JP2016136125A - Thermal analysis data processing method and thermal analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate a superimposed waveform for each single response and enable analysis for each response for thermal analysis data.SOLUTION: There are provided a thermal analysis data processing method and a thermal analysis device for executing the method. The method includes a measurement waveform acquisition step for acquiring a measurement waveform, a differential step for generating a differential waveform by differentiating the measurement waveform, a peak separation step for separating a superimposed peak waveform included in the differential waveform into a plurality of single peak waveforms, an integration step for individually integrating the plurality of single peak waveforms and generating a plurality of single response waveforms respectively, and a waveform shift step for moving any single waveform to any position to each of the plurality of single response waveforms by individually adding a predetermined movement amount to an XY direction.SELECTED DRAWING: Figure 3

Description

  The present invention relates to thermal analysis for investigating the temperature dependence of material properties, and more specifically to a method for separating superimposed waveforms in thermogravimetric measurement data or thermomechanical measurement data.

  Thermal analysis is an effective means for investigating how the physical properties of a sample change as the temperature changes, and records the change in physical properties as a function of temperature while heating the sample at a constant rate. Typical analysis methods include differential scanning calorimetry (DSC), differential calorimetry (DTA), thermogravimetry (TG), and thermomechanical measurement (TMA). Each of them measures temperature dependence of physical properties such as enthalpy balance, differential temperature, weight, and length of a sample (for example, Patent Document 1).

  In thermal analysis, there are those that generate a plurality of reactions in a temperature range measured by a sample, and there are those that generate a plurality of reactions in close temperature ranges. When a plurality of reactions occur in a very close temperature range, the waveform data acquired by these reactions becomes a superimposed waveform, making analysis for each reaction difficult. This tendency becomes prominent particularly when the temperature increase rate is increased in order to shorten the measurement time. This is because the signal to be obtained shows time dependency because the detector of the measurement signal in the thermal analysis has a unique time constant and the reaction rate of the sample affects.

  Even in such a situation, the normal DSC data measures the difference in heat quantity with respect to a reference material showing a certain specific heat capacity with respect to the heat change, and the chart showing the relationship between the temperature and the heat quantity shows the heat quantity. It becomes the shape which shows the peak according to a difference. In this way, the waveform showing the peak shape can be separated into a single waveform for each reaction relatively easily by nonlinear fitting.

  On the other hand, the TG data is obtained by plotting the weight of the sample with respect to the temperature rise, and indicates the amount of weight reduction during heating between arbitrary temperatures, and is different from the peak shape. In this case, it is usually difficult to quantify the amount of weight loss for each component depending on the closeness of the temperature such as thermal decomposition of each of the plurality of components. Such a situation is the same in the TMA data for measuring the deformation amount of the sample due to the static load with respect to the temperature change.

  Therefore, as a measure other than the method of slowing the rate of temperature rise from a normal fraction to a few tenths, measurement is performed while changing the temperature so that it is controlled according to the change in the substance in the sample. A method of using a rate-controlled thermal analysis (CRTA: Controlled Rate Thermal Analysis) or a sample-controlled thermal analysis (also referred to as SCTA: Sample Controlled Thermal Analysis) is well known. Both methods can improve the separation of the waveform in the measurement data, and in some cases, the superimposed waveform can be separated into a plurality of single waveforms. However, these methods basically tend to increase the measurement time.

  Therefore, a measure based on the premise of shortening the measurement time is, for example, calculating the activation energy from the acquired thermal analysis signal, and based on this, the thermal analysis signal that will be acquired at a sufficiently small heating rate. It has been proposed to acquire and estimate (Patent Document 2).

JP-A-9-26402 JP-A-11-160262

  However, according to the countermeasure of Patent Document 2, in order to determine the peak position and determine the presence or absence of peak overlap based on the second and third differential signals of the measurement signal, a superimposed waveform obtained by adding a plurality of component reactions is added. Therefore, there is a problem that it is difficult to perform analysis such as quantification of the amount of weight loss with respect to a single reaction waveform or to visually perform a difference between single reaction waveforms.

  In order to solve the problem, the thermal analysis data processing method of the present invention includes a measurement waveform acquisition step (S1) for acquiring a measurement waveform, and a differentiation step (S2) for differentiating the measurement waveform to generate a differential waveform. A peak separation step (S3) for separating the superimposed peak waveform included in the differential waveform into a plurality of single peak waveforms, and an integration step for individually integrating the plurality of single peak waveforms to generate a plurality of single reaction waveforms. (S4), and a waveform shift step (S5) for moving any single waveform to an arbitrary position by individually adding a predetermined amount of movement in the XY direction to each of the plurality of single reaction waveforms, It is characterized by including. In this manner, the superimposed waveforms of a plurality of reactions are separated into individual waveforms for each reaction, and each waveform is shifted (moved) to an arbitrary position, so that comparison between reactions can be easily visually examined.

