Rotors for rheological measurements of materials with variable volume

Abstract

The present invention provides a rheology system, the rheology system comprising: a sample chamber; a compressed air system configured to provide compressed air to pressurize the sample chamber; and a rotor configured to perform rheological measurements on a material having a variable volume, the rotor including an elongated shaft extending to a measurement portion having a widened geometry relative to the elongated shaft. The rotor is sized such that a compression ratio of at least 5:1 can be achieved while maintaining material coverage of the sample over the entire measurement portion of the rotor, the compression ratio being defined as the ratio of the decompressed volume of the sample when the sample chamber is not pressurized to the compressed volume of the sample when the sample chamber is pressurized. A method of performing rheological measurements using such a rotor is also disclosed.

Description

[0001] Related Applications

[0002] This patent application is a non - provisional patent application claiming priority to U.S. Provisional Patent Application No. 62 / 915,266, filed on October 15, 2019, entitled "Rotor for Rheological Measurements of Material with Variable Volume", which is incorporated herein by reference. Technical Field

[0003] The present invention generally relates to rheological measurement systems. More specifically, the present invention relates to a rotor for rheological measurements of materials with variable volume, and related systems and methods. Background Art

[0004] A rheometer is an instrument used to characterize the rheological properties of materials such as oils, dispersions, suspensions, emulsions, adhesives, biological fluids, polymers, gels, pastes, slurries, melts, resins, powders, foams, or mixtures of the above materials. As used herein, the term "rheometer" shall include rheometers, viscometers, viscosimeters, and any other instrument that can be used to measure the viscoelastic properties of fluids or powders. A typical rheometer applies a specific stress field or deformation to a fluid and monitors the resulting deformation or stress. Rheological measurements in a rotational rheometer are performed by applying a stress or deformation in the rotational direction. A rotational rheometer can apply a predetermined torque in the rotational direction to a material and measure the resulting displacement of the material to be measured, or alternatively can measure the torque required to obtain a predetermined displacement.

[0005] Many materials undergo volume changes during production, synthesis, transportation, end - use, or disposal. Volume changes can occur due to environmental changes (pressure or temperature), compositional changes (material burning or reaction of single or multiple materials), or due to mechanical input (mechanical mixing). Accurate rheological measurements during these changes are crucial for the development and manufacture of new materials, new processes, and new equipment. Current rheometers are sensitive to the volume of the material and cannot make accurate measurements when the volume of the material is variable. For example, when subjected to a pressure 100% higher than atmospheric pressure, the volume of some foams (liquid / gas structures) decreases by approximately 50%. A typical rheometer geometry will be "under - filled" due to this volume reduction, which will result in inaccurate measurements.

[0006] Therefore, a rheometer that provides accurate measurements of materials with variable volume would be highly desirable in the art. Summary of the Invention

[0007] In one embodiment, a rheology system includes: a sample chamber; a compressed air system configured to provide compressed air to pressurize the sample chamber; and a rotor configured to perform rheological measurements on a material having a variable volume, the rotor including an elongated shaft extending to a measurement portion that has a widened geometry relative to the elongated shaft, wherein the rotor is sized such that a compression ratio of at least 1.5 to 1 can be achieved while maintaining material coverage of the sample over the entire measurement portion of the rotor, wherein the compression ratio is defined as the ratio of the decompressed volume of the sample when the sample chamber is not pressurized to the compressed volume of the sample when the sample chamber is pressurized.

[0008] In addition or alternatively, the measurement portion is cylindrical and includes a circumference and a thickness, wherein the circumference is less than the circumference of the sample chamber and greater than the circumference of the elongated shaft.

[0009] In addition or alternatively, the measurement portion includes a cylindrical wall having straight knurling with a vertical orientation.

[0010] In addition or alternatively, the measurement portion includes a plurality of outwardly projecting vanes disposed vertically around the circumference.

[0011] In addition or alternatively, the circumference is greater than twice the circumference of the elongated shaft.

[0012] In addition or alternatively, the thickness of the measurement portion is less than 1 / 5 of the length of the elongated shaft.

[0013] In addition or alternatively, a space separates the bottom of the measurement portion from the bottom of the sample chamber, and wherein the height of the space is less than the difference between the radius of the elongated shaft and the radius of the sample chamber.

