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Reologie & Viscositeit
Reologie, waaronder viscositeit, bestudeert de stromingseigenschappen en vervorming van materialen. De reologie beschrijft de relatie tussen de opgelegde spanning (of kracht) op een materiaal en de vervormingen die daardoor teweeggebracht worden. Bedrijven en onderzoeksinstellingen zijn om verschillende redenen geïnteresseerd in de reologische eigenschappen van grondstoffen die worden verwerkt in producten en eindproducten. Reologische eigenschappen hebben invloed op alle stadia van het materiaalgebruik in de industrie, van formulering en stabiliteit tot verwerking en productprestaties.
Over ATAGO
ATAGO is een Japans bedrijf opgericht in 1940. Het bedrijf is een hoogwaardig ontwikkelaar en producent van refractometers. De basis voor de technologieën werd gelegd door uitvoerige optische studies. Later werden ook andere innovatieve producten ontwikkeld: Viscositeitsmeters en polarimeters. Sysmex is een officiële distribiteur van ATAGO.
About microrheology
Rheology is the study of flow and deformation of materials. Rheological properties, such as viscosity and viscoelasticity, can be measured from bulk sample deformation using a mechanical rheometer, or on a micro-scale using an optical technique such as Microrheology.
Microrheology involves tracking the motion of dispersed tracer particles of known size by Dynamic Light Scattering (DLS) and determining the rheological properties of the sample using the Generalized Stokes-Einstein Relation. DLS Microrheology is a passive microrheology technique, whereby the colloidal probe particles only undergo thermal fluctuations in a system at thermodynamic equilibrium.
DLS Microrheology is applicable for the rheological characterization of low viscosity and weakly-structured complex fluids, such as dilute solutions of polymers and surfactants through to concentrated protein formulations. For these types of materials, Microrheology offers significant advantages:
- Probes very high frequencies necessary for characterizing inherent short timescale, viscoelastic responses (whereas mechanical techniques are fundamentally limited by inertia).
- Only requires microliter-scale volumes for rheological characterization of materials where sample volume is limited e.g. protein-based formulations.
Applications of DLS Microrheology include:
- Rheological characterization of therapeutic proteins and biopolymer solutions.
- Viscoelastic measurements of protein solutions to assess onset of protein-protein interactions and insoluble aggregate formation
- Formulation development and screening.
- High frequency rheology of dilute systems on process-relevant timescales.
- Monitoring structure development in complex fluids with time or temperature, or structure breakdown on dilution.
Wat is rheologie (viscositeit)?
Rheology is the study of flow and deformation of materials under applied forces. The measurement of rheological properties is applicable to all materials – from fluids such as dilute solutions of polymers and surfactants through to concentrated protein formulations, to semi-solids such as pastes and creams, to molten or solid polymers. Rheological properties can be measured from bulk sample deformation using a mechanical rheometer, or on a micro-scale by using a microcapillary viscometer or an optical technique such as Microrheology.
Many commonly-used materials and formulations exhibit complex rheological properties, whose viscosity and viscoelasticity can vary depending upon the external conditions applied, such as stress, strain, timescale and temperature. Internal sample variations such as protein concentration and stability, and formulation type for biopharmaceuticals, are also key factors that determine rheological properties.
Rheological properties impact at all stages of material use across multiple industries – from formulation development and stability to processing to product performance. Examples of rheological measurements include:
- Viscosity profiling for non-Newtonian shear-dependent behavior to simulate processing or use conditions.
- Viscoelastic fingerprinting for material classification to determine extent of solid-like or liquid-like behavior.
- Optimising dispersion stability.
- Determination of thixotropy of paints and coatings for product application and final finish quality.
- Impact of molecular architecture of polymers on viscoelasticity for processing and end-use performance.
- Benchmarking Food and Personal Care products for ability to pump or spread.
- Full cure profiling for bonding or gelling systems.
- Preformulation screening for therapeutics, particularly biopharmaceuticals.
