Method for the rheological characterisation of a complex medium
AssigneeFormulaction
InventorLaurent Brunel
Life of this patent
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Abstract
A method for quantitatively determining the viscoelastic properties of a complex medium with suspended particles in suspension, which involves: characterizing the medium opacity by measuring the medium's transport length l*; introducing a sample of the medium into a flask; placing the flask in a thermostatically-controlled measuring chamber; projecting a coherent light beam on the sample and detecting scattered light as a series of sequenced images; analyzing the movement of particles based on time by calculating the inter-image distance d2 and the ratio d2/d2max; and establishing an analytical expression E putting into direct relationship, the measured l*, the ratio d2/d2max and the mean square displacement MSD for the purpose of calculating the medium's viscous and elastic moduli.
Claims17
Method for determination of the viscoelastic properties of a complex medium starting from the movement of particles in suspension, in which a sample of the medium is placed in a device for measuring the light that is scattered by the particles in suspension, able to project a coherent light on said sample, and to detect and analyze the scattered light for calculating the inter-image distance d2, characterized in that it comprises the stages that essentially consist in:
- a) Characterizing the opacity of the medium by measuring the transport length l* of said medium,
- b) Introducing a sample of said medium into a flask of given dimensions,
- c) Placing the flask in a thermostatically-controlled measuring chamber (1) of said measuring device,
- d) Projecting a coherent light beam on the sample and detecting the light that is scattered by the particles in the form of a series of sequenced images,
- e) Analyzing the movement of the particles based on time by calculating the inter-image distance d2 and the ratio d2/d2max, d2max denoting a maximum value towards which d2 converges asymptotically,
- f) Establishing an analytical expression E putting into direct relationship, for the value of l* that is determined in stage a), the ratio d2/d2max and the mean square displacement MSD for the purpose of calculating the viscous and elastic moduli of the medium.
Device for determining viscoelastic properties of a complex medium starting from the movement of particles in suspension, comprising means for projecting a coherent light on said medium and means for detecting and analyzing the scattered light for calculating the inter-image distance d2, wherein it comprises:
- An optical module (5) that comprises, on the one hand, a coherent light source (6) that is able to project a beam to a sample of the medium that is to be analyzed, and, on the other hand, means (7) for detection of the scattered light by said medium, in the form of successive matrix images, whereby said means are combined with a unit for image analysis that is able to provide values of the inter-image distance of the sample,
- A thermostatically-controlled measuring chamber (1) that is equipped with at least one housing (4) that is able to accommodate a flask of given dimensions that contains a sample of said medium, at a suitable distance from said optical module,
- Means for recording and processing data, comprising means for acquisition of values of l* that characterize the opacity of the media to be analyzed, means for analysis and calculation that are able to put into direct relationship, for a value of l*, the ratio d2/d2max, d2max denoting a maximum value towards which d2 converges asymptotically, and the mean square displacement MSD, for the purpose of calculating the viscous and elastic moduli of the medium.
Dependencies are inferred from the claim text.