WO2016101902A1 - Device for testing thermal oxidation aging kinetics, and method for testing thermal oxidation absorption curve - Google Patents

Abstract

Provided are a device for testing the thermal oxidation aging kinetics of rubber, and a method for testing a thermal oxidation absorption curve; the testing device comprises a test bench (1), an evacuation and oxygen-supply system (7), a temperature control system (8), an oxygenation system (9), and an automatic recording system (10); the test bench (1) is an integrated structure; test chambers (2) are arranged symmetrically inside the test bench; the center and edge positions of the test bench (1) are provided with a center temperature measurement sensor (6) and an edge temperature measurement sensor (6'), respectively; the periphery of the test bench (1) is provided with, in sequence, a heating band (3) and a thermal layer (5); a sealed end of the test chambers (2) is provided with a pressure sensor; the test chambers (2) are separately in communication with the evacuation and oxygen-supply system (7) and the oxygenation system (9); the heating band (3) is connected to the temperature control system (8); the oxygenation system (9) is connected to the automatic recording system (10). The device of the present invention can be used for accurate, rapid, and bulk testing of the thermal oxidation properties of rubber.

Description

Rubber thermo-oxidative aging kinetics test device and method for testing thermal oxygen absorption curve Technical field

The invention relates to a high-temperature thermal oxygen absorption testing device and method, in particular to a rubber thermo-oxidative aging kinetic testing device and method for measuring organic solid materials such as rubber and polymer.

Background technique

The phenomenon of aging of rubber or rubber products during storage or use due to both heat and oxygen in the air is called thermal oxygen aging. Thermo-oxidative aging is the aging of various rubbers and their products at all times, which is the main cause of rubber damage. The thermal aging of rubber is a free-radical chain autocatalytic oxidation reaction in which the structure of the rubber changes and its properties change accordingly. The rubber undergoes thermal oxygen aging at temperatures below 200 ° C. Oxygen is the main cause of aging, and heat only acts to activate oxidation and accelerate oxidation. However, at a high temperature of 200 ° C or higher, the action of thermal energy alone is sufficient to degrade the rubber macromolecular chain. The higher the temperature, the more dominant the thermal degradation, and the thermal degradation becomes the main cause of rubber damage. Whether it is thermal oxidation or thermal degradation can not be eliminated, but can try to delay their occurrence, so that rubber products can maximize their use value. To this end, we should understand the mechanism of oxidation and thermal degradation of rubber and its influencing factors.

Ozone is another important factor that causes rubber to age in the atmosphere. Ozone is more active than oxygen, so its attack on rubber, especially unsaturated rubber, is much more severe than oxygen. Ozone in the atmosphere is formed by oxygen molecules absorbing short-wave ultraviolet light in sunlight, and the decomposed oxygen atoms are combined with oxygen molecules. In addition, ozone is generated in places where ultraviolet light is concentrated, in discharge places, and in electric motors, especially where electric sparks are generated. Usually the concentration of ozone in the atmosphere is 0 to 5 x 10 ^-8 . Unsaturated rubber is prone to ozonation and its appearance after ozonation. Unlike thermo-oxidative aging, first, the ozonation of rubber is carried out only in the surface layer contacted by ozone. The whole ozonation process is performed by the process in the surface. Second, the rubber reacts with ozone to form a silver-white hard film (about 10 nm thick). Under static conditions, the film can prevent deep contact between ozone and rubber, but under dynamic strain conditions or under static tension, when rubber When the elongation or tensile stress exceeds its critical elongation or critical stress, the film will crack, allowing the ozone to contact the new rubber surface, continuing the ozonation reaction and causing the crack to grow. There is stress concentration at the base, so it is easier to deepen the crack and form a crack.

At present, there is no standard standard for testing the thermal oxygen aging and ozone aging of rubber, and there is no uniform index for characterizing the thermal oxidation resistance of rubber.

