CN1865912A - Thermal analysis method for determining silicane mixture content - Google Patents

Abstract

The thermal analysis method for determining the content of silane mixture is to measure the relationship between the quality of the substance and the temperature under the program control temperature: the sample is placed in an inert atmosphere and heated at a rate of 10°C/min; 550°C isothermal for 60 minutes; 650°C is replaced by Oxygen isotherm for 60 minutes; calculate by thermogravimetric curve: read the initial mass M ₀ of the sample and the mass M ₁ at 105°C, and the content of low boiling point substances is: (M ₁ -M ₀ )/M ₀ ×100%; Read the mass M ₂ , the content of the silane coupling agent in the mixture is: (M ₂ -M ₁ )/M ₀ ×100%; read the final mass M ₃ of the mixture under the oxygen atmosphere, the silane mixture The percentage content of carbon black is: (M ₃ -M ₂ )/M ₀ ×100%; the content of the final residue is: M ₃ /M ₀ ×100%. The invention has the advantages of accurate determination, high sensitivity, simplicity and speed. It has practical significance to the quality control of silane mixture.

Description

Thermal analysis method for determination of silane mixture content

technical field

The invention relates to a thermal analysis detection method, in particular to a thermal analysis method for measuring the content of silane mixture by thermogravimetric analysis.

Background technique

Silane compound is a new type of mixture of silane coupling agent and carbon black. It is a very important raw material in the production of rubber industry. It is widely used as vulcanizing agent and activator. Because there are two types of functional groups (RS _i X ₃ ) in the special molecular structure of the silane coupling agent, the inorganic filler and the rubber can be chemically combined, so that the rubber is wear-resistant, tear-resistant, and durable. The physical properties such as flexibility and the performance of finished products have been significantly improved, and the production energy consumption is only half of that of similar products. However, it is difficult to accurately measure the content of water, ethanol and other low boiling point substances, silane coupling agent, carbon black and final residue in the sample silane mixture by conventional methods. The content of components is very necessary. First of all, the content of water and ethanol directly affects the quality of rubber products such as tires. If the content is too high, there will be many pores in the finished product, which will make the rubber product easy to break and reduce its service life. Secondly, most of the final residues come from the silane coupling agent, and the more residues, the worse the quality of the silane coupling agent and the worse the production process. Finally, the mixing ratio of carbon black and silane coupling agent is different, which will also affect the quality performance of the product and the energy consumption of production. At present, silane mixtures have been gradually converted from imports to localization, all of which put forward higher requirements for the accuracy and simplicity of the content determination of silane mixtures, and time-consuming and laborious chemical analysis methods such as combustion, titration, extraction, etc. It can no longer meet the needs of production and development, its accuracy is low, and human factors have a greater influence.

The thermal analysis method is a technique to measure the relationship between the physical properties of a substance and the temperature at a programmed temperature. In the process of heating or cooling, changes in the structure, phase and chemical properties of substances will be accompanied by corresponding changes in physical properties. However, there is no report on the use of thermal analysis methods to determine the content of silane mixtures.

Contents of the invention

As a raw material silane mixture in the rubber industry, its application is becoming more and more extensive. In order to improve the accuracy and convenience of the determination of its component content, improve the quality of the finished product, and meet the needs of industrial production, it is aimed at the general chemical analysis method. Shortcoming, the present invention will provide a kind of quick, easy, accurate, highly sensitive detection method of the quality of silane mixture: use the thermogravimetric analysis method to measure the content of each component in the silane mixture, be specifically moisture content, ethanol Such as low boiling point content, silane coupling agent, carbon black and final residual amount.

The thermogravimetric method used in the present invention is that it is a technique for measuring the relationship between mass and temperature of a substance under program-controlled temperature. The basic principle is: fully pyrolyze the polymer compound in nitrogen, then burn the carbon black in the air, and the remaining residue is residue.

