Method for determining density of sample which is at least viscous and is specifically liquid

Abstract

To provide a method for determining density of a sample which is at least viscous and is specifically liquid by using a rotary rheometer.SOLUTION: A rheometer 100 includes: a first measurement unit 7 for containing a sample 12 which is at least viscous and is specifically liquid; and a second measurement unit 8 immersed in the sample 12. The first measurement unit 7 and the second measurement unit 8 are capable of making a relative motion to each other and a second measurement unit 8 has a known volume V. A method includes the steps of: measuring perpendicular resistance between measurement units 7 and 8 after the second measurement unit 8 is immersed in the sample 12, the measured perpendicular resistance corresponding to buoyance between the sample 12 and the second measurement unit 8; and calculating density of the sample 12, using the known volume of the second measurement unit 8 and the measured resistance, on the basis of the principle of Archimedes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for determining the density of at least a viscous, particularly liquid, sample using a rheometer, as described in claim 1, and to a rheometer for carrying out the above method, as described in claim 10. [Background technology]

[0002] From the prior art, various rheometers are known for determining the rheological properties of viscous, particularly liquid, samples. However, a drawback of known rheometers is that the density of the sample being tested cannot be determined in situ, that is, directly in the rheometer during the process of determining the rheological properties of the sample being tested. To determine the density of a viscous or liquid sample, it is necessary to place the sample in an external density measuring instrument separate from the rheometer. From the prior art, various density measuring instruments are known; in one example, a balance-type instrument measures the interval value when the measuring body is immersed in the liquid sample. Subsequently, it is possible to determine the density of the liquid sample based on this measured interval. However, removing the sample to be tested for density measurement afterward is only possible by interrupting the experiment in the rheometer.

[0003] The fact that the density of a viscous, especially liquid, sample cannot be measured directly in relation to or during the measurement of its rheological properties is a particularly significant drawback when determining the rheological measurement variables of the sample to be examined, for example during a test at high temperature. On the other hand, when a non-reactive substance with a chemically constant composition is heated to a high temperature, not only does a density jump occur when the substance melts, but it is also possible for the density to decrease as the temperature increases in the molten state. On the other hand, many samples not only exhibit high reactivity towards the components of the coexisting atmosphere (e.g., oxygen) at high temperature, but also towards the container material (e.g., ceramic or metal) surrounding this substance. When such reactions occur, it is often difficult to infer whether the fluctuations in the measurement signal during rheological measurement are due to the rheological properties of the sample itself, due to temperature changes, or due to chemical changes. Summary of the Invention Problems to be Solved by the Invention

[0004] Therefore, an object of the present invention is to provide a method or a corresponding rheometer that realizes a solution to this problem and enables the determination of the density of a viscous, especially liquid, sample, without the need to remove the sample from the rheometer and introduce it into an external density measuring device. Means for Solving the Problems

[0005] The present invention solves this problem by a method for determining the density of at least a viscous, especially liquid, sample using a rheometer, having the features of claim 1. In this method, the rheometer comprises a first measuring part for accommodating at least a viscous, especially liquid, sample and a second measuring part immersed in the sample, the first measuring part and the second measuring part being relatively movable with respect to each other, and the volume of the second measuring part being known.

[0006] Here, according to the present invention, the following steps are included. That is, After immersing the second measuring part into the sample, measuring the vertical resistance force between the two measuring parts, wherein the measured vertical resistance force corresponds to the buoyancy force acting between the sample and the second measuring part, and calculating the density of the sample based on Archimedes' principle using the volume of the known second measuring part and the measured vertical resistance force are included.

[0007] When the second measuring part is immersed in the sample that has been placed in the first measuring part, the second measuring part receives different buoyancy forces depending on the viscosity, especially the density of the liquid sample to be inspected. Here, while the second measuring part is being immersed in the sample, first, a resistance force acts against the displacement by the sample during immersion. After the second measuring part is immersed in the sample, only the buoyancy force within the sample acts on the second measuring part. Therefore, technically speaking, the density of the sample can be measured using the buoyancy force of the measuring part having a known volume of the liquid or viscous sample, or can be determined using the measured vertical resistance force (Archimedes' principle in a body as stationary as possible). This advantageously enables continuous density measurement of viscous, especially liquid samples directly in a rheometer.

[0008] Particularly preferably, the method according to the invention is available for, for example, measuring the density of polymers, molten salts, molten metals, molten glass, lava, or clinker.

[0009] To enable inspection of the temperature dependence of density, which is particularly important for rheology experiments at high temperatures, the sample is temperature-controlled during the measurement of the vertical resistance force, specifically heated and / or cooled, and the determination of the density of the sample is repeated at different temperatures. Specifically, it is possible to be configured to heat the sample up to a temperature of 1730°C.

[0010] In this way, it is advantageous that the melting of the sample can be observed using the measured normal force, and the density jump during melting derived from this, as well as the decrease in density as the temperature rises in the molten state of substances that are unreactive at high temperatures and have a chemically constant composition, can be examined using a rheometer. Furthermore, it is possible to explain the behavior of samples that are highly reactive at high temperatures, especially with respect to components of the atmosphere coexisting in the rheometer (e.g., oxygen, inert gas, or forming gas), or samples that have temperature-dependent reactions and / or phase transitions with the measurement part material in contact with said components.

[0011] Accurate determination of the viscosity being tested, particularly the density of liquid samples, is possible if, before determining the density, the thermal expansion of the second measuring section at various reference temperatures is calculated and stored, specifically in the form of a volume correction curve or volume correction table, and then, when determining the sample density, the temperature effect on the volume of the second measuring section at each measurement temperature is corrected and / or considered based on the stored values.

[0012] This procedure also advantageously allows for correction of the effect of thermal expansion of the measurement unit on density measurements when using a measurement unit with related thermal expansion during rheological experiments performed at high temperatures in a rheometer.

[0013] To accurately determine the viscosity, particularly the density of a liquid sample being tested, it is possible to further configure the system to perform test measurements at various reference temperatures using a reference liquid whose density at a predetermined reference temperature is known, before measuring the density of the sample. This allows for determining the temperature effect on the combination of volume of the second measurement unit and normal force measurement, specifically saving this information in the form of a normal force correction curve or normal force correction table. Subsequently, when determining the density of the liquid sample, the temperature effect on the combination of volume of the second measurement unit and the measured normal force at each measurement temperature can be corrected based on the saved values.

[0014] One particular advantage is that, when calculating the viscosity, especially the density of a liquid sample being tested, it is possible to simultaneously consider the volume fluctuations and thermal expansion of the second measuring section, as well as additional effects specific to the device, such as the rigidity of the rheometer at high temperatures, and / or the expansion of the measuring axis.

[0015] To enable the determination of viscosity, particularly the density of liquid samples being tested, using a variety of methods, In a typical rheological measurement, the first or second measuring part, which rotates, is kept stationary during the measurement of the normal force, or The first or second measuring unit may be configured to rotate and / or vibrate during the measurement of the normal force.