[0014] In addition or alternatively, the rotor further includes a first end and a second end, and the rotor further includes a circumferential plate located at the first end, wherein the measurement portion is located at the second end.

[0015] In addition or alternatively, the rheology system further includes a parallel visualization chamber connected to the compressed air system, the rheometer being configured to maintain the parallel visualization chamber under the same environmental conditions as the sample chamber; and a camera connected to the parallel visualization chamber, the camera being configured to detect an image within the parallel visualization chamber.

[0016] In addition or alternatively, the rheology system further includes a camera connected to the sample chamber, the camera being configured to detect an image within the sample chamber.

[0017] In another embodiment, a rotor for rheological measurements of a material having a variable volume includes: an elongate shaft extending between a first end and a second end, wherein the first end includes an attachment location configured to provide attachment to a drive of a rheometer; and a measurement portion located at the second end of the elongate shaft and having a widened geometry relative to the elongate shaft, the measurement portion having a thickness, wherein the ratio of the length of the elongate shaft configured to be located within the sample chamber in use to the thickness of the measurement portion is at least 2 to 1.

[0018] In addition or alternatively, the measurement portion is cylindrical and includes a circumference and a thickness, wherein the circumference is greater than the circumference of the elongate shaft.

[0019] In addition or alternatively, the cylindrical widened geometry includes a cylindrical wall having straight knurling with a vertical orientation.

[0020] In addition or alternatively, the cylindrical widened geometry includes a plurality of outwardly projecting vanes disposed vertically around the circumference.

[0021] In addition or alternatively, the circumference is greater than twice the circumference of the elongate shaft.

[0022] In addition or alternatively, the thickness of the cylindrical widened geometry is less than 1 / 5 of the length of the elongate shaft configured to be located within the sample chamber in use.

[0023] In addition or alternatively, the rotor further includes a circumferential plate located at the first end, wherein the measurement portion is located at the second end.

[0024] In another embodiment, a method of performing rheological measurements on a material having a variable volume includes: at least partially filling a sample chamber of a rheometer with a sample, wherein a rotor extends into the sample chamber, the rotor including an elongate shaft extending to a measurement portion having a widened geometry relative to the elongate shaft; pressurizing the sample chamber such that a compression ratio of at least 1.5 to 1 of the material is achieved, wherein the compression ratio is defined by the ratio of the decompressed volume of the sample when the sample chamber is not pressurized to the compressed volume of the sample when the sample chamber is pressurized; and maintaining material coverage of the sample over the entire measurement portion of the rotor during pressurization.

[0025] In addition or alternatively, the method further includes detecting an image within the sample chamber with a camera during pressurization.

[0026] In addition or alternatively, the method further includes maintaining a parallel visualization chamber under the same environmental conditions as the sample chamber; and detecting an image within the parallel visualization chamber with a camera during pressurization. Description of the Drawings

[0027] The above and other advantages of the present invention can be better understood by reference to the following description in conjunction with the accompanying drawings, in which like reference numerals refer to like elements and features in each of the various drawings. For clarity, not every element is labeled in every drawing. The drawings are not necessarily to scale, and emphasis is placed on illustrating the principles of the present invention.

[0028] Figure 1 A schematic diagram of a rheometer according to an embodiment is depicted.

[0029] Figure 2 Depicts a rheometer having a rotor according to an embodiment Figure 1 The side cross-sectional view of the pressure unit of the rheometer.

[0030] Figure 3 Depicts a perspective view of a Figure 2 rotor before being installed into the pressure unit of Figure 2 according to an embodiment.

[0031] Figure 4 Depicts a perspective view of another rotor before being installed into the pressure unit of Figure 2 according to an embodiment.

[0032] Figure 5 Depicts a perspective view of another rotor before being installed into the pressure unit of Figure 2 according to an embodiment.

[0033] Figure 6 Depicts a perspective view of another rotor before being installed into the pressure unit of Figure 2 according to an embodiment.

[0034] Figure 7 Depicts a perspective view of another rotor before being installed into the pressure unit of Figure 2 according to an embodiment.

[0035] Figure 8 Depicts a pressure unit having a Figure 7 rotor and filled with a sample before compression of Figure 2 according to an embodiment. The side cross-sectional view.

[0036] Figure 9 Depicts a pressure unit having a Figure 7 rotor and filled with a sample after compression of Figure 2 according to an embodiment. The side cross-sectional view.