A thermal analysis method for determining the content of a silane mixture, which measures the relationship between the mass of a substance and the temperature at a temperature controlled by a program, comprising the following steps:

Place the sample in an inert gas atmosphere (such as nitrogen) and heat it at a rate of 10°C/min;

Continue heating to 550°C, isothermal for 60 minutes;

Heating up to 650°C;

The gas was replaced with oxygen, and the temperature was maintained for 60 minutes;

Calculation by thermogravimetric curve:

From the thermogravimetric curve, read the initial mass M ₀ of the sample, read the mass M ₁ at 105°C, and the content of low boiling point substances (such as water and ethanol) is: (M ₁ -M ₀ )/M ₀ ×100%;

Read the mass M ₂ of the sample, and the content of the silane coupling agent in the silane mixture is: (M ₂ -M ₁ )/M ₀ ×100%;

Read the final mass M ₃ of the silane mixture under an oxygen atmosphere, and the percentage of carbon black in the silane mixture is: (M ₃ -M ₂ )/M ₀ ×100%;

The content of the final residue is: M ₃ /M ₀ ×100%.

More optimally and more specifically, the steps of the present invention are as follows:

1. Selection of sample dosage: take 5-10mg sample and place it in the aluminum oxide sample dish;

2. Program design: heat from room temperature to 550°C at a rate of 10°C/min in a nitrogen atmosphere; isothermally at 550°C for 60 minutes; heat up to 650°C at a rate of 10°C/min; replace the gas with nitrogen into oxygen; at 650 ° C for another 60 minutes.

3. Selection of atmosphere: the flow rates of nitrogen and oxygen are both: 40ml/min.

4. Calculation by thermogravimetric curve: the curve is shown in Figure 1, from the thermogravimetric curve,

a. You can directly read the initial mass M ₀ at the beginning of heating and the mass M ₁ at 105°C, then the content of low boiling point substances such as water and ethanol is (M ₁ -M ₀ )/M ₀ *100% ;

b. Read the mass M ₂ at 650°C under a nitrogen atmosphere, then (M ₂ -M ₁ )/M ₀ *100% is the content of the silane coupling agent in the silane mixture;

c. Read the final mass M ₃ of the silane mixture under oxygen atmosphere from the thermogravimetric curve, then, the percentage of carbon black in the silane mixture is: (M ₃ -M ₂ )/M ₀ *100%;

d. The content of the final residue is: M ₃ /M ₀ *100%.

In the above scenario:

1. The basic structure of the thermogravimetric analyzer is composed of a precision balance and a heating furnace with linear program temperature control. The thermal balance is measured according to the relationship between the inclination of the balance beam and the weight change, and the sensitivity can reach 0.1μg; the program control temperature is controlled by two thermocouples in the furnace and near the heating wire, which can provide accurate and sensitive temperature programs. The temperature accuracy can reach ±2℃.

2. In the present invention, the amount of sample measured by thermogravimetric method is only 5-10 mg, which is a small amount. Multiple sampling tests can be carried out for a certain batch of samples.

3. The whole experiment process takes about two hours. The method is convenient and fast, and can quickly and accurately detect the content of each component of the sample silane mixture.

4. The whole process is automatically executed by the instrument, which reduces the error of human operation and the influence of the surrounding environment.

The Al2O3 sample dish described in step 1 can also be replaced with a Pt sample dish.

In the present invention, the inventor has done a large amount of comparison experiments in terms of the isothermal time of the test, the flow rate of the atmosphere, the speed of the heating rate, and the amount of the sample, so as to grasp the best experimental conditions. The technical progress of the present invention lies in: accurate measurement, The dosage is small, the sensitivity is high, and the method is simple and fast. It has practical significance for the quality control of industrialization of silane mixture.

Description of drawings

Fig. 1 is the thermogravimetric curve of silane mixture standard product;

Figure 2 is the thermogravimetric curve of the sample silane mixture.

Detailed ways

Embodiment 1, measure the thermal analysis method of silane mixture content,

The instrument adopts the 7 series thermogravimetric analyzer produced by the American PE company, and takes 8.539 mg of imported silane mixture sample and 8.417 mg of domestic sample, and the flow rates of nitrogen and oxygen are both: 40ml/min.