[0016] One of the particular advantages is that, for example, it is possible to directly determine the density during a rheological vibration test in the rheometer, or to briefly interrupt a rheological rotation test in the rheometer, measure the normal force, and then resume the rheological rotation test, without having to remove the sample from the first measurement unit.

[0017] In rheological testing, particularly at each temperature during the test, it is possible to configure the system to directly obtain the viscosity, especially the accurate density, of the liquid sample being tested in a molten state, without causing distortion such as rapid cooling or removal of the sample from the rheometer. Specifically, this configuration allows for the determination of the density of the liquid sample, and simultaneously, the determination of the rheological parameters of the liquid sample, particularly viscosity.

[0018] To ensure particularly accurate determination of viscosity, and especially density, of liquid samples being tested, the system can be configured to measure the temperature of the liquid sample and / or the first and / or second measuring units, and to perform density determination only when the temperature of the liquid sample and / or the first and / or second measuring units reaches a predetermined temperature threshold.

[0019] In this way, it is possible to particularly efficiently avoid the thermal expansion of the second measuring section, or any additional effects specific to the device, from adversely affecting density measurement.

[0020] In rheological testing, particularly at each temperature in which the test is performed, in order to directly obtain the viscosity, and especially the accurate density of the liquid sample being tested, in the molten state, Before determining the density of the sample, The steps include: calculating the geometric density of at least one reference liquid from the mass of the reference liquid introduced into the first measuring unit, the position of the reference liquid's surface determined when the second measuring unit is brought closer, and the known shape of the first measuring unit, particularly at a predetermined reference temperature; In particular, the density of a reference liquid at a predetermined reference temperature is determined according to the method of any one of the preceding claims, and a correction coefficient is determined by comparing a predetermined value of the density of the reference liquid with a predetermined value of the geometric density of the reference liquid, and specifically stored in the evaluation unit. When determining the density of the sample afterward, it is possible to configure the system to correct the effect of the immersion depth of the second measuring section into the sample at each measurement temperature based on the calculated correction coefficient.

[0021] Therefore, the geometric density of at least one reference liquid is determined when positioning the second measuring unit, specifically the measuring body. For this purpose, the height or position of the sample surface in the first measuring unit is measured from the rise in normal force upon contact with the reference liquid, and the density is geometrically determined from this, the previously measured or known mass of the sample placed in the first measuring unit, and the known shape and filling height of the sample mass in the first measuring unit. According to the present invention, this initial value of geometric density is compared with the density value determined after immersion, and the difference between these values ​​is used as a correction value to further correct for the effects of the depth to which the second measuring unit is immersed in the sample, and, in some cases, the effects caused by different proportions of the measuring shaft.

[0022] To avoid that fluctuations in the immersion depth during the measurement of the normal force affect the density determined according to the present invention, the two measuring sections may be configured to maintain a substantially constant vertical distance from each other while the normal force is being measured.

[0023] The vertical distance between the two measuring parts, or the height gap, is understood below to be the distance between the first measuring part 7, i.e., the bottom of the measuring cup, and the second measuring part 8, i.e., the tip of the measuring cylinder having a flat or pointed bottom.

[0024] The object of the present invention is to provide a rheometer that enables direct measurement of density within the rheometer itself during rheological testing, eliminating the need to remove the sample from the rheometer and place it in another density measuring instrument to determine the density.

[0025] The present invention solves this problem with a rheometer for determining at least viscosity, particularly density, of a liquid sample, as described in claim 8. According to the present invention, the rheometer, specifically a rotary rheometer, comprises the following components, namely: A first measuring section for containing a liquid sample, and a second measuring section having a known volume, wherein the second measuring section is positioned on a rheometer so as to be immersed in the liquid sample, and the first measuring section and the second measuring section are positioned on the rheometer so as to be able to move relative to each other, A normal force measuring unit is positioned and configured on a rheometer to measure the normal force between two measuring units, particularly before, during, and after immersion of the second measuring unit in the sample, wherein the measured normal force corresponds to the buoyancy acting between the liquid sample and the measuring unit. The system is configured to include a control and processing unit that calculates the density of a liquid sample based on Archimedes' principle, specifically according to a method according to the present invention.

[0026] The present invention also advantageously enables the direct determination of viscosity, particularly the density of a liquid sample, by measuring the normal force in the rheometer. Therefore, it is not necessary to remove the sample from the rheometer for density determination, or the density determination can be performed independently of rheological testing.

[0027] Viscosity, especially a particularly effective test for liquid samples, When the first measuring section is configured as a measuring cup having a substantially cylindrical cross-section, The second measuring section is formed as a measuring body having a substantially cylindrical cross-section, specifically as a rheological measuring spindle, and the outer diameter of the second measuring section is smaller than the inner diameter of the first measuring section, and This can be ensured when the first and second measuring sections are arranged coaxially in a rheometer, and a measuring gap of a predetermined width can be formed between the concentric walls of the first and second measuring sections.

[0028] Such coaxial cylinder measurement systems have the advantage that the sample cannot flow out laterally, and for example, the precipitation of particles within the sample, which may occur, has little effect on the measurement results.

[0029] Precise temperature control of a sample in a rheometer is possible if the rheometer is equipped with a heating and / or cooling device for temperature control. In this way, for samples that are highly reactive at high temperatures, it is possible to examine whether fluctuations in the measurement signal are due to rheological processes, temperature fluctuations, or chemical changes.

[0030] This method not only allows for obtaining further measurement variables at high temperatures by directly measuring the density in situ, but also enables simultaneous analysis and comparison with temperature and rheological measurement variables through continuous measurement. In this way, it is possible to infer the relationship between chemical changes due to reactions with the material at the measurement site or reactions within the sample, and the resulting density changes.

[0031] The rheometer configuration according to the present invention allows for easy correction of undesirable effects, as well as the intentional induction of density changes, or the density change may be part of a high-temperature process or experiment. Technically relevant examples of density changes include redox processes in redox-sensitive solutions, such as separating natural metals (suspension) or molten metals (emulsion) from clinker in metal extraction, corrosion of refractory materials in the same, thermal degradation of glass or ionic liquids, and alloy changes due to evaporation or dissolution in the metal material of the measuring section.

[0032] The rheometer according to the present invention includes a heating and / or cooling device, In the first measuring unit, specifically, at least one Peltier element is arranged, and / or Specifically, it is formed as a temperature control cover that can be placed on both measuring units, and / or Both measuring units and the sample are formed as a convection heating chamber and / or convection cooling chamber, with the temperature controlled by gas or liquid, and / or When formed as a high-temperature furnace in which the first and second measuring sections are located, it is possible to have an extremely compact structure.

[0033] According to one effective modification of the rheometer according to the present invention, the rheometer is The device comprises at least one measuring motor having a measuring shaft, the first measuring unit or the second measuring unit being connected to the measuring shaft, and each measuring unit being capable of relative rotational and / or vibrational motion with respect to the other measuring unit. The control and processing unit is configured to define the rotational speed of the measuring motor and measure the torque generated in the measuring shaft, and / or to define the torque of the measuring motor and measure the rotational speed of the measuring motor.

