Multifunctional modularized rheological mixing method and device based on controllable flow fieldTechnical Field
The invention relates to the technical field of blending forming and rheological property measurement, in particular to a multifunctional modularized rheological mixing method and device based on a controllable flow field.
Background
Today, with continuous advancement of social development and technology, rheological property measurement, material mixing and different flow field change rules generally need to be operated by independent equipment, which increases equipment cost, operation complexity and energy consumption. Therefore, the controllable flow field compound equipment integrated with the rheometer and the mixing instrument is developed to meet the requirements of rheological property measurement and mixing integrated treatment under different flow fields, and has important application value.
Rheological property measurement is an important means for researching rheological behavior of materials, and can provide mechanical properties and viscosity characteristics of materials. However, conventional rheometers generally require separate operations and stringent requirements for conforming material classes, production isolation from material mixing, which also results in the rheometers not enabling real-time monitoring and improvement of solution mixing. On the other hand, the material mixing is a process of dispersing and mixing different materials, and is widely applied to the fields of rubber, plastics, chemical industry and the like. However, the traditional mixing apparatus has strict requirements on the types of solutions, the traditional mixing apparatus is difficult to mix the solutions with extremely high molecular weight, poor melt fluidity and poor heat and mass transfer effects, the mixing apparatus does not have rheological property measurement capability, the dispersion mixing capability and the molecular chain disentanglement capability of the solutions in a flow field cannot be adjusted based on the rheological property, and finally, the method of optimizing a material formula or improving the flow field structure cannot be adopted to solve the problems. Therefore, the controllable flow field compounding equipment integrating the rheometer and the mixing instrument is developed to meet the requirements of carrying out integrated treatment on rheological property measurement and material mixing of solutions such as polymer compound solution, polymer compound melt, polymer hydrogel and the like under different flow fields, and has important application value.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a multifunctional modularized rheological mixing method based on a controllable flow field, which can realize rheological property measurement and material mixing integrated treatment in different flow fields, and can further optimize parameters such as material formula, flow structure or mixing times in the next treatment process by using rheological property parameters obtained by measurement.
The invention further aims at providing a multifunctional modularized rheological mixing device based on a controllable flow field, which is used for realizing the method, integrates the advantages of a rheometer and a mixing meter, and can realize integrated treatment of rheological property measurement and material mixing under different flow fields.
According to the multifunctional modularized rheological mixing method based on the controllable flow field, a push-pull shaft is arranged in a mixing cavity, under the reciprocating motion of the push-pull shaft, a solution reciprocates in the mixing cavity with periodically changing shape, and the solution is fully mixed by utilizing a stretching flow generated by expansion and contraction of a converging flow channel formed in the mixing cavity or a shearing flow generated by wall surface speed difference of a flat flow channel, so that the continuous stretching flow or the shearing flow is obtained, and the fully mixed solution is obtained under the circulating stretching flow or the shearing flow, wherein the converging flow channel is formed between the push-pull shaft with circular cross section and the inner wall of the mixing cavity, and the flat flow channel is formed between the push-pull shaft with rectangular cross section and the inner wall of the mixing cavity, and in the dispersing mixing process, the solution undergoes dispersing, reciprocating, redispersing and reciprocating pulsation dispersing processes, so that the molecular chains of the solution are gradually opened and entangled, and the fully dispersed mixing between the molecular chains and the particles is realized;
In the process of dispersing the mixed solution, a pressure sensor arranged on the mixing cavity and a load sensor arranged on the push-pull shaft record the pressure of the solution in the mixing cavity and the thrust on the push-pull shaft in real time respectively, and when the current push-pull shaft is used, the obtained data are utilized to solve the viscous resistance of the solution on the surface of the push-pull shaft and the shearing viscosity and the shearing rate of the solution, so that an optimization basis is provided for the material formula, the flow field structure and/or the mixing times of the next solution mixing.