In another invention, the shift to the arbitrary position crosses the measurement waveform at the maximum slope point of each of the plurality of single reaction waveforms, or the start point of the plurality of single reaction waveforms crosses the measurement waveform. Shift any single reaction waveform in the Y direction. Alternatively, a predetermined amount of movement in the XY direction is shifted so that each of arbitrary single reaction waveforms among the plurality intersects at each maximum inclination point. By doing in this way, comparison with the measurement waveform by visual observation and arbitrary single reaction waveforms becomes easy.
And it mounts in a thermal analyzer so that said method may be implemented.

  By using the waveform separation method according to the present invention, a superimposed waveform of a plurality of reactions in the thermal analysis data can be separated into a single reaction waveform and can be quantified for each reaction. This eliminates the need for time-consuming measurement and determination and setting of appropriate conditions associated with the conventional method of measuring at a slower rate of temperature increase than usual and CRTA measurement. Furthermore, even when multiple reactions occur in a very close temperature range, and even when it is difficult to separate waveforms using the above-described conventional method, the efficiency can be improved by using the waveform separation method according to the present invention. The separation into a single waveform can be performed appropriately and appropriately.

  In addition, according to the operation of the waveform shift process of the present invention, it is possible to display the separated single reaction waveform by shifting by various methods, and to compare the measured waveform with the single reaction waveform or between the single reaction waveforms. Can be made visually easy to understand.

It is a flowchart of the waveform separation method of the thermal analysis data concerning this invention. It is an example of the thermogravimetry apparatus concerning this invention. It is a flowchart of the 1st Example of this invention. (A) Example of measurement waveform of TG, (B) Example of DTG waveform and peak separation waveform, and (C) Example of single reaction waveform calculated by integrating DTG peak separation waveform. (A) It is a figure which shows the relationship between a measurement waveform, (B) DTG waveform, and (C) integral waveform. It is a figure which shows the example of the (A) shift position reference | standard of an integrated waveform in a 1st Example, (B) the relationship between a measured waveform, an integrated waveform, and the shifted integrated waveform, and (C) the output result. It is a flowchart of the 2nd Example of this invention. It is a figure which shows the example of the relationship between the (A) measurement waveform in the 2nd Example, an integrated waveform, and the shifted integrated waveform, and (B) output result. It is a flowchart of the 3rd Example of this invention. It is a figure which shows the example of the relationship between the (A) integrated waveform and the shifted integrated waveform in a 3rd Example, and the (B) output result. It is a figure which shows the variation of the alignment point in a 1st and 3rd Example.

  Hereinafter, a thermogravimetric measurement device (TG device) will be given as an example of the thermal analysis device according to the present invention, and its operation will be described in detail.

  The configuration of the thermogravimetric measurement apparatus according to the present invention is shown in FIG. A sample S, a heating furnace 21 for heating the sample S, a heating furnace controller 11 for controlling the temperature of the heating furnace 21 according to a temperature profile set by an operator, and a physical quantity sensor for measuring the temperature and weight (TG value) of the sample 12, a measurement data acquisition unit 13 that samples the temperature and TG value input from the physical quantity sensor 12 and captures them as a measurement waveform, a waveform separator 14 that separates a single weight reduction waveform from the superimposed waveform included in the measurement waveform, and a single unit An offset adder 16 that adds an offset to the weight decrease waveform, and a waveform display 17 that displays a single weight decrease waveform that has been offset added to a display medium such as a display or a printer, and a measurement waveform are provided.

  Next, the operation of the thermogravimetric measuring apparatus according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.

  Step 1) The operation of the heating furnace controller 11 is started by an instruction from the operator, and the temperature of the heating furnace 21 is controlled according to the temperature profile designated by the operator. The physical quantity sensor 12 outputs a sample temperature and weight (TG) signal.

  Step 2) The measurement waveform acquisition unit 13 samples the temperature and TG signal input from the physical quantity sensor 12 and outputs them as a measurement waveform F (x). FIG. 4A shows an example of F (x). The X axis is temperature or time, and the increasing direction is to the right. In this embodiment, the case where the temperature is taken on the X-axis will be described. However, the case where time is taken is similarly applicable. The Y axis is TG, and the decreasing direction is downward. The measurement waveform of TG starts from the TG value at the start of measurement, and becomes a waveform in which the weight decreases stepwise each time a reaction occurs. The TG value at the start of measurement is hereinafter referred to as TGini. In FIG. 4A, two reactions occur in a close temperature range, and respective waveforms are superimposed. Since the baseline portion (horizontal portion) between the two reactions is not clear, it is difficult to quantify the weight loss of the two reactions alone.