[0034] According to an effective further modification of the rheometer according to the present invention, A rheometer is, The system comprises a first measuring motor having a first measuring shaft, a first measuring unit connected to the first measuring shaft, and the first measuring unit capable of rotation and / or vibration motion. The system includes a second measuring motor having a second measuring shaft, a second measuring unit connected to the second measuring shaft, and the second measuring unit capable of rotation and / or vibration motion independently of the first measuring unit. The control and processing unit is: In either case, the system is configured to measure the torque generated on the first measuring shaft and / or the second measuring shaft by defining the rotational speed of the first measuring motor and / or the second measuring motor, and / or In either case, the torque of the first measuring motor and / or the second measuring motor is defined, and the rotational speed of the first measuring motor and / or the second measuring motor is measured.

[0035] An effective modification of the rheometer according to the present invention, which allows experiments at various temperatures to be performed with particularly little effort, is available when the control and processing unit is configured to control a heating and / or cooling device.

[0036] When the control and processing unit includes a memory device, and is specifically configured to store a volume correction curve and / or volume correction table and / or normal force correction curve and / or normal force correction table, which have been determined in advance, in accordance with a method according to the present invention, particularly accurate density determination can be ensured by simultaneously and particularly easily considering additional device-specific effects that may occur during volume changes or thermal expansion and / or temperature changes in the second measuring unit.

[0037] An effective embodiment of the rheometer according to the present invention, which enables particularly accurate and minimally invasive evaluation of rheological experiments, is provided when the control and processing unit is configured to evaluate the measured values ​​obtained with respect to each measuring shaft and / or each measuring motor, in particular, simultaneously with the determination of the density of the liquid sample, and to determine at least one rheological parameter of the liquid sample, specifically its viscosity.

[0038] According to one effective modification of the rheometer according to the present invention, a normal force measuring unit is connected to a first measuring section, a further normal force measuring unit is connected to a second measuring section, and the further normal force measuring unit is preferably configured to measure the normal force between the two measuring sections simultaneously with the normal force measuring unit, particularly before, during, and after immersion of the second measuring section in the sample.

[0039] Further advantages and configurations of the present invention will become apparent from the specification and the accompanying drawings.

[0040] Exemplary embodiments of the present invention are schematically shown in the drawings and will be described below with reference to the drawings. [Brief explanation of the drawing]

[0041] [Figure 1] This figure shows a first embodiment of the rheometer according to the present invention. [Figure 2] This figure shows a second embodiment of the rheometer according to the present invention. [Figure 3] This figure shows a third embodiment of the rheometer according to the present invention. [Figure 4] This diagram shows the relationship between the density of the sample and the normal force of the rheometer measured, for various measurement section diameters. [Figure 5] This figure compares the densities of various samples determined according to the present invention with the reference values ​​for each sample. [Figure 6]This figure shows the accuracy obtained for the density of a sample measured according to the present invention using a rheometer with various measuring section diameters, for different sample densities. [Figure 7] This figure shows the accuracy obtained for the density of a sample measured according to the present invention using a rheometer with various measuring section diameters, for different sample densities. [Modes for carrying out the invention]

[0042] In the present invention, different rheometers 100 can be used or utilized. The rheometer 100 according to the present invention may be, for example, a rotary rheometer. This rheometer 100 comprises a configuration or components known from the prior art. The rheometer 100 includes, for example, a base 1, a spindle 2, a rheometer housing 3, a measuring motor 4, and a measuring shaft 14. The spindle 2 can be adjusted to a predetermined height in combination with the spindle motor 11, and other automated solutions are known that allow the spacing between the two measuring sections 7 and 8 to be changed. The rheometer housing 3 usually houses a control and processing unit. Such a rheometer 100 according to the present invention further includes a normal force F between the two measuring sections 7 and 8. N It includes at least one normal force measuring unit 5 for determining the normal force.

[0043] A rotary rheometer typically has a measuring shaft with interchangeable measuring sections, namely, a first measuring section 7 which is, for example, a measuring cup for holding a viscous, particularly liquid, sample 12 to be tested, and a second measuring section 8 which is, for example, a measuring cylinder or measuring tube that is immersed in the sample 12 during measurement.

[0044] The sample 12 to be inspected is placed in the measurement space between the first measuring section 7 and the second measuring section 8 of the rotary rheometer. During measurement, the sample 12 is sheared between the rotating or vibrating part and the stationary part of this configuration. The first measuring section 7 and the second measuring section 8 are offset from each other around a common axis of rotation during rotational motion, and the sample is subjected to a shear load as the measuring sections 7 and 8 twist relative to each other. In this case, not only rotational motion but also rotational vibration motion is possible.

[0045] The shear rate is determined from the shape of the measurement configuration and the rotational speed and / or rotational frequency of each moving measurement part. The torque generated in the sample as it counteracts this motion is measured, and based on this, shear stress, viscosity, and other rheological parameters can then be measured.

[0046] The measuring sections 7 and 8 can, in principle, have different shapes in the rheometer 100. These may be, for example, a plate / plate measuring system, a concentric cylindrical measuring system, or a cone / plate measuring system, or they may be configurations specific to different application ranges, such as measuring the immobilization reaction of a dispersion or constituent material, or electrorheological measurements. Here, during rheological measurements, the first measuring section 7 can remain stationary and the second measuring section 8 can rotate (Searle system), or vice versa (Couette system).

[0047] For example, if a second measuring unit 8, which is a simple measuring cylinder, is immersed in a sample placed inside a first measuring unit 7, which is a measuring cup, the second measuring unit 8 will experience different buoyancy F depending on the density of the sample. A To receive.

[0048] The normal force acting on the second measuring section 8 during immersion, or the increase in the first normal force, corresponds to the resistance of the sample 12 against being pushed back during immersion. Therefore, the increase in the first normal force when the second measuring section 8 collides with the sample surface can be used, for example, to determine the height of the sample.

[0049] The gap height needs to be maintained constant, and the immersed second measuring part 8 should be stationary and, for example, not twisted. Therefore, the rheometer 100 itself has high rigidity on the pedestal 1. The weight of the second measuring part 8 is recorded by the measuring motor 4 of the pedestal 1. Thus, the generated vertical resistance force F N corresponds to the buoyancy or buoyant force F A acting between the sample 12 and the measuring parts 7 and 8. That is, without applying additional pushing-back resistance, the buoyant force F A acting on the second measuring part 8 by pushing back the sample 12 according to Archimedes' principle is related to the adjustment of the fixed or constant measuring gap 13 and the constant height of the second measuring part 8 in the first measuring part 7, for example, the measuring cup, after the second measuring part 8 is immersed in the sample 12, that is, when the second measuring part 8 is in a stationary state.

[0050] The measuring gap 13 in the concentric measuring system is understood to be the interval between the substantially cylindrical planes of the measuring parts 7 and 8 that rotate relative to each other. The height gap, that is, the vertical interval or the minimum interval, between the bottom of the first measuring part 7, that is, the measuring cup, and the tip of the second measuring part 8, for example, the tip of the measuring cylinder having a flat or pointed bottom, is maintained constant in the rheometer 100, and the rheometer 100 is required to have high rigidity by the pedestal 1 and the bearings of the measuring shaft used.