In the process, the obtained data are utilized to solve rheological performance parameters such as viscous resistance of the surface of a push-pull shaft, shearing viscosity of a solution, shearing rate and the like in the current state, then, the influence rule of factors such as stretching times, molecular weight, solid content, push-pull shaft structure and the like on the rheological performance of the solution is researched, and the critical point of the solution for converting the heterogeneous state into complete dispersion and molecular chain disentanglement is clear, so that the real-time optimization of a material formula, a flow field structure and mixing times is realized, and the requirements of full dispersion and molecular chain disentanglement of different solution systems are met.
In the method, when the current push-pull shaft is used, the specific processes of the viscous resistance of the solution on the surface of the push-pull shaft, the shearing viscosity of the solution and the shearing rate are as follows:
In order to establish a mathematical simplified model in a flow field, firstly, the solution in a mixing cavity is set to be isothermal and steady laminar flow, and the weight is ignored; in the following rectangular coordinate system (x, y, z), the origin O of the rectangular coordinate system is set at the inner center of the push-pull shaft, and the whole following coordinate system reciprocates together with the push-pull shaft, the x shaft is arranged along the moving direction of the push-pull shaft, the positive direction is the opposite direction of the movement of the push-pull shaft, the y shaft is perpendicular to the x shaft, the positive direction is directly directed to the upper cavity wall surface of the mixing cavity, the z shaft is wound from the x shaft to the y shaft in the anticlockwise direction by using four fingers of the right hand, the direction of the thumb is the positive direction of the z shaft, but the cross section shape of the cavity is only prolonged and not changed in the direction of the z shaft, so that the speed, the y shaft and the y shaft of the solution are not changed in the X and y shaft under the certain conditions;
in the mathematical model, the width of a mixing cavity along the z-axis direction is B, the linear distance from x2 to x1 is L, when the abscissa is x, the distance from the position of the surface of a push-pull shaft structure to the axis is Y (x), the distance from the position of a solution to be measured to the x-axis is Y (Y is more than or equal to Y (x)), Y1＝y2, the cross-sectional area of the abscissa which is x and is perpendicular to the x-axis is A, the viscous resistance of the surface of the push-pull shaft is Ftui, the consistency coefficient is k, and the power law index is n;
when the rheological mixing device operates, the pressure value P1 and the pressure value P2 measured by the pressure sensor and the thrust F of the push-pull shaft measured by the load sensor are recorded, and then the current solution shearing viscosity eta Shear with cutting edge is calculated, wherein the calculation process is as follows:
Substituting the pressure value P1, the pressure value P2 and the thrust force F of the push-pull shaft into a hydrodynamic basic equation to simplify the equation into a formula (1),
Performing double integration on x and y by using a formula (1) and multiplying the double integration by the width B of the rheological mixing cavity along the z axis to obtain a formula (2), wherein x is a coordinate value of the solution on the x axis (the x axis is the movement direction of the push-pull axis), and y is a coordinate value of the solution on the y axis (the y axis is the positive direction and is directly directed to the upper cavity wall surface of the mixing cavity);
The pressure sensor measures that the pressure value of the solution at the position of an x1 coordinate and the cross section perpendicular to the x axis is P1, the pressure value of the solution at the position of the cross section of an x2 coordinate is P2, B is the width of the rheological mixing cavity along the z axis, Y (x) is the distance from the position of the surface of the push-pull shaft structure to the axis when the abscissa is x, Y (x) is the distance (Y (x) not less than Y (x)) from the position of the solution to be measured to the x axis when the abscissa is x, Y (x1)＝y(x2), L is the linear distance from x2 to x1, F is the thrust of the push-pull shaft, Ftui is the viscous resistance of the surface of the push-pull shaft, and tauyx is the shearing stress of the solution at the corresponding coordinates (x, Y) along the x axis.
And then, a functional relation between the shear rate and each sensor parameter is established by using a power law equation and a formula (2), wherein the shear rate is equal to the velocity gradient, so that the velocity gradient du/dy of the solution in the (x, y) coordinates is solved:
Wherein gamma is the shear rate, k is the consistency coefficient, and n is the power law index;
and solving sigmax of the solution in the (x, y) coordinate according to a force balance equation of the solution in the x-axis direction:
The velocity u (x) of the solution at the (x, y) coordinates is further solved by the fixed integral of y from equation (3):
Wherein the method comprises the steps ofThen solving the numerical solution of the viscous resistance Ftui on the surface of the push-pull shaft through the characteristic that the flow flowing through different cross sections is the same, namely A1u(x1)＝A3u(x3;
Finally, solving the shear viscosity eta Shear with cutting edge of the solution in the (x, y) coordinates by using a formula (3) and a power law equation:
Finally, the values of shearing viscosity eta Shear with cutting edge, shearing rate gamma and viscous resistance Ftui on the surface of the push-pull shaft are obtained.