Selection of sample dosage: take 5-10 mg sample and place it in an aluminum oxide sample dish;

Program design: heating from room temperature to 550°C at a rate of 10°C/min in nitrogen atmosphere; isothermal at 550°C for 60 minutes; heating to 650°C at a rate of 10°C/min; changing gas from nitrogen to oxygen ; Isothermal at 650°C for another 60 minutes.

Selection of atmosphere: the flow rates of nitrogen and oxygen are both: 40ml/min.

Calculation by the thermogravimetric curve: the curve is shown in Figure 1, from the thermogravimetric curve, heated from room temperature to 550 °C at a rate of 10 °C/min in a nitrogen atmosphere; isothermal at 550 °C for 60 min; The temperature was raised to 650°C at a rate of 1 min; the gas was changed from nitrogen to oxygen; the temperature was maintained at 650°C for another 60 minutes; the thermogravimetric curve was obtained, and its schematic diagram is shown in Figure 2; The initial mass M ₀ and the mass M ₁ at 105°C, then the content of low boiling point substances such as water and ethanol is (M ₁ -M ₀ )/M ₀ *100%; read at 650°C under nitrogen atmosphere Mass M ₂ , then (M ₂ -M ₁ )/M ₀ *100% is the content of the silane coupling agent in the silane mixture; read the final mass M of the silane mixture under oxygen atmosphere from the thermogravimetric curve ₃ , then, the percentage of carbon black in the silane mixture is:

(M ₃ -M ₂ )/M ₀ *100%;

The content of the final residue is:

M ₃ /M ₀ *100%.

Claims (3)

1, a kind of heat analysis method of measuring silicane mixture content, under programed temperature, measurement of species quality and temperature relation may further comprise the steps:

Sample is positioned in the inert gas atmosphere, with the speed program heating of 10 ℃/min;

Continue to be heated to 550 ℃, isothermal 60min;

Be warming up to 650 ℃;

Gas is replaced with oxygen, isothermal 60min;

Calculate by thermogravimetric curve:

From thermogravimetric curve, read the initial mass M of sample ₀, the mass M when reading 105 ℃ ₁, the content of low-boiling point material is: (M ₁-M ₀)/M ₀* 100%;

Read the mass M of sample ₂, the content of the silane coupling agent in the silane mixture is: (M ₂-M ₁)/M ₀* 100%;

Read in the silane mixture final mass M under the oxygen atmosphere ₃, the percentage composition of carbon black is in the silane mixture: (M ₃-M ₂)/M ₀* 100%;

The content of final residue thing is: M ₃/ M ₀* 100%.

According to the heat analysis method of the described mensuration silicane mixture content of claim 1, it is characterized in that 2, concrete steps are as follows:

Choosing of amount of samples: get 5～10mg sample, be positioned in the planchet;

The design of program: in nitrogen atmosphere, be heated to 550 ℃ with the speed of 10 ℃/min from room temperature; Isothermal 60min under 550 ℃ of temperature; Speed with 10 ℃/min is warming up to 650 ℃; Change gas, change oxygen into by nitrogen; At 650 ℃ of isothermal 60min again;

Choosing of atmosphere: the flow of nitrogen and oxygen is: 40ml/min;

Calculate by thermogravimetric curve, from thermogravimetric curve:

A. directly read the initial mass M when beginning to heat ₀With the mass M 105 ℃ the time ₁, the content of low-boiling point material such as moisture content and ethanol is (M ₁-M ₀)/M ₀* 100%;

Mass M when b. reading in following 650 ℃ of nitrogen atmosphere ₂, (M ₂-M ₁)/M ₀* 100% is the content of the silane coupling agent in the silane mixture;

C. read in silane mixture final mass M under the oxygen atmosphere from thermogravimetric curve ₃, the percentage composition of carbon black is in the silane mixture: (M ₃-M ₂)/M ₀* 100%;

D. the content of final residue thing is: M ₃/ M ₀* 100%.

3, according to the heat analysis method of claim 1 or 2 described mensuration silicane mixture contents, it is characterized in that,

Described inert gas is a nitrogen;

Described planchet is the alundum (Al planchet.

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