[0051] Utilizing this state, in the rheometer 100, it is possible to determine the density ρ of the sample 12 according to Archimedes' principle by measuring the vertical resistance force. Here, the density ρ of the sample 12 is represented by the following relational expression or equation. m = F N / g (1) ρ = m / V (2) ρ = F N / (V * g) (3) Here, m is the mass of the sample 12, F N is the measured vertical resistance force of the sample 12, g is the acceleration due to gravity, ρ is the density of the sample 12, and V is the volume of the second measuring part 8.

[0052] This means that, according to the present invention, the rheological parameters of sample 12, such as the viscosity and density ρ of sample 12, can be measured in situ almost simultaneously using the rheometer 100.

[0053] Normal force F N Measuring the normal force F between the first measuring section 7 and the second measuring section 8 can be achieved in various ways using the rheometer 100 according to the present invention. N The precise method of measurement is not important here.

[0054] For example, as described in US 2006 / 081037 A1, a normal force measuring unit 5 may be provided for determining the normal force and / or torque generated in the measuring shaft 14 during measurement. The normal force measuring unit 5 includes a first retainer connected to the measuring shaft 14 and a second retainer securely fixed to the base. The second retainer is connected to the first retainer via spring-like connectors, and at least one of the connectors is fitted with a strain gauge capable of determining the deformation of the connector.

[0055] The normal force measuring unit 5, as in DE No. 10310676 A1, is equipped with an encoder disc extending almost perpendicular to the longitudinal axis of the measuring shaft 14, measures the axial motion of the encoder disc oriented in the direction of the longitudinal axis of the measuring shaft 14, and calculates the normal force F of the measuring shaft 14 from the measured motion of the encoder disc. N It is possible to find this.

[0056] Furthermore, the normal force measuring unit 5 may have a circular pressure sensor, as shown in DE 19632589 A1. This pressure sensor is positioned perpendicular to the axis of the measuring unit at the center of the first measuring unit 7 or the lower measuring plate, and the pressure sensor's, for example, electrical measurement signal, measures the normal force F generated in the viscoelastic sample 12 by shear in the measuring gap 13. N It is clearly associated with that.

[0057] Furthermore, the first measuring unit 7 and / or the second measuring unit 8 may be equipped with multiple normal force sensors, or a distance sensor may be provided to measure the change in the axial distance of the spring 7 connected to the second measuring unit 8. This allows the normal force F to be determined from the measurements provided by these sensors. N It is possible to calculate this.

[0058] Furthermore, the vertical force measuring unit 5 may be housed in its own housing, separate from both measuring units 7 and 8.

[0059] When conducting a rheological vibration test, the density ρ of sample 12 can be directly determined according to the present invention, and during a rotation test, the normal force F N It is sufficient to interrupt the measurement for a short time. In other words, the density ρ of the sample 12 may be measured directly in the first measurement unit 7 by briefly interrupting the rheological measurement, or it may be measured directly during the rheological measurement. In this case, it is not important which of the measurement units 7 and 8 is actually moved, or which of the two measurement units 7 and 8 is stationary, when measuring the rheological properties. What is important is simply that the measurement units 7 and 8 are in relative motion to each other.

[0060] Therefore, different principles in the rheometer 100 according to the present invention, or in the method for measuring the density ρ of at least viscous, particularly liquid, sample 12 using the rheometer 100 according to the present invention, can also be applied to measuring motors. On the one hand, for example, the rotational speed of the motor can be defined and the resulting torque can be measured. Or conversely, the torque of the motor can be defined and the resulting rotational speed can be measured. Here, the rotational speed can be measured, for example, with an angle encoder, and the torque can be determined from the power consumption. The two separate motor principles simply include a rotating motor and torque measurement.

[0061] When controlling the temperature of sample 12, it is also possible to determine the density ρ and rheological properties of sample 12 as temperature-dependent parameters.

[0062] This temperature control can be performed in various ways. For example, the first measuring section 7 may be configured as a heatable measuring cup, as described in US No. 6240770 B1 or DE No. 19911441 A1. The rheometer 100 according to the present invention may include a temperature control cover, as described in US No. 6571610 B1 or AT No. 409422 B, or it may include a high-temperature furnace for performing rheological tests. Convective heating chambers and / or convective cooling chambers for temperature control of the measuring sections 7 and 8 and the sample 12 by gas or liquid are also known. Such a system is described, for example, in AT No. 513661 B1.

[0063] For density measurement, the second measuring section 8 may have any configuration, and the weight of the second measuring section 8 plays no role because the second measuring section 8 is fixed or held vertically.

[0064] In this invention, the known volume V of the second measuring unit 8 is important. For determining the density ρ of the sample 12 according to the present invention, the volume V of the second measuring unit 8 is a known or predetermined temperature-dependent volume, and is stored, for example, in the control and processing unit. Therefore, the known volume V of the second measuring unit 8 can be read out at any time, making it possible to determine the density ρ of the sample 12, for example, during the rheological inspection of the sample 12.

[0065] The following applies depending on the density ρ of the sample 12 being evaluated. That is, the lighter the sample 12 (the smaller the density ρ), the more difficult the measurement. This is because the distinguishable buoyancy F A This is because a larger volume is required to generate it. As is clear from the above equations (1) to (3), if not only is the sample density ρ high, but the displaced volume V (volume V of the second measurement section 8) is large, the normal force signal F NIt becomes even larger. In other words, the measurable sample density or measurement accuracy can be controlled by the selection of the second measuring unit 8.

[0066] Therefore, it is possible to provide a measuring body or a second measuring section 8 having a volume V that has been accurately measured over various density ranges. The dimensions of the first measuring section 7 and the second measuring section 8 are such that for each sample 12, the normal force F N To obtain a good measurement signal, that is, buoyancy F A It is possible to make selections such that the change is sufficiently large.

[0067] Alternatively, the smaller the density ρ of the sample 12 or liquid being tested, the larger the second measuring unit 8 that needs to be used.

[0068] From equation (3), we obtain buoyancy or lift F. A Alternatively, the signal of the object being measured for normal force can be obtained. F N =ρ * (V * g) Therefore, in order to generate comparable measurements or to derive a comparable normal force difference during relative density changes, the volume V of the second measuring unit 8 or measuring body must be larger as the density ρ decreases.

[0069] In other words, the usable dimensions of the second measuring unit 8 or measuring body are determined by the normal force separation force and the sample being inspected. For example, the minimum measurable normal force is 5 * 10 -5 The value is N (50 μN). At the same time, selectively, the measurement gap 13 between the measurement sections 7 and 8 must be large enough to avoid boundary effects. Here again, each option is influenced by the viscosity and surface tension of the sample 12.

[0070] Furthermore, it is possible to perform a more accurate calibration at the start of measurement. Here, for example, after the sample 12 has melted, the immersion process of the second measurement unit 8 and the position of the sample surface can be observed by the rise in the normal force signal. This allows the precise volume of the molten sample 12 in the first measurement unit 7 to be determined from the geometric data of the first measurement unit 7 and the position of the sample surface. Since the initial weight is known, the geometric density ρ of the sample 12 can be determined by equation (2) above. Geo It is possible to determine this.

