An evaluation method and system for the storage life of a polymer material under time-varying temperature conditions

Abstract

The present invention provides a method and system for evaluating the storage life of a polymer material under time-varying temperature conditions. By conducting a thermal accelerated aging test on the polymer material, based on the polymer aging mathematical model, the environmental effects of the polymer material within a short unit time are accumulated in time series, an environmental cumulative damage model is constructed to simulate the micro-change process of the natural storage environmental effects, an environmental effects cumulative damage curve is obtained, and according to the performance failure threshold of the polymer material, the storage life of the material is determined on the environmental effects cumulative damage curve. Compared with the traditional life prediction method based on the statistical average of environmental factors, the prediction accuracy of the present invention is greatly improved, and the problem of accurately predicting the storage life of polymer materials under the condition that the temperature changes continuously with time is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material aging life, and particularly relates to a method and system for evaluating the storage life of polymer materials under time-varying temperature conditions. Background Art

[0002] Polymer materials, as macromolecular materials, are widely used in many fields such as military, automotive, electrical appliances, construction, packaging, etc. However, due to the structural weaknesses of this macromolecular material itself (double bonds, long-chain structures, easily hydrolyzable functional groups such as ester groups and amide groups), it is extremely vulnerable to the influence of external environmental factors (light, oxygen, heat, humidity, etc.) during long-term use, resulting in chemical aging (molecular chain scission or crosslinking) or physical aging (molecular chain relaxation and fatigue fracture), leading to material failure.

[0003] Research shows that the life of polymer materials can be predicted by constructing a relationship model between environmental factors and environmental effects. In existing polymer material environmental effect prediction models, the temperature parameter is always constant or changes regularly according to a certain function. However, under actual natural environmental conditions, the change of temperature over time is very complex, and its law is difficult to be expressed by a simple function. There is a large gap between the environmental effects of materials predicted by the average temperature value or function change value within a certain time range and the actual environmental effects of materials, and the accurate evaluation of the natural storage life of polymer materials cannot be achieved. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for evaluating the storage life of polymer materials under time-varying temperature conditions, which can achieve the accurate evaluation of the natural storage life of polymer materials.

[0005] The present invention adopts the following technical solutions.

[0006] A method for evaluating the storage life of polymer materials under time-varying temperature conditions, the steps include:

[0007] Step 1, select aging characteristic indexes according to the test materials, and prepare test samples for testing the corresponding aging characteristic indexes;

[0008] Step 2, determine the upper limit temperature of the test samples in combination with thermal analysis means;

[0009] Step 3, conduct thermal aging acceleration tests to obtain the performance degradation data of the test samples in different aging test cycles;

[0010] Step 4, according to the obtained performance degradation data, use formula (Ⅰ) to determine the performance change rate constant of the test samples;

[0011]

[0012] Wherein: P is the performance at aging time t, A is the initial performance data, t is the aging time, and α is a constant;

[0013] Step 5: Combine the obtained performance change rate constant, and use Equation (Ⅱ) to determine the frequency factor Z and the apparent activation energy E of the test sample;

[0014] K = Ze -E / RT ………………………………(Ⅱ)

[0015] Wherein: R is the gas constant, T is the absolute temperature, and e is a constant;

[0016] Step 6: Combine the data obtained in Step 4 and Step 5, and use Equation (Ⅲ) to determine the initial aging times t1, t2, …, t of the performance degradation curve of the test sample at each unit interval time temperature n-1 ;

[0017]

[0018] Wherein: Δt represents the unit interval time, E a represents the activation energy of the aging reaction, and n is the number of unit interval times;

[0019] Step 7: Combine the obtained performance degradation data and the initial aging times obtained in Step 6 to construct an environmental cumulative damage model, as shown in Equation (Ⅳ),

[0020]

[0021] Wherein,

[0022] ΔP represents the performance degradation value of the material during the evaluation period;

[0023] ΔP1, ΔP2, …, ΔP n respectively represent the performance degradation value of the first time interval, the performance degradation value of the second time interval, …, the performance degradation value of the nth time interval;

[0024] P0 represents the initial value of the performance of the material;

[0025] P0′, P1′, …, P n-1 ′ respectively represent the performance value after experiencing the first time interval, the performance degradation value after experiencing the second time interval, …, the performance degradation value after experiencing the nth time interval;

