CN113551990A - Method for detecting internal heat generation of polyurethane material - Google Patents
Method for detecting internal heat generation of polyurethane material Download PDFInfo
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- CN113551990A CN113551990A CN202110726049.5A CN202110726049A CN113551990A CN 113551990 A CN113551990 A CN 113551990A CN 202110726049 A CN202110726049 A CN 202110726049A CN 113551990 A CN113551990 A CN 113551990A
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- 238000011084 recovery Methods 0.000 claims abstract description 41
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0003—Steady
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0676—Force, weight, load, energy, speed or acceleration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0682—Spatial dimension, e.g. length, area, angle
Abstract
The invention discloses a method for detecting internal heat generation of a polyurethane material, which is characterized in that a polyurethane sample strip is stretched in an environment with controlled temperature, and integration treatment is carried out on a stretching curve to obtain a data graph which can reflect the internal heat generation condition of the polyurethane material, such as total energy, energy recovery, energy consumption ratio and the like of the polyurethane in the stretching process. The method detects the condition of internal heat generation of the polyurethane through the energy change of the polyurethane at different stretching rates, and is an intuitive method for evaluating the internal heat generation of the polyurethane material. Compared with the common method for detecting the internal heat generation of the polyurethane material by using a dynamic thermomechanical analysis method (DMA), the method is simple and easy to implement, and has the advantages of simple operation, low cost and the like, so that the method has a good application prospect. The method provided by the invention can predict the internal heat generation condition of the polyurethane material in different application scenes, and has guiding significance for the practical application of the polyurethane material.
Description
Technical Field
The invention belongs to the technical field of high polymer material performance detection, and particularly relates to a method for detecting heat generation in a polyurethane material.
Background
Polyurethane is a synthetic high molecular material developed at a high speed, and new technology, new products and new applications related to the polyurethane are continuously emerged and almost extend to various industries. The thermoplastic polyurethane elastomer is recognized as a novel environment-friendly polymer material with excellent performance. At present, polyurethane mainly takes low-end consumption as main, the high-end consumption field of polyurethane is basically dominated by a plurality of international companies, including Germany Bayer, Pasfu, Luborun, Housmei and the like, the research and development of new products are enhanced, polyurethane products with high added values are continuously developed and put into the market, and thermoplastic polyurethane elastomer materials become one of elastomer materials which develop the fastest with excellent performance and wide application.
Polyurethane is a multi-block polymer composed of soft and hard segments, and the molecular chain contains more strong polar groups, such as ester groups, ether groups, urethane groups, urea groups, biuret groups, allophanate groups and the like, and the polar groups promote a large number of hydrogen bonds to be formed in the molecular chain and among the molecular chains, so that the acting force among the molecular chains is improved, and the internal rotation of the single chain bond is seriously hindered by the chemical crosslinking and the steric hindrance effect among the molecular chains. Therefore, under the action of an alternating external force with certain frequency and amplitude, strain cannot be synchronously stressed to generate a hysteresis phenomenon, dynamic mechanical loss is caused, internal heat is gradually increased due to the friction in a molecular chain, the service performance of the material is seriously influenced, and the application of the material in some fields, such as automobile tires, high-speed rubber rollers and the like, is limited.
Chinese patent with application publication No. CN110951034 discloses a preparation method of a low endogenous heat polyurethane elastomer, and a dynamic thermomechanical analysis (DMA) method is used for detecting endogenous heat. DMA is a commonly used method for detecting heat generation in polyurethane materials at present, but the method is complex to operate and high in cost; the macrocyclic stretching method is easy to operate, results are more visual, and the endogenous heat condition of the polyurethane material can be detected through the energy change trend under different stretching strain rates
Disclosure of Invention
The invention aims to provide a method for detecting internal heat generation of a polyurethane material, and solves the following technical problems.
The purpose of the invention can be realized by the following technical scheme:
a method of detecting heat generation within a polyurethane material, comprising the steps of:
(1) cutting the polyurethane to be detected to obtain a tensile sample strip;
(2) and (3) performing programmed stretching on the stretched sample strip in a temperature-controlled environment, and performing integration treatment on the stretching curve at different stretching rates to obtain a data graph of the heat generation condition in the reactive polyurethane material.
