CN108827819A - A method for judging the content of silicone rubber based on regression analysis - Google Patents

Abstract

The invention provides a regression analysis-based silicone rubber content determination method, which is characterized in that a scalpel is used for cutting a small amount of samples from silicone rubber to be detected, wherein the mass of the samples is about 5 mg; putting the sample into a synchronous thermal analyzer, and setting program parameters of the synchronous thermal analyzer: a reaction environment with a temperature range of 50-800 ℃, a temperature rise rate of 15 ℃/min and nitrogen; acquiring a turning point mass ratio and a terminal point mass ratio from the thermal weight loss curve, and taking the turning point mass ratio and the terminal point mass ratio as basic parameters for calculating the content of the silicone rubber; calculating the content of the silicone rubber, wherein the calculation formula is as follows: 115.259Mass_{Turning part}‑80.041Mass_{Remainder of}20.848, wherein y represents the content of silicone rubber, and the thermal weight loss curve is divided into 3 stages with the increase of temperature, Mass_{Turning part}The Mass residual ratio of the TGA turning point is shown, the Mass residual ratio of the TGA termination point is shown, and the TGA is shown in thermogravimetric analysis. The method can quickly obtain the content of the silicone rubber.

Description

A method for judging the content of silicone rubber based on regression analysis

technical field

The invention relates to a method for judging the glue content of high-temperature vulcanized silicone rubber, and more specifically, to a method for judging the glue content of silicone rubber based on regression analysis.

Background technique

High-temperature vulcanized silicone rubber is an insulating material widely used in power grid equipment such as composite insulators for transmission lines and substation circuit breakers. It is composed of polydimethylsiloxane PDMS, aluminum hydroxide ATH, white carbon black SiO ₂ and other additives. The content ratio of PDMS is the rubber content of silicone rubber. Since silicone rubber is an organic polymer material, aging phenomena such as pulverization, hardening, water repellency drop, cracking, and fading will inevitably occur during long-term outdoor operation, which directly affects the external insulation performance of composite material equipment and affects the safety of power systems. Stable operation brings hidden dangers. Only a suitable and appropriate silicone rubber content can ensure that the silicone rubber still has excellent aging resistance in harsh operating environments. Therefore, the accurate determination of the silicone rubber content can monitor the content of the vulcanized molded silicone rubber. On the other hand, it can also detect the rubber content of silicone rubber materials in electrical equipment.

Contents of the invention

In order to solve the problems pointed out in the background technology, the present invention provides a method for judging the content of silicone rubber based on regression analysis.

In order to solve the problems of the technologies described above, the technical solution of the present invention is as follows:

A method for judging the content of silicone rubber based on regression analysis, comprising the following steps:

S1: Use a scalpel to cut a small amount of sample from the silicone rubber to be tested, with a mass of about 5 mg;

S2: Put the sample into the synchronous thermal analyzer, and set the program parameters of the synchronous thermal analyzer: the temperature range is 50-800°C, the temperature rise rate is 15°C/min, and the reaction environment is nitrogen;

S3: Obtain the mass ratio of the turning point and the mass ratio of the end point from the thermogravimetric curve, as the basic parameters for calculating the content of silicone rubber;

S4: Calculate the silicone rubber content, the calculation formula is:

y=115.259Mass _turn -80.041Mass _remaining -20.848

Among them, y represents the content of silicone rubber. With the increase of temperature, the thermogravimetric curve is divided into three stages. The Mass _{turning point} represents the mass remaining ratio of the TGA turning point, and the Mass remaining represents the mass remaining ratio of the TGA end point. TGA represents the thermogravimetric analyze.

Compared with the prior art, the beneficial effect of the technical solution of the present invention is: the present invention provides a method for determining the content of silicone rubber based on regression analysis, using a scalpel to cut a small amount of samples from the silicone rubber to be tested, with a mass of about 5 mg; Put the sample into the synchronous thermal analyzer, and set the program parameters of the synchronous thermal analyzer: the temperature range is 50-800°C, the temperature rise rate is 15°C/min, and the reaction environment of nitrogen; the mass ratio of the turning point is obtained from the thermal weight loss curve and the mass ratio of the end point, as the basic parameter for calculating the silicone rubber content; to calculate the silicone rubber content, the calculation formula is:

y=115.259Mass _turn -80.041Mass _remaining -20.848

Among them, y represents the content of silicone rubber. With the increase of temperature, the thermogravimetric curve is divided into three stages. The Mass _{turning point} represents the mass remaining ratio of the TGA turning point, and the Mass _remaining represents the mass remaining ratio of the TGA end point. TGA represents the thermogravimetric analyze. The silicone rubber content that can be obtained rapidly by the method of the present invention.

