Accelerated aging test method for simulating damp and hot rainforest natural environment by using rubber sealing material

Abstract

The invention belongs to the technical field of environmental adaptability evaluation of materials, and relates to an accelerated aging test method of a rubber sealing material for simulating a damp and hot rainforest natural environment. According to the invention, aging resistance evaluation and environmental adaptability evaluation of the rubber sealing material in a humid and hot rainforest natural environment are carried out by adopting a cyclic test method consisting of three stages of high and low temperature circulation, mould growth, humid and hot alternation and the like; typical environmental effects such as hot air aging, thermal expansion and cold contraction, mould erosion, moisture absorption / moisture liberation and the like of the rubber sealing material in the damp and hot rainforest natural environment are comprehensively considered, and the aging process and mechanism of the rubber sealing material in the damp and hot rainforest natural environment can be well simulated by the test mode and the magnitude of related condition parameters. The aging resistance of the rubber sealing material in the humid and hot rainforest natural environment can be evaluated more accurately, and a basic accelerated aging test method is provided for verifying the environmental adaptability of the rubber sealing material in the humid and hot rainforest natural environment.

Description

Technical field:

[0001] The invention belongs to the technical field of material environmental adaptability evaluation, and relates to an accelerated aging test method for rubber sealing materials simulating a hot and humid rain forest natural environment, and is particularly suitable for evaluating the aging resistance and environmental adaptability of synthetic rubber sealing materials in a hot and humid rain forest natural environment. Background technology:

[0002] my country's hot and humid rain forest natural environment is mainly distributed in the southwest of Yunnan Province, Hainan Province and the southern part of Taiwan Province. It has the characteristics of high temperature, high humidity, abundant rainfall, long wet time, vigorous growth of plants and microorganisms, low air pollution, sufficient sunshine, long condensation time, etc. The monthly average temperature is higher than or equal to 20℃ for more than 9 months, there are 4 or more hot and humid months in the whole year (hot and humid months are the months with 12 hours of temperature higher than 20℃ and humidity not less than 80% every day), and the annual precipitation exceeds 1300mm. Rubber sealing materials are made of polymer elastomer materials. In the natural environment of hot and humid rain forest, the performance may be degraded due to environmental effects such as heat aging, moisture absorption, and mold erosion, which may lead to sealing failure.

[0003] In order to examine the aging resistance or environmental adaptability of rubber sealing materials in the natural environment of hot and humid rainforests, natural exposure tests or storage tests in actual use or storage environments are usually used for evaluation. However, except for natural rubber and a few varieties of synthetic rubber, the natural aging process of most synthetic rubbers (such as nitrile rubber, ethylene propylene rubber, fluororubber, silicone rubber, fluorosilicone rubber, etc.) is relatively slow. The cycle of using natural exposure tests or storage tests to evaluate their aging resistance or environmental adaptability is often very long, and the evaluation efficiency is low. The accelerated aging test reasonably strengthens the significant influencing factors of rubber sealing material aging under the test conditions (the strengthening value does not exceed the typical extreme value of natural environmental conditions, or does not exceed the boundary value required by the rubber aging reaction), and can reproduce the long-term aging effect of rubber sealing materials in actual use or storage environments in a shorter period of time. It is more convenient and efficient to use it to evaluate the aging and environmental adaptability of rubber sealing materials.

[0004] At present, the common accelerated aging test methods for rubber sealing materials mainly include hot air (oxygen) aging test, wet heat aging test, ozone aging test, liquid medium resistance aging test, salt spray test, mold test, etc. However, the use of these single-factor accelerated aging tests to evaluate the aging resistance or environmental adaptability of rubber sealing materials often cannot reflect the aging behavior or environmental damage laws during storage or use in the actual natural environment. Summary of the invention:

[0005] In response to the above problems, taking into account the influence of factors such as high and low temperature cycles, mold and alternating humidity and heat in the natural environment of a humid and hot rainforest, the accelerated aging test method for rubber sealing materials simulating the natural environment of a humid and hot rainforest provided by the present invention can effectively simulate the environmental effects of rubber sealing materials in the natural environment of a humid and hot rainforest, and improve the accuracy of the aging resistance or environmental adaptability evaluation of rubber sealing materials in the natural environment of a humid and hot rainforest.