As a further scheme of the invention: cutting the polyurethane in the step (1) into dumbbell-shaped tensile sample bars with the size of 2 multiplied by 35 mm.
As a further scheme of the invention: the environment temperature of the process stretching in the step (2) is 23 +/-0.5 ℃.
As a further scheme of the invention: five stretching rates are set in the step (2), wherein the stretching rates are respectively 1mm/min, 10mm/min, 100mm/min, 250mm/min and 500mm/min, the original length of the sample strip is 20mm, and the corresponding nominal strain rates are respectively 0.0008s-1、0.008s-1、0.08s-1、0.2s-1And 0.4s-1。
As a further scheme of the invention: in the step (2), in the stretching process, the stretching is firstly set to be 200% of strain, and then the stretching is stopped when the stress is recovered to be zero, and a stretching curve forms a large ring.
As a further scheme of the invention: and (3) integrating a curve extending to the strain of 200%, a curve returning to the stress of zero and a large ring curve obtained by stretching and returning in the step (2) to obtain the total energy, the energy recovery, the energy consumption and the energy consumption ratio of the polyurethane in the stretching process.
As a further scheme of the invention: the polyurethane in the step (1) comprises an NDI type and a TDI type, and the internal heat generation of the NDI type polyurethane is smaller than that of the TDI type polyurethane at a high stretching speed.
Compared with the prior art, the invention has the beneficial effects that: the method comprises the steps of stretching the polyurethane sample strip in the environment with controlled temperature, and performing integration treatment on the stretching curves at different stretching rates to obtain the conditions of internal heat generation of the polyurethane in the stretching process, such as total energy, energy recovery, energy consumption ratio and the like. The method is simple and easy to implement, has the advantages of simplicity in operation, low cost and the like, can predict the internal heat generation condition of the polyurethane material in different application scenes, and has guiding significance for the practical application of the polyurethane material.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a schematic representation of an NDI polyurethane of examples 1-5 of the present invention before cutting.
FIG. 2 is a schematic representation of NDI polyurethane cut into dumbbell-shaped tensile bars measuring 2X 35mm in examples 1-5 of the present invention;
FIG. 3a is a graph showing an example of the strain at 0 during the stretching of an NDI polyurethane of examples 1-5 of the present invention, and FIG. 3b is a graph showing an example of the strain at 200% during the stretching of an NDI polyurethane of examples 1-5 of the present invention;
FIG. 4 is a schematic representation of the TDI polyurethane of examples 6-10 of the present invention before cutting;
FIG. 5 is a schematic diagram of TDI polyurethane cut into dumbbell type tensile sample bars of 2X 35mm in size according to examples 6-10 of the present invention;
FIG. 6a is a graph showing an example of the strain at 0% in the stretching process of the TDI type polyurethane of examples 6 to 10 of the present invention, and FIG. 6b is a graph showing an example of the strain at 200% in the stretching process of the TDI type polyurethane of examples 6 to 10 of the present invention;
FIG. 7a shows the nominal strain rate of 0.0008s for the NDI polyurethane obtained in example 1 of the present invention-1FIG. 7b is a graph showing the nominal strain rate of 0.0008s for the NDI polyurethane obtained in example 1 of the present invention-1FIG. 7c is a graph showing the nominal strain rate of the NDI polyurethane obtained in example 1 of the present invention as 0.0008s-1The energy recovery integral map of (1);
FIG. 8a shows the nominal strain rate of the NDI polyurethane obtained in example 3 of the present invention as 0.08s-1FIG. 8b is a graph showing the tensile stress-strain curves of the macrocyclic ring of the NDI-type polyurethane obtained in example 3 of the present inventionNominal strain rate of ester of 0.08s-1FIG. 8c is a graph showing the nominal strain rate of the NDI polyurethane obtained in example 3 of the present invention as 0.08s-1The energy recovery integral map of (1);
FIG. 9a shows the nominal strain rate of 0.4s for the NDI polyurethane obtained in inventive example 5-1FIG. 9b is a graph showing the nominal strain rate of 0.4s for the NDI polyurethane obtained in example 5 of the present invention-1FIG. 9c is a graph showing the nominal strain rate of the NDI polyurethane obtained in example 5 of the present invention as 0.4s-1The energy recovery integral map of (1);