Description of drawings

Figure 1 is a thermogravimetric graph.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example 1

A method for judging the content of silicone rubber based on regression analysis, comprising the following steps:

S1: Use a scalpel to cut a small amount of sample from the silicone rubber to be tested, with a mass of about 5 mg;

S2: Put the sample into the synchronous thermal analyzer, and set the program parameters of the synchronous thermal analyzer: the temperature range is 50-800°C, the temperature rise rate is 15°C/min, and the reaction environment is nitrogen;

S3: Obtain the mass ratio of the turning point and the mass ratio of the end point from the thermogravimetric curve, as the basic parameters for calculating the content of silicone rubber;

S4: Calculate the silicone rubber content, the calculation formula is:

y=115.259Mass _turn -80.041Mass _remaining -20.848

Among them, y represents the content of silicone rubber. With the increase of temperature, the thermogravimetric curve is divided into three stages. The Mass _{turning point} represents the mass remaining ratio of the TGA turning point, and the Mass remaining represents the mass remaining ratio of the TGA end point. TGA represents the thermogravimetric analyze.

Derivation of mass ratio-glue content formula based on regression analysis:

Firstly, high-temperature vulcanized silicone rubber samples with different rubber contents were prepared, and the contents of each component are shown in Table 1.

Table 1

Numbering Glue content/% Numbering Glue content/% B21 43.48 AH23 34.48 B11 43.48 AH24 33.33 B12 38.46 AV11 37.04 B13 34.48 AV12 35.71 B14 31.25 AV13 34.48 AH21 37.04 AV14 33.33 AH22 35.71 AH23 34.48

Since the thermal stability ranges of the three main components in silicone rubber are different, the thermal weight loss curve of the silicone rubber sample will show the characteristics shown in Figure 1.

Among them, there are two obvious change points of the remaining proportion, which are respectively the "TGA turning point" near 84% and 350°C and the "TGA end point" at the end of the weightlessness process. Mass _turning and Mass _remaining , as shown in the table below.

Table 2

Numbering MassTurn Mass remaining Numbering MassTurn Mass remaining B21 0.886278 0.457716 AH23 0.84455 0.517135 B11 0.876564 0.472657 AH24 0.850268 0.53818 B12 0.865942 0.521962 AV11 0.836606 0.494491 B13 0.84713 0.527029 AV12 0.843424 0.507668 B14 0.832266 0.548201 AV13 0.844552 0.526989 AH21 0.837754 0.475307 AV14 0.852744 0.544872 AH22 0.840458 0.505644 AH23 0.84455 0.517135

In the SPSS software, the Mass _transition and the Mass _remainder are taken as independent variables, and the glue content is taken as a dependent variable, and the relationship between them is analyzed by the method of multiple linear regression, and the following relationship can be obtained.

y=115.259Mass _turn -80.041Mass _remaining -20.848

The fitting error thus calculated is shown in Table 3, which shows that the accuracy of the formula is quite high.

table 3

Run sample verification:

The test samples were taken from a batch of returned composite insulator shed inner layers. Firstly, the density was measured by the drainage method, and then the glue content of the samples was calculated. The current research results show that the accuracy of this method is relatively high. The results are compared with the results of the rubber content calculated by the patent of the present invention, and the results are shown in the table below.

It can be seen that there is not much difference in the glue content calculated by the two methods, and both are feasible methods, but the method described in the patent of the present invention requires very little sample volume, and basically achieves non-destructive testing.

Theoretical derivation:

Assuming that the mass change rates of base rubber, aluminum hydroxide and silica in the first stage of weight loss are a ₁ , a ₂ and a ₃ respectively, the mass change rate of this period can be expressed as:

Similarly, assuming that the total mass change rate of the three components in the whole weight loss process is b ₁ , b ₂ and b ₃ respectively, then the total mass change rate

Combining the above two formulas, m ₂ and m ₃ can be obtained respectively, as follows

Substituting into the definition formula of glue content, simplification can be obtained

It can be seen that it is reasonable to use the mass remaining ratio of two key turning points in the thermogravimetric curve to linearly express the glue content in this paper.

Claims (2)

1. A method for judging the content of silicone rubber based on regression analysis is characterized in that it comprises the following steps: S1: Use a scalpel to cut a sample from the silicone rubber to be tested; S2: Put the sample into the synchronous thermal analyzer, and set the program parameters of the synchronous thermal analyzer: the temperature range is 50-800°C, the temperature rise rate is 15°C/min, and the reaction environment is nitrogen; S3: Obtain the mass ratio of the turning point and the mass ratio of the end point from the thermogravimetric curve, as the basic parameters for calculating the content of silicone rubber; S4: Calculate the silicone rubber content, the calculation formula is: y=115.259Mass _turn -80.041Mass _remaining -20.848 Among them, y represents the content of silicone rubber. With the increase of temperature, the thermogravimetric curve is divided into three stages. The Mass _{turning point} represents the mass remaining ratio of the TGA turning point, and the Mass remaining represents the mass remaining ratio of the TGA end point. TGA represents the thermogravimetric analyze. 2. The method for judging the content of silicone rubber based on regression analysis according to claim 1, characterized in that, in step S1, a scalpel is used to cut 5mg samples from the silicone rubber to be tested.