Summary of the invention

In order to solve the problem in the prior art that there is no standard quantitative test rubber thermal oxygen aging and ozone aging, and there is no uniform problem of characterizing the thermal oxidation resistance of rubber, the invention invents a rubber thermal aging kinetics. Test device and test method, which can simulate the actual use environment, generate a constant temperature environment and a fixed oxygen pressure. It is possible to measure the oxidation reaction induction period and the oxidation reaction rate of rubber samples of different formulations, thereby comparing the degree of rubber oxidation reaction and further judging the performance of the rubber.

The technical solution of the present invention is:

A rubber thermal oxygen aging kinetic testing device comprises a test bench 1, a vacuum oxygen supply system 7, a temperature control system 8, an oxygen supplementation system 9, and an automatic recording system 10, wherein the test bench 1 is an integrated structure, and the test The test chamber 2 is symmetrically disposed inside the table, and the center temperature sensor 6 and the edge temperature sensor 6' are respectively disposed at the center and the edge position of the test station 1, and the heating belt 3 and the heat insulating layer 5 are sequentially disposed on the periphery of the test station 1; the test chamber 2 is sealed The pressure sensor is disposed at the end, the test chamber 2 is connected to the vacuuming oxygen supply system 7 and the oxygen supply system 9, respectively, the heating belt 3 is connected to the temperature control system 8, and the oxygen supply system 9 is connected to the automatic recording system 10.

At least four test chambers are symmetrically disposed on the test stand 1, and each test chamber can directly place a sample to be tested or a container containing the sample to be tested. The vacuuming oxygen supply system 7 includes a vacuum pump, an oxygen storage device, and a gas control valve, and the gas control valve controls the communication between the vacuum pump and the oxygen storage device and the test chamber 2.

The temperature control system 8 includes a heating belt 3, a temperature detecting device and a heating control device, wherein the temperature detecting device is respectively connected with the central temperature measuring sensor 6 and the edge temperature measuring sensor 6', and the heating control device is connected and controlled with the temperature detecting device. Heating belt 3. The oxygen supplementation system 9 includes a supplemental oxygen device, an oxygen supplementation control device, and an oxygen pressure detecting device, wherein the oxygen pressure detecting device is connected to the pressure sensor, the oxygen pressure detecting device is connected to the oxygen supplement control device, and the oxygen pressure detecting result is timely according to the result. Turn the supplemental oxygen unit on or off. The automatic recording system 10 is connected to a supplemental oxygen device to record the oxygen replenishment amount in a timely manner.

The invention also relates to a method for testing a rubber thermal oxygen absorption curve by using the rubber thermal aging kinetics test device described above, the operation steps of which are as follows:

(1) Start the temperature control system and heat the test chamber to the specified temperature;

(2) Put the samples to be tested into the test chamber and close the test chamber;

(3) starting the vacuuming oxygen supply system, first vacuuming the test chamber;

(4) Turn on the gas control valve to fill the test chamber with oxygen;

(5) The oxygen supply system automatically supplies oxygen to the test chamber according to the pressure value of the pressure sensor;

(6) The automatic recording system records the amount of supplemental oxygen in a timely manner and outputs a thermal oxidation curve.

Further, when the pressure in the test chamber is lower than 10 Pa in the step (3), the vacuuming is stopped; the heating temperature of the test chamber ranges from 50 to 200 °C. The oxygen pressure in step (4) is 1-2 bar.

Further, in step (4), oxygen containing a small amount of ozone may be charged.

The beneficial effects produced by the test apparatus and method of the present invention are:

(1) The device can generate a constant temperature environment and a fixed oxygen pressure in the test chamber, which provides a guarantee for simulating the actual environment of the sample to be tested, and improves the accuracy and objectivity of the test.

(2) The apparatus of the present invention can obtain the oxygen absorption amount and the oxidation kinetic curve of the sample, and the oxidation reaction induction period and the oxidation reaction speed can be obtained according to the recorded reaction curve, thereby comparing the degree of the rubber oxidation reaction. Used to study the oxidation properties of different types of raw rubber or some other high polymers, different antioxidants and vulcanizates of different formulations.