[0026] P1, P2, …, P n-1It represents the initial value of the performance degradation curve at the temperature of the second time interval after experiencing the first time interval, and its magnitude is the same as P0'; the initial value of the performance degradation curve at the temperature of the third time interval after experiencing the second time interval, and its magnitude is the same as P1';...; the initial value of the performance degradation curve at the temperature of the nth time interval after experiencing the (n - 1)th time interval, and its magnitude is the same as P n-2 ';

[0027] Δt represents the unit interval time;

[0028] K0, K1,..., K n-1 represent the reaction rate constants at the temperatures of the 1st, 2nd,..., nth time intervals;

[0029] t1, t2,..., t n-1 represent the times required when the performance values solved from the performance degradation curve equations with the temperatures of the 2nd, 3rd,..., nth time intervals as the isothermal aging temperatures are P1, P2,..., P n-1 respectively;

[0030] E a represents the activation energy of the aging reaction, and Z represents the frequency factor;

[0031] Step 8: Based on the obtained environmental cumulative damage model, form an environmental effect cumulative damage curve, and determine the material storage life on the environmental effect cumulative damage curve according to the performance failure threshold of the polymer material.

[0032] Preferably, for rubber or adhesive, the upper limit temperature of the thermal acceleration test is determined by TGA test, and the temperature corresponding to a 0.5 wt% weight loss is taken as the set upper limit temperature of the thermal acceleration test; for plastic polymers, it is determined by DSC test, and the upper limit temperature of the thermal acceleration test is comprehensively determined according to the glass transition and melting temperature; among them, the highest temperature of the thermal acceleration test shall not exceed the upper limit temperature, and then it is decreased by 10°C in turn to set a thermal aging acceleration test with more than 4 temperature gradients.

[0033] Preferably, rubber materials are made into columnar compression or tensile specimens, plastic materials are made into tensile or impact specimens, and adhesive materials are made into shear specimens or peel specimens.

[0034] Preferably, the number of performance detections under each temperature condition is not less than 8 times.

[0035] In order to more accurately evaluate the natural storage life of polymer materials, the natural environmental factor data for 1 year is decomposed into 8760 consecutive time value data, with each hour as the unit interval time.

[0036] The present invention also provides an evaluation system for the storage life of a polymer material under time-varying temperature conditions, including a computer device. The computer device includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the following steps are implemented:

[0037] S1. Read the input material type, specification of the test sample, and its performance degradation data at different aging test cycles;

[0038] S2. Calculate and output the performance change rate constant of the test sample according to formula (Ⅰ);

[0039]

[0040] In the formula: P is the performance at aging time t, A is the initial performance data, t is the aging time, and α is a constant;

[0041] S3. Calculate and output the frequency factor Z and the apparent activation energy E of the test sample according to formula (Ⅱ);

[0042] K = Ze -E / RT ………………………………(Ⅱ)

[0043] In the formula: R is the gas constant, T is the absolute temperature, and e is a constant;

[0044] S4. Calculate and output the initial aging times t1, t2, …, t for determining the performance degradation curves of the test sample at the temperatures of each unit interval time according to formula (Ⅲ) n-1 ;

[0045]

[0046] In the formula: Δt represents the unit interval time, E a represents the activation energy of the aging reaction, and n is the number of unit interval times;

[0047] S5. Combine the input performance degradation data and the initial aging times obtained in step S4 to construct an environmental cumulative damage model, as shown in formula (Ⅳ),

[0048]

[0049] In the formula,

[0050] ΔP represents the performance degradation value of the material during the evaluation period;

[0051] ΔP1, ΔP2, …, ΔP n respectively represent the performance degradation values of the first time interval, the second time interval, …, the nth time interval;

[0052] P0 represents the initial value of the material's properties;

[0053] P0′, P1′, …, P n-1 ′ represent the property values after experiencing the 1st time interval, the performance degradation values after experiencing the 2nd time interval, …, the performance degradation values after experiencing the nth time interval, respectively;