  Step 3) The waveform separator 14 differentiates F (x) to calculate a differential TG (DTG) waveform dF (x). An example obtained by differentiating the measurement waveform of FIG. 4A is shown in FIG. 4B dF (x). Thus, the DTG waveform has a peak shape. The Y coordinate of the baseline section is almost zero. Since F (x) in FIG. 4A has a waveform in which two weight reductions are superimposed, dF (x) in FIG. 4B also has a peak waveform in which two peaks are superimposed.

  Step 4) The waveform separator 14 performs peak separation on dF (x) to separate a plurality of single peak waveforms from the superimposed peak waveform. Peak separation is a known method, and is a method of separating a single peak waveform from a waveform in which a plurality of peaks are superimposed using a non-linear fit.

  FIG. 4B shows an example in which dF (x) is peak-separated. Hereinafter, the nth single peak waveform obtained by the peak separation is referred to as dFn (x). The coordinates of the peak top of dFn (x) are also obtained by peak separation. The X coordinate of the nth peak top is hereinafter referred to as Tn.

  Step 5) The waveform separator 14 calculates a waveform obtained by integrating the single peak waveform. The integrated waveform of dFn (x) is hereinafter referred to as Fn (x). An example of Fn (x) is shown in FIG.

  The Y coordinate of the start point of Fn (x) is almost zero. Fn (x) is a waveform obtained by independently extracting a plurality of weight decrease waveforms included in F (x). FIG. 5 shows the relationship between (A) the measured waveform, (B) the DTG waveform, and (C) the integrated waveform.

Step 6) The waveform shifter 15 starts a loop for shifting the integrated waveform Fn (x). Hereinafter, the index variable of the loop is set to i (a positive integer of 1 to N), the i-th integrated waveform is set to Fi (x), and the X coordinate of the i-th peak top is set to Ti.
Step 7) The waveform shifter 15 calculates the shift amount ΔYi of Fi (x) in the Y direction as shown in the following equation.
ΔYi = F (Ti) −Fi (Ti)
As shown in FIG. 6A, Ti is the X coordinate of the maximum inclination point of the integrated waveform Fi (x), and Fi (Ti) is the Y coordinate of the maximum inclination point.
Step 8) The waveform shifter 15 calculates a new waveform Gi (x) obtained by shifting Fi (x) according to the following equation.
Gi (x) = Fi (x) + ΔYi

The shift waveform Gi (x) is a waveform obtained by shifting the integrated waveform Fi (x) by ΔYi in the Y direction. As shown in the following equation, Gi (x) has a measured waveform F (x) coincident with the Y coordinate at the point of the X coordinate Ti.
Gi (Ti) = Fi (Ti) + ΔYi
= Fi (Ti) + F (Ti) -Fi (Ti)
= F (Ti)
FIG. 6B shows the relationship between F (x), Gi (x), and Fi (x).
Step 9) The loop index variable i is incremented, and Steps 7 and 8 are performed until i becomes equal to N.

  Step 10) The waveform display unit 17 outputs F (x) and Gn (x) to a display medium such as a display or a printer. An output example is shown in FIG. By displaying in this way, the relationship between F (x) and Gn (x) is visualized, and it becomes easier to understand than seeing each of them alone. Specifically, when Gn (x) or F (x) intersects at the maximum inclination point, there is an effect that can be understood at a glance by looking at the weight ratio or reaction start-end temperature that the single reaction occupies in the whole.

Next, the operation of the second embodiment of the thermogravimetric measuring apparatus of the present invention will be described based on the flowchart of FIG.
Steps 1 to 6 are the same as those in the first embodiment. Step 7 and subsequent steps will be described.

Step 7) The waveform shifter 15 calculates the shift amount ΔYi in the Y direction of the integrated waveform Fi (x) as follows: Here, Ts is the temperature at which the measurement is started, and is the X coordinate of the starting point of the measured waveform F (x) and the integrated waveform Fn (x).
ΔYi = F (Ts) −Fi (Ts)
Step 8) The waveform shifter 15 calculates a new waveform Gi (x) obtained by shifting Fi (x) according to the following equation.
Gi (x) = Fi (x) + ΔYi

The shift waveform Gi (x) is a waveform obtained by shifting the integrated waveform Fi (x) by ΔYi in the Y direction. As shown in the following equation, Gi (x) has the same measurement waveform F (x) and Y coordinate at the point of the X coordinate Ts.
Gi (Ti) = Fi (Ti) + ΔYi
= Fi (Ti) + F (Ts) -Fi (Ts)
When Ti = Ts,
Gi (Ts) = Fi (Ts) + F (Ts) -Fi (Ti)
= F (Ts)
FIG. 8A shows the relationship between F (x), Gi (x), and Fi (x).
Step 9) The loop index variable i is incremented, and Steps 7 and 8 are performed until i becomes equal to N.