FIG. 10a shows that the nominal strain rate of TDI polyurethane obtained in example 6 of the present invention is 0.0008s-1FIG. 10b shows the nominal strain rate of the TDI polyurethane obtained in example 6 of the present invention as 0.0008s-1FIG. 10c shows the nominal strain rate of TDI polyurethane obtained in example 6 of the present invention as 0.0008s-1The energy recovery integral map of (1);
FIG. 11a shows that the nominal strain rate of TDI polyurethane obtained in example 8 of the present invention is 0.08s-1FIG. 11b shows the nominal strain rate of the TDI polyurethane obtained in example 8 of the present invention as 0.08s-1FIG. 11c is a graph showing the nominal strain rate of TDI type polyurethane obtained in example 8 of the present invention as 0.08s-1The energy recovery integral map of (1);
FIG. 12a shows that the nominal strain rate of TDI polyurethane obtained in example 10 of the present invention is 0.4s-1FIG. 12b is a graph showing the nominal strain rate of the TDI polyurethane obtained in example 10 of the present invention as 0.4s-1FIG. 12c is a graph showing the nominal strain rate of TDI polyurethane obtained in example 10 of the present invention as 0.4s-1The energy recovery integral map of (1);
FIG. 13 is a graph showing the total energy versus nominal strain rate for NDI and TDI polyurethanes prepared in examples 1-10 of the present invention;
FIG. 14 is a graph showing the energy recovery versus nominal strain rate for NDI and TDI polyurethanes obtained in examples 1-10 of the present invention;
FIG. 15 is a graph showing the energy consumption versus nominal strain rate for the NDI and TDI polyurethanes obtained in examples 1-10 of the present invention;
FIG. 16 is a graph showing the energy consumption ratio of NDI polyurethane to TDI polyurethane obtained in examples 1-10 of the present invention as a function of nominal strain rate;
FIG. 17 is a wide angle X-ray diffraction pattern of the NDI polyurethane obtained in example 11 of the present invention;
FIG. 18 is a graph showing the azimuthal intensity distribution of NDI polyurethane obtained in example 11 of the present invention;
FIG. 19 is a wide angle X-ray diffraction pattern of the TDI polyurethane obtained in example 12 of the present invention;
FIG. 20 is a graph showing the azimuthal intensity profile of TDI polyurethane obtained in example 12 of the present invention;
FIG. 21 is a graph showing the relationship between the orientation parameters and the strain of the NDI polyurethane and TDI polyurethane obtained in examples 11 and 12 of the present invention;
FIG. 22 is a graph showing in situ small angle X-ray scattering of an NDI polyurethane obtained in example 13 of the present invention;
fig. 23a is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the NDI polyurethane obtained in example 13 of the present invention in the equatorial direction during stretching, fig. 23b is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the equatorial direction during recovery, fig. 23c is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the meridian direction during stretching, and fig. 23d is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the meridian direction during recovery;
FIG. 24 is a graph showing in situ small angle X-ray scattering of TDI polyurethane obtained in example 14 of the present invention;
fig. 25a is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the TDI-based polyurethane obtained in example 14 of the present invention in the equatorial direction during stretching, fig. 25b is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the TDI-based polyurethane in the equatorial direction during recovery, fig. 25c is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the TDI-based polyurethane in the meridian direction during stretching, and fig. 25d is a graph showing an in-situ small angle-X-ray scattering one-dimensional integral of the TDI-based polyurethane in the meridian direction during recovery;
FIG. 26a is a graph showing equatorial phase spacing versus strain for NDI polyurethane and TDI polyurethane obtained in examples 13 and 14 in accordance with the present invention; FIG. 26b is a graph showing the relationship between meridional phase separation and strain for NDI and TDI polyurethanes.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 to 26, in an embodiment of the present invention, a method for detecting heat generation in a polyurethane material includes:
(1) cutting the NDI type and TDI type thermoplastic polyurethane elastomers to obtain tensile sample strips;
(2) and (3) carrying out programmed stretching on the sample strip in a temperature control environment, and carrying out integral treatment on the stretching curves at different stretching rates to obtain a data graph capable of reflecting the heat generation condition in the polyurethane material.
