Earlier Research Projects

Catalytic bleach processes
(T. Topalovic, V.A. Nierstrasz and M.M.C.G. Warmoeskerken)
The goal of this project is to focus on the potentials of different innovative oxidative catalysts, redox-mediator systems and enzymes for the industrial bleaching of cotton fabrics. Environmentally friendly processes on the basis of oxidative catalysts can accomplish low temperatures (e.g. 40°C) and short residence time and therefore result in a dramatic decrease in energy consumption with significant reduction of chemicals and water compared to the conventional process. Our primary aim within this project is to delineate mechanisms, and in particular the factors governing reactivity and catalysis. For that the project extends the investigation by examining the reaction mechanisms of the catalytic hydrogen peroxide oxidation of cotton pigments and model compounds in a homogeneous model system. Model compounds, mostly polyphenolic compounds, should be well characterised and chosen in the way to adopt the structural motifs of pigments giving the colour to the cotton fibre. Using advanced analytical techniques this approach allows us to study reaction kinetics and analyse the nature of active bleaching species, reaction intermediates and products. Like this, by excluding transport phenomena and with the assumption that the mechanism of oxidation of pigments that are present in cotton fibre is similar to that in a homogeneous system, it is possible to provide direct information about kinetics and reaction mechanisms at molecular level and a comparison of structure-reactivity towards catalytic oxidation relationships of a series of polyphenolic substrates.

Enzymatic improvement of the properties of recycled paper fibres
(V.A. Nierstrasz and M.M.C.G. Warmoeskerken)
There is a continuous demand to increase the percentage of recycled fibres in the recycled-paper process. The main obstacles are a loss of fibre properties, a reduced drainage rate on the paper machine and a high amount of fines. The markets as well as requirements for environmentally friendly production is forcing pulp and paper producers to continuously look for more selective processes. Enzyme technology seems to be the method of choice. The aim of this project is to improve the properties of recycled-paper fibres using enzymes. Properly applied, enzymes (and specifically cellulases) can enhance or restore paper strength, reduce beating times and increase inter-fibre bonding through fibrillation. In order to study the mechanism and the kinetics of the reaction and the main parameters that are affecting the cellulase performance a model substrate has been selected. In order to decide if the enzymatic treatment is effective or not the standard properties of fibres will be tested. A systematic analysis will determine which parameters are key in the papermaking process.

Mechanisms and kinetics of textile wetting
(V.A. Nierstrasz and M.M.C.G. Warmoeskerken)
The general aim is to generate new knowledge and to develop technologies to create materials with unique surface properties and functionalities. Surface properties of engineered surfaces are affected by chemical composition, surface topography and the combination of the two. Functionality of textile materials depend on the dynamic behaviour of liquids at the surface. Textiles with advanced wetting properties can be based on nanoscale surface structures and (physisco-chemical) functionalities found in nature. The desired functionality of the material will be related to material properties, surface characteristics and processing. Models and methodologies will be developed to establish the interrelationships.

Hydrodynamics in textile materials
(M.M.C.G. Warmoeskerken)
In all wet textile processes, the flow through the porous material is the key phenomenon. Despite of that little is known about flow phenomena in textiles. This project is aimed at gaining more and better knowledge of the hydrodynamics in porous textile structures. The textile material has been characterised in terms of a bi-porous medium. A theory based on a combination of Darcy flow and orifice models has been developed and validated by model experiments. This work has been resulted in a PhD-thesis. The work will be continued with emphasis on LDA and the application of numerical techniques like CFD and lattice Boltzman.

Enzymatic modification of synthetic materials
(V.A. Nierstrasz, P.B. Agrawal and M.M.C.G. Warmoeskerken)
The potential of enzymes like cutinases have been evaluated for surface modification of the persistent synthetic polymer poly(ethylene terephthalate), the most important synthetic fiber in the textile industry. The aim of the surface modification is to improve the hydrophilicity of the polymer and to facilitate functionalsation, and not to change the bulk properties. The most conventional, and industrially most common, way of rendering polyester hydrophilic is an alkali treatment, thus hydrolyzing the polyester bonds. Although hydrophilicity is achieved, the favorable bulk properties of polyester, particularly the strength, are also affected. Furthermore, the high amount of NaOH and the high operating temperatures necessary are a disadvantage. An environmentally more benign process is therefore desirable.