(3) The present invention can simultaneously set a plurality of test chambers and can test a plurality of samples, and the settings of the plurality of sensors can accurately ensure the accuracy of the temperature and pressure of the test chamber. The device of the invention can accurately and quickly test the thermal oxidation performance of the rubber, and greatly improves the test efficiency and the accuracy of the test result.

It is worth mentioning that the apparatus and test method of the present invention can be used to test the thermal oxidation performance of certain high molecular polymers or other organic solid materials in addition to the rubber thermal oxidation performance.

DRAWINGS

Figure 1 Schematic diagram of the rubber thermal aging kinetics test device

Figure 2 test bench structure

Figure 3 shows the method of testing the rubber thermal oxygen absorption curve

Figure 4 is a graph showing the thermal oxygen absorption curve of the actual performance test of the device of the present invention.

Figure 5 is a diagram showing the thermal oxygen absorption curve of the second experiment of the device of the present invention.

1 test bench, 2 test chambers, 3 heating belts, 5 insulation layers, 6 center temperature measurement points, 6' edge temperature measurement points, 7 vacuum supply system, 8 temperature control system, 9 oxygen supply system, 10 automatic recording system

detailed description

Example

Example 1

Rubber thermo-oxidative aging kinetic testing device, comprising a test stand 1, an evacuation oxygen supply system 7, a temperature control system 8, an oxygen supply system 9, and an automatic recording system 10, wherein the test bench 1 is an integrated structure, and the test bench interior The test chamber 2 is symmetrically disposed, and the center temperature sensor 6 and the edge temperature sensor 6' are respectively disposed at the center and the edge position of the test station 1, and the heating belt 3 and the heat insulating layer 5 are sequentially disposed on the periphery of the test station 1; the sealed end of the test chamber 2 is set The pressure sensor, the test chamber 2 is connected to the vacuum oxygen supply system 7 and the oxygen supply system 9, respectively, the heating belt 3 is connected to the temperature control system 8, and the oxygen supply system 9 is connected to the automatic recording system 10. Six test chambers are symmetrically arranged on the test stand 1, and each test chamber can directly place a sample to be tested or a container containing the sample to be tested. The vacuuming oxygen supply system 7 includes a vacuum pump, an oxygen storage device, and a gas control valve, and the gas control valve controls the communication between the vacuum pump and the oxygen storage device and the test chamber 2. The temperature control system 8 includes a heating belt 3, a temperature detecting device and a heating control device, wherein the temperature detecting device is respectively connected with the central temperature measuring sensor 6 and the edge temperature measuring sensor 6', and the heating control device is connected and controlled with the temperature detecting device. Heating belt 3. The oxygen supplementation system 9 includes a supplemental oxygen device, an oxygen supplementation control device, and an oxygen pressure detecting device, wherein the oxygen pressure detecting device is connected to the pressure sensor, the oxygen pressure detecting device is connected to the oxygen supplement control device, and the oxygen pressure detecting result is timely according to the result. Turn the supplemental oxygen unit on or off. Place The automatic recording system 10 is connected to the supplemental oxygen device to record the oxygen replenishment amount in a timely manner.

Example 2

Start the temperature control system, heat the test chamber, and stop heating when heated to 150 °C; put the samples to be tested into the test chamber and close the test chamber; start vacuuming the oxygen system, first evacuate the test chamber separately. When the pressure in the test chamber is lower than 10pa, the vacuum is stopped, and the gas control valve is opened to charge the test chamber with 1 bar of oxygen; the oxygen supply system automatically supplies oxygen to the test chamber according to the pressure value of the pressure sensor; the automatic recording system records the time The amount of oxygen was replenished and the thermal oxidation curve was output after the test.

Example 3

Start the temperature control system, heat the test chamber, stop heating when heated to 200 °C; put the sample to be tested into the test chamber, close the test chamber; start the vacuum to the oxygen system, first vacuum the test chamber When the pressure in the test chamber is lower than 10pa, the vacuum is stopped, and then the gas control valve is opened to charge the test chamber with 1 bar of oxygen; the oxygen supply system automatically supplies oxygen to the test chamber according to the pressure value of the pressure sensor; The amount of supplemental oxygen was recorded and the thermal oxidation curve was output after the test.