The solution is a dilute solution, a semi-dilute solution, a concentrated solution, a melt, a polyelectrolyte, or a gel.
The invention discloses a multifunctional modularized rheological mixing device based on a controllable flow field for the rheological mixing method, which comprises an upper cavity, a lower cavity, a push-pull rod, a push-pull shaft, a pressure sensor and a load sensor, wherein the upper cavity and the lower cavity are matched to form a mixing cavity, the push-pull shaft is arranged in the mixing cavity, a gap for passing solution is reserved between the surface of the push-pull shaft and the inner wall of the mixing cavity, the push-pull rod is connected with two sides of the push-pull shaft, two ends of the push-pull rod are arranged between the upper cavity and the lower cavity, one end of the push-pull rod is externally connected with the load device, the load sensor is arranged at the joint of the push-pull rod and the load device, and a plurality of pressure sensors are distributed on one side of the mixing cavity. The pressure sensor is used for detecting the pressure in the mixing cavity in real time in the mixing process, and the load sensor is coaxially arranged with the push-pull shaft and used for detecting the thrust of the push-pull shaft in the mixing process in real time.
The push-pull shaft reciprocates in the mixing cavity, and a circulating flow field area is formed between the push-pull shaft and the mixing cavity and is used as a sealed working area. The push-pull shaft is matched with the mixing cavity, when the push-pull shaft performs forward and backward reciprocating motion, the mixing cavity forms a front cavity and a rear cavity at the front side and the rear side of the push-pull shaft, and the volumes of the front cavity and the rear cavity are periodically changed.
The flow field area is a shear flow field area or a tensile flow field area.
The section of the push-pull shaft is round, rectangular, trapezoidal or pentagonal.
The push-pull rod comprises a front support push-pull rod and a rear support push-pull rod, the front support push-pull rod and the rear support push-pull rod are respectively detachably connected with two sides of the push-pull shaft, the push-pull shafts with different section shapes or sizes can be replaced according to actual needs through the disassembly and the assembly of the front support push-pull rod and the rear support push-pull rod, and the specific connection mode of the push-pull shafts is achieved through the conventional installation mode of the existing similar push-pull shafts.
The connecting surface of the upper cavity and the lower cavity is also provided with a gasket and a packing, and the gasket and the packing are respectively distributed on the periphery of the mixing cavity. The packing is used as sealing device to prevent the solution from leaking out due to the internal pressure, and the washer has buffering and sealing functions and may be used in regulating the interval between the upper cavity and the lower cavity.
The top of the upper cavity is also provided with a gland and a visual window, and the gland and the visual window are respectively distributed above the mixing cavity. The visual window can be made of quartz glass and arranged at a non-middle part on the upper cavity, after the solution is added, the tightening and fixing condition of the gland can be observed through the visual window, so that a completely sealed mixing cavity is formed between the upper cavity and the lower cavity, and in the process of dispersing and mixing the solution, the mixing process of the solution can be observed in real time through the visual window.
Compared with the prior art, the invention has the following beneficial effects:
in the multifunctional modularized rheological mixing method and device based on the controllable flow field, the controllable flow field is provided for the solution by utilizing the periodic reciprocating motion, so that the solution which is fully dispersed and mixed and the molecular chain disentangled under different flow fields can be obtained. Meanwhile, data during mixing of the solutions are recorded in real time through sensors (comprising the pressure sensors and the load sensors), and after analysis, parameters such as material formula, flow field type, mixing times and the like required by different solutions under the conditions of full dispersion and full disentanglement can be determined, so that mixing effects of various solutions are optimized and improved. Secondly, by utilizing the design of a flow field of reciprocating motion, the fluidity of the solution in the mixing cavity is uniformly improved, the phenomenon of local overheating or uneven mass transfer is avoided, and the performance problems such as molecular chain degradation and the like can be solved by controlling parameters such as mixing times, push-pull rod speed, heating temperature and the like by means of real-time feedback of a sensor.