[0071] By comparing the density ρ of the second measuring section 8 after immersion, which is determined according to the present invention, it is possible to obtain accurate knowledge regarding the precise immersion depth and the volume displaced by the second measuring section 8 and the measuring shaft, and the buoyancy F generated when the sample 12 is displaced by the measuring shaft and the second measuring section 8. A Minimization is possible.

[0072] In this way, it is possible to use two methods for determining the (melt) density within the measurement process. That is, one of the two methods is based on the normal force F measured according to equations (1) to (3) above. N The present invention provides a density determination method using the known volume V of the second measuring section 8, and the other method provides a method to determine the volume of the sample 12 using the first normal force increase while the second measuring section 8 is immersed in the sample 12, which corresponds to the position of the sample surface when the measuring sections 7 and 8 are brought close together, and to calculate the density ρ of the sample 12 via the mass m of the sample 12, which is determined on the spot based on equation (1) by weighing the sample 12 before putting it into the second measuring section 8, or by measuring the normal force in the first measuring section 7. That is, the mass of the sample 12 can be selectively determined, for example, by determining the change in normal force when it is put into the first measuring section 7.

[0073] By comparing these two types of density determination methods, it is possible to improve accuracy or validate density values ​​determined by Archimedes' measurement method. Selectively, correction values ​​obtained for immersion depth or measurement shaft ratio are used in subsequent measurements of density ρ, for example, during the execution of a temperature profile.

[0074] Figure 1 shows a first embodiment of the rheometer 100 according to the present invention, where the rheometer 100 is a rotary rheometer. The rheometer 100 comprises a base 1, a spindle 2 for height adjustment driven by a spindle motor 11, a rheometer housing 3 housing a control and processing unit, and a measuring motor 4 positioned on the base 1 and also housed within the rheometer housing 3.

[0075] In Figure 1, the control and processing unit is connected to all measuring units or sensors and evaluates the obtained measurement data, but it is not shown individually in Figures 1 to 3. This is because the control and processing unit can be integrated into various positions on the rheometer 100, or it can be a unit separated from the rheometer 100 and connected to the rheometer's components by wire or wireless means to control these components or receive data. The control and processing unit can be housed, for example, within the rheometer housing 3. The control and processing unit not only controls the measuring motor 4, but also calculates or receives measured values ​​in relation to the measuring shaft 14, evaluates these measured values, and derives or determines rheological parameters.

[0076] The rheometer 100 also measures the normal force F between the two measuring sections 7 and 8. NTo measure the density of the sample 12, a normal force measuring unit 5 is included, located in the rheometer housing 3. This control and processing unit is connected to the normal force measuring unit 5 and enables the implementation of the method according to the present invention for determining the density of the sample 12. The normal force measuring unit 5 has a storage device. The storage device can store known volumes of the second measuring unit 8, and optionally calibration data, and volume correction curves and / or volume correction tables and / or normal force correction curves and / or normal force correction tables, and based on these, the density ρ of the sample 12 obtained can be corrected. Furthermore, the geometric density ρ Geo To determine this, geometric data from the first measuring unit 7 may be stored.

[0077] In the interchangeable fastener 6, also known as the tool master, the second measuring unit 8 is interchangeable, and the data characterizing the measuring body of the second measuring unit 8 can be transmitted non-contact here. This is particularly preferable for adapting the second measuring unit 8 to the density ρ of the sample 12, or for forming the second measuring unit 8 from various materials suitable for the temperature reached during inspection.

[0078] In the first embodiment, measuring sections 7 and 8 are measuring cylinders arranged concentrically. Inside the first measuring section 7, which is a hollow cylinder that is a measuring cup, is a second measuring section 8, which is a coaxial closed cylindrical measuring body having the same axis of rotation. The sample 12 to be measured is placed in the measuring gap 13 between measuring sections 7 and 8. Since measuring sections 7 and 8 are arranged with a specified distance between them, the gap width and gap height are defined.

[0079] Alternatively, in all embodiments of the rheometer 100 according to the present invention, the first measuring section 7 and the second measuring section 8 may have additional structures on the outer surface of their cylinders to prevent wall slippage during measurement.

[0080] In the first embodiment, the second measuring unit 7 is connected to the measuring shaft 14, and the measuring motor 4 drives the measuring shaft 14. Therefore, the second measuring unit 8 rotates and / or vibrates relative to the first measuring unit 7, while the first measuring unit 7 remains stationary. In this case, the control and processing unit, for example, defines the rotational speed of the measuring motor 4 and measures the torque generated in the measuring shaft 14, and / or defines the torque of the measuring motor 4 and measures the rotational speed of the measuring motor 4. Subsequently, the control and processing unit evaluates the measured values ​​obtained with respect to the measuring shaft 14 and / or the measuring motor 4, for example, simultaneously with determining the density ρ of the liquid sample 12, and based on this, determines the rheological parameters of the sample 12, such as viscosity, according to methods known from the prior art.

[0081] The coaxial cylinder measurement system has the advantage that the sample cannot flow out laterally, and for example, any precipitation of particles within the sample that may occur has little effect on the measurement results.

[0082] For cylinder measurement systems, it is preferable to use materials such as a specified glass-ceramic / metal alloy or platinum (platinum alloy) whose coefficient of thermal expansion in the temperature range of the object being inspected is as low as possible, or is known with extreme precision.

[0083] In measurements that do not involve testing for reactions, it is also convenient to use materials that are unresponsive or hardly react to the sample material, such as many precious metal alloys, in the cylinder measuring system, or generally in the first measuring section 7 and the second measuring section 8.

[0084] In the first embodiment, the temperature of the sample 12 is controlled via a first measuring unit 7 and a second measuring unit 8. In this cylinder measuring system, the measuring cup and measuring body are temperature-controlled by a Peltier element. Since a double measuring cup is used, temperature uniformity can be achieved. In this way, it is possible to suppress the temperature gradient that occurs in the sample 12 within the measuring gap 13 or shear gap between the inner wall of the measuring cup and the outer wall of the measuring cylinder. In this case, the measuring cup is made of a material having good thermal conductivity. Here, a separation gap separates the inner measuring cup from the outer constant-temperature cup that surrounds it.

[0085] In the first embodiment, the normal force measurement is performed in an air bearing as described in AT No. 404192 B and US No. 6167752 B1. The rheometer 100 has a measuring motor 4 that drives a measuring shaft 14. The measuring shaft 14 supports a disk mounted in an air bearing of the stator. The normal force measuring unit 5 of the rheometer 100 further includes at least one path sensor that determines the axial motion of the measuring shaft 14 based on the viscoelastic properties of the sample under test 12. For normal force measurement, the path sensor is positioned on the stator in the region of the air bearing and records the motion of the disk relative to the stator in the axial direction of the measuring shaft 14.

