German Textile Research Center North - West

Krefeld, Germany

German Textile Research Center North - West

Krefeld, Germany
SEARCH FILTERS
Time filter
Source Type

Grant
Agency: European Commission | Branch: FP7 | Program: CP-TP | Phase: NMP-2007-4.0-2 | Award Amount: 4.21M | Year: 2008

The goal of the project is to research and develop textile solar cells in order to get flexible photovoltaic textiles based on novel fibres allowing taking benefit from the solar radiation so as to turn it into energy. Photovoltaic solar energy is being widely studied as one of the sources of renewable energy with major application potential, being considered a real alternative to fossil fuels. Since the development of first photovoltaic cells, solar energy is being an object of continuous research focused on improving the energy efficiency as well as the structure of photovoltaic cells. Last innovations on photovoltaic technology have allowed obtaining flexible solar cells which offer a wide range of possibilities, mainly in wearable applications that need autonomous systems. The present project is in line with last developments and the target is to research on the development of flexible and textile solar cells to obtain photovoltaic textiles, which offer a range of useful applications in a variety of consumer application sectors: home textiles, sports, leisure, clothing, automotive industry For instance, solar tents and parasols with the capability of energy generation. The project research is based on the development of novel fibres with conductive properties as substrate of the structure of flexible photovoltaic cells. From the development of a conductive textile substrate, the project will focus on the research and deposition of different layers that will compose the structure of a textile photovoltaic cell. These cells will be developed with organic and inorganic semiconductive materials. The main technological innovation is based on the development of a wearable and flexible energy source directly on textile products. Fabrics with the capability of generation of clean, usable and wearable energy thanks to their sun exposure, offer a great added value.


Messik F.,University of Marburg | Oberthur M.,University of Marburg | Oberthur M.,German Textile Research Center North - West
Angewandte Chemie - International Edition | Year: 2013

Reliably stable: A dipeptide building block with fully elaborated N-acyl hemiaminal proved to be a versatile precursor for echinocandinC, a prototypical member of the echinocandin group of antimycotic drugs. This first total synthesis of an N-acyl hemiaminal-containing echinocandin is concise and highly convergent, thereby making additional derivatives easily accessible. PG=protecting group. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Bucksch A.,Technical University of Delft | Fleck S.,German Textile Research Center North - West | Fleck S.,University of Gottingen
Photogrammetric Engineering and Remote Sensing | Year: 2011

Modeling the 3D canopy structure of trees provides the structural mapping capability on which to assign distributed values of light-driven physiological processes in tree canopies. We evaluate the potential of automatically extracted skeletons from terrestrial lidar data as a basis for modeling canopy structure. The automatic and species independent evaluation method for lidar data of trees is based on the SKELTRE algorithm. The SKELTRE skeleton is a graphical representation of the branch hierarchy. The extraction of the branch hierarchy utilizes a graph splitting procedure to extract the branches from the skeleton. Analyzing the distance between the point cloud points and the skeleton is the key to the branch diameter. Frequency distributions of branch length and diameter were chosen to test the algorithm performance in comparison to manually measured data and resulted in a correlation of up to 0.78 for the branch length and up to 0.99 for the branch diameter. © 2011 American Society for Photogrammetry and Remote Sensing.


Buschmann H.-J.,German Textile Research Center North - West
Israel Journal of Chemistry | Year: 2011

Cucurbit[6]uril forms stable complexes with amine compounds in aqueous solutions. Some of the preformed complexes can be used for the synthesis of rotaxanes or polyrotaxanes. Polymers with threaded cucurbit[6]uril are also obtained from these complexes. Even by mixing a solid amino acid with solid cucurbit[6]uril a threading process takes place in the melt during the polycondensation. Structural flexible amino compounds are completely rigid after complex formation with cucurbit[6]uril. As a result, they are used as one component for the formation of polyelectrolyte layers on substrates. Furthermore some of the complexes, together with cations, are able to act as components in the formation of metal-organic networks. Spectroscopic measurements indicate a well-ordered formation of these networks. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA.


Opwis K.,German Textile Research Center North - West | Gutmann J.S.,German Textile Research Center North - West
Textile Research Journal | Year: 2011

Hydrophobins are native proteins with outstanding properties. Because of their special bifunctional molecular structure they can influence the wetting behavior of polymeric substrates. Here, the influence of thermally deposited hydrophobins on properties of various textile substrates is studied. The successful immobilization of hydrophobins can be demonstrated by a protein-selective color reaction with ninhydrin, which is positive even after a harsh washing and extraction procedure indicating the high permanence of the finishing process. Regarding the wetting properties, the modification of hydrophobic fabrics (demonstrated on polyethylene terephthalate) results in a significant hydrophilization, while hydrophilic textile substrates made of cotton and polyamide attain strong hydrophobic character. Moreover, the developed thermal deposition technique seems to be practical for use with coating technologies established in the textile industry and could be easily transferred to industrial praxis. Thus, non-toxic and biodegradable hydrophobins copied from nature could have great potential in textile surface modification. © The Author(s) 2011.


