CN110068521B - A rotary shearing device - Google Patents
A rotary shearing deviceInfo
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- CN110068521B CN110068521B CN201910160448.2A CN201910160448A CN110068521B CN 110068521 B CN110068521 B CN 110068521B CN 201910160448 A CN201910160448 A CN 201910160448A CN 110068521 B CN110068521 B CN 110068521B
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- shearing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G01N2011/006—Determining flow properties indirectly by measuring other parameters of the system
- G01N2011/0093—Determining flow properties indirectly by measuring other parameters of the system thermal properties
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- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
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- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
The invention discloses a rotary shearing device which comprises a sample shearing mechanism, a cooling air cavity and a heating device, wherein the sample shearing mechanism comprises a movable shearing plate and a static shearing plate, the movable shearing plate can be matched with the static shearing plate to clamp a sample and can relatively rotate to shear the sample, the cooling air cavity surrounds the static shearing plate and the movable shearing plate, an air channel for ventilating and cooling the sample is formed in the cooling air cavity, the heating device can be inserted into the cooling air cavity to heat the sample and can be withdrawn from the cooling air cavity to conduct the air channel, when the rotary shearing device is used, the sample is clamped between the movable shearing plate and the static shearing plate, then the sample shearing temperature is set, the heating device is inserted into the cooling air cavity to heat the sample to a required temperature, the movable shearing plate is rotated to shear the sample, after melt rheological property detection is completed, the heating device is withdrawn, the sample is cooled by the cooling air cavity, so that the cooling time is shortened, the relaxation phenomenon of the sheared sample is reduced or avoided, and the accuracy of a detection result is improved.
Description
Technical Field
The invention relates to the technical field of processing performance test and characterization of high polymer products, in particular to a rotary shearing device.
Background
The research of the crystallization of the polymer material induced by the flow field has important guiding significance for the processing of the polymer material. Under industrial production and material service conditions, different external field parameters, including strain, strain rate, stress, etc., can affect the final structure and performance of the finished product. Based on these factors, it is important to study the mechanism of action of different external field parameters on the structural evolution of flow field induced crystallization. The basic idea of the research is to apply a flow field to a material under the set conditions of temperature, pressure and the like, and analyze the structure and performance characteristics of different dimensions by using different optical characterization means. And then directly correlating some parameters of the shear flow field, such as shear rate, shear strain, flow work and the like, with experimental phenomena of material structure evolution, and taking the parameters as quantitative criteria in flow induced crystallization. It should be noted, however, that the true rheological behavior of the melt is often ignored when conducting flow-induced crystallization experiments. In fact, some self-contained shear rheological devices do not have the ability to detect melt rheology. On one hand, because the shearing equipment does not have accessories for representing rheological behaviors (such as detection viscosity, normal stress and the like), and on the other hand, even if the rheological behavior can be represented, the rheological detection is generally carried out at a higher temperature, and the melt crystallization is slow at the high temperature and is unfavorable for maintaining a shearing induction structure, so that the effect of the shearing induction crystallization is likely not to be represented. And when the temperature shearing is suitable for crystallization, the structure generated in the shearing process can generate larger interference on the rheological behavior of the melt, so that the result is inaccurate. The above reasons lead to rheological and flow-induced crystallization disjointing and even affect the correctness of the existing theory.
Disclosure of Invention
Accordingly, the present invention is directed to a rotary shearing device, which can quickly reduce the temperature of a sample from a high temperature to an isothermal crystallization temperature after shearing, reduce the relaxation phenomenon of the sample during the temperature reduction process, and improve the accuracy of the detection result.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a rotary shearing device comprising:
The sample shearing mechanism comprises a movable shearing plate and a static shearing plate, wherein the movable shearing plate can be matched with the static shearing plate to clamp a sample, and the movable shearing plate can rotate relative to the static shearing plate to shear the sample;
The cooling air cavity surrounds the static shearing plate and the dynamic shearing plate, and an air channel for ventilating and cooling the sample is formed on the cooling air cavity;
the heating device can be inserted into the cooling air cavity to heat the sample, and can exit from the cooling air cavity so as to conduct the air duct.