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Home Staff Publications Research Foundation for Engineering of Fibrous Smart Materials Sitemap Search Print version	Earlier Research Projects Catalytic bleach processes (T. Topalovic, V.A. Nierstrasz and M.M.C.G. Warmoeskerken) The goal of this project is to focus on the potentials of different innovative oxidative catalysts, redox-mediator systems and enzymes for the industrial bleaching of cotton fabrics. Environmentally friendly processes on the basis of oxidative catalysts can accomplish low temperatures (e.g. 40°C) and short residence time and therefore result in a dramatic decrease in energy consumption with significant reduction of chemicals and water compared to the conventional process. Our primary aim within this project is to delineate mechanisms, and in particular the factors governing reactivity and catalysis. For that the project extends the investigation by examining the reaction mechanisms of the catalytic hydrogen peroxide oxidation of cotton pigments and model compounds in a homogeneous model system. Model compounds, mostly polyphenolic compounds, should be well characterised and chosen in the way to adopt the structural motifs of pigments giving the colour to the cotton fibre. Using advanced analytical techniques this approach allows us to study reaction kinetics and analyse the nature of active bleaching species, reaction intermediates and products. Like this, by excluding transport phenomena and with the assumption that the mechanism of oxidation of pigments that are present in cotton fibre is similar to that in a homogeneous system, it is possible to provide direct information about kinetics and reaction mechanisms at molecular level and a comparison of structure-reactivity towards catalytic oxidation relationships of a series of polyphenolic substrates. Enzymatic improvement of the properties of recycled paper fibres (V.A. Nierstrasz and M.M.C.G. Warmoeskerken) There is a continuous demand to increase the percentage of recycled fibres in the recycled-paper process. The main obstacles are a loss of fibre properties, a reduced drainage rate on the paper machine and a high amount of fines. The markets as well as requirements for environmentally friendly production is forcing pulp and paper producers to continuously look for more selective processes. Enzyme technology seems to be the method of choice. The aim of this project is to improve the properties of recycled-paper fibres using enzymes. Properly applied, enzymes (and specifically cellulases) can enhance or restore paper strength, reduce beating times and increase inter-fibre bonding through fibrillation. In order to study the mechanism and the kinetics of the reaction and the main parameters that are affecting the cellulase performance a model substrate has been selected. In order to decide if the enzymatic treatment is effective or not the standard properties of fibres will be tested. A systematic analysis will determine which parameters are key in the papermaking process. Mechanisms and kinetics of textile wetting (V.A. Nierstrasz and M.M.C.G. Warmoeskerken) The general aim is to generate new knowledge and to develop technologies to create materials with unique surface properties and functionalities. Surface properties of engineered surfaces are affected by chemical composition, surface topography and the combination of the two. Functionality of textile materials depend on the dynamic behaviour of liquids at the surface. Textiles with advanced wetting properties can be based on nanoscale surface structures and (physisco-chemical) functionalities found in nature. The desired functionality of the material will be related to material properties, surface characteristics and processing. Models and methodologies will be developed to establish the interrelationships. Hydrodynamics in textile materials (M.M.C.G. Warmoeskerken) In all wet textile processes, the flow through the porous material is the key phenomenon. Despite of that little is known about flow phenomena in textiles. This project is aimed at gaining more and better knowledge of the hydrodynamics in porous textile structures. The textile material has been characterised in terms of a bi-porous medium. A theory based on a combination of Darcy flow and orifice models has been developed and validated by model experiments. This work has been resulted in a PhD-thesis. The work will be continued with emphasis on LDA and the application of numerical techniques like CFD and lattice Boltzman. Enzymatic modification of synthetic materials (V.A. Nierstrasz, P.B. Agrawal and M.M.C.G. Warmoeskerken) The potential of enzymes like cutinases have been evaluated for surface modification of the persistent synthetic polymer poly(ethylene terephthalate), the most important synthetic fiber in the textile industry. The aim of the surface modification is to improve the hydrophilicity of the polymer and to facilitate functionalsation, and not to change the bulk properties. The most conventional, and industrially most common, way of rendering polyester hydrophilic is an alkali treatment, thus hydrolyzing the polyester bonds. Although hydrophilicity is achieved, the favorable bulk properties of polyester, particularly the strength, are also affected. Furthermore, the high amount of NaOH and the high operating temperatures necessary are a disadvantage. An environmentally more benign process is therefore desirable.