Opwis K.,German Textile Research Center North - West
Chemical Engineering Transactions | Year: 2010

Low-cost textile fabrics made of polyester (PET) or polyamides (PA) are alternative carrier materials for the immobilization of enzymes. With a low preparative and economic expense fabrics with a high enzyme load, a high relative activity and good permanence against enzyme desorption can be produced by photo-induced cross-linking and grafting processes using monochromatic excimer-UV-lamps. The flexible and open construction of fabrics allows a high substrate conversion. Moreover, conventional immobilization products are mostly produced as granulates or pellets, which must be filtered after the enzymatic reactions. Fabrics can be removed very quickly from the reactor without any filtration step and the solution contains no proteinous residues after the enzymatic reaction. Here, the enzyme catalase was immobilized on PET and PA fabrics by different photochemical processes. Depending on the support and the used reactive agents 20 - 70 mg enzyme per gram carrier could be fixed durably, which can be quantitatively analyzed by atomic absorption spectroscopy due to the iron content of catalase. The efficiency of the immobilization products were investigated by measuring the enzymatic decomposition of hydrogen peroxide in comparison to the free enzyme. The relative activity of the catalase after the immobilization was 5 - 20 % of the free, not fixed catalase. The immobilized enzyme showed even after 20 reuses a distinct activity and the integral activity over all reuses was nearly 3.5 times higher than the activity of the free catalase. Therefore, these promising new photo-induced immobilization techniques open widespread applications in bio-catalysis in the future. Copyright © 2010 AIDIC Servizi S.r.l.


Bahners T.,German Textile Research Center North - West
Journal of Adhesion Science and Technology | Year: 2011

Surface treatments introduce chemical modifications to the fiber surface that affect the surface free energy (SFE). This is done either with the obvious aim to change the wetting behavior, or to affect related properties, such as, e.g., adhesion phenomenon, surface conductivity, adsorption of proteins, etc. On planar substrates, the measurement of contact angles of specific liquids and making use of formalisms such as Neumann or Owens-Wendt equations is a commonly used approach to determine the surface free energy. It is to be observed that this direct approach is often and lightheartedly applied to porous and textured samples, such as textiles, too. The geometry of a textile is extremely complex and defined by the topography of the fiber, the construction of the yarn, and the construction of the fabric. In addition, polymer fibers may be porous and take up water from the environment. Accordingly, wetting is the result of simultaneous spreading on a rough surface, penetration, and capillary motion in the multi-porous system. Therefore, the critical consideration of any analytical method for wettability measurements cannot be overemphasized, and the present paper is meant to critically discuss the pros and cons of various methods common to the textile researcher. It can be summarized that contact angles can be useful for comparative measurements on hydrophobic samples, while the established drop penetration tests characterize the effects of fabric finishing, fiber surface modifications, etc. with limited quantification. By no means can these test be used to derive the SFE, and in all cases it is essential to avoid accidental distortions of the fabric. The single fiber micro-Wilhelmy method can be regarded as the only reliable method to obtain advancing and receding contact angles. © Koninklijke Brill NV, Leiden, 2011.


Netravali A.N.,Cornell University | Bahners T.,German Textile Research Center North - West
Journal of Adhesion Science and Technology | Year: 2010

Obtaining good bonding between two dissimilar materials is critical for several aspects in textile finishing, processing and application, including the durability of common textile finishes and fabric coatings, and the performance of fiber reinforced composites. Both functional properties and long term performance are dependent on the effective adhesion between the fiber on one hand and finishing agent, coating polymer or resin on the other. It is generally accepted that good adhesion is achieved through covalent chemical bonding, acid-base interactions or hydrogen bonding, surface energies that favor complete wetting of the fibers, large specific surface area of fibers, and surface roughness that allows lock and key type mechanical bonding. In practice, various surface treatments have been applied to fibers to alter their surface characteristics and to improve their adhesion properties. For example, chemical modifications such as acid oxidation, corona or plasma pre-treatments have been commonly employed. This paper aims to provide some insight into photon-based processes which, depending on the spectral range of radiation and the characteristics of the radiation sources, can be used to bring about chemical as well as morphological changes to fiber surfaces. We have considered two major applications of surface modification; (1) textiles for improving adhesion to finishes and (2) fiber/resin adhesion enhancement in fiber reinforced composites to improve their mechanical properties. The technical approaches cover photo-chemical surface modification and micro-roughening of fiber surfaces using monochromatic UV lamps and pulsed UV excimer lasers. © 2010 Koninklijke Brill NV, Leiden.


Ameri Dehabadi V.,German Textile Research Center North - West | Buschmann H..-J.,German Textile Research Center North - West | Gutmann J.S.,German Textile Research Center North - West
Coloration Technology | Year: 2013

In this study, polyamino carboxylic acids have been used to improve the dyeability of cotton in a salt-free reactive dyeing process. These polyamino carboxylic acids were prepared by partial carboxylation of polyvinylamine. Cotton fabric was pretreated with polyamino carboxylic acids and dyed with reactive dyes. The colour strengths of the dyed fabrics were evaluated by measuring the K/S values. The fastness properties (washing, rubbing and light fastness) of the dyed cotton fabrics were also measured. The pretreatment of cotton with polyamino carboxylic acids creates positive charges on the fabric surface. In this way, salt-free reactive dyeing of cotton or dyeing with only a small amount of electrolyte is possible. © 2013 The Authors. Coloration Technology © 2013 Society of Dyers and Colourists.


Opwis K.,German Textile Research Center North - West | Wego A.,German Textile Research Center North - West | Bahners T.,German Textile Research Center North - West | Schollmeyer E.,German Textile Research Center North - West
Polymer Degradation and Stability | Year: 2011

A new photochemical method for a permanent flame retardant finishing of textiles made of cotton (CO), polyamide (PA) and polyester (PET) is described. Using a mercury vapour UV lamp vinyl phosphonic acid (VPA) can be fixed durable to different fabrics made of CO, PA and PET in the presence of a cross-linking agent and a photo-initiator. After a home laundering cycle up to 50 wt% of the reaction mixture is retained on the fabrics and the absolute phosphorus content was found to be more than 2.0% in all investigated cases. The photochemically modified textiles showed high levels of flame retardant performance and passed a vertical flammability test for protective clothing. © 2010 Elsevier Ltd. All rights reserved.

Loading German Textile Research Center North - West collaborators
Loading German Textile Research Center North - West collaborators