[0037] Figure 10 Depicts a side cross-sectional view of a pressure unit according to an embodiment further including three optional vision systems of Figure 2 according to an embodiment. Detailed implementation manners

[0038] As used in this specification, the mention of "an embodiment" or "embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the present teachings. References to specific embodiments within this specification are not necessarily all referring to the same embodiment.

[0039] The present teachings will now be described in more detail with reference to exemplary embodiments of the present teachings as shown in the accompanying drawings. Although the present teachings are described in connection with various embodiments and examples, the present teachings are not intended to be limited to such embodiments. In contrast, the present teachings cover various alternatives, modifications, and equivalents, as will be understood by those skilled in the art. Those of ordinary skill in the art who can use the teachings herein will recognize additional embodiments, modifications, and implementations within the scope of the present disclosure as described herein, as well as other fields of use.

[0040] As described herein, a rheological measurement system is described that includes a novel method for performing rheological measurements on materials having a variable volume. Specifically, the method recognizes that certain materials having a variable volume, such as foams, whipped cream, mousses, or other foaming compositions, can cause problems with existing rheometers when subjected to high pressures in a pressure chamber during rheological testing. The inventors have found that when the material is compressed in a pressurized sample chamber such that the material does not adequately cover the rotor or pendulum, the accuracy of the measurement results is affected. The present invention seeks to maintain accurate rheological measurements across various test volumes of the material in the case of materials having a variable volume. To achieve this, novel methods and structures are envisioned for the rheological rotor.

[0041] Specifically, a rotor is envisioned that is sized such that a compression ratio of at least 1.5 to 1 can be achieved while maintaining material coverage of the sample across the entire widened measurement geometry of the rotor. Hereinafter, the "compression ratio" is defined by the ratio of the decompressed volume of the sample (e.g., when the sample chamber is not pressurized or when the sample expands in volume in some other way, such as through a chemical reaction or drying) to the compressed volume of the sample (e.g., when the sample chamber is pressurized). Compression and decompression of the sample may be caused by pressure, drying, chemical reaction, subambient pressurization, or any other means of compressing or decompressing the sample. Thus, the rotors described herein are configured to maintain accurate measurements when the volume of the material is reduced by a factor of 1.5 or more. Although a compression ratio of at least 1.5 to 1 is envisioned, the embodiments shown in the figures all achieve a compression ratio of at least 5 to 1.

[0042] Embodiments of the present invention can be deployed with any pressurized rheological measurement system and / or method that employs rheological measurements. Figure 1 An exemplary rheological system is shown. Specifically, Figure 1Depicts a schematic view of a rheometer 100 according to one embodiment. Although rheometer 100 includes various features described herein, it should be understood that the principles of the present invention can be applied to any other pressurized rheological measurement system configured to measure rheological properties having fewer or more schematic components than shown in Figure 1 those shown.

[0043] Rheometer 100 includes a drive motor 110 that drives output 112, a torque rebalance transducer 114, and a normal force rebalance transducer 116 having an output 118. The surrounding body 120 of sample chamber 122 is shown attached to the output 112 of drive motor 110, while the rotor 124 located within sample chamber 122 is shown attached to the outputs 118 of torque rebalance transducer 114 and normal force rebalance transducer 116. A compressed air system 126 is operatively connected to sample chamber 122 to pressurize sample chamber 122 with compressed air. A control system 128 having a user interface 130 is shown operatively connected to each of drive motor 110, torque rebalance transducer 114, normal force rebalance transducer 116, and compressed air system 126. Although the illustrated embodiment includes a single control system 128 for controlling drive motor 110, torque rebalance transducer 114, normal force rebalance transducer 116, and compressed air system 126, other embodiments may include separate control systems. For example, compressed air system 126 may include a separate manual or automatic control system that controls only compressed air system 126 in a manner independent of drive motor 110, torque rebalance transducer 114, and normal force rebalance transducer 116.

[0044] Drive motor 110 may be configured to deliver accurate rotational motion of output 112 over a wide range of angular displacements and speeds. For example, drive motor 110 may include an air bearing system, a high torque frictionless brushless DC motor, an optical encoder, and a temperature sensing system. Drive motor 110 and its features may be controlled by control system 128 and guided by input from user interface 130.