Example 4

Start the temperature control system, heat the test chamber, stop heating when heated to 50 °C; put the sample to be tested into the test chamber, close the test chamber; start the vacuum to the oxygen system, first vacuum the test chamber When the pressure in the test chamber is lower than 10 Pa, the vacuum is stopped, and then the gas control valve is opened to charge the test chamber with oxygen mixed with 1 volume of ozone; the oxygen supply system automatically gives the test chamber according to the pressure value of the pressure sensor. The oxygen is supplemented; the amount of supplemental oxygen is recorded by the automatic recording system at the right time, and the thermal oxidation curve is output after the test.

Example 5

Start the temperature control system, heat the test chamber, stop heating when heated to 100 °C; put the sample to be tested into the test chamber, close the test chamber; start the vacuum to the oxygen system, first vacuum the test chamber When the pressure in the test chamber is lower than 10 Pa, the vacuum is stopped, and then the gas control valve is opened to charge the test chamber with oxygen mixed with 1 volume of ozone; the oxygen supply system automatically gives the test chamber according to the pressure value of the pressure sensor. The oxygen is supplemented; the amount of supplemental oxygen is recorded by the automatic recording system at the right time, and the thermal oxidation curve is output after the test.

The present invention has been described in detail with reference to FIGS. 1 to 3, but the present invention is not limited to the embodiments, and various modifications can be made without departing from the spirit and scope of the invention. It is obvious.

Device measurement accuracy experiment

In order to investigate the measurement accuracy of the device, we made 18 samples with a thickness of 0.21-0.234 mm, a width of 10 mm and a length of 15 mm using the vulcanizate of the same formulation, taking the oxygen induction time as an indicator, under the same reaction conditions. Next, the test was carried out in batches, and the results are shown in Table 1.

Test formula: butadiene rubber 100; medium super wear-resistant furnace black 45; stearic acid 2; accelerator TT3; zinc oxide 4.

Vulcanization conditions: 143 ° C - 30 minutes

Experimental conditions: oxidation reaction temperature 135 ° C; ambient constant temperature 25 ° C

Reaction oxygen pressure: 1 atmosphere

Table 1 test accuracy results

Sample No	Induction time: minute	Test number	Induction time: minute
1	730	10	728
2	702	11	730
3	708	12	712
4	735	13	730
5	737	14	745
6	726	15	735
7	725	16	724
8	710	17	720
9		18	750

The test accuracy is calculated as follows:

The arithmetic mean obtained from Table 1 is

Number of measurements n=17;

Standard error

Standard error coefficient

It can be seen from the above calculation that the test accuracy of the device in the rubber thermal oxygen aging test is high.

Device actual performance test

In order to investigate the actual performance of the device, we made the following two sets of experiments for comparison.

experiment one:

(1) Preparation of unvulcanized rubber samples

The cis-butadiene (BR) was dissolved in toluene to prepare a 3% rubber solution, and a certain weight of the solution was dropped onto a glass slide of known weight by a pipette. After the solvent is volatilized, the rubber-loaded glass slide is placed in a vacuum desiccator and pumped at room temperature. Vacuum, until constant weight, to determine the weight of the rubber on the slide.

(2) Preparation of anti-aging agent unvulcanized rubber sample

The method for preparing an anti-vulcanized rubber sample of the anti-aging agent is the same as the above, except that 2% of the given anti-aging agent is added to the rubber solution prepared by the dry rubber, and the anti-aging agent solvent is evenly mixed, and then the liquid pipe is used to contain a certain amount. The amount of the rubber solution containing the antioxidant is dropped onto a glass slide of known weight.