The multifunctional modularized rheological mixing device based on the controllable flow field integrates the characteristics of a rheometer and a mixing meter, forms the replaceable design and the multifunctional modularized design of the equipment structure, realizes the efficient collaborative operation mode of rheological property measurement and material mixing treatment of solutions such as polymer composite solution, polymer composite melt, polymer hydrogel and the like under the condition of different flow fields, tightly combines the rheological property measurement and material mixing process under different flow fields, realizes the integrated operation of measurement and treatment, does not need to separately carry out mixing and rheological test, and saves time, experimental steps and material cost.
Drawings
Fig. 1 (a) is a schematic diagram of a stretching flow field in the process of dispersing and mixing in a mixing cavity in the multifunctional modularized rheological mixing device.
Fig. 1 (b) is a schematic diagram of a shear flow field in the process of dispersing and mixing in a mixing cavity in the multifunctional modularized rheological mixing device.
Fig. 2 is a schematic diagram of the principle of the multifunctional modular rheological mixing device.
Fig. 3 is a sectional view in the direction A-A of fig. 2.
Fig. 4 is a sectional view in the B-B direction of fig. 2.
FIG. 5 is a schematic view of the structure of the kneading chamber.
Fig. 6 is a top view of fig. 5.
Fig. 7 is a partial cross-sectional view of the gland of fig. 6.
Fig. 8 is a schematic structural view of the push-pull shaft when the cross section is rectangular.
Fig. 9 is a schematic structural view of a push-pull shaft with a trapezoidal cross section.
Fig. 10 is a schematic view of the structure when the push-pull shaft is pentagonal in cross section.
Fig. 11 is a schematic view of the structure of the push-pull shaft when the cross section is circular.
In the above figures, the components shown by the reference numerals are as follows:
1 is the surface of a push-pull shaft, 2 is the position of a composite material to be tested in the solution, V is the running speed of the push-pull shaft, and F is the thrust of the push-pull shaft;
3 is packing, 4 is the upper cavity, 5 is solution, 6 is visual window, 7 is push-pull rod, 8 is the lower cavity, 9 is push-pull shaft, 10 is pressure sensor, 11 is load sensor, 12 is gland, 13 is the packing ring.
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the present invention are not limited thereto.
Example 1
The embodiment provides a multi-functional modularization rheology mixing device based on controllable flow field, as shown in fig. 2 to 7, including the upper chamber, 4, lower cavity 8, push-pull rod 7, push-pull shaft 9, pressure sensor 10 and load sensor 11, the upper chamber forms the mixing chamber with lower cavity looks cooperation, the push-pull shaft is located the mixing intracavity, and leave the clearance that solution was used between the surface of push-pull shaft and the inner wall in mixing chamber, the both sides of push-pull shaft are connected with the push-pull rod, the both ends of push-pull rod are installed between upper chamber and lower cavity, the external load device of one end of push-pull rod, and the junction of push-pull rod and load device is equipped with load sensor, one side in mixing chamber distributes and has a plurality of pressure sensors. The pressure sensor is used for detecting the pressure in the mixing cavity in real time in the mixing process, and the load sensor is coaxially arranged with the push-pull shaft and used for detecting the thrust of the push-pull shaft in the mixing process in real time. The connecting surface of the upper cavity and the lower cavity is also provided with a gasket 13 and a packing 3, and the gasket and the packing are respectively distributed on the periphery of the mixing cavity. The packing is used as sealing device to prevent the solution from leaking out due to the internal pressure, and the washer has buffering and sealing functions and may be used in regulating the interval between the upper cavity and the lower cavity. The top of the upper cavity is also provided with a gland 12 and a visual window 6, and the gland and the visual window are respectively distributed above the mixing cavity. The visual window can be made of quartz glass and arranged at a non-middle part on the upper cavity, after the solution is added, the tightening and fixing condition of the gland can be observed through the visual window, so that a completely sealed mixing cavity is formed between the upper cavity and the lower cavity, and in the process of dispersing and mixing the solution, the mixing process of the solution can be observed in real time through the visual window.