Preferably, the device further comprises a detection ray channel, wherein the detection ray channel penetrates through the heating device, the cooling air cavity, the dynamic shearing plate and the static shearing plate.
Preferably, the movable shearing plate is connected to the sleeve, the static shearing plate is connected to the mounting plate, and the inner cavity of the sleeve, the through hole of the movable shearing plate, the through hole of the static shearing plate and the through hole of the mounting plate form the detection ray channel.
Preferably, the sleeve inner cavity, the through hole of the movable shearing plate, the through hole of the static shearing plate and the through hole of the mounting plate are internally provided with mounting beams, the mounting beams in the sleeve inner cavity are connected with the mounting beams in the through hole of the movable shearing plate through first connecting rods, and the mounting beams in the through hole of the static shearing plate are connected with the mounting beams in the through hole of the mounting plate through second connecting rods.
Preferably, the size of the through hole of the movable shearing plate is not larger than the size of the inner cavity of the sleeve, the diameter of the through hole of the static shearing plate is not smaller than the width of the through hole of the movable shearing plate, and the size of the through hole of the mounting plate is not smaller than the diameter of the through hole of the static shearing plate.
Preferably, the mounting plate is connected with a tension-pressure sensor connected with an information acquisition device for tracking the change of the shear stress.
Preferably, the sleeve is connected with a first driving device through a first transmission mechanism, the first driving device drives the sleeve to rotate through the first transmission mechanism, and the first transmission mechanism is used for enabling the first driving device to avoid an end opening of the sleeve.
Preferably, the first driving device comprises a first servo motor, the first transmission mechanism comprises a worm and a worm wheel which are meshed with each other, the worm wheel and the sleeve are coaxially arranged, and one end of the worm is connected with the first servo motor.
Preferably, the heating device comprises a heating sleeve and a second driving device, the heating sleeve is slidably sleeved outside the sleeve, and the second driving device is used for driving the heating sleeve to axially move along the sleeve so as to be inserted into or withdrawn from the cooling air cavity.
Preferably, the second driving device comprises a second servo motor, the heating sleeve is connected with the second servo motor through a second transmission mechanism, the second transmission mechanism comprises a screw rod assembly and a belt pulley assembly, a sliding block of the screw rod assembly is connected with the heating sleeve, a screw rod of the screw rod assembly is in threaded fit with the sliding block, a driving wheel of the belt pulley assembly is sleeved on an output shaft of the second servo motor, a driven wheel of the belt pulley assembly is sleeved on the screw rod, and a belt of the belt pulley assembly is wound around the driving wheel and the driven wheel.
Preferably, the heating device further comprises a thermal resistor, a temperature control probe and a temperature controller, wherein the temperature control probe is used for measuring the ambient temperature in the heating sleeve, and the temperature controller adjusts the working state of the thermal resistor according to the measurement data of the temperature control probe so as to control the ambient temperature in the heating sleeve.
Preferably, at least two of the thermal resistors are provided, and the temperature controller controls each of the thermal resistors.
Preferably, inlets of the air duct are formed on two sides of the cooling air cavity, and the inlets are opposite to the clamping positions of the sample shearing mechanism.
Preferably, the air duct also comprises a hot air device for introducing hot air into the air duct, and the temperature of the hot air provided by the hot air device is adjustable.
Preferably, the air duct also comprises a nitrogen-introducing device for introducing nitrogen into the air duct.