Antioxidant 264——2,6-di-tert-butyl-4-methylphenol

Antioxidant 2246 - 2,2'-methylenebis(4-methyl-6-tert-butylphenol)

Experiment 2:

This experiment is carried out for the determination of different formulations of vulcanized rubber for butadiene rubber. The test formula is shown in Table 2.

Antioxidant BLE: high temperature reaction product of acetone and diphenylamine

Antioxidant 4020: N-(1,3-dimethyl)butyl-N'-phenyl-p-phenylenediamine

Promoter TMTD: tetramethylthiuram disulfide

Crosslinker DCP: dicumyl peroxide

After a long period of practical use test, the device has good performance, can meet the requirements of rubber thermal oxygen aging test, and has the characteristics of convenient operation, high precision and reliable data.

Claims (10)

1. A rubber thermal oxygen aging kinetic testing device, characterized in that the device comprises a test bench (1), a vacuuming oxygen supply system (7), a temperature control system (8), an oxygen supplementation system (9), an automatic recording system (10), wherein the test bench (1) is an integrated structure, the test chamber is symmetrically disposed inside the test chamber (2), and the center temperature sensor (6) and the edge temperature measurement are respectively set at the center and the edge position of the test bench (1). The sensor (6'), the test stand (1) is provided with a heating belt (3) and a heat insulating layer (5) in sequence; the test chamber (2) is provided with a pressure sensor at the sealed end, the test chamber (2) and the vacuuming oxygen supply system (7) The oxygen supply system (9) is connected to each other, the heating belt (3) is connected to the temperature control system (8), and the oxygen supply system (9) is connected to the automatic recording system (10).
2. The rubber thermal aging kinetics testing device according to claim 1, wherein at least four test chambers are symmetrically disposed on the test bench (1), and the test sample can be directly placed in each test cavity. Or place the container containing the sample to be tested.
3. A rubber thermal aging kinetics testing apparatus according to claim 1, wherein said vacuuming oxygen supply system (7) comprises a vacuum pump, an oxygen storage device and a gas control valve, and the gas control valve controls the vacuum pump and the oxygen gas. The storage device is in communication with the test chamber (2).
4. The rubber thermal aging kinetics testing device according to claim 1, wherein the temperature control system (8) comprises a heating belt (3), a temperature detecting device and a heating control device, wherein the temperature detecting device The central temperature sensor (6) and the edge temperature sensor (6') are respectively connected, and the heating control device is connected to the temperature detecting device and controls the heating belt (3).
5. The rubber thermal aging kinetics testing device according to claim 1, wherein the oxygen supplementation system (9) comprises a supplemental oxygen device, an oxygen supplementation control device and an oxygen pressure detecting device, wherein the oxygen pressure detecting device The device is connected with the pressure sensor, and the oxygen pressure detecting device is connected with the oxygen supplement control device, and the supplemental oxygen device is turned on or off according to the oxygen pressure detection result.
6. The rubber thermal aging kinetics testing apparatus according to claim 5, wherein the automatic recording system (10) is connected to the supplemental oxygen device to timely record the oxygen replenishing amount.
7. A method for testing a rubber thermal oxygen absorption curve by using the rubber thermal aging kinetics testing device according to any one of claims 1 to 6, the operation steps are as follows:

   (1) Start the temperature control system and heat the test chamber to the specified temperature;

   (2) Put the samples to be tested into the test chamber and close the test chamber;

   (3) starting the vacuuming oxygen supply system, first vacuuming the test chamber;

   (4) Turn on the gas control valve to fill the test chamber with oxygen;

   (5) The oxygen supply system automatically supplies oxygen to the test chamber according to the pressure value of the pressure sensor;

   (6) The automatic recording system records the amount of supplemental oxygen in a timely manner and outputs a thermo-oxygen absorption curve.
8. The method according to claim 7, wherein in the step (3), when the pressure in the test chamber is lower than 10 Pa, the evacuation is stopped.
9. The method according to claim 7, wherein the test chamber heating temperature range in the step (1) is 50-200 ° C.
10. The method according to claim 7, wherein the step (4) is filled with an oxygen pressure of 1-2 bar.

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