  Step 10) The waveform display unit 17 outputs F (x) and Gn (x) to a display medium such as a display or a printer. FIG. 8B shows an output example. By displaying in this way, the ratio of the weight reduction amount for each reaction and the ratio of the weight reduction amount for each reaction to the total weight reduction amount are visualized, which makes it easier to understand than viewing each of them individually.

Next, the operation of the third embodiment of the thermogravimetric measurement apparatus of the present invention will be described based on the flowchart of FIG.
Steps 1 to 6 are the same as those in the first embodiment. Step 7 and subsequent steps will be described below.

Step 7) The waveform shifter 15 calculates the shift amount ΔXi in the X direction and the shift amount ΔYi in the Y direction of Fi (x) as follows. Here, Ti is the X coordinate of the i-th peak top. ConstX and ConstY are arbitrary constants and may have any value.
ΔXi = ConstX-Ti
ΔYi = ConstX-Fi (Ti)
Step 8) The waveform shifter 15 calculates a new waveform Gi (x) obtained by shifting Fi (x) according to the following equation.
Gi (x) = Fi (x + ΔXi) + ΔYi

As shown in FIG. 10A, Gi (x) is a waveform obtained by shifting Fi (x) by ΔXi in the X direction and ΔYi in the Y direction, and the coordinates of the maximum tilt point are (ConstX, ConstY).
Step 9) The loop index variable i is incremented, and the processing of Step 7 and Step 8 is repeated until i becomes equal to N.

Step 10) The waveform display unit 17 outputs F (x) and Gn (x) to a display medium such as a display or a printer. FIG. 10B shows an output example. By displaying in this way, the difference in waveform for each reaction is visualized, and it becomes easier to understand than looking at each individually.
It should be noted that the technical scope of the present invention is not limited to the above-described embodiments and extends to various modifications including equivalents without departing from the spirit of the present invention.

  For example, in the first or third embodiment, the integrated waveform and the measurement waveform or the integrated waveforms are aligned using the maximum inclination point of each integrated waveform, but not only the maximum inclination point but also the points shown in FIG. A method of performing alignment using (upper extrapolation point, height bisection point, lower extrapolation point) can be similarly implemented.

S: Sample 10 ... Heating furnace 11 ... Heating furnace controller 12 ... Physical quantity sensor 13 ... Measurement waveform acquirer 14 ... Waveform separator 15 ... Waveform shifter 16 ...・ Offset adder 17 ・ ・ ・ Waveform display

Claims (5)

In the method of processing thermal analysis data that separates the superimposed waveform data by a plurality of reaction waveforms out of the waveform data acquired by the thermal analysis device into individual waveforms for each reaction,
A measurement waveform acquisition step (S1) for acquiring a measurement waveform;
A differentiation step (S2) for differentiating the measurement waveform to generate a differential waveform;
A peak separation step (S3) for separating the superimposed peak waveform included in the differential waveform into a plurality of single peak waveforms;
An integration step (S4) of individually integrating a plurality of the single peak waveforms to generate a plurality of single reaction waveforms;
A waveform shift step (S5) for moving any single waveform to an arbitrary position by individually adding a predetermined movement amount in the XY direction to each of the plurality of single reaction waveforms;
A method for processing thermal analysis data, comprising:   2. The thermal analysis according to claim 1, wherein the waveform shifting step shifts any single reaction waveform in the Y direction so as to intersect the measurement waveform at each maximum inclination point of the plurality of single reaction waveforms. How to process the data.   2. The thermal analysis data according to claim 1, wherein the waveform shift step shifts any single reaction waveform in the Y direction so as to intersect with the measurement waveform at each start point of the plurality of single reaction waveforms. Processing method.   2. The heat according to claim 1, wherein the waveform shifting step shifts a predetermined amount of movement in the XY directions so that each of the single individual reaction waveforms among a plurality intersects at each maximum inclination point. How to process analytical data. A heating furnace for heating the sample;
A furnace controller for controlling the temperature of the furnace;
A physical quantity sensor for measuring the temperature and physical quantity of the sample;
A measurement data acquisition device that samples the temperature and physical quantity of the sample input from the physical quantity sensor and captures it as a measurement waveform;
A waveform separator for separating a plurality of single reaction waveforms from a superimposed waveform included in the measurement waveform;
An offset adder that individually adds a predetermined amount of movement in the XY direction to the plurality of single reaction waveforms;
A waveform display for displaying the measurement data and a plurality of the single reaction waveforms;
A thermal analysis apparatus that executes the thermal analysis data processing method according to any one of claims 1 to 4.

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