In summary, the invention provides a rotary shearing device, which comprises a sample shearing mechanism, a cooling air cavity and a heating device, wherein the sample shearing mechanism comprises a movable shearing plate and a static shearing plate, the movable shearing plate and the static shearing plate are arranged in parallel, the movable shearing plate can be matched with the static shearing plate to clamp a sample, the movable shearing plate can rotate relative to the static shearing plate to shear the sample, the cooling air cavity is surrounded by the static shearing plate and the movable shearing plate, an air channel for ventilating and cooling the sample is formed on the cooling air cavity, the temperature of the sample is reduced in a ventilation mode in the air channel when the rotary shearing device is used, meanwhile, the cooling air cavity is surrounded outside the sample, a relatively independent space is formed, the stable and controllable sample temperature can be maintained, the heating device has a movable function, and can be inserted into the cooling air cavity to heat the sample, and can exit the cooling air cavity to conduct the air channel so as to ventilate the sample to the air channel for an experimenter to cool the sample;
When an experiment is carried out, a high polymer sheet sample is clamped between the dynamic shearing plate and the static shearing plate, the sample is placed in the cooling air cavity, then the shearing temperature of the high polymer sheet sample is set, the heating device is inserted into the cooling air cavity to heat the sample, when the high polymer sheet sample reaches the required temperature, the dynamic shearing plate is rotated to shear the high polymer sample sheet, after the detection of the rheological property of a melt is completed at a high temperature, the heating device is withdrawn from the cooling air cavity, the sample is rapidly cooled by an air duct of the cooling air cavity, so that the cooling time is shortened, the relaxation phenomenon of the sheared sample in the process is reduced or avoided, and the accuracy of a detection result is improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a rotary shearing device according to an embodiment of the present invention;
FIG. 2 is a schematic view of a rotary shearing device according to an embodiment of the present invention in a heating station;
Fig. 3 is a schematic structural diagram of a rotary shearing device according to an embodiment of the present invention when the rotary shearing device is at a cooling station;
FIG. 4 is a graph showing a comparison of 2D-WAXS after crystallization of the sample under fast (left) and slow (right) cooling conditions;
FIG. 5 is a graph showing crystallization kinetics of isothermal crystallization of samples in two different cooling modes;
FIG. 6 is a graph of rheological data for samples at the same final shear rate and at different acceleration times;
FIG. 7 is a comparison plot of 2D-WAXS of structural evolution of a sample during isothermal crystallization at different acceleration times;
FIG. 8 is a graph of crystallization kinetics for samples at the same shear rate and at different acceleration times.
In the figure:
the device comprises a sample shearing mechanism 1, a sleeve 2, a mounting plate 3, a first transmission mechanism 4, a worm wheel 401, a worm 402, a first servo motor 5, a pull-pressure sensor 6, a compilable motion controller 7, a mounting beam 8, a cooling air cavity 9, an inlet of an air duct 901, a heating sleeve 10, a second servo motor 11, a belt pulley assembly 12, a driven wheel 1201, a tensioning wheel 1202, a driving wheel 1203, a belt 1204, a lead screw assembly 13, a sliding block 1301 and a lead screw 1302.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1 to 3, fig. 1 is a schematic structural diagram of a rotary shearing device according to an embodiment of the present invention, fig. 2 is a schematic structural diagram of the rotary shearing device according to an embodiment of the present invention when the rotary shearing device is at a heating station, and fig. 3 is a schematic structural diagram of the rotary shearing device according to an embodiment of the present invention when the rotary shearing device is at a cooling station.
The embodiment of the invention provides a rotary shearing device which comprises a sample shearing mechanism 1, a cooling air cavity 9 and a heating device.
The sample shearing mechanism 1 comprises a movable shearing plate and a static shearing plate, the movable shearing plate and the static shearing plate are arranged in parallel and side by side, the movable shearing plate can be matched with the static shearing plate to clamp the sample, and the movable shearing plate can rotate relative to the static shearing plate to shear the sample, and of course, the movable shearing plate and the static shearing plate are opposite and do not mean that the static shearing plate is completely static, therefore, the relative movement between the movable shearing plate and the static shearing plate can be realized by one rotation of the movable shearing plate or by the opposite rotation of the movable shearing plate and the static shearing plate, and the movable shearing plate and the static shearing plate also need to clamp the sample, and in the process, the movable shearing plate and the static shearing plate possibly need to be close to or far away from each other, so that at least one of the movable shearing plate and the static shearing plate also needs to be close to or far away from the other; the cooling air cavity 9 surrounds the static shear plate and the dynamic shear plate, an air channel for ventilating and cooling the sample is formed on the static shear plate and the dynamic shear plate, the temperature of the sample is reduced in a ventilation mode in the air channel during use, meanwhile, the cooling air cavity 9 surrounds the outside of the sample, a relatively independent space can be formed, the stability and the controllability of the temperature of the sample are maintained, the temperature regulation and control speed in the cooling air cavity 9 is improved, energy is saved, and the heating device has a movable function, can be inserted into the cooling air cavity 9 to heat the sample, and can be withdrawn from the cooling air cavity 9 to enable the air channel to be conducted, so that the sample is ventilated into the air channel by an experimenter to cool the sample.