The detection method is characterized in that stretching is carried out in an environment with controlled temperature, and the deformation of polyurethane can be divided into two parts in the process of stretching to set strain, wherein firstly, a polyurethane molecular chain is converted from a curling state to a stretching state, the deformation of the part belongs to elastic deformation, and energy is stored; secondly, the molecular chains of the polyurethane slide mutually, and the deformation of the part belongs to plastic deformation. The function of the external force on the system is used for generating heat by friction among polyurethane molecular chains, and the heat is lost in the form of heat energy. There is hysteresis during the stress-strain cycle, leaving only that portion of the energy stored in the polyurethane during the return to stress zero. The difference between the total energy and the energy recovery yields the energy consumption, i.e. the energy generated by the heat generation in the polyurethane during stretching.
Cutting polyurethane to obtain a tensile sample strip; the polyurethane is preferably cut and then stretched; the cut size is 2 multiplied by 35mm dumbbell-shaped tensile sample strip;
in the present invention, the size of the tensile sample bar is not particularly limited, and may be any international standard, and the polyurethane type is not limited to two polyurethanes detected in the present application, and is also not limited to a polyurethane material, and may be applied to various internal heat generating materials.
Subjecting the sample strip to macrocyclic stretching in a temperature-controlled environment;
the ambient temperature for the stretching of the macrocycle in the present invention is preferably 23 ± 0.5 ℃; the stretching rate of the stretching of the large ring is preferably 0.5-1000mm/min, and more preferably 1-500 mm/min; the original length of the tensile sample strip is 20 mm; further:
the stretching rate of the macrocyclic stretching is preferably 1mm/min, and the nominal strain rate is 0.0008s-1；
The stretching rate of the macrocyclic stretching is preferably 10mm/min, and the nominal strain rate is 0.008s-1；
The stretching rate of the macrocyclic stretching is preferably 100mm/min, and the nominal strain rate is 0.08s-1；
The stretching rate of the macrocyclic stretching is preferably 250mm/min, and the nominal strain rate is 0.2s-1；
The stretching rate of the macrocyclic stretching is preferably 500mm/min, and the nominal strain rate is 0.4s-1；
The maximum strain of the stretching of the large ring is preferably 5% to 1200%, more preferably 20% to 1000%, still more preferably 50% to 500%, most preferably 100% to 300%, and the maximum strain of the stretching of the large ring is preferably 200%;
the maximum strain of the stretching of the large ring is not limited to 200% which is preferably obtained in the application, and the maximum strain can be adjusted according to the specific characteristics of the material according to the type of the detection material.
After stretching, integrating the stretching curve to obtain a relational graph capable of detecting the heat generation in the polyurethane material;
the range of the integration treatment is preferably 0 to 200%; the total energy in the stretch recovery process is represented by the integrated area from zero strain to 200% maximum strain, the energy recovery in the stretch recovery process is represented by the integrated area from 200% maximum strain to zero stress, the energy consumption in the stretch recovery process is represented by the integrated area of the macrocycle, and the energy consumption ratio in the stretch recovery process is represented by the ratio of the integrated area of the macrocycle to the total energy. And (3) plotting the total energy, energy recovery, energy consumption and energy consumption ratio against the nominal strain rate to obtain a relational graph capable of detecting the heat generation in the polyurethane material.
According to the detection method, macrocyclic stretching is carried out in a temperature control environment, and a relationship graph capable of detecting the internal heat generation of the polyurethane material is obtained after the integral treatment of a stretching curve;
the total energy of the NDI type polyurethane basically keeps unchanged along with the increase of the nominal strain rate, the energy recovery is in an ascending trend, and the energy consumption ratio are in a descending trend;
the total energy, energy recovery, energy consumption and energy consumption ratio of the TDI type polyurethane all rise;
the detection result shows that the internal heat generation of the NDI polyurethane is smaller than that of the TDI polyurethane at high stretching speed.
To further illustrate the present invention, the following describes in detail a method for detecting heat generation in a polyurethane material provided by the present invention with reference to the following examples, in which the tensile test is performed according to the standard GB/T528-2009.