[0086] As clearly shown in Figure 1, the rheometer 100 includes a first temperature measuring unit 10 located in a first measuring section 7, which is a measuring cup, and a second temperature measuring unit 9 located in a second measuring section 8, which is a measuring cylinder. When the measuring gap 13 stops changing due to temperature fluctuations, these temperature measuring units 9 and 10 can determine whether the temperature of the sample 12 has reached a predetermined temperature. To confirm whether the measuring gap 13 is still changing, a non-contact distance sensor for checking fluctuations may be provided below the first measuring section 7, which is the measuring cup.

[0087] Figure 2 shows a second embodiment of the rheometer 100 according to the present invention, which has a configuration similar to the first embodiment. However, unlike the first embodiment, in the second embodiment, the first measuring unit 7 or measuring cup is not kept in a stationary state but rotates. The second measuring unit 8 is connected to the measuring shaft 14, and the control and processing unit specifies the rotational speed of the measuring motor 4 to measure the torque generated in the measuring shaft 14.

[0088] The two interchangeable fasteners 6 allow for the exchange of both measuring units 7 and 8, enabling non-contact transmission of data characterizing the measuring body. This is not only to adjust the second measuring unit 8 according to the density ρ of the sample 12, or to allow the second measuring unit 8 to be constructed from various materials suitable for the temperature reached during inspection, but also to measure the volume of the sample 12 contained in the first measuring unit 7, and the buoyancy F of the sample 12. A This is particularly convenient because it allows for variation depending on the size of the sample or the density ρ of the sample 12.

[0089] Figure 3 shows a third embodiment of the rheometer 100 according to the present invention, which has a configuration similar to the first and second embodiments. However, in the third embodiment, the rheometer 100 is equipped with two measuring motors 4 and 4'.

[0090] The first measuring motor 4 is located within the first housing 3 and includes a first measuring shaft 14 to which the first measuring unit 7 is connected. Therefore, the first measuring shaft 14 causes the first measuring unit 7 to rotate and / or vibrate. The second measuring motor 4' is located within the second housing 3' and includes a second measuring shaft 14' to which the second measuring unit 8 is connected. Therefore, the second measuring shaft 14' causes the second measuring unit 8 to rotate and / or vibrate independently of the first measuring unit 7.

[0091] The control and processing unit defines the rotational speeds of the first measuring motor 4 and the second measuring motor 4' and measures the torque generated in the first measuring shaft 14 and the second measuring shaft 14', or defines the torque of the first measuring motor 4 and the second measuring motor 4' and measures the rotational speeds of the first measuring motor 4 and the second measuring motor 4'.

[0092] In the third embodiment, the vertical force measuring unit 5 is housed in the first housing 3. Similar to the second embodiment, both measuring units 7 and 8 can be interchanged using two interchangeable fasteners 6, and data characterizing the measuring body or the second measuring unit 8 can be transmitted non-contact here.

[0093] However, in the rheometer 100 shown in the third embodiment, the normal force measuring unit 5 may preferably be located in the first housing 3 or the second housing 3', or possibly both housings 3 and 3'. This allows for the measurement of the normal force F N It can be measured not only from above but also from below, or in some cases from both sides.

[0094] [Example of density measurement] Figures 4 to 7 below summarize the results of a series of test measurements for determining density using the method according to the present invention. This method was performed on various sticky or liquid samples 12, or on rheometers 100 having various measurement system diameters, i.e., rheometers 100 in which the second measuring section 8 immersed in the sample 12 has various diameters DM or outer diameters.

[0095] In Figures 4, 6, and 7, the measured normal force F, indicated by [N], of rheometers 100 with various measurement system diameters is shown. N And, respectively, [kg / m 3The general relationship between the density ρ of the inspected sample 12, indicated by ], is shown. In Figures 4 to 7, CC represents a concentric cylinder, that is, a rheometer 100 formed as a cylindrical measuring cup and measuring cylinder with the first measuring section 7 and the second measuring section 8 arranged concentrically. The combination of letters PT represents platinum material or platinum-rhodium alloy, and DM represents the diameter of the second measuring section 8, reflecting its letter. Here, the exact gap width 13 is the normal force F N It is selected so as not to affect the measurement. The measuring section diameter DM of the second measuring section 8, which corresponds to the rheometer symbol in Figure 4, is shown in [mm] and is also shown in Figures 6 and 7.

[0096] As clearly shown in Figure 4, the measured normal force F N This increases as the density ρ of sample 12 increases. This measured normal force F N The relationship between the density ρ of the inspected sample 12 is independent of the measurement system diameter DM in all rheometers 100. Here, a predetermined density, for example 2000 kg / m³ 3 The normal force F measured for sample 12 having N This increases with each unit of the measurement system's diameter DM (assumed horizontal line). That is, the normal force F N This value is smaller when the measuring system diameter is smaller (e.g., rheometer CC11, PtCC14) than when the measuring system diameter is larger (e.g., rheometer CC27, CC27.6).

[0097] The accuracy of each rheometer 100 or associated measurement system was determined by calculations using each data point. The buoyant force acting on the second measurement section 8 is smaller when it is smaller than when it is larger. Therefore, the normal force F N The difference in this regard is also extremely small, and the density ρ of sample 12 is equal to the normal force F. NThe relative accuracy decreases when determining from this. This is as shown in Figures 6 and 7 for various sample densities ρ. However, in all rheometers 100 or all measurement systems, the density ρ of the sample 12 is the normal force F measured for the reaction and temperature fluctuations described above. N Therefore, it is possible to measure with sufficient accuracy.

[0098] Furthermore, the extent to which the rheometer 100 could distinguish the density difference (percentage) with a cylinder of a predetermined size was determined. For this purpose, the measured normal force F available in the rheometer 100 was used. N And a solution having density ρ was referenced.

[0099] In Figures 6 and 7, the horizontal axis represents the diameter DM of the second measuring section 8, and the vertical axis represents the density accuracy (relative accuracy) ACC for different measuring body diameters. rel The values ​​are shown as percentages. The values ​​were obtained from the normal force solution of the rheometer 100 for each specified density value. When the initial density of the diameter DM of the second measuring section 8 is selected to be sufficiently large, the detectable change in density ρ is in the sub-percentage range (e.g., CC27.6). For high-temperature measurements, this solution is 114 kg / m³. 3 In MCR measurements, the value for CC28 is 19 kg / m³. 3 In the case of CC39, the load is 7 kg / m³. 3 That is the case.

[0100] In Figure 5, various tested samples 12 are compared to a density reference value ρ ref The measurement results compared to the above are shown. Here, the horizontal axis represents the density reference value ρ of the tested sample 12. ref However, [kg / m 3 The plot is shown as follows: on the other hand, the vertical axis represents the normal force F according to the present invention. N The density ρ of the sample 12, obtained from the known volume V of the second measuring unit 8, is [kg / m³ 3The data is plotted in [ ]. Various liquids were tested. Sample numbers N26 and AK1000 are silicone oil, H2O is water, and H2O + 10 wt% NaCl and H2O + 20 wt% NaCl are saline solutions. All samples were tested in the temperature range of -20°C to 140°C. Although this temperature is not directly shown in Figure 5, in Figure 5, the highest density ρ calculated for each component corresponds to the lowest measurement temperature, and conversely, the lowest density ρ for each component was calculated at the highest measurement temperature. In the tests summarized in Figure 5, two different measurement systems were used, indicated in Figure 5 as CC28 (where the diameter DM of the second measurement section 8 is 28 mm) and CC39 (where the diameter DM of the second measurement section 8 is 39 mm). These measurement systems were selected to compensate for the low density ρ of the tested sample 12 through the larger volume V of the second measurement section 8 or the measurement cylinder, thereby providing a sufficiently large normal force F. N This is to generate [the specified value]. These measurement systems or the measuring section diameter DM advantageously allow for particularly accurate determination of the density ρ of the sample 12, which is, for example, lower than the density of a very high silicate melt.