[0045] Torque rebalance transducer 114 may be configured to measure accurate sample stress based on the torque required to maintain a zero position on output 118. Torque rebalance sensor 114 may include, for example, a dynamic torque range of 5,000,000 to 1. Torque rebalance transducer 114 may include an air bearing, a high resolution capacitive angle sensor, and a temperature sensing system. Like drive motor 110, torque rebalance transducer 114 and its features may be controlled by control system 128 and guided by input from user interface 130.

[0046] The normal force rebalance transducer 116 can be configured to measure the accurate normal force from a sample within the sample chamber 122 at the output 118. The normal force rebalance transducer 116 can utilize position feedback to hold the axis of the output 118 at the zero position. The normal force rebalance transducer 116 and its features can be controlled by the control system 128 and guided by inputs from the user interface 130. Additionally, the normal force rebalance transducer 116 can be equipped with a pressure sensing system for measuring the pressure in the sample chamber 122.

[0047] The surrounding body 120, the sample chamber 122, the rotor 124, and the compressed air system 126 can be integral parts of the rheometer 100. Alternatively, it is envisioned that these components 120, 122, 124, 126 are separately attachable additional features of a pressure unit 150 that can be attached to and detached from the outputs 112, 118. Regardless of the implementation, the surrounding body 120 that defines the sample chamber 122 can be attached to the drive motor 110 and its output 112 so as to rotate as the output 112 rotates. Similarly, the rotor 124 can be attached to the outputs 118 of the torque rebalance transducer 114 and the normal force transducer 116 and can be configured to move as the output 112 moves. The rotor 124 can be configured to rotate relative to the surrounding body 120 that defines the sample chamber 122. The air compression system 126 can be configured to provide compressed air to the sample chamber 122 through a cap attached to the rotor 124. The air compression system 126 is configured to maintain the pressurization of the sample chamber 122 during rotation of the surrounding body 120 around the rotor 124.

[0048] The control system 128 can be configured to control and monitor stress, strain, force, velocity, etc. on the components of the system. The control system 128 can be configured to provide output information related to measurements taken during testing of a material or sample within the sample chamber 122. The control system 128 can be configured to control the movement of the outputs 112, 118 and further control the pressure within the sample chamber 122 by controlling the compressed air system 126. The user interface 130 can be a screen or other input interface that is configured to allow a technician to interact with the rheometer 100, change settings, define test conditions, etc.

[0049] Figure 1 The illustrated embodiment shows a separate motor and transducer system with a dual-head design. However, the principles of the present invention are not limited to this design. Instead, the pressure unit 150 and the sample chamber 122 described herein can be applied to other rheometer designs, such as a rheometer having a combined motor and transducer where the sample is placed on a static sample chamber 122. In such embodiments, the bottom output 118 will remain static.

[0050] Figure 2Depicts a side cross-sectional view of a pressure unit 150 with a rotor 124a attached thereto, according to an embodiment. The pressure unit 150 includes a surrounding body 120 that defines a sample chamber 122. The surrounding body 120 includes a heat transfer jacket 132 and an output shaft 134 having a connection interface 136 configured to connect to an output end 118. A threaded connection interface 138 connects the output shaft 134 to the rotor 124a. The threaded interface 138 may further include a thermal insulation device, which may include a reinforced polymer layer separating two halves of the threaded interface 138. A compressed air inlet 140 is configured to receive compressed air from an air compression system 126. A cover 144 is attached to the surrounding body 120 and the heat transfer jacket 132 with attachment bolts 146. There is an air gap 142 between the cover 144 and the output shaft 134, and an air flow is configured to escape from the sample chamber 122 through this air gap during pressurization. In the illustrated embodiment, the output shaft 134 and the attached rotor 124a are configured to rotate about the surrounding body 120, the heat transfer jacket 132, and the cover 144. Figure 1 The pressure unit 150 of Figure 1 may be a highly sensitive pressure unit that provides a complete viscoelastic characterization of materials or fluids in a pressurized environment at high pressures. The pressure unit 150 may employ an air bearing seal that allows for low torque performance and increased torque sensitivity, thereby allowing for the characterization of critical material behaviors such as the dependence of time, frequency, and strain on the widest range of fluids, including at temperatures above the boiling point of volatile components. This range of test conditions may provide an understanding of material properties representative of extreme processing or use conditions, such as downhole or extrusion environments. Such a system may provide stable and accurate temperature control from -5°C to 150°C through a concentric cylindrical heat transfer jacket 132. Atmospheric pressure control up to 5 bar may be achieved to simulate the processing and use conditions of the material under test. While the various rotors described herein may be used with such a pressure unit 150, the rotors may also be used in any form of rheological environment, including standard rheological units, cavities, etc. Additionally, while the enclosed and pressurized unit is envisioned as the primary use case for the rotors described herein, it may also be applied to an open test chamber that is only subjected to atmospheric pressure conditions and does not pressurize the sample.

[0051] Figure 1 The pressure unit 150 of Figure 1 may be a highly sensitive pressure unit that provides a complete viscoelastic characterization of materials or fluids in a pressurized environment at high pressures. The pressure unit 150 may employ an air bearing seal that allows for low torque performance and increased torque sensitivity, thereby allowing for the characterization of critical material behaviors such as the dependence of time, frequency, and strain on the widest range of fluids, including at temperatures above the boiling point of volatile components. This range of test conditions may provide an understanding of material properties representative of extreme processing or use conditions, such as downhole or extrusion environments. Such a system may provide stable and accurate temperature control from -5°C to 150°C through a concentric cylindrical heat transfer jacket 132. Atmospheric pressure control up to 5 bar may be achieved to simulate the processing and use conditions of the material under test. While the various rotors described herein may be used with such a pressure unit 150, the rotors may also be used in any form of rheological environment, including standard rheological units, cavities, etc. Additionally, while the enclosed and pressurized unit is envisioned as the primary use case for the rotors described herein, it may also be applied to an open test chamber that is only subjected to atmospheric pressure conditions and does not pressurize the sample.

[0052] Figure 3 Depicts, according to an embodiment, before being installed into Figure 2 the pressure unit 150 of Figure 2Perspective view of the rotor 124a. The rotor 124a includes an elongate shaft 151 that extends along a length L1 from a first end 152 to a second end 154. The first end 152 includes an attachment location 156 that is configured to provide attachment of the rotor 124a to the drive motor 110 of the rheometer 100 via the output 118. The attachment location 156 is shown as a hole that may include internal threads therein configured to receive the external threads of the threaded connection interface 138. A circumferential plate 160 is also located at the first end 152. The circumferential plate 160 is sized to substantially hold a volumetrically expanding sample below the circumferential plate 160 during testing and prior to removal from the sample chamber 122 and to prevent sample material from climbing upward along the elongate shaft 151 past the circumferential plate 160 and into the air gap 142, the compressed air inlet 140, and the lid 144.

[0053] The hole of the attachment location 156 is shown as extending into the circumferential plate 160 and within a thicker top region 161 of the elongate shaft 151. The thicker top region 161 is configured to accommodate the threaded connection interface 138, as Figure 2 shown. The thicker top region 161 is further configured to provide structural support at the connection point to maintain the structural alignment between the rotor 124a and the output shaft 134.

[0054] The rotor 124a further includes a measurement portion 158 located at the second end 154 of the elongate shaft 151. The measurement portion 158 includes a widened geometry relative to the elongate shaft 151. As shown, the measurement portion 158 is cylindrical and includes a circumference and a thickness T. The relative dimensions between the elongate shaft 151 and the measurement portion 158 are important in order to provide a measurement rotor that maintains accuracy during the various compression and expansion volumes of the sample under test. In one embodiment, the ratio of the length L of the elongate shaft 150 to the thickness T of the measurement portion 158 is at least 2 to 1. In the illustrated embodiment, the ratio of the length L of the elongate shaft 150 to the thickness T of the measurement portion 158 is approximately 4 to 1. In another embodiment, the ratio may be at least 2 to 1, at least 3 to 1, at least 5 to 1, or at least 6 to 1. The greater the ratio of the length L of the elongate shaft 150 to the thickness T of the measurement portion 158, the less the underfill inaccuracy that will occur when a variable volume sample is significantly compressed.

[0055] The circumference of the measurement portion 158 is less than the circumference of the sample chamber 122 and greater than the circumference of the elongate shaft 150. A small space may exist between the outer circumferential wall of the measurement portion 158 and the wall of the sample chamber 122. The space may be, for example, 1 mm or any other distance that allows movement between the sample chamber 122 and the measurement portion 158. In the illustrated embodiment, the circumference of the measurement portion 158 is greater than twice the circumference of the elongate shaft 151. The circumference of the measurement portion 158 may be greater than three times the circumference of the elongate shaft 151.

[0056] The gap and height between the measurement portion 158 and the surrounding body 120 can be configured to generate sufficient measurement sensitivity such that the measurement artifacts caused by the gap and length between the elongated shaft 151 and the surrounding body 120 are less than 5%. Texturing of the outer wall or outer surface of the measurement portion 158 can be envisioned to minimize potential artifacts from sample wall slippage.

[0057] The thickness T of the measurement portion 158 can be sufficient to create a shear surface of the sample material within the sample chamber 122, but otherwise, the thickness may be narrow enough such that a variable volume sample material that has been significantly compressed can maintain material coverage of the sample over the entire measurement portion 158 of the rotor 124a. In the illustrated embodiment, the thickness T is less than 1 / 5 of the length of the elongated shaft 151. Thus, a substantial portion of the total height of the sample chamber 158 is occupied by the elongated shaft 151, while a smaller portion of the sample chamber 158 is occupied by the thickness T of the measurement portion 158.

[0058] As Figure 2 shown, the overall length dimension of the rotor 124a can be such that the space S separates the bottom of the measurement portion 158 and the bottom of the sample chamber 122. The space S can be, for example, 5 mm or 6 mm. The space S can be significantly greater than the space between the cylindrical wall of the measurement portion 158 and the side wall of the sample chamber 122. For example, the height of the space S can be less than the difference between the radius of the elongated shaft and the radius of the sample chamber.

[0059] Figure 4 Depicts a perspective view of another rotor 124b prior to installation into Figure 2 the pressure unit 150 according to one embodiment. The rotor 124b can include a structure that is substantially the same as the rotor 124a, except for the different measurement portion 168. Different from the measurement portion 158 of the rotor 124a, the measurement portion 168 of the rotor 124b includes a plurality of outwardly projecting vanes 169 vertically disposed around the circumference of the measurement portion 168. Specifically, the outwardly projecting vanes 169 are shown as short vanes that, when added to the circumference of the remainder of the measurement portion 168, extend a distance equal to or substantially equal to the circumference of the measurement portion 158 of the rotor 124a. The illustrated embodiment includes four vanes 169, each vane being spaced 90 degrees around the circumference of the measurement portion 168.

[0060] Figure 5 Depicts a perspective view of another rotor 124b prior to installation into Figure 2Perspective view of another rotor 124c prior to installation in the pressure unit 150 of. Except for the different measurement section 178, rotor 124c may include substantially the same structure as rotor 124a. Different from the measurement section 158 of rotor 124a, the measurement section 178 of rotor 124c includes a plurality of outwardly protruding vanes 179 vertically arranged around the circumference of the measurement section 178. Specifically, the outwardly protruding vanes 179 are shown as elongated vanes, which cover a substantial portion of the circumference of the measurement section 178 and extend a distance equal to or substantially equal to the circumference of the measurement section 158 of rotor 124a. The illustrated embodiment includes eight elongated vanes 179, each vane being spaced 45 degrees around the circumference of the measurement section 178.

[0061] Figure 6 Depicts, according to one embodiment, another rotor 124d prior to installation in Figure 2 the pressure unit 150 of. Except for the different measurement section 188, rotor 124d may include substantially the same structure as rotor 124a. Different from the measurement section 158 of rotor 124a, the measurement section 188 of rotor 124d includes a plurality of outwardly protruding vanes 189 vertically arranged around the circumference of the measurement section 188. Specifically, the outwardly protruding vanes 189 are shown as elongated vanes, which cover a substantial portion of the circumference of the measurement section 188 and extend a distance equal to or substantially equal to the circumference of the measurement section 158 of rotor 124a. The illustrated embodiment includes four elongated vanes 189, each elongated vane being spaced 90 degrees around the circumference of the measurement section 188.

[0062] Figure 7 Depicts, according to one embodiment, another rotor 124e prior to installation in Figure 2 the pressure unit 150 of. Except for the different measurement section 198, rotor 124e may include substantially the same structure as rotor 124a. Different from the measurement section 158 of rotor 124a, the measurement section 178 of rotor 124e includes a cylindrical wall having a straight knurl with a vertical orientation disposed around the entire cylindrical wall.