[0006] In order to achieve the above purpose, the technical solution of the present invention is that the accelerated aging test method of rubber sealing materials simulates the natural environment of hot and humid rain forest, and adopts a cyclic test method consisting of three stages: high and low temperature cycle, hot and humid alternation, and mold growth, wherein:

[0007] 1) High and low temperature cycle

[0008] Place the auxiliary tooling containing the rubber sealing material sample in a hot air aging test chamber to perform a high and low temperature cycle test on the rubber sealing material;

[0009] 2) Fungal growth

[0010] A mixed spore suspension of microbial strains is prepared and sprayed evenly in the form of fine mist on the exposed part of the rubber sealing material sample for inoculation. The sample is then placed in a special temperature and humidity test chamber for mold growth test.

[0011] 3) Alternating humidity and heat

[0012] Place the auxiliary tooling containing the rubber sealing material samples in the temperature and humidity test chamber to carry out a humidity and heat alternation test on the rubber sealing material; after the humidity and heat alternation test is completed, repeat the three-stage test process of high and low temperature cycle, mold growth, and humidity and heat alternation in the next cycle within 1 hour, and repeat this cycle until the preset total number of cycles is reached.

[0013] The step 1) high and low temperature cycle is divided into two sub-stages, high temperature and low temperature, wherein the high temperature is a temperature in the range of 10°C to 30°C above the highest temperature that the rubber sealing material can withstand when working, and the low temperature is the average of the annual average temperatures in the past five years obtained by actual monitoring of a typical hot and humid rainforest natural environment.

[0014] In the step 1) high and low temperature cycle, the high temperature test is first run for 24 hours to 48 hours, and then the low temperature test is run for 1 hour to 2 hours, and the high and low temperature cycle test is repeated for 5 cycles.

[0015] The microbial species involved in the mold growth in step 2) are microbial species actually existing in a typical hot and humid rainforest natural environment.

[0016] The mold growth in step 2) is carried out at a constant temperature of 30° C. and a constant relative humidity of 95% RH.

[0017] The mold growth test in step 2) must be run for 14 to 28 days.

[0018] The step 3) heat and humidity alternation is divided into two sub-stages, high temperature and high humidity and low temperature and low humidity, wherein: the temperature of the high temperature and high humidity sub-stage is a temperature in the range of 40°C to 60°C, and the relative humidity is a relative humidity in the range of 90%RH to 98%RH; the temperature of the low temperature and low humidity sub-stage is a temperature in the range of 20°C to 30°C, and the relative humidity is a relative humidity in the range of 30%RH to 50%RH.

[0019] The step 3) of humidity and heat alternation first runs the high temperature and high humidity test for 12 hours to 18 hours, and then runs the low temperature and low humidity test for 4 hours to 6 hours, and repeats the humidity and heat alternation test for 5 cycles.

[0020] The present invention adopts a cyclic test method consisting of three stages, namely, high and low temperature cycle, mold growth, and wet and hot alternation, to evaluate the aging resistance and environmental adaptability of rubber sealing materials in a natural environment of wet and hot rain forests. The typical environmental effects of hot air aging, thermal expansion and contraction, mold erosion, moisture absorption / desorption, etc., which occur to rubber sealing materials in the natural environment of wet and hot rain forests are comprehensively considered. The test method and the values ​​of relevant condition parameters can better simulate the aging process and mechanism of rubber sealing materials in the natural environment of wet and hot rain forests, and can more accurately evaluate the aging resistance of rubber sealing materials in the natural environment of wet and hot rain forests, providing a basic accelerated aging test method for verifying the environmental adaptability of rubber sealing materials in the natural environment of wet and hot rain forests. Specific implementation method:

[0021] The steps of high and low temperature cycle, mold growth, and wet and hot alternation are further described below in conjunction with the embodiments:

