Spray and Yay!
The Büchi S-290 mini spray dryer can be used to produce powders with a defined particle size from aqueous or organic solutions and dispersions. The efficiency and reproducibility of the S-290 offer the working group the opportunity to advance basic research and application-orientated projects in equal measure.
New PhD Student
Fabian Weitenhagen joined our team in the field of bio-based building materials in December. He is continuing his research into bio-based polycondensation resins and is building on the results of previous work. He is also developing innovative bio-based composites to promote sustainable solutions for the construction industry.
New PhD Student
In April, we welcomed Tim Mrohs to the gels department. As part of his dissertation, he is researching hydrogels based on highly alkaline diallyldimethylammonium hydroxide (DADMAOH) for use in building preservation. He is focussing in particular on the development of alkali-stable crosslinkers and the formulation and investigation of molecular gel network structures. We wish him every success in his research and welcome him to the working group.
New publication:
Duroplasts with a difference
Nature avoids highly reactive functional groups, such as isocyanate and epoxy, by using highly specialised enzymes as catalysts in condensation reactions. Consequently, bio-based raw materials require in vitro reaction conditions that are often difficult to reconcile with the requirements for thermoset resins. In addition, condensation reactions release small molecules (often water), which leads to the formation of foams under standard reaction conditions. It would therefore appear that natural building blocks would not be suitable for the production of thermosetting resins.
We show here that the addition of chopped feathers prevents the previously reported foaming of highly cross-linked combinations such as citric acid/glycerol, increases conversion and improves flame retardant properties.
M. Brenner, C. Popescu, O. Weichold
Anti-Frothing E ffect of Poultry Feathers in Bio-Based, Polycondensation-Type Thermoset Composites
Appl. Sci. 2020, 10, 2150; https://doi:10.3390/app10062150
Completed Master Thesis
Congratulations to Tim Mrohs on successfully completing his master’s thesis in the field of alkaline hydrogels entitled ‘Synthesis of cross-linked copolymer electrolyte gels based on diallyldimethylammonium chloride and hydroxide’.
Hot Affair
The physical and chemical properties of materials can be modified in a targeted manner through the simultaneous application of temperature and pressure. Our Collin type 300 P heating press, which operates at temperatures of up to 300 °C and pressures of up to 300 kN, is particularly suitable for the precise processing and compression of materials such as thermoplastics, bonding or for the production of composite materials. A variety of three-dimensional target geometries are possible.
Getting in the Flow
To characterise and optimise the rheological properties of our materials, we have put the state-of-the-art MCR 102 rheometer from Anton Paar into operation. This precision instrument makes it possible to analyse the flow and deformation behaviour of a wide range of materials with the utmost accuracy.
Thanks to its outstanding measuring precision and versatile configuration options, the rheometer forms an ideal basis for the further development of our innovative material solutions. It helps us to precisely determine viscosity, yield points and elastic properties – essential for the development and processing of modern, sustainable materials.
Totally Extruded with Excitement!
We have commissioned a Haake kneader-extruder for the further development and precise processing of our bio-based materials. With its robust design and flexible configuration, it enables optimum mixing and extrusion of a wide range of material combinations. Torque guaranteed.
The Haake Kneader-Extruder offers excellent control over the process, which is particularly important for the development of new, sustainable building materials. Its adaptability allows us to efficiently test and further develop a wide variety of formulations.
Now the heat is on
To precisely analyse the thermal properties of our bio-based materials, we have purchased the TGA 4000 from PerkinElmer. This sophisticated device enables precise thermogravimetric analysis (TGA) and provides valuable insights into the decomposition and stability of materials.
A particular highlight of the TGA 4000 is the optional IR coupling, which allows us to analyse the gases released during the analysis process in real time. This extension enables us to understand the chemical reactions and decomposition mechanisms even more precisely and to carry out further research.
New publication:
Gentle dissolution of chitosan
Despite its very low pKa value, hydrochloric acid is one of the most commonly used acids in the production of chitosan hydrogels for biomedical applications. Although hydrochloric acid is widely used, the occurrence of unwanted depolymerisation in the production of hydrogels from chitosan hydrogels is often disregarded. In order to fully exploit the potential of chitosan as a renewable resource, a new, very mild method for the preparation of chitosan solutions is described here.
These solutions dry to clear, transparent films that remain completely water soluble and absorb up to 70 wt% water from the water in the 90 % RH vapour phase at 25 °C. Absorption follows simple first-order kinetics and the rate constants The rate constants increase with increasing humidity up to about 71 % RH, where a metastable chitosan trihydrate salt appears to be formed. Desorption is slightly faster, but more complex, as it involves two different first-order processes. In addition, the films produced in this way are thermally more stable than the usual chitosan hydrochloride.
M. B. Endres, O. Weichold
Sorption-active transparent films based on chitosan
Carbohydrate Polym. 2019, 208, 108–114. https://doi.org/10.1016/j.carbpol.2018.12.031