[0054] P1, P2, …, P n-1 represent the initial values of the performance degradation curves at the temperatures of the 2nd time interval after experiencing the 1st time interval, which are the same size as P0′; the initial values of the performance degradation curves at the temperatures of the 3rd time interval after experiencing the 2nd time interval, which are the same size as P1′; …; the initial values of the performance degradation curves at the temperatures of the nth time interval after experiencing the (n - 1)th time interval, which are the same size as P n-2 ′;

[0055] Δt represents the unit interval time;

[0056] K0, K1, …, K n-1 represent the reaction rate constants at the temperatures of the 1st, 2nd, …, nth time intervals;

[0057] t1, t2, …, t n-1 represent the times required when the performance values obtained by solving the performance degradation curve equations with the temperatures of the 2nd, 3rd, …, nth time intervals as the isothermal aging temperatures are P1, P2, …, P n-1 respectively;

[0058] E a represents the activation energy of the aging reaction, and Z represents the frequency factor;

[0059] S6. Generate the environmental effect cumulative damage curve based on the obtained environmental cumulative damage model, and input the failure threshold of the polymer material performance to calibrate the storage life of the material on the environmental effect cumulative damage curve.

[0060] Beneficial effects: By adopting the present invention, the micro-change process of the long-term natural storage environmental effect of polymer materials can be accurately simulated through a short-term accelerated aging test, the performance degradation law of polymer materials in the natural storage environment can be revealed, and the long-term performance degradation curve of polymer materials in the natural storage environment can be drawn to evaluate the natural environment adaptability of polymer materials. Compared with the traditional life prediction method that uses the statistical average value of environmental factors and is based on the Arrhenius formula, the prediction accuracy is greatly improved, and the problem that the storage life of polymer materials cannot be accurately predicted under the condition of continuously changing temperature over time is solved. Description of the Drawings

[0061] Figure 1 It is a schematic diagram of the environmental cumulative damage model in the embodiment;

[0062] Figure 2 For the comparison chart of the statistical average value of environmental factors, the performance degradation simulation curve of the environmental cumulative damage model and the experimental data of the natural environment in Mohe in the embodiment, in the figure, part (a) corresponds to a compression ratio of 20%, and part (b) corresponds to a compression ratio of 30%. Specific embodiments

[0063] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments and the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0064] Embodiment 1

[0065] A method for evaluating the storage life of a polymer material under time-varying temperature conditions, the steps include:

[0066] Step 1, select the aging characteristic index according to the test material, and prepare the test samples for testing the corresponding aging characteristic index; among them, rubber materials are prepared into columnar compression or tensile specimens, plastic materials are prepared into tensile or impact specimens, and adhesive materials are prepared into shear specimens or peel specimens;

[0067] Step 2, determine the upper limit temperature of the test for the test samples in combination with thermal analysis means; for rubber or adhesives, the upper limit temperature of the thermal acceleration test is determined by TGA test, and the temperature corresponding to a thermal weight loss of 0.5 wt% is used as the set upper limit temperature of the thermal acceleration test; for plastic polymers, it is determined by DSC test, and the upper limit temperature of the thermal acceleration test is comprehensively determined according to the glass transition and melting temperature; among them, the highest temperature of the thermal acceleration test shall not exceed the upper limit temperature, and then it shall be decreased by 10°C in turn, and set up a thermal aging acceleration test with 4 or more temperature gradients;

[0068] Step 3, carry out the thermal aging acceleration test, and obtain the performance degradation data of the test samples in different aging test cycles. The number of performance detections under each temperature condition is not less than 8 times, and the test termination time is based on the occurrence of a significant performance change trend recognized by those of ordinary skill in the art;

[0069] Step 4, according to the obtained performance degradation data, use formula (Ⅰ) to determine the performance change rate constant of the test samples;

[0070]

[0071] In the formula: P is the performance at aging time t, A is the initial performance data, t is the aging time, and α is a constant;

[0072] Step 5: Combine the obtained performance change rate constant, and use Equation (II) to determine the frequency factor Z and the apparent activation energy E of the test sample;

[0073] K = Ze -E / RT ………………………………(II)

[0074] where: R is the gas constant, T is the absolute temperature, and e is a constant;

[0075] Step 6:

[0076] Refine and decompose the natural environmental factor data for 1 year into 8,760 continuous time value data. Taking each hour as a time interval (unit interval time), regarding the environmental factors within each hour as constant values, and then accumulating the material property changes within each hour, the performance degradation curve of the polymer material for 1 year can be calculated;