[0022] 1) High and low temperature cycle

[0023] For rubber sealing materials that are intended to be used or stored in a typical hot and humid rainforest natural environment, prepare corresponding material specimens and their auxiliary tooling according to their specific performance test requirements (such as tensile strength and elongation at break, compression permanent deformation rate, compression stress relaxation rate, Shore hardness, etc.), and conduct corresponding initial monitoring; consult the rubber material manual to obtain the maximum temperature that the rubber sealing material can withstand during operation, and use a temperature 10°C to 30°C lower than the maximum temperature as the high temperature temperature for the high and low temperature cycle test; consult the meteorological factor data of the area where the typical hot and humid rainforest natural environment is located, obtain the annual average temperature monitored in the area in the past five years, and use the average of the annual average temperatures in the area in the past five years as the high and low temperature cycle test temperature. Low temperature of the test; in a hot air aging test chamber with programmable temperature control, pre-set the temperature and operating time of the high temperature sub-stage, and the temperature and operating time of the low temperature sub-stage. The typical operating time of the high temperature sub-stage is 48h, and other times within the range of 24h to 48h are also acceptable. The typical operating time of the low temperature sub-stage is 2h, and other times within the range of 1h to 2h are also acceptable; debug the test parameters of the high and low temperature cycle test, and after its operation is stable, place the rubber sealing material sample and its auxiliary tooling in the hot air aging test chamber for testing; after 5 cycles of high and low temperature cycle tests are completed, transfer the rubber sealing material sample and its auxiliary tooling to the mold growth sub-stage for testing within 10min.

[0024] 2) Fungal growth

[0025] The microbial species actually existing in the natural environment of a typical hot and humid rainforest include, but are not limited to: Annulohypoxylonstygium, Fusarium solani, Nigrosporus phaerica, Coprinellus radians, Fusarium graminearum, etc. Before the mold growth test, a mixed spore suspension of the corresponding species is cultured and prepared in advance; the mixed spore suspension is evenly sprayed in the form of fine mist on the exposed part of the rubber sealing material sample that has just undergone the high and low temperature cycle test in the previous sequence for inoculation; then, the sample and the auxiliary tooling are immediately placed in a special temperature and humidity test box that is pre-set and debugged to a constant temperature of 30° C. and a constant humidity of 95% RH for mold growth test; the typical running time of the mold growth test is 14 days, and other times within the range of 14 to 28 days are also acceptable; after the mold growth test is completed, the rubber sealing material sample and its auxiliary tooling are immediately transferred to the wet and hot alternating sub-stage for testing without cleaning.

[0026] 3) Alternating humidity and heat

[0027] In the temperature and humidity test chamber with programmable temperature and humidity control, the temperature, relative humidity and operating time of the high temperature and high humidity sub-stage, the temperature, relative humidity and operating time of the low temperature and low humidity sub-stage are pre-set. Among them, the typical temperature of the high temperature and high humidity sub-stage is 60°C, and other temperatures in the range of 40°C to 60°C are also acceptable. The typical relative humidity is 95%RH, and other relative humidity in the range of 90%RH to 98%RH is also acceptable. The typical operating time is 18h, and other times in the range of 12h to 18h are also acceptable. The typical temperature of the low temperature and low humidity sub-stage is 30°C, and other temperatures in the range of 20°C to 30°C are also acceptable. The typical relative humidity is 45%RH, 30%RH to 50%RH. Other relative humidities within the RH range are also acceptable. The typical operating time is 6 hours, and other times within the range of 4 hours to 6 hours are also acceptable. Debug the test parameters of the humidity and heat alternation test, and after its operation is stable, place the rubber sealing material sample and its auxiliary tooling that have just undergone the mold growth test in the previous sequence in the temperature and humidity test chamber for testing; after 5 cycles of humidity and heat alternation tests are completed, the rubber sealing material has completed the accelerated aging test of this cycle. If the total number of cycles of the accelerated aging test has not been reached, then continue to repeat the accelerated aging test of three stages of high and low temperature cycles, mold growth, and humidity and heat alternation within 1 hour until the preset total number of cycles is reached.

[0028] Example:

[0029] In order to make the technical solution of the present invention clearer, a more detailed description is given below in conjunction with the embodiments. The described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, those skilled in the art can obtain all other embodiments without creative work, which are all within the protection scope of the present invention.

[0030] For FX-4 fluororubber to be stored and used in the natural environment of typical hot and humid rain forest in Xishuangbanna, it is agreed that the total number of cycles of accelerated aging test required to evaluate its aging resistance and environmental adaptability is 10 cycles. The following test conditions can be selected according to the actual situation of FX-4 fluororubber and Xishuangbanna area:

[0031] 1) High and low temperature cycle

[0032] The rubber sealing material sample is made of FX-4 fluororubber. In order to detect the compression permanent deformation performance of the sample, the sample is made into a B-type cylindrical sample (GB / T7759.1-2015) with a size of Φ13×6.3 (mm), a total of 50 pieces. Before the high and low temperature cycle test, the original height h0 of each sample is measured with a vernier caliper, and then the samples are clamped in a permanent compression fixture in groups of 5, for a total of 10 permanent compression fixtures. The permanent compression fixture is composed of an upper pressing plate, a lower pressing plate, a limiter, a fastening bolt and other accessories, wherein the upper and lower pressing plates are parallel, flat, and highly polished steel plates with sufficient rigidity and size, with a surface roughness Ra of no more than 0.4μm and a size of 110×50×10mm; according to the height of the B-type cylindrical sample and a compression rate of 20% (the compression rate requirement for actual sealing applications), the limiter height h1 is determined to be 5.04mm.

[0033] The rubber material manual was consulted to obtain the maximum temperature that FX-4 fluororubber can withstand when working, which is 250℃. 220℃, which is 30℃ lower than it, was used as the high temperature of the high and low temperature cycle test. The meteorological factor data under the semi-sheltered shed in the area where the typical hot and humid rainforest natural environment is located was consulted, and the average annual average temperature of the semi-sheltered shed in the area in the past five years, 27.3℃, was obtained as the low temperature of the high and low temperature cycle test. In the STPH-101M hot air aging test chamber with programmable temperature control, the high and low temperature cycle test program and test parameters of "running at 220℃ for 48h + running at 27.3℃ for 2h" were pre-set. The test program and test parameters were debugged, and after the operation was stable, the long-term compression fixture clamped with the FX-4 fluororubber B-type cylindrical specimen was placed in the STPH-101M hot air aging test chamber for high and low temperature cycle test. After the high and low temperature cycle test of 5 cycles was completed, the long-term compression fixture clamped with the FX-4 fluororubber B-type cylindrical specimen was transferred to the mold growth sub-stage for testing within 10 minutes.

[0034] 2) Fungal growth

[0035] Five fungal species, including Annulohypoxylonstygium, Fusarium solani, Nigrosporus phaerica, Coprinellus radians, and Fusarium graminearum, were selected as the test fungal species for the mold growth test. Before the mold growth test, a mixed spore suspension of the five fungal species was pre-cultured and prepared; the mixed spore suspension was suspended in water. The liquid is sprayed evenly on the side (exposed non-assembly surface) of each FX-4 fluororubber B-type cylindrical specimen in the form of fine mist for inoculation; then, the inoculated FX-4 fluororubber B-type cylindrical specimen and its durable compression tooling are immediately placed in a SM2 temperature and humidity test chamber (mold test chamber) that is pre-set and debugged to a constant temperature of 30°C and a constant humidity of 95%RH for a mold growth test; after the 14-day mold growth test is completed, the FX-4 fluororubber B-type cylindrical specimen and its durable compression tooling are immediately transferred to the wet and hot alternating sub-stage for testing without surface cleaning.

[0036] 3) Alternating humidity and heat

[0037] In the GSL-10KA temperature and humidity test chamber with programmable temperature and humidity control, the wet heat alternation test program and test parameters of "running at 60℃, 95% RH for 18h + 30℃, 45% RH for 6h" are pre-set; the test program and test parameters are debugged, and after it runs stably, the FX-4 fluororubber B-type cylindrical specimen and its durable compression tooling that have just undergone the mold growth test are immediately placed in the temperature and humidity test chamber for wet heat alternation test; after the 5 cycles of wet heat alternation test are completed, the FX-4 fluororubber has completed the accelerated aging test of this cycle. If the total number of cycles of the accelerated aging test has not been reached, then the accelerated aging test of the three-stage cycle of high and low temperature cycle, mold growth, and wet heat alternation is repeated within 1 hour until the pre-set total number of cycles is reached.

[0038] After each cycle of accelerated aging test, a group of samples (5 samples, 1 permanent compression fixture) were collected from the FX-4 fluororubber B-type cylindrical samples for compression permanent deformation rate testing. During the test, the permanent compression fixture of the group of samples must be disassembled immediately, and the samples and fixture components must be cleaned and sterilized with anhydrous ethanol. After the B-type cylindrical sample is allowed to recover freely in room temperature air for more than 0.5 hours, the height h2 of the cylindrical sample after recovery is measured, and the compression permanent deformation rate c of the corresponding cylindrical sample is calculated by formula (1).

[0039]

[0040] Finally, the aging resistance and environmental adaptability of FX-4 fluororubber during storage and use in the typical hot and humid rain forest environment of Xishuangbanna were evaluated by using the change curve of compression permanent deformation rate in different cycles of accelerated aging test.

Claims

1. The accelerated aging test method for rubber sealing materials simulating the natural environment of hot and humid rain forest is characterized by: The cyclic test method consists of three stages: high and low temperature cycle, humidity and heat alternation, and mold growth. 1) High and low temperature cycle Place the auxiliary tooling containing the rubber sealing material sample in a hot air aging test chamber to perform a high and low temperature cycle test on the rubber sealing material; 2) Fungal growth A mixed spore suspension of microbial strains is prepared and sprayed evenly in the form of fine mist on the exposed part of the rubber sealing material sample for inoculation. The sample is then placed in a special temperature and humidity test chamber for mold growth test. 3) Alternating humidity and heat Place the auxiliary tooling containing the rubber sealing material samples in the temperature and humidity test chamber to carry out a humidity and heat alternation test on the rubber sealing material; after the humidity and heat alternation test is completed, repeat the three-stage test process of high and low temperature cycle, mold growth, and humidity and heat alternation in the next cycle within 1 hour, and repeat this cycle until the preset total number of cycles is reached.

2. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rainforest natural environment according to claim 1 is characterized in that: The step 1) high and low temperature cycle is divided into two sub-stages, high temperature and low temperature, wherein the high temperature is a temperature in the range of 10°C to 30°C above the highest temperature that the rubber sealing material can withstand when working, and the low temperature is the average of the annual average temperatures in the past five years obtained by actual monitoring of a typical hot and humid rainforest natural environment.

3. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rainforest natural environment according to claim 1 is characterized in that: In the step 1) high and low temperature cycle, the high temperature test is first run for 24 hours to 48 hours, and then the low temperature test is run for 1 hour to 2 hours, and the high and low temperature cycle test is repeated for 5 cycles.

4. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rain forest natural environment according to claim 1, characterized in that: The microbial species involved in the mold growth in step 2) are microbial species actually existing in a typical hot and humid rainforest natural environment.

5. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rain forest natural environment according to claim 1 is characterized in that: The mold growth in step 2) is carried out at a constant temperature of 30° C. and a constant relative humidity of 95% RH.

6. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rain forest natural environment according to claim 1, characterized in that: The mold growth test in step 2) must be run for 14 to 28 days.

7. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rain forest natural environment according to claim 1 is characterized in that: The step 3) the heat and humidity alternation is divided into two sub-stages, high temperature and high humidity and low temperature and low humidity, wherein: the temperature of the high temperature and high humidity sub-stage is a temperature in the range of 40°C to 60°C, and the relative humidity is a relative humidity in the range of 90%RH to 98%RH; the temperature of the low temperature and low humidity sub-stage is a temperature in the range of 20°C to 30°C, and the relative humidity is a relative humidity in the range of 30%RH to 50%RH.

8. The accelerated aging test method for rubber sealing materials in a simulated hot and humid rain forest natural environment according to claim 1 is characterized in that: The step 3) of humidity and heat alternation first runs the high temperature and high humidity test for 12 hours to 18 hours, and then runs the low temperature and low humidity test for 4 hours to 6 hours, and repeats the humidity and heat alternation test for 5 cycles.

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