Example 1
Referring to FIGS. 1-7, NDI polyurethane is cut into dumbbell-shaped tensile sample strips with dimensions of 2X 35mm, the ambient temperature is 23 + -0.5 ℃, the tensile rate is 1mm/min, namely the nominal strain rate is 0.0008s-1And the tensile strain is 200%, and the macrocyclic tensile curve is obtained after the predetermined strain is reached and the macrocyclic tensile curve is stopped when the stress returns to zero.
Integrating the macrocyclic stretching curve, wherein the integration range is 0-200%, the integration area from zero strain to 200% maximum strain is the total energy in the stretching recovery process, the integration area from 200% maximum strain to zero stress is the energy recovery in the stretching recovery process, the integration area of the macrocyclic is the energy consumption in the stretching recovery process, the ratio of the integration area of the macrocyclic is the energy consumption ratio in the stretching recovery process, and the total energy, the energy recovery, the energy consumption and the energy consumption ratio are plotted against the nominal strain rate to obtain a relational graph capable of detecting the heat generation in the polyurethane material;
as can be seen from the graph a in FIG. 7, the nominal strain rate of the NDI type polyurethane is 0.0008s-1The energy consumption is 12.5MJ/m3；
As can be seen from the graph b in FIG. 7, the nominal strain rate of the NDI polyurethane is 0.0008s-1The total energy at that time was 16.1MJ/m3；
As can be seen from the graph c in FIG. 7, the nominal strain rate of the NDI polyurethane is 0.0008s-1The energy recovery time is 3.6MJ/m3；
In summary, as can be seen from the graphs a and b in FIG. 7, the nominal strain rate of NDI polyurethane is 0.0008s-1The energy consumption ratio was 77.9%.
Example 2
The internal heat generation of the NDI polyurethane material was examined as described above, and the procedure was as in example 1, except that the stretching rate was 10mm/min, i.e., the nominal strain rate was 0.008s-1。
Example 3
Referring to FIG. 8, the NDI polyurethane material was tested for internal heat generation as described above, which was performed in the same manner as example 1, except that the stretching rate was 100mm/min, i.e., the nominal strain rate was 0.08s-1。
As can be seen from the graph a in FIG. 8, the nominal strain rate of the NDI polyurethane is 0.08s-1The energy consumption is 11.9MJ/m3；
As can be seen from the graph b in FIG. 8, the nominal strain rate of the NDI polyurethane is 0.08s-1The total energy is 16.0MJ/m3；
As can be seen from the graph c in FIG. 8, the nominal strain rate of the NDI polyurethane is 0.08s-1The energy recovery in time was 4.1MJ/m3；
In summary, as can be seen from the graphs a and b in FIG. 8, the nominal strain rate of NDI polyurethane is 0.08s-1The energy consumption ratio was 74.5%.
Example 4
The internal heating of the NDI polyurethane material was examined as described above, and the procedure was as in example 1, except that the stretching rate was 250mm/min, i.e., the nominal strain rate was 0.2s-1。
Example 5
Referring to FIG. 9, the NDI polyurethane material was tested for internal heat generation as described above, which was performed in the same manner as example 1, except that the stretching rate was 500mm/min, i.e., the nominal strain rate was 0.4s-1；
As can be seen from the graph a in FIG. 9, the nominal strain rate of the NDI polyurethane is 0.4s-1The energy consumption is 11.3MJ/m3；
As can be seen from the graph b in FIG. 9, the nominal strain rate of the NDI polyurethane is 0.4s-1The total energy is 16.3MJ/m3；
As can be seen from the graph c in FIG. 9, the nominal strain rate of the NDI polyurethane is 0.4s-1The energy recovery in time was 4.9MJ/m3；
In summary, as can be seen from the graphs a and b in FIG. 9, the nominal strain rate of NDI polyurethane is 0.4s-1The energy consumption ratio was 69.7%.