[0063] The above-described embodiments of rotors 124a, 124b, 124c, 124d, 124e are intended to be exemplary, and each rotor maintains measurement accuracy when performing a rheological test on a sample with a variable volume under pressure. The various rotors 124a, 124b, 124c, 124d, 124e may be placed within the pressure unit 150 as described above and in Figure 2Shown in. In addition to rotors 124a, 124b, 124c, 124d, 124e, other rotor embodiments are also envisioned. For example, rotors with more or fewer blades, longer or shorter blades, or other types of knurling (e.g., diamond knurling) can be envisioned. For example, the rotor can include a cylindrical wall having a surface roughness designed by sandblasting, 3D printing layering, or other intentionally applied wear.

[0064] Figure 8 Depicts a rotor 124e according to one embodiment having Figure 7 and filled with sample 200 before compression of the Figure 2 side cross-sectional view of pressure unit 150. Similarly, Figure 9 Depicts a rotor 124e according to one embodiment having Figure 7 and filled with sample 200 after compression of the Figure 2 side cross-sectional view of pressure unit 150. As shown, while maintaining accurate results, the maximum sample volume in sample chamber 122 can be defined as the volume between the bottom of sample chamber 122 and the bottom of circumferential plate 160. While maintaining accurate results, the minimum sample volume in sample chamber 122 can be defined as the volume between the bottom of sample chamber 122 and the volume covered by the material holding sample 200 over the entire measurement portion of rotor 124e (i.e., directly above the measurement portion of the rotor). As shown, before and after compression, Figure 8 and Figure 9 the sample 200 shown in is held within the maximum and minimum volumes. Thus, rheological testing can be done in the decompressed state and compressed state of the sample and any pressurized state in between without affecting measurement accuracy. For example, the measurement accuracy can have an error of less than 5%.

[0065] The "compression ratio," defined as the ratio of the maximum volume to the minimum volume of the material within sample chamber 122, can be, for example, at least 1.5 to 1 while maintaining material coverage over the entire measurement portion of the rotor. Depending on the size and dimensions of the rotor and its measurement portion, compression ratios of at least 2 to 1, 3 to 1, 4 to 1, 5 to 1, and 10 to 1 can be envisioned. The larger the volume of the measurement portion (e.g., in the Figure 3 and Figure 7 larger measurement portion shown), the higher the maximum compression ratio allowed in the system without changing the dimensions of sample chamber 122. The methods envisioned herein include creating a rheological rotor sized to maintain material coverage over the measurement portion of the rotor when the material has a specified compression ratio.

[0066] Figure 10 Depicts according to one embodiment also including three optional vision systems Figure 2Side cross-sectional view of the pressure unit. Although this embodiment shows all three vision systems, any combination of one or more of the shown vision systems is conceivable. Specifically, the rheometer 100 is shown in Figure 10 as including a parallel visualization chamber 300 connected to a compressed air system 126. The parallel visualization chamber 300 is a parallel chamber having the same pressure characteristics as the sample chamber 122. This can be achieved by connecting an air pressure line 310 between the sample chamber 122 and the parallel visualization chamber 300. Thus, the rheometer 100 can be configured to maintain the parallel visualization chamber 300 under the same environmental conditions as the sample chamber 122. The air pressure line 310 can be connected to the sample chamber 122 at a first port 320 and can be connected to the parallel visualization chamber 300 at a second port 330. A camera 340 is shown connected to the parallel visualization chamber 300. The camera 340 can be configured to detect or otherwise capture an image within the parallel visualization chamber 300. For example, the camera 340 can provide the image to the user interface 130 or the control system 128 of the rheometer 100, or can provide the captured image to an external device (not shown).

[0067] Two additional cameras 350, 360 are also shown. The cameras 350, 360 are each shown connected to the sample chamber 122 and can each be configured to detect an image within the sample chamber 122. The camera 350 can extend through the side wall of the sample chamber 122 at a position directly above the measurement portion of the rotor. Other side wall positions are conceivable, such as at or below the measurement portion. The camera 360 can extend through the bottom of the sample chamber 122 and point to the space between the bottom of the sample chamber 122 and the measurement portion of the rotor. One or more of the cameras 340, 350, 360 can be implemented to provide real-time visual observation of the sample under pressure.