[0101] In contrast, for silicate melts with extremely high density ρ, it is possible to use a second measuring section 8 having a small diameter DM, as shown in Figures 6 and 7 (see, for example, CC11, PtCC14, etc.).

[0102] Here, each inspection was carried out according to the following steps according to the present invention. 1) Measure the initial weight and determine the sample volume. 2) Place the sample 12 into the first measuring unit 7 and attach the measuring unit 7 to the rheometer 100, or vice versa. 3) Immerse the second measuring unit 8 in the sample 12. 4) In some cases, the temperature of the first measuring unit 7 is controlled by, for example, a Peltier element, or by the measuring cup, and the system waits until the sample 12 and the second measuring unit 8 reach thermal equilibrium. 5) After immersing the second measuring unit 8 in the sample 12, the normal force F N Measure. 6) Based on equation (3), the measured normal force F N The density ρ of the sample 12 is calculated using the volume of the known second measurement unit 8.

[0103] As described above, in order to enable particularly accurate density determination, optionally, after step 3), the state of the sample surface during the immersion process of the second measuring unit 8 is determined, and the geometric density ρ Geo It is also possible to calculate the normal force F. In this case, the normal force F is calculated. N Following the measurement, the normal force F of each normal force value after immersing the second measuring section 8 during the immersion process or immediately after the start of the immersion process is measured. N The deviation from the initial value is calculated, and this normal force F N It is also possible to calculate density variations from these variations.

[0104] Normal force F N In the CC28 measurement system, the reading is in the range of 0.2 to 0.3 N, while in the CC39 measurement system, it is approximately 3 points higher, in the range of 0.7 to 0.8 N.

[0105] The measured values ​​(30 measurements taken over 3 minutes, averaged) are used to determine the known density reference value ρ for the above components according to equations (1) to (3) above. ref This was compared with the previous result. The results are shown in Figure 5.

[0106] The normal force F that results after all liquids have been completely immersed. N We were able to characterize it in this regard. As expected, samples 12 with extremely high viscosity or high elasticity are difficult to measure in terms of density.

[0107] The components used have a viscosity of <1 mPas to 100 Pas in the temperature range in which the tests were conducted, which meaningfully represents the viscosity range of silicate (glass) molten materials, saline solutions, and molten metals.

[0108] The results in Figure 5 show that, although some temperature drift occurs in all samples 12 because the thermal expansion of the second measuring unit 8 or the measuring body was not taken into account, the reference value and the measured value are in systematic agreement. This means that even without considering the thermal expansion of the second measuring unit 8, the density ρ of each inspected sample 12 can be measured with sufficient accuracy according to the method of the present invention.

[0109] As described above, if the thermal expansion of the second measuring unit 8 for various reference temperatures is determined in advance, that is, before the inspection for determining the density ρ of the sample 12, and stored in the control and processing unit in the form of a volume correction curve or volume correction table, for example, it is possible to increase the accuracy of the calculated density ρ. Subsequently, when determining the density ρ of the sample 12, the effect of temperature on the volume V of the second measuring unit 8 at each measurement temperature is known, and this effect can be corrected or taken into consideration when calculating the density based on the stored values.

[0110] Optionally, before testing to determine the density ρ of sample 12, it is possible to determine the effect of temperature on the volume V of the second measuring unit 8. Furthermore, by measuring the density ρ of a reference liquid whose density ρ is known at a predetermined reference temperature, it is also possible to determine the effect on the normal force measurement at various reference temperatures. The effects of temperature on the volume V of the second measuring unit 8 and the normal force measurement are stored in the control and processing unit, for example, in the form of a normal force correction curve or normal force correction table. This effect can then be corrected or taken into consideration during density measurement based on these stored values.

[0111] As further illustrated in Figure 5, the measured values ​​or density values ​​are remarkably constant, and the standard deviation for the 30 measured values ​​is shown by error bars considerably smaller than the symbol size used.

[0112] Silicone oil does not evaporate within the temperature range in which it is used and has a relatively low surface tension (0.02 N / m), which makes measurement somewhat easier or more accurate (maximum deviation of 5%, often only 1%).

[0113] As expected, the aqueous sample exhibits a somewhat large dispersion near its boiling point. This is because evaporation of the sample begins at this point, and it fluctuates somewhat more strongly due to its significantly higher surface tension (0.06 N / m) compared to silicone oil (a maximum deviation of 5-10%). However, using the method according to the present invention, sufficiently accurate density measurements are possible for all samples 12.

Claims

1. A method for determining the density (ρ) of an at least viscous sample (12) with a rheometer (100), said rheometer (100) comprising a first measuring part (7) for receiving said at least viscous sample (12) and a second measuring part (8) immersed in said sample (12), said first measuring part (7) and said second measuring part (8) being movable relative to each other, said second measuring part (8) having a volume (V) known, After the second measurement part (8) is immersed in the sample (12), a normal force (F) acting on the second measurement part (8) by the sample (12) is measured. Ｎ ), the measured normal force (F Ｎ ) is the buoyancy force (F) acting on the second measurement part (8) due to the sample (12). Ａ ) and The density (ρ) of the sample (12) is calculated based on Archimedes' principle using the known volume (V) of the second measuring portion (8) and the measured normal force (F Ｎ ) and calculating the Prior to determining the density (ρ), the thermal expansion of the second measuring part (8) at various reference temperatures is stored in the form of a volumetric correction curve or volumetric correction table, 4. A method according to claim 3, characterized in that, at each measurement temperature, the temperature effect on the volume (V) of the second measurement portion (8) is corrected and / or taken into account when determining the density (ρ) of the sample (12) thereafter, based on the stored value.

2. The method according to claim 1, characterized in that the at least viscous sample (12) is liquid.

3. The sample (12) is subjected to the normal force (F Ｎ 3. The method according to claim 1 or 2, characterized in that the sample (12) is heated and / or cooled during the measurement of density (ρ) and the determination of density (ρ) is repeated at different temperatures.

4. Before measuring the density (ρ) of the sample (12), test measurements are carried out at various reference temperatures using a reference liquid whose density (ρ) at a given reference temperature is known, and the temperature effect on the combination of the volume (V) and normal force measurement of the second measuring section (8) is stored in the form of a volume correction curve or volume correction table; During the subsequent determination of the density (ρ) of the sample (12), the volume (V) of the second measurement portion (8) at each measurement temperature and the measured normal force (F Ｎ 4. The method according to claim 1, further comprising correcting the temperature effect on the combination of the two components based on the stored values.

5. Before determining the density (ρ) of the sample (12), The geometric density (ρ ｇｅｏ ) from the mass of the reference liquid introduced into the first measurement unit (7), the position of the surface of the reference liquid determined when the second measurement unit (8) is brought closer, and the known shape of the first measurement unit (7) at a predetermined reference temperature; The density (ρ) of the reference liquid at the predetermined reference temperature is determined according to a method according to any one of the preceding claims, and the predetermined value of the density (ρ) of the reference liquid is calculated based on the geometric density (ρ) of the reference liquid. ｇｅｏ ) determining a correction factor by comparing it with a predetermined value of the correction factor and storing it in the evaluation unit, 5. The method according to claim 1, further comprising: correcting the influence of the immersion depth of the second measuring portion (8) into the sample (12) at each measuring temperature when determining the density (ρ) of the sample (12) thereafter based on the determined correction factor.

6. The first measuring unit (7) or the second measuring unit (8) measures the normal force (F Ｎ ) is kept stationary during the measurement, or The first measuring unit (7) or the second measuring unit (8) measures the normal force (F Ｎ 6. The method according to claim 1, wherein the measuring device is rotated and / or rotated oscillated during the measurement of the distance .

7. 7. The method according to claim 1, further comprising, in addition to determining the density (ρ) of the sample (12), determining rheological parameters of the sample (12) at the same time as determining the density (ρ) of the sample (12).

8. The method of claim 7, wherein the rheological parameter is viscosity.

9. 9. The method according to claim 1, further comprising measuring the temperature of the sample (12) and / or the first measuring section (7) and / or the second measuring section (8) and determining the density (ρ) only when the temperature of the sample (12) and / or the first measuring section (7) and / or the second measuring section (8) reaches a predefined temperature threshold.

10. The normal force (F Ｎ 10. The method according to claim 1, wherein the vertical distance of both measuring parts (7, 8) relative to one another is kept approximately constant during the measurement of the measuring points (7, 8).

11. A rheometer (100) for determining the density (ρ) of at least a viscous sample (12), comprising: a first measuring section (7) for accommodating the sample (12) and a second measuring section (8) having a known volume (V), the second measuring section (8) being arranged in the rheometer (100) so as to be immersed in the sample (12), and the first measuring section (7) and the second measuring section (8) being arranged in the rheometer (100) so as to be capable of relative movement; A normal force (F) acting on the second measurement part (8) by the sample (12) before, during, and after immersion of the second measurement part (8) in the sample (12) is Ｎ A normal force measuring unit (5) arranged in the rheometer (100) and configured to measure the normal force (F Ｎ ) is the buoyancy force (F) acting between the sample (12) and the second measurement part (8). Ａ ) a normal force measuring unit (5), a control and processing unit for calculating the density (ρ) of the sample (12) based on Archimedes' principle, the rheometer (100) includes a heating and / or cooling device for temperature control of the viscous sample (12); The heating and / or cooling device comprises: in the first measuring part (7) in the form of at least one Peltier element; and / or and / or formed as a temperature-controlled cover that can be placed on both measuring parts (7, 8); Both the measuring section and the sample are formed as a convection heating chamber and / or a convection cooling chamber, in which the temperature is controlled by gas or liquid, and / or A rheometer (100) in which the first measuring part (7) and the second measuring part (8) are arranged, characterized in that the rheometer is formed as a high-temperature furnace.

12. A rheometer (100) as described in claim 11, characterized in that the at least viscous sample (12) is liquid.

13. The rheometer (100) of claim 11, characterized in that the rheometer is a rotational rheometer.

14. A rheometer (100) as described in claim 11, characterized in that the control and processing unit is configured to calculate the density (ρ) of the sample (12) according to a method described in any one of claims 1 to 10.

15. the first measuring part (7) being configured as a measuring cup having an approximately cylindrical cross section, the second measuring part (8) is formed as a measuring body having an approximately cylindrical cross section, the outer diameter of the second measuring part (8) being smaller than the inner diameter of the first measuring part (7); The rheometer (100) according to any one of claims 11 to 14, characterized in that the first measuring part (7) and the second measuring part (8) are arranged coaxially in the rheometer (100), and a measuring gap (13) having a predetermined width can be formed between the concentric walls of the first measuring part (7) and the second measuring part (8).

16. A rheometer (100) as described in claim 15, characterized in that the measuring body is a rheology measuring spindle.

17. the rheometer (100) comprises at least one measuring motor (4) having a measuring shaft (14), the first measuring part (7) or the second measuring part (8) being connected to the measuring shaft (14), each measuring part (7, 8) being capable of a relative rotational and / or oscillatory movement with respect to the other measuring part (7, 8), The rheometer (100) according to any one of claims 11 to 16, characterized in that the control and processing unit is configured to define the rotation speed of the measurement motor (4) and to measure the torque occurring on the measurement shaft (14) and / or to define the torque of the measurement motor (4) and to measure the rotation speed of the measurement motor (4).

18. The rheometer (100) a first measuring motor (4) having a first measuring shaft (14), said first measuring part (7) being connected to said first measuring shaft (14), said first measuring part (7) being capable of performing a rotational and / or oscillatory movement, a second measuring motor (4') having a second measuring shaft (14'), said second measuring part (8) being connected to said second measuring shaft (14'), said second measuring part (8) being capable of performing a rotational and / or oscillatory movement independently of said first measuring part (7), The control and processing unit comprises: configured to determine the rotation speed of the first measuring motor (4) and / or the second measuring motor (4') in order to measure the torque acting on the first measuring shaft (14) and / or on the second measuring shaft (14'); and / or 18. The rheometer (100) according to any one of claims 11 to 17, characterized in that a torque of the first measuring motor (4) and / or the second measuring motor (4') is defined and the number of revolutions of the first measuring motor (4) and / or the second measuring motor (4') is measured.

19. the control and processing unit is configured to control a heating and / or cooling device; The rheometer (100) according to any one of claims 11 to 18, characterized in that the control and processing unit comprises a memory device and is configured to store in the memory device a volume correction curve and / or a volume correction table and / or a normal force correction curve and / or a normal force correction table determined by the method according to claim 1 or 4.

20. 19. The rheometer (100) according to claim 17 or 18, characterized in that the control and processing unit evaluates the measured values ​​obtained in connection with each of the measuring shafts (14) and / or each of the measuring motors (4) simultaneously with determining the density of the sample (12) and determines at least one rheological parameter of the sample (12).

21. A rheometer (100) as described in claim 20, characterized in that the rheological parameter is viscosity.

22. The normal force measuring unit (5) is connected to the first measuring part (7) and a further normal force measuring unit is connected to the second measuring part (8), which measures the normal force (F) between both measuring parts (7, 8) simultaneously with the normal force measuring unit (5). Ｎ 22. The rheometer (100) according to claim 11, characterized in that the second measuring part (8) is immersed in the sample (12) and the second measuring part (8) is immersed in the sample (12).

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