[0077] Combining the data obtained in Steps 4 and 5, use Equation (III) to determine the initial aging times t1, t2,..., t of the performance degradation curve of the test sample at the temperatures of each unit interval time; n-1 ;

[0078]

[0079] where: Δt represents the unit interval time, E a represents the activation energy of the aging reaction, and n is the number of unit interval times;

[0080] Step 7: Combine the obtained performance degradation data and the initial aging times obtained in Step 6 to construct an environmental cumulative damage model, as shown in Equation (IV),

[0081]

[0082] where,

[0083] ΔP represents the performance degradation value of the material within the evaluation time period;

[0084] ΔP1, ΔP2,..., ΔP n successively represent the performance degradation values of the first time interval, the second time interval,..., the nth time interval;

[0085] P0 represents the initial value of the material performance;

[0086] P0′, P1′,..., P n-1 ′ respectively represent the performance values after experiencing the first time interval, the performance degradation values after experiencing the second time interval,..., the performance degradation values after experiencing the nth time interval;

[0087] P1, P2,..., Pn-1 It represents the initial values of the performance degradation curves at the temperatures of the second time interval after experiencing the first time interval, and their magnitudes are the same as P0'; the initial values of the performance degradation curves at the temperatures of the third time interval after experiencing the second time interval, and their magnitudes are the same as P1'; …; the initial values of the performance degradation curves at the temperatures of the nth time interval after experiencing the (n - 1)th time interval, and their magnitudes are the same as P n-2 ';

[0088] Δt represents the unit interval time;

[0089] K0, K1, …, K n-1 represent the reaction rate constants at the temperatures of the first, second, …, nth time intervals;

[0090] t1, t2, …, t n-1 represent the times required when the performance values solved from the performance degradation curve equations with the temperatures of the second, third, …, nth time intervals as the isothermal aging temperatures are P1, P2, …, P n-1 respectively;

[0091] E a represents the activation energy of the aging reaction, and Z represents the frequency factor;

[0092] Based on Equation (Ⅰ) and Equation (Ⅱ), and combined with the real-time temperature data of the corresponding natural environment test sites, a series of performance degradation curves under real-time temperature conditions can be obtained. When determining the performance degradation amount in the first unit time interval, first obtain the performance degradation curve equation at this temperature T Δt , then substitute the initial performance P0 of the material, substitute the unit time interval Δt0, and obtain the performance value P0' and the performance change value ΔP1 after the first unit time interval; when calculating the performance degradation value in the second unit interval time, substitute the performance P0' after degradation by the unit interval time in the previous curve as P1 into the performance degradation curve at the temperature T(2Δt) of the second unit interval time, and obtain the initial aging time t1 at the T(2Δt) stage. t1 is a numerical calculation time, which reflects the theoretical degradation time required when the performance reaches P1 in the performance degradation curve at the temperature of T(2Δt). Add the unit interval time Δt to this t1, and substitute t1 + Δt into the performance degradation curve equation at the temperature of T 2Δt , and obtain the performance value P1' and the performance change value ΔP2 after the second unit interval time; and so on, the performance degradation points P0', P1', …, P n-1 ' and the performance change values ΔP1, ΔP2, …, ΔP n-1 after the first, second, …, n unit time intervals can be calculated, and the time-sequence performance degradation curve under the natural temperature environment profile can be plotted;

[0093] Step 8: Based on the obtained environmental cumulative damage model, form an environmental effect cumulative damage curve, and determine the material storage life on the environmental effect cumulative damage curve according to the performance failure threshold of the polymer material.