Example 6
Referring to FIG. 10, the procedure for detecting the internal heat generation of TDI type polyurethane material is the same as that of example 1, except that the stretching rate is 1mm/min, i.e. the nominal strain rate is 0.0008s-1；
As can be seen from the graph a in FIG. 10, the nominal strain rate of TDI type polyurethane is 0.0008s-1The energy consumption is 9.6MJ/m3；
As can be seen from the graph b in FIG. 10, the nominal strain rate of TDI polyurethane is 0.0008s-1The total energy is 15.6MJ/m3；
As can be seen from the graph c in FIG. 10, the nominal strain rate of TDI polyurethane is 0.0008s-1The energy recovery time was 6.1MJ/m3；
In summary, FIG. 10 showsAs can be seen from the graphs a and b, the nominal strain rate of TDI type polyurethane is 0.0008s-1The energy consumption ratio was 61.2%.
Example 7
The procedure for examining the internal heat generation of TDI polyurethane materials was as described above in example 1, except that the stretching rate was 10mm/min, i.e., the nominal strain rate was 0.008s-1。
Example 8
Referring to FIG. 11, the procedure for detecting the internal heat generation of TDI type polyurethane material is the same as that of example 1, except that the stretching speed is 100mm/min, i.e. the nominal strain rate is 0.008s-1；
As can be seen from the graph a in FIG. 11, the nominal strain rate of TDI type polyurethane is 0.08s-1The energy consumption is 12.7MJ/m3；
As can be seen from the graph b in FIG. 11, the nominal strain rate of TDI type polyurethane is 0.08s-1The total energy at that time was 19.3MJ/m3；
As can be seen from the graph c in FIG. 11, the nominal strain rate of TDI polyurethane is 0.08s-1The energy recovery was 6.5MJ/m3；
In summary, as can be seen from the graphs a and b in FIG. 11, the nominal strain rate of TDI type polyurethane is 0.08s-1The energy consumption ratio was 66.2%.
Example 9
The TDI polyurethane material was tested for internal heat generation as above, and the procedure was as in example 1, except that the draw rate was 250mm/min, i.e., the nominal strain rate was 0.2s-1。
Example 10
Referring to FIG. 12, the procedure for detecting the internal heat generation of TDI type polyurethane material is the same as that of example 1, except that the stretching speed is 500mm/min, i.e. the nominal strain rate is 0.4s-1；
As can be seen from the graph a in FIG. 12, the nominal strain rate of TDI type polyurethane is 0.4s-1The energy consumption is 13.6MJ/m3；
As can be seen from the graph b in FIG. 12, the nominal strain rate of TDI polyurethane is 0.4s-1The total energy at that time was 20.4MJ/m3；
As can be seen from the graph c in FIG. 12, the nominal strain rate of TDI polyurethane is 0.4s-1The energy recovery was 6.7MJ/m3；
In summary, as can be seen from the graphs a and b in FIG. 12, the nominal strain rate of TDI type polyurethane is 0.4s-1The energy consumption ratio was 67.1%.
From the total energy, energy recovery, energy consumption and energy consumption ratio of the NDI and TDI polyurethanes obtained in examples 1-10, a graph of the total energy versus nominal strain rate can be obtained, as shown in fig. 13; energy recovery versus nominal strain rate as shown in fig. 14; energy consumption versus nominal strain rate as shown in fig. 15; energy consumption ratio versus nominal strain rate as shown in fig. 16.
As can be seen from fig. 13, the total energy of the NDI type polyurethane is substantially constant with the increase of the nominal strain rate, and the total energy of the TDI type polyurethane gradually increases with the increase of the nominal strain rate;
as can be seen from fig. 14, the energy recovery of both the NDI polyurethane and TDI polyurethane increases gradually with increasing nominal strain rate;
as can be seen from fig. 15, the energy consumption of the NDI type polyurethane gradually decreases with increasing nominal strain rate, and the energy consumption of the TDI type polyurethane gradually increases with increasing nominal strain rate;
as can be seen from fig. 16, the power consumption ratio of the NDI type polyurethane gradually decreases with an increase in the nominal strain rate, and the power consumption ratio of the TDI type polyurethane gradually increases with an increase in the nominal strain rate, and since the total energy of the NDI type polyurethane is smaller than that of the TDI type polyurethane, the power consumption ratio of the NDI type polyurethane is always larger than that of the TDI type polyurethane;
the detection results show that the internal heat generation of the NDI type polyurethane is smaller than that of the TDI type polyurethane under high-speed motion.
