Method for measuring liquid viscosity in capillary tube based on micro volume sample measurement

Abstract

The invention discloses a method for measuring the liquid viscosity in a capillary tube based on micro volume sample measurement, comprising the following steps of: filling the flow path with the flowing medium and then introducing the sample fluid, which is pushed by the flowing medium through the capillary tube; setting the volume V of the injection liquid to be larger than the volume Vc of thecapillary tube when the viscosity of the sample fluid is small or the sample fluid is compressed under high pressure so that the reduced volume thereof is negligible; and performing multiple injections and ensuring that the volume V of each injection liquid is smaller than the volume Vc of the capillary tube when the viscosity of the sample fluid is large and the sample fluid is compressed under high pressure but the reduced volume is not negligible. According to the method for measuring the liquid viscosity in a capillary tube based on micro volume sample measurement, the consumption of the sample is reduced by the setting of the flowing medium; the viscosity of the sample can be calculated without standard sample calibration, which also contribute to the consumption reduction of the sample; the sample consumption of the invention is small, thereby facilitating the testing of the micro volume sample and broadening the test range of the sample; and the method is suitable for the viscosity determination of non-Newtonian fluids and is excellent in practicability.

Description

technical field [0001] The invention belongs to the technical field of liquid viscosity measurement, in particular to a capillary viscosity testing method based on micro sample measurement. Background technique [0002] Viscosity is an important physical parameter of fluid. Common viscometers include rotational viscometer, falling ball viscometer, vibrating viscometer, capillary viscometer, etc. The first three methods use the movement resistance of the fluid to achieve viscosity measurement, which requires a large amount of samples and complicated viscosity calculation methods. The most widely used capillary viscometer is represented by the Ubbelohde viscometer. Its working principle is to count the liquid flow at both ends of the capillary with constant pressure difference, that is, the constant pressure method. It has simple structure, good precision and easy operation, and is widely used in the viscosity detection of polymer solutions, blood plasma, gasoline, diesel and...

AI Technical Summary

Problems solved by technology

However, the temperature control generally uses a water bath, which is bulky, slow to rise and fall in temperature, and the test takes a long time and manual operation is complicated. The most critical thing is that it is impossible to measure the viscosity of non-Newtonian fluids (viscosity changes with flow rate) at different shear rates.

The constant rate capillary method for measuring viscosity is more common in polymer rheometers. Although it can measure the viscosity of non-Newtonian fluids at different shear rates, its structure is complex, bulky, consumes a lot of samples, and it is difficult to clean after use.

[0003]The biggest drawbacks of existing viscosity detection methods are that the required sample volume is large, the temperature control is not precise enough, the non-Newtonian fluid cannot be measured, and the detection efficiency is low

At present, there is no fluid viscosity detection equipment that can accurately and quickly measure a small amount or even a small amount (<1ml) of samples, especially for the viscosity measurement of non-Newtonian fluids at different shear rates, there is still a blank

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