[0094] In an application scenario, ethylene propylene diene monomer (EPDM) rubber was selected and prepared into cylindrical compression specimens with a diameter of 10 mm. Thermal accelerated aging tests were carried out at four temperatures of 70 °C, 80 °C, 90 °C, and 100 °C, and pre-compression stresses were applied at compression ratios of 20% and 30% respectively. The compression set retention rate (1 - ε, where ε is the compression set rate) was detected according to the sampling period. The test results are shown in Tables 1 and 2;

[0095] Table 1 Compression set retention rate of EPDM rubber with a compression ratio of 20%

[0096]

[0097]

[0098] Table 2 Compression set retention rate of EPDM rubber with a compression ratio of 30%

[0099]

[0100]

[0101] Based on the obtained thermal aging acceleration test data (data in Tables 1 and 2), and referring to the data processing method in GJB 92.2 - 86 "Guide for Determining the Storage Performance of Vulcanized Rubber by Hot Air Aging Method Part 2: Statistical Method", solve the frequency factor Z, apparent activation energy E, and constant α in Formula (Ⅰ) and Formula (Ⅱ) to obtain the aging mathematical model of EPDM rubber at a constant storage temperature T and storage time t, as shown in Table 3;

[0102] Table 3 Aging mathematical models of EPDM rubber under two compression conditions

[0103]

[0104] In this embodiment, according to the material type (EPDM rubber), when the compression ratio is 30%, α = 0.36, when the compression ratio is 30%, α = 0.35, R is the gas constant, R = 8.314, and e = 2.7183.

[0105] To compare the prediction accuracy of the environmental cumulative damage model life prediction method and the traditional life prediction method based on the statistical average value of environmental factors, the scenario of EPDM rubber stored at Mohe Test Station was selected, and the following two data processing methods were adopted:

[0106] 1. Refine the natural environmental temperature data of Mohe Test Station for 1 year into 8,760 consecutive time-value data, and conduct life prediction based on the environmental cumulative damage model (Equation (IV)) constructed in the present invention to obtain the performance degradation curve;

[0107] 2. Based on the life prediction method of the statistical average value of environmental factors, perform arithmetic averaging on the time-value data of the natural environmental temperature at Mohe Test Station for 1 year, and substitute the obtained average value into the aging mathematical model of ethylene propylene diene monomer rubber (i.e., the model in Table 3) to calculate and obtain the performance degradation curve.

[0108] Compare the performance degradation curves obtained by the above two data processing methods with the results of the natural environmental test data in Mohe (Tables 4 and 5). The comparison results are shown in Figure 2 . It can be seen from the figure that the natural environmental test results of ethylene propylene diene monomer rubber are closer to the performance degradation curve obtained by solving through the environmental cumulative damage model.

[0109] Table 4 Natural environmental test conditions of ethylene propylene diene monomer rubber

[0110]

[0111] Table 5 Compression set (%) of ethylene propylene diene monomer rubber after exposure test under the shed in Mohe

[0112]

[0113] The prediction accuracies of the above two performance degradation simulation curves are shown in Table 6. It can be seen from the table that the prediction accuracy of the performance degradation simulation curve based on the statistical average value of environmental factors gradually decreases with the increase of the test time, and the prediction accuracy of individual data points is already lower than 90%, while the prediction accuracy of the performance degradation simulation curve based on the environmental cumulative damage model of the present invention is above 94%. Therefore, adopting the life prediction method based on the environmental cumulative damage model of the present invention can greatly improve the life prediction accuracy of polymer materials.

[0114] Table 6 Prediction accuracy of the performance degradation simulation curve of the statistical average value of environmental factors

[0115]

[0116] Example 2

[0117] This example provides an evaluation system for the storage life of polymer materials under time-varying temperature conditions, including a computer device. The computer device includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the following steps are implemented:

[0118] S1. Read the type, specification of the input test sample material and its performance degradation data at different aging test cycles;

[0119] S2. Calculate and output the performance change rate constant of the test sample according to Equation (Ⅰ);

[0120]

[0121] In the formula: P is the performance at aging time t, A is the initial performance data, t is the aging time, and α is a constant;

[0122] S3. Calculate and output the frequency factor Z and apparent activation energy E of the test sample according to Equation (Ⅱ);

[0123] K = Ze -E / RT ………………………………(Ⅱ)

[0124] In the formula: R is the gas constant, T is the absolute temperature, and e is a constant;

[0125] S4. Calculate and output the initial aging times t1, t2, …, t for determining the performance degradation curve of the test sample at the temperature of each unit interval time according to Equation (Ⅲ) n-1 ;

[0126]

[0127] In the formula: Δt represents the unit interval time, E a represents the activation energy of the aging reaction, and n is the number of unit interval times;

[0128] S5. Combine the input performance degradation data and the initial aging times obtained in step S4 to construct an environmental cumulative damage model, as shown in Equation (Ⅳ),