Example 11
Referring to fig. 17 to 18, the NDI-type polyurethane is cut into dumbbell-type tensile sample bars with the size of 2 × 2 × 35mm, wide-angle X-ray diffraction data (the tensile direction is in the vertical direction) of the NDI-type polyurethane is collected on a Mar165CCD detector on a beam line of a shanghai synchrotron radiation device BL16B1, the X-ray wavelength is 0.124nm, the distance from a sample to the detector is 180mm, background scattering correction is performed on the WARD mode, as shown in fig. 17, a wide-angle X-ray diffraction pattern of the NDI-type polyurethane is obtained, an azimuth angle integral is performed on the wide-angle X-ray diffraction pattern at a main peak position (2 θ ═ 20.8 °), as shown in fig. 18, and an azimuth angle intensity distribution map of the NDI-type polyurethane is obtained.
Example 12
Referring to fig. 19-20, the operation procedure of collecting the wide-angle X-ray diffraction data of the TDI-type polyurethane material in the same manner as in example 11 as shown in fig. 19 is as above to obtain a wide-angle X-ray diffraction pattern of the TDI-type polyurethane; as shown in fig. 20, the azimuthal intensity profile of TDI polyurethane is shown.
As can be seen from fig. 17 and fig. 19, before stretching (a-diagram in fig. 17, a-diagram in fig. 19) appears as non-preferred orientation concentric diffraction rings attributed to the crystalline state and isotropic diffuse scattering rings attributed to the amorphous state;
after stretching (panels b, d in fig. 17, and b, d in fig. 19), the preferentially non-oriented concentric diffractive rings gradually transition into a pair of broad diffractive arcs parallel to the stretching direction, indicating that the molecular chains are gradually oriented in the stretching direction during stretching;
as can be seen in fig. 18 and 20, the azimuthal intensity profile before stretching appears horizontal, indicating that the sample before stretching is not oriented; after stretching, a peak appears near 270 degrees, the peak strength gradually increases along with the increase of stretching strain, the peak strength gradually decreases along with the decrease of strain in the recovery process, an orientation parameter capable of representing the orientation degree is obtained through calculation, and the relationship between the orientation parameters of the NDI type polyurethane and the TDI type polyurethane and the strain is shown in FIG. 21. As can be seen from fig. 21, in the stretching and recovery processes, the orientation degree of NDI type polyurethane under higher strain is always greater than that of TDI type polyurethane because NDI molecular structure is symmetrical, the motion resistance to prevent rotation in a single bond is small, and the segment orientation is easily completed by the segment motion caused by rotation in the single bond, which corroborates the result obtained by the detection method of the present invention.
Example 13
The small angle X-ray scattering data for the NDI polyurethane material was collected as above and operated as in example 11 except that the sample to detector distance was 2195 mm. As shown in fig. 22, an in situ small angle X-ray scattering plot of the NDI polyurethane was obtained; as shown in a and b of fig. 23, integrating along the direction perpendicular to the stretching direction to obtain an in-situ small angle-X-ray scattering one-dimensional integral diagram of the equatorial direction of the NDI polyurethane; as shown in the c diagram and the d diagram in FIG. 23; integrating along the stretching direction to obtain an in-situ small-angle X-ray scattering one-dimensional integral diagram in the meridian direction;
example 14
Referring to fig. 24-25, the small angle X-ray diffraction data of TDI-type polyurethane material was collected as above and the procedure was the same as in example 13.
As shown in fig. 24, an in situ small angle X-ray scattering plot of TDI polyurethane was obtained, as shown in fig. 24;
as shown in a and b of fig. 25, integrating along the direction perpendicular to the stretching direction to obtain an in-situ small angle-X-ray scattering one-dimensional integral diagram of the equatorial direction of the TDI type polyurethane;
as shown in fig. 25, which are c and d, the in-situ small angle-X-ray scattering one-dimensional integral diagram in the meridian direction is obtained by integrating along the stretching direction.