The push-pull shaft reciprocates in the mixing cavity, and a circulating flow field area is formed between the push-pull shaft and the mixing cavity and is used as a sealed working area. The push-pull shaft is matched with the mixing cavity, when the push-pull shaft performs forward and backward reciprocating motion, the mixing cavity forms a front cavity and a rear cavity at the front side and the rear side of the push-pull shaft, and the volumes of the front cavity and the rear cavity are periodically changed. The flow field region is a shear flow field region or a tension flow field region.
The push-pull rod comprises a front support push-pull rod and a rear support push-pull rod, the front support push-pull rod and the rear support push-pull rod are respectively and detachably connected with two sides of the push-pull shaft, the push-pull shafts with different section shapes or sizes can be replaced according to actual needs through the disassembly and the assembly of the front support push-pull rod and the rear support push-pull rod, and the specific connection mode of the push-pull shafts is achieved through the conventional installation mode of the existing similar push-pull shafts. As shown in fig. 8 to 11, a push-pull shaft having a circular, rectangular, trapezoidal or pentagonal cross section may be employed.
Example 2
The embodiment provides a multifunctional modularized rheological mixing method based on a controllable flow field, which is realized by the multifunctional modularized rheological mixing device in embodiment 1.
According to the method, a push-pull shaft is arranged in a mixing cavity, under the reciprocating motion of the push-pull shaft, a solution reciprocates in the mixing cavity with a periodically changing shape, a stretching flow generated by expansion-contraction of a convergent flow channel formed in the mixing cavity or a shearing flow generated by wall surface speed difference of a flat flow channel is utilized to fully mix the solution, so that continuous stretching flow or shearing flow is obtained, and the fully mixed solution is obtained under the effect of circulating stretching flow or shearing flow, wherein according to the different cross-section shapes of the push-pull shaft, the convergent flow channel is formed between the push-pull shaft with an arc-shaped surface with a circular cross section and the inner wall of the mixing cavity (the formed stretching flow field is shown as a figure 1 (a)), the flat flow channel is formed between the push-pull shaft with a plane with a rectangular cross section and the inner wall of the mixing cavity (the formed shearing flow field is shown as a figure 1 (b)), and in the dispersing, reciprocating, redispersing and reciprocating pulsation dispersing processes are carried out on the solution in the dispersing and mixing processes, so that molecular chains of the solution are gradually opened, and fully dispersed and mixed between the molecular chains and the particles are realized. In the process of dispersing the mixed solution, a pressure sensor arranged on the mixing cavity and a load sensor arranged on the push-pull shaft record the pressure of the solution in the mixing cavity and the thrust on the push-pull shaft in real time respectively, and when the current push-pull shaft is used, the obtained data are utilized to solve the viscous resistance of the solution on the surface of the push-pull shaft and the shearing viscosity and the shearing rate of the solution, so that an optimization basis is provided for the material formula, the flow field structure and/or the mixing times of the next solution mixing. In the process, the obtained data are utilized to solve rheological performance parameters such as viscous resistance of the surface of a push-pull shaft, shearing viscosity of a solution, shearing rate and the like in the current state, then, the influence rule of factors such as stretching times, molecular weight, solid content, push-pull shaft structure and the like on the rheological performance of the solution is researched, and the critical point of the solution for converting the heterogeneous state into complete dispersion and molecular chain disentanglement is clear, so that the real-time optimization of a material formula, a flow field structure and mixing times is realized, and the requirements of full dispersion and molecular chain disentanglement of different solution systems are met.