[0068] A method for performing rheological measurements on a material having a variable volume is further disclosed herein. The method includes at least partially filling a sample chamber of a rheometer with a sample, wherein the rheometer includes a rotor extending into the sample chamber, the rotor including an elongated shaft extending into a measurement portion that has a widened geometry relative to the elongated shaft. The method includes pressurizing the sample chamber such that a material compression ratio of at least 1.5 to 1, 2 to 1, 4 to 1, 5 to 1, or even 10 to 1 is achieved. The compression ratio can be defined by the ratio of the decompressed volume of the sample when the sample chamber is not pressurized to the compressed volume of the sample when the sample chamber is pressurized. The method can include maintaining material coverage of the sample over the entire measurement portion of the rotor during pressurization. The method further includes detecting an image within the sample chamber with a camera during pressurization. Alternatively, the method includes: maintaining a parallel visualization chamber under the same environmental conditions as the sample chamber; and detecting an image within the parallel visualization chamber with a camera during pressurization.

[0069] Although the present invention has been shown and described with reference to particular embodiments, those skilled in the art will understand that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as recited in the appended claims.

Claims

1. A rheology system, the rheology system comprising: A sample chamber; A compressed air system configured to provide compressed air to pressurize the sample chamber; And A rotor configured to perform rheological measurements on a material having a variable volume, the rotor including an elongated shaft extending to a measurement portion having a widened geometry relative to the elongated shaft, A parallel visualization chamber connected to the compressed air system, the rheology system configured to maintain the parallel visualization chamber at the same pressure as the sample chamber; and A camera configured to detect an image within the parallel visualization chamber, Wherein the rotor is sized such that a compression ratio of at least 1.5 to 1 can be achieved while maintaining material coverage of the sample over the entire measurement portion of the rotor, wherein the compression ratio is defined by the ratio of the decompressed volume of the sample when the sample chamber is not pressurized to the compressed volume of the sample when the sample chamber is pressurized.

2. The rheology system according to claim 1, wherein the measurement portion is cylindrical and includes a circumference and a thickness, wherein the circumference is less than the circumference of the sample chamber and greater than the circumference of the elongated shaft.

3. The rheology system according to claim 2, wherein the measurement portion includes a cylindrical wall having straight knurling with a vertical orientation.

4. The rheology system according to claim 2, wherein the measurement portion includes a plurality of outwardly projecting vanes vertically disposed around the circumference.

5. The rheology system according to claim 2, wherein the circumference is greater than twice the circumference of the elongated shaft.

6. The rheology system according to claim 5, wherein the thickness of the measurement portion is less than 1 / 5 of the length of the elongated shaft.

7. The rheology system according to claim 6, wherein a space separates the bottom of the measurement portion and the bottom of the sample chamber, and wherein the height of the space is less than the difference between the radius of the elongated shaft and the radius of the sample chamber.

8. The rheology system according to claim 1, wherein the rotor further includes a first end and a second end, the rotor further including a circumferential plate located at the first end, wherein the measurement portion is located at the second end.

9. The rheology system according to claim 1, further comprising an air pressure line connecting the sample chamber and the parallel visualization chamber.

10. The rheological system according to claim 1, wherein, The system is further configured to maintain the parallel visualization chamber at the same temperature as the sample chamber.

11. A method of performing rheological measurements on a material having a variable volume, the method comprising: At least partially filling a sample chamber of a rheometer with a sample, wherein a rotor extends into the sample chamber, the rotor including an elongated shaft extending to a measurement portion having a widened geometry relative to the elongated shaft; Pressurizing the sample chamber such that a compression ratio of at least 1.5 to 1 of the material is achieved, wherein the compression ratio is defined by the ratio of the decompressed volume of the sample when the sample chamber is not pressurized to the compressed volume of the sample when the sample chamber is pressurized; And Maintain a material coverage of the sample over the entire measurement section of the rotor during said pressurization, maintain the parallel visualization chamber at the same pressure as the sample chamber; and detect an image in the parallel visualization chamber with a camera during said pressurization.

12. The method according to claim 11, further comprising connecting the sample chamber and the parallel visualization chamber with an air pressure line.

13. The method according to claim 11, further comprising maintaining the parallel visualization chamber at the same temperature as the sample chamber.

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