[0129]

[0130] In the formula,

[0131] ΔP represents the performance degradation value of the material during the evaluation period;

[0132] ΔP1, ΔP2, …, ΔP n successively represent the performance degradation value of the first time interval, the performance degradation value of the second time interval, …, the performance degradation value of the nth time interval;

[0133] P0 represents the initial performance value of the material;

[0134] P0′, P1′, …, P n-1 ′ respectively represent the performance value after experiencing the first time interval, the performance degradation value after experiencing the second time interval, …, the performance degradation value after experiencing the nth time interval;

[0135] P1, P2, …, P n-1 represent the initial values of the performance degradation curves at the temperatures of the 2nd time interval after experiencing the 1st time interval, with the same magnitude as P0'; the initial values of the performance degradation curves at the temperatures of the 3rd time interval after experiencing the 2nd time interval, with the same magnitude as P1'; …; the initial values of the performance degradation curves at the temperatures of the nth time interval after experiencing the (n - 1)th time interval, with the same magnitude as P n-2 ';

[0136] Δt represents the unit interval time;

[0137] K0, K1, …, K n-1 represent the reaction rate constants at the temperatures of the 1st, 2nd, …, nth time intervals;

[0138] t1, t2, …, t n-1 represent the times required when the performance values solved from the performance degradation curve equations with the temperatures of the 2nd, 3rd, …, nth time intervals as the isothermal aging temperatures are P1, P2, …, P n-1 respectively;

[0139] E a represents the activation energy of the aging reaction, and Z represents the frequency factor;

[0140] S6. Generate the cumulative environmental effect damage curve based on the obtained environmental cumulative damage model, and calibrate the material storage life on the cumulative environmental effect damage curve by inputting the performance failure threshold of the polymer material.

Claims

1. A method for evaluating the storage life of a polymer material under time-varying temperature conditions, characterized in that the steps Including: Step 1: Select aging characteristic indexes according to test materials and prepare test samples for testing the corresponding aging characteristic indexes. Step 2: Determine the upper limit temperature of the test samples in combination with thermal analysis means. Step 3: Conduct thermal aging acceleration tests to obtain performance degradation data of the test samples at different aging test cycles. Step 4: According to the obtained performance degradation data, use Equation (Ⅰ) to determine the performance change rate constant of the test samples. In the formula: P is the performance at aging time t, A is the initial performance data, t is the aging time, and α is a constant. Step 5: In combination with the obtained performance change rate constant, use Equation (Ⅱ) to determine the frequency factor Z and the apparent activation energy E of the test samples. K = Ze -E / RT ....................................(II) In the formula: R is the gas constant, T is the absolute temperature, and e is a constant. Step 6: Combining the data obtained in Steps 4 and 5, use Equation (III) to determine the initial aging times t1, t2, …, t of the performance degradation curves of the test samples at the temperatures for each unit interval of time n-1 ; Where: Δt represents the unit interval time, E a represents the activation energy of the aging reaction, and n is the number of unit interval times; Step 7: In combination with the obtained performance degradation data and the initial aging time obtained in Step 6, construct an environmental cumulative damage model, as shown in Equation (Ⅳ). In the formula, ΔP represents the performance degradation value of the material during the evaluation period. ΔP1, ΔP2, …, ΔP n represent the performance degradation value of the first time interval, the performance degradation value of the second time interval, …, the performance degradation value of the nth time interval, respectively; P0 represents the initial performance value of the material. P0′, P1′, …, P n-1 ′ represent the performance value after the first time interval, the performance degradation value after the second time interval, …, the performance degradation value after the nth time interval, respectively; P1, P2, …, P n-1 represent the initial values of the performance degradation curves at the temperatures of the second time interval after experiencing the first time interval, which are the same size as P0'; the initial values of the performance degradation curves at the temperatures of the third time interval after experiencing the second time interval, which are the same size as P1'; …; the initial values of the performance degradation curves at the temperatures of the nth time interval after experiencing the (n - 1)th time interval, which are the same size as P n-2 '; Δt represents the unit interval time. K0, K1, …, K n-1 represent the reaction rate constants at the temperatures for the 1st, 2nd, …, nth time intervals; t1, t2, