component. More advanced methods require local damage variables, e.g. stress-or strain-measures as well as energy variables or quantities motivated by fracture mechanical approaches. However, it turns out, that some of these variables are only valid for certain applications and fail in general. Damage variables from fracture mechanics yield the most general approach to fatigue evaluation, although their practical computation is challenging. This paper is dedicated to the discussion of local damage variables and to a better and more differentiated understanding of the behavior of small cracks under complex loading conditions. © 2012 Taylor & Francis Group.


Staub P.,Klüber Lubrication | Kuhn M.,Klüber Lubrication | Schweigkofler M.,Klüber Lubrication | Orendorz A.,Freudenberg Forschungsdienste KG
17th International Colloquium Tribology 2010 - Solving Friction and Wear Problems | Year: 2010

Lubricants with suitable EP/AW additives reduce wear in rolling bearings and other machine elements subject to mixed friction. The effect of such additives depends on the conditions existing on the interacting surfaces. The aim of the tests described in the following was to determine the additives' reactivity under various kinds of motion. For this purpose, several surface-active additives were tested under motion conditions such as oscillating-sliding, oscillating-rolling-sliding and continuously sliding. As a result, strengths and weaknesses of additive groups under the tested contact conditions and the extent to which the test benches used are suitable for the evaluation of additives were identified.


Bossuyt F.,Ghent University | Guenther J.,Freudenberg Forschungsdienste KG | Loher T.,TU Berlin | Seckel M.,TU Berlin | And 2 more authors.
Microelectronics Reliability | Year: 2011

Stretchable electronic circuit boards have been developed based on three different technologies. Such substrates serve to connect rigid interposers or electronic components. The conducting traces have a meandering shape and consist of Cu-foil or screen-printed Ag-paste. These conducting traces are attached to or embedded in polyurethane, polydimethylsiloxane, or breathable non-woven stretchable substrate material. The long-term endurance behavior of this novel type of boards is studied by cyclic elongation at strain ranges of up to 20% and monitoring the electrical connectivity. The main failure mode in the Cu-foil based technologies is fatigue of the conducting traces and can be described in terms of the Manson-Coffin relation. Indications for high-cycle fatigue were found. The screen-printed conductors on non-woven substrates fail by breaking of the connection between the metallic grains. The application areas are electronic monitoring systems that need to be placed directly on the skin, or conformable systems for curved surfaces. © 2010 Elsevier Ltd. All rights reserved.

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