Compared with the prior art, when the rotary shearing device provided by the embodiment of the invention is used for experiments, a high polymer sheet sample is clamped between the dynamic shearing plate and the static shearing plate, the sample is placed in the cooling air cavity 9, then the shearing temperature of the high polymer sheet sample is set, the heating device is inserted into the cooling air cavity 9 to heat the sample, when the high polymer sheet sample reaches the required temperature, the dynamic shearing plate is rotated to shear the high polymer sample sheet, after the melt rheological property detection is completed at high temperature, the heating device is withdrawn from the cooling air cavity 9, the sample is rapidly cooled by using the air duct of the cooling air cavity 9, so that the cooling time is shortened, the relaxation phenomenon of the sheared sample in the process is reduced or avoided, and the accuracy of the detection result is improved.
The rotary shearing device is often required to be combined with detection equipment such as X rays and infrared rays in the experimental process so that experimenters can track the evolution process of a sample structure, the rotary shearing device is conveniently combined with the radiation detection equipment, the rotary shearing device further comprises a detection ray channel, the detection ray channel is provided with an inlet and an outlet, and the detection ray channel penetrates through the heating device, the cooling air cavity 9, the dynamic shearing plate and the static shearing plate.
Specifically, in the embodiment of the present invention, as shown in fig. 1, the movable shearing plate is connected to the sleeve 2, the static shearing plate is connected to the mounting plate 3, the sleeve 2 is a hollow sleeve body, the inner cavity of the sleeve 2, the through hole of the movable shearing plate, the through hole of the static shearing plate and the through hole of the mounting plate 3 form a detection ray channel, during an experiment, incident light enters from an opening at one end of the sleeve 2 far from the movable shearing plate, sequentially passes through the inner cavity of the sleeve 2, the through hole of the movable shearing plate, the through hole of the static shearing plate and the through hole of the mounting plate 3, and then is ejected out, so that an experimenter can receive a ray scattering signal from one side of the mounting plate 3 far from the static shearing plate.
Preferably, when the X-ray passes through the sample, more obvious scattering occurs, as shown in fig. 1, in order to avoid shielding and interference to the scattering signal of the ray, the size of the through hole of the movable shearing plate is not greater than the size of the through hole of the static shearing plate of the inner cavity of the sleeve 2, the diameter of the through hole of the movable shearing plate is not less than the width of the through hole of the mounting plate 3, and the size of the through hole of the mounting plate is not less than the diameter of the through hole of the static shearing plate.
Preferably, for the installation of the movable shearing plate and the static shearing plate, the installation beams 8 can be arranged in the inner cavity of the sleeve 2, the through hole of the movable shearing plate, the through hole of the static shearing plate and the through hole of the mounting plate 3, the installation beams 8 in the inner cavity of the sleeve 2 are connected with the installation beams 8 in the through hole of the movable shearing plate through the first connecting rod, and the installation beams 8 in the through hole of the static shearing plate are connected with the installation beams 8 in the through hole of the mounting plate 3 through the second connecting rod.
Since the mounting beam 8 is located in the detection beam path, the cross section of the detection beam path forms two parts around the mounting beam 8, and in order to avoid the influence of the mounting beam 8 on the radiation, the rotary shearing device in the above embodiment should deviate from the axis of the sleeve 2 when in use.
Preferably, the mounting plate 3 is connected with a tension-pressure sensor 6, the tension-pressure sensor 6 is connected with the information acquisition device for tracking the change of the shearing stress, and the tension-pressure sensor 6 is arranged and connected with the information acquisition device, so that an experimenter can track and record the change of the shearing stress in real time, the rheological behavior is represented, and meanwhile, the control of the dynamic shearing plate is facilitated.
Preferably, the sleeve 2 is connected with a first driving device through a first transmission mechanism 4, the first driving device drives the sleeve 2 to rotate through the first transmission mechanism 4, and the first transmission mechanism 4 is used for enabling the first driving device to avoid an end opening of the sleeve 2, so that the rotary shearing equipment is convenient to be combined with the detection ray generating device.
Specifically, the first driving device comprises a first servo motor 5, the first servo motor 5 is connected with a compilable motion controller 7 so as to accurately control the shear rate of the sample, the first transmission mechanism 4 comprises a worm 402 and a worm wheel 401 which are meshed with each other, the worm wheel 401 is coaxially arranged with the sleeve 2, and one end of the worm 402 is connected with the first servo motor 5.
Of course, other structures, such as a gear mechanism, may be adopted for the first transmission mechanism 4, so long as the opening of the sleeve 2 is exposed while the sleeve 2 and the movable shearing plate are driven to rotate.
Preferably, as shown in fig. 2 and 3, the heating device includes a heating sleeve 10 and a second driving device, the heating sleeve 10 is slidably sleeved outside the sleeve 2, the second driving device is used for driving the heating sleeve 10 to axially move along the sleeve 2 to insert into or withdraw from the cooling air cavity 9, after the heating sleeve 10 enters the cooling air cavity 9, the moving shear plate, the static shear plate and the sample can be wrapped in the heating sleeve from the circumferential direction, so that the sample is heated from the circumferential direction, the temperature of the sample is conveniently and uniformly increased, and meanwhile, the sample is isolated from an air duct of the cooling air cavity 9, and the heat loss of the sample is reduced.
Further, as shown in fig. 2 and 3, the second driving device includes a second servo motor 11, the heating jacket 10 is connected with the second servo motor 11 through a second transmission mechanism, the second transmission mechanism includes a screw assembly 13 and a belt 1204 wheel assembly 12, a slider 1301 of the screw assembly 13 is connected to the heating jacket 10, a screw 1302 of the screw assembly 13 is in threaded fit with the slider 1301, a driving wheel 1203 of the belt 1204 wheel assembly 12 is sleeved on an output shaft of the second servo motor 11, a driven wheel 1201 of the belt 1204 wheel assembly 12 is sleeved on the screw 1302, a belt 1204 of the belt 1204 wheel assembly 12 is wound around the driving wheel 1203 and the driven wheel 1201, the second servo motor 11 and the compilatable motion controller 7 uniformly control the first servo motor 5 and the second servo motor 11, and of course, the heating device can also be controlled by the compilatable motion controller 7.
Further, the pulley assembly 12 further includes a tensioning pulley 1202, the tensioning pulley 1202 for tensioning the pulley 1204.
Preferably, the heating device comprises a thermal resistor, a temperature control probe and a temperature controller, wherein the temperature control probe is used for measuring the ambient temperature in the heating jacket 10, the temperature controller adjusts the working state of the thermal resistor according to the measurement data of the temperature control probe so as to control the ambient temperature in the heating jacket 10, when the heating device is used, the temperature control probe detects the temperature in the heating jacket 10 in real time, the temperature control probe sends the measured temperature data to the temperature controller, the temperature controller compares the temperature measured value with a preset value input by an experimenter, when the measured value is lower than the preset value, the temperature controller is connected with the power supply of the thermal resistor, and when the measured value is higher than the preset value, the power supply of the thermal resistor is disconnected, and through the device, the automatic and accurate control of the temperature in the heating jacket 10 can be realized, and the environment required by an experiment can be provided more accurately.
Of course, in other embodiments, the temperature within the heating jacket 10 may also be manually controlled by an experimenter by adjusting the power of the thermal resistor via an adjustment knob.
Further optimizing the above technical solution, in order to make the temperature in the heating jacket 10 more accurate, the heating device may include at least two thermal resistors, and the temperature controller controls each thermal resistor respectively, preferably, in the embodiment of the present invention, the heating device includes two thermal resistors, so as to form a dual-channel temperature control structure, and realize accurate control on the temperature in the heating chamber.
Preferably, the two sides of the cooling air cavity 9 are both provided with inlets 901 of air channels, the inlets 901 are opposite to the clamping positions of the sample shearing mechanism 1, and flowing gas can be simultaneously introduced into the cooling air cavity 9 from the two sides of the cooling air cavity 9 in the experimental process to realize cooling of samples.
Preferably, the rotary shearing device further comprises a hot air device for introducing hot air into the air duct, the temperature of the hot air provided by the hot air device is adjustable, the sample can be quickly cooled to a set temperature by introducing the hot air device into the air duct, the relaxation of the sample in the cooling process is reduced, meanwhile, the cooling rate is controllable, the structural change of the sample is conveniently observed by an experimenter at different cooling rates, and the hot air device can also help the sample to keep at isothermal crystallization temperature after the heating device exits from the cooling air cavity 9.
Specifically, the hot air device is an industrial hot air blower.
Preferably, the rotary shearing device further comprises a nitrogen-introducing device for introducing nitrogen into the air duct, and before the sample is heated, an experimenter can introduce nitrogen into the cooling air cavity 9 first to discharge air in the cooling air cavity, so that the temperature of the sample is ensured to be uniform in the heating process, and meanwhile, the sample is prevented from being degraded at a high temperature.
The following is an example of an application of the rotary shearing device of the present disclosure.
Experimental example 1:
influence of the cooling rate on the isothermal crystallization kinetics of the sample.
The purpose of the experiment is as follows:
When a flow induced crystallization experiment is performed, the sample is usually cooled to a proper isothermal crystallization temperature for isothermal crystallization after being sheared at a high temperature, and the temperature reduction process is performed for a time, namely the temperature reduction rate can greatly influence the isothermal crystallization result of the sample, so that the correct correlation between the apparent rate and the crystallization result is directly related. Therefore, it is necessary to control the cooling time after the sample is sheared. The experiment shows the effectiveness and importance of the rapid cooling system by comparing the difference between isothermal crystallization kinetics of the sample in the two modes of normal cooling and rapid cooling of the device.
The experimental process comprises the following steps:
the test sample was isotactic polypropylene and pressed into a 25 mm diameter and 1 mm thick disc using a tablet press. Wide angle X-ray scattering records the internal structure evolution process during isothermal crystallization of the sample.
Experimental results:
FIG. 4 is a graph showing a comparison of 2D-WAXS after completion of crystallization of a sample under conditions of rapid cooling (left) and slow cooling (right), and it can be seen from the graph that the degree of crystal orientation obtained after shearing of the sample is high in the rapid cooling mode.
Fig. 5 is a graph showing the crystallization kinetics of isothermal crystallization of samples in two different cooling modes, and it can be seen from the graph that the crystallization kinetics in the rapid cooling mode are faster than those in the slower cooling mode.
Conclusion of experiment:
The rapid cooling function in the invention can effectively reduce the relaxation of molecular chains in the cooling process, so that the effect of shear induced crystallization is maintained.
Experimental example 2:
In situ studies of wide angle X-ray scattering accelerated time effects on isotactic polypropylene shear induced crystallization.
The purpose of the experiment is as follows:
with the development of rheology, many experimental results show that when a polymer entanglement system is subjected to start-up deformation, the system can exhibit non-uniform flow behavior, which makes the mere correlation of flow field parameters with crystallization behavior, regardless of the true flow behavior of the melt, questionable. By changing the acceleration time at the initial stage of the application of the shear field (i.e., the motor acceleration time), the non-uniform flow behavior of the melt can be changed so that the flow becomes uniform. Therefore, in the flow induced crystallization experiment, the acceleration time must be considered as an apparent parameter. In the experiment, isotactic polypropylene (iPP) is used as a raw material, and the influence of motor acceleration time under fixed shear strain on the rheological property of an iPP melt and the shear-induced crystallization behavior is studied.
The experimental process comprises the following steps:
The test sample was isotactic polypropylene and pressed into a 25mm diameter and 1 mm thick disc using a tablet press. The X-ray linewidth angle scattering tracks the evolution of the internal structure of the sample during isothermal crystallization after shearing, and the tension-pressure sensor 6 records the change of stress during shearing. Combining the shear stress and X-ray scattering data, the information of the rheological and crystallization phase change of the isotactic polypropylene sample under the same shear rate and different acceleration time can be obtained.
Experimental results:
FIG. 6 is a graph of rheological data for samples at the same final shear rate, at different acceleration times, i.e., the change in shear process stress over time, at a shear rate of 30s -1. It can be seen from the graph that at different acceleration times, the stress of the sample rises with the increase of strain, and starts to fall after reaching the maximum stress, which indicates that the sample is converted into fluid for flowing after undergoing elastic deformation under a shearing field. When the acceleration time is 0 and 0.7s, the stress of the sample is rapidly reduced after the maximum stress is reached, the obvious stress overshoot phenomenon is shown, but the sample with the acceleration time of 1.4s does not exist, and the stress-strain curve is correspondingly and continuously and slowly reduced along with the increase of the strain after the maximum stress is reached. The melt flow conditions of the samples were different for different acceleration times.
FIG. 7 is a comparative 2D-WAXS of the structural evolution of a sample during isothermal crystallization at various acceleration times, from left to right, at the initial stage of crystallization to the end of crystallization. The first plot collected during isothermal crystallization had no crystal structure signal, and as crystallization progressed, an arc diffraction signal of iPP crystals appeared in the 2D-WAXS plot of the sample. During crystallization, the radian of the circular arc-shaped crystal signal gradually becomes larger, which indicates that the crystal orientation gradually becomes weaker, mainly because the shear-induced chain orientation is relaxed to a certain extent during isothermal crystallization, and meanwhile, the unoriented crystals formed during isothermal process can reduce the overall crystal orientation degree of the system.
FIG. 8 is a graph showing the crystallization kinetics of samples at the same shear rate and at different acceleration times, and it can be seen from the graph that the crystallization kinetics of samples at acceleration times of 0s and 0.7s are almost the same for samples having a shear rate of 30s -1, and are faster than for samples having an acceleration time of 1.4 s. Indicating that the acceleration time has an effect on the crystallization rate of the sample when the final shear rate is the same.
Conclusion of experiment:
by utilizing a shearing device which is combined with X-ray scattering and has a rapid cooling function, the rheological property of an isotactic polypropylene sample under the same shearing rate and different acceleration time conditions and the structure evolution process of the sample in the isothermal crystallization process are successfully observed through experiments. From the rheological data and the X-ray structure evolution, the following two conclusions can be drawn:
1) At different acceleration times, the samples have different entanglement melt flow behaviors;
2) The crystallization results after shearing of the samples at different acceleration times are also different due to the different flow behavior.
In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (15)
1. A rotary shearing device, comprising:
The sample shearing mechanism comprises a movable shearing plate and a static shearing plate, wherein the movable shearing plate and the static shearing plate are arranged in parallel and side by side, the movable shearing plate can be matched with the static shearing plate to clamp a sample, and the movable shearing plate can rotate relative to the static shearing plate to shear the sample;
the cooling air cavity surrounds the static shearing plate and the dynamic shearing plate, and an air channel for ventilating and cooling the sample is arranged on the cooling air cavity;
the heating device can be inserted into the cooling air cavity to heat the sample, and can exit from the cooling air cavity so as to conduct the air duct.
2. The rotary shearing device as recited in claim 1, further comprising a detection radiation passage extending through the heating device, the cooling plenum, the dynamic shear plate, and the static shear plate.
3. The rotary shearing device as recited in claim 2, wherein the movable shearing plate is connected to a sleeve, the static shearing plate is connected to a mounting plate, and the inner cavity of the sleeve, the through hole of the movable shearing plate, the through hole of the static shearing plate, and the through hole of the mounting plate constitute the detection ray path.
4. The rotary shearing device according to claim 3, wherein the sleeve inner cavity, the through hole of the movable shearing plate, the through hole of the static shearing plate and the through hole of the mounting plate are respectively provided with a mounting beam, the mounting beams in the sleeve inner cavity and the mounting beams in the through hole of the movable shearing plate are connected through a first connecting rod, and the mounting beams in the through hole of the static shearing plate and the mounting beams in the through hole of the mounting plate are connected through a second connecting rod.
5. The rotary shearing device as recited in claim 3 or 4, wherein the through hole dimension of the dynamic shearing plate is not greater than the sleeve inner cavity dimension, the through hole diameter of the static shearing plate is not less than the through hole width of the dynamic shearing plate, and the through hole dimension of the mounting plate is not less than the through hole diameter of the static shearing plate.
6. The rotary shearing device as recited in claim 3 or 4, wherein a pull-pressure sensor is attached to the mounting plate, the pull-pressure sensor being coupled to the information gathering device for tracking changes in shear stress.
7. The rotary shearing device as recited in claim 3 or 4, wherein the sleeve is coupled to a first drive means by a first transmission means for rotating the sleeve by the first transmission means, the first transmission means for causing the first drive means to avoid an end opening of the sleeve.
8. The rotary shearing device as recited in claim 7, wherein said first drive means comprises a first servo motor, said first transmission means comprises a intermeshing worm and a worm gear, said worm gear being coaxially disposed with said sleeve, said worm being connected at one end to said first servo motor.
9. The rotary shearing device as recited in any one of claims 3, 4 and 8, wherein the heating device comprises a heating jacket slidably disposed over the sleeve and a second driving device for driving the heating jacket to move axially along the sleeve to insert into or withdraw from the cooling air chamber.
10. The rotary shearing device as recited in claim 9, wherein the second driving device comprises a second servo motor, the heating jacket is connected with the second servo motor through a second transmission mechanism, the second transmission mechanism comprises a screw rod assembly and a belt pulley assembly, a sliding block of the screw rod assembly is connected with the heating jacket, a screw rod of the screw rod assembly is in threaded fit with the sliding block, a driving wheel of the belt pulley assembly is sleeved on an output shaft of the second servo motor, a driven wheel of the belt pulley assembly is sleeved on the screw rod, and a belt of the belt pulley assembly is wound outside the driving wheel and the driven wheel.
11. The rotary shearing device as recited in claim 9, further comprising a thermal resistor, a temperature control probe for measuring an ambient temperature within the heating jacket, and a temperature controller for adjusting an operating state of the thermal resistor according to measurement data of the temperature control probe to control the ambient temperature within the heating jacket.
12. The rotary shearing apparatus as recited in claim 11, wherein said thermal resistors are provided in at least two, and said temperature controller controls each of said thermal resistors individually.
13. The rotary shearing device as recited in claim 9, wherein the cooling air chamber is formed with inlets to the air duct on both sides thereof, the inlets being opposite to the clamping position of the sample shearing mechanism.
14. The rotary shearing device as recited in any of claims 1 to 4, 8 and 10 to 13, further comprising a hot air device for introducing hot air into the air duct, the hot air device providing hot air having an adjustable temperature.
15. The rotary shearing device as recited in any of claims 1-4, 8 and 10-13, further comprising nitrogen introducing means for introducing nitrogen into said air duct.
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| CN106124362B (en) * | 2016-06-07 | 2019-02-12 | 中南大学 | A kind of ultrasonic plasticizing capillary rheometer and viscosity testing method |
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