The specific process of solving the viscous resistance of the solution on the surface of the push-pull shaft and the shear viscosity and shear rate of the solution when the current push-pull shaft is used by using the obtained data is as follows (the principle of the specific process is shown in figure 1):
In order to establish a mathematical simplified model in a flow field, firstly, the solution in a mixing cavity is set to be isothermal and steady laminar flow, and the weight is ignored; in the following rectangular coordinate system (x, y, z), the origin O of the rectangular coordinate system is set at the inner center of the push-pull shaft, and the whole following coordinate system reciprocates together with the push-pull shaft, the x shaft is arranged along the moving direction of the push-pull shaft, the positive direction is the opposite direction of the movement of the push-pull shaft, the y shaft is perpendicular to the x shaft, the positive direction is directly directed to the upper cavity wall surface of the mixing cavity, the z shaft is wound from the x shaft to the y shaft in the anticlockwise direction by using four fingers of the right hand, the direction of the thumb is the positive direction of the z shaft, but the cross section shape of the cavity is only prolonged and not changed in the direction of the z shaft, so that the speed, the y shaft and the y shaft of the solution are not changed in the X and y shaft under the certain conditions;
in the mathematical model, the width of a mixing cavity along the z-axis direction is B, the linear distance from x2 to x1 is L, when the abscissa is x, the distance from the position of the surface of a push-pull shaft structure to the axis is Y (x), the distance from the position of a solution to be measured to the x-axis is Y (Y is more than or equal to Y (x)), Y1＝y2, the cross-sectional area of the abscissa which is x and is perpendicular to the x-axis is A, the viscous resistance of the surface of the push-pull shaft is Ftui, the consistency coefficient is k, and the power law index is n;
when the rheological mixing device operates, the pressure value P1 and the pressure value P2 measured by the pressure sensor and the thrust F of the push-pull shaft measured by the load sensor are recorded, and then the current solution shearing viscosity eta Shear with cutting edge is calculated, wherein the calculation process is as follows:
Substituting the pressure value P1, the pressure value P2 and the thrust force F of the push-pull shaft into a hydrodynamic basic equation to simplify the equation into a formula (1),
Performing double integration on x and y by using a formula (1) and multiplying the double integration by the width B of the rheological mixing cavity along the z axis to obtain a formula (2), wherein x is a coordinate value of the solution on the x axis (the x axis is the movement direction of the push-pull axis), and y is a coordinate value of the solution on the y axis (the y axis is the positive direction and is directly directed to the upper cavity wall surface of the mixing cavity);
The pressure sensor measures that the pressure value of the solution at the position of an x1 coordinate and the cross section perpendicular to the x axis is P1, the pressure value of the solution at the position of the cross section of an x2 coordinate is P2, B is the width of the rheological mixing cavity along the z axis, Y (x) is the distance from the position of the surface of the push-pull shaft structure to the axis when the abscissa is x, Y (x) is the distance (Y (x) not less than Y (x)) from the position of the solution to be measured to the x axis when the abscissa is x, Y (x1)＝y(x2), L is the linear distance from x2 to x1, F is the thrust of the push-pull shaft, Ftui is the viscous resistance of the surface of the push-pull shaft, and tauyx is the shearing stress of the solution at the corresponding coordinates (x, Y) along the x axis.
And then, a functional relation between the shear rate and each sensor parameter is established by using a power law equation and a formula (2), wherein the shear rate is equal to the velocity gradient, so that the velocity gradient du/dy of the solution in the (x, y) coordinates is solved:
Wherein gamma is the shear rate, k is the consistency coefficient, and n is the power law index;
and solving sigmax of the solution in the (x, y) coordinate according to a force balance equation of the solution in the x-axis direction:
The velocity u (x) of the solution at the (x, y) coordinates is further solved by the fixed integral of y from equation (3):
then solving the numerical solution of the viscous resistance Ftui on the surface of the push-pull shaft through the characteristic that the flow flowing through different cross sections is the same, namely A1u(x1)＝A3u(x3;
Finally, solving the shear viscosity eta Shear with cutting edge of the solution in the (x, y) coordinates by using a formula (3) and a power law equation:
Finally, the values of shearing viscosity eta Shear with cutting edge, shearing rate gamma and viscous resistance Ftui on the surface of the push-pull shaft are obtained.
The solution is a dilute solution, a semi-dilute solution, a concentrated solution, a melt, a polyelectrolyte, or a gel.
As described above, the present invention can be better realized, and the above-mentioned embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of the present invention, i.e. all equivalent changes and modifications made in accordance with the present invention are covered by the scope of the claims of the present invention.