As can be seen from fig. 22 and 24, the in-situ small angle X-ray scattering patterns before stretching (a-diagram in fig. 22, a-diagram in fig. 24) show isotropic circular scattering rings, indicating that the hard phase of the polyurethane is randomly dispersed in the soft matrix and the internal microstructure is randomly oriented;
after stretching (panels b and d in fig. 22, and panels b and d in fig. 24) the scattering pattern exhibited anisotropic elliptical scattering rings, oriented along the stretching direction, indicating that the hard phases were aligned along the stretching direction while the soft matrix was stretched;
during the retraction of the sample (e and f in fig. 22, e and f in fig. 24), the scattering ring gets closer to the original shape as the strain gradually decreases, however, it cannot be fully restored to the original isotropic circular scattering ring shape due to plastic deformation of the sample.
From FIG. 23As can be seen from the graph a in fig. 25, the maximum peak q of the scattering of the sample in the equatorial direction increases with the increase of the strain during the stretching processmaxMoving towards a high q value, qmaxGradually increasing, according to the formula d ═ 2 pi/q, where d represents the microphase-separated interphase spacing, indicating that along the stretch direction, the hard phases are oriented in an ordered arrangement along the stretch direction, resulting in a decrease in the interphase spacing between the soft and hard phases;
as can be seen from the graph b in FIG. 23 and the graph b in FIG. 25, the maximum peak value q of the sample scattering in the direction is reduced along with the reduction of the strain during the retraction processmaxReverting to a low q value, qmaxA gradual decrease, which indicates that, along the retraction direction, the hard phase gradually reverts to the initial position, increasing the phase separation;
from the graph c in fig. 23 and the graph c in fig. 25, it can be seen that the sample scattering maximum peak q in the meridian direction increases with the increase of the strain during the stretching processmaxReverting to a low q value, qmaxGradually decrease, which indicates that the phase spacing increases perpendicular to the direction of stretching;
as can be seen from the plots d in FIG. 23 and d in FIG. 25, the sample scattering maximum peak q in this direction is reduced with the strain during the retraction processmaxReverting to high q values, qmaxGradually increasing, which indicates that the phase separation decreases along the retraction direction;
as shown in a and b of fig. 26, which show the relationship between the phase distance in the equatorial direction and the meridian direction and the strain, it can be known from fig. 26 that the phase distance of the NDI type polyurethane in both directions is always larger than that of the TDI type polyurethane during the stretching process, so that the internal friction between the phase regions of the NDI type polyurethane is small, and the internal heat generation is small, and the result proves the result obtained by the detection method of the present invention again.
As can be seen from the above examples and figures, the internal heat generation of the NDI polyurethane is less than that of the TDI polyurethane at high stretching speeds. The reliability of the detection method is proved by the relationship between the structure and the performance obtained by the actual use condition and the X-ray diffraction and scattering characterization.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation and a specific orientation configuration and operation, and thus, should not be construed as limiting the present invention. Furthermore, "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate member, or they may be connected through two or more elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (7)
1. A method for detecting heat generation in a polyurethane material is characterized by comprising the following steps:
(1) cutting the polyurethane to be detected to obtain a tensile sample strip;
(2) and (3) performing programmed stretching on the stretched sample strip in a temperature-controlled environment, and performing integration treatment on the stretching curve at different stretching rates to obtain a data graph capable of reflecting the heat generation condition in the polyurethane material.
2. The method for detecting the generation of heat in the polyurethane material according to claim 1, wherein the polyurethane in the step (1) is cut into 2 x 35mm dumbbell-shaped tensile bars.
3. The method for detecting the generation of heat in the polyurethane material as claimed in claim 1, wherein the ambient temperature of the process drawing in the step (2) is 23 ± 0.5 ℃.
4. The method of claim 1, wherein five nominal strain rates of 0.0008s are set in step (2)-1、0.008s-1、0.08s-1、0.2s-1And 0.4s-1。
5. The method of claim 1, wherein the stretching step (2) is performed by first setting the stretching to 200% strain and then stopping when the stress returns to zero, and the stretching curve forms a large loop.
6. The method for detecting the internal heat generation of polyurethane material as claimed in claim 5, wherein the curve of stretching to 200% strain, the curve of returning to zero stress and the macrocyclic curve obtained by stretching return are integrated in step (2) to obtain the total energy, energy recovery, energy consumption and energy consumption ratio of the polyurethane during stretching.
7. The method for detecting the generation of heat in the polyurethane material according to claim 1, wherein the polyurethane in the step (1) comprises NDI type and TDI type.
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