Rheology is the study of the flow of matter. Acting of external force (shear stress times shear area) on a material causes its flowing (deformation). The measure of this external force and the rate of deformation is so-called shear viscosity characterising the measure of internal fluid friction. Based on shear viscosity, the materials can be divided into two basic groups – Newtonian and non-Newtonian. Newtonian materials are such materials whose shear viscosity does not change with changing of the shear rate at a given temperature. On the other hand, the viscosity of non-Newtonian liquid (e.g. ketchup, mayonnaise, blood) is dependent on the shear rate. The non-Newtonian liquids can be further divided into plastic, pseudo-plastic and dilatant.
The rheological group at the Institute of Hydrodynamics studies non-Newtonian liquids, mainly the polymeric materials. These materials exhibit strong nonlinear rheological properties caused by their viscous and elastic effects. The knowledge of the rheological properties of the polymeric materials plays an important role for the producers and manufacturers of the materials and also for the tool and device makers. For the producers of the materials, the rheological properties (shear and elongational) are essential guideline for proposing of new materials (homopolymers, copolymers) with a specific properties suitable for a given process (extrusion, injection moulding, thermoforming, blow moulding) or product (pressure tubes, artificial joints). For the manufactures, the knowledge of material rheology is essential for the proper process conditions (temperature, pressure, cooling rate, etc.). The rheological properties of the materials are also important for the tools makers due to the possibility to simulate the complex flow situations in 3D simulating software.
Based on these needs given mainly by the development of new materials and by the processing, our group deals with the topics specified below.
Electro-rheological and magneto-rheological properties of polymers
Modelling of rheological properties of polymeric materials
Relation of sensory analysis and rheology of cosmetic materials
Properties and vapour permeation through polymer composites with carbon nanotubes and biocompatibility of polymer nanoparticles
Cooperation of IH and AGH University of Science and Technology (Poland) within COST Actions
Zuzanna Krysiak, a PhD student from Cracow, Poland, succeeded in applying for a short term scientific mission within COST Action "European Network to connect research and innovation efforts on Advanced Smart Textiles” CA17107. She had been working at the Institute of Hydrodynamics under a supervision of Ing. Petra Peer, Ph.D., for 3 weeks. This cooperation has lead to publishing a paper in the ACS Applied Bio Materials Journal.
Characterization of different oils can bring new solutions for atopic skin treatment using fibers patches and natural moisturizers. For example, the application of sunflower oil is widely known, but there is no research on other oils and their usage in textile treatment for atopic dermatitis.
Among many polymers used poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVB), which has good elasticity and optical transparency, was not investigated for medical applications in the form of electrospun fibers. Therefore, the goal of the study was to characterize different oils and then investigate their behavior on electrospun PVB fibers.
ZUZANNA KRYSIAK is a PhD student working on the project Nanofiber-based sponges for atopic skin treatment (Nano4Skin) at AGH University of Science and Technology (Cracow, Poland). The aim of her PhD thesis is to produce electrospun polymer fibers and assess viability and cell interactions with produced structure; and also to find and characterize oils which can be used for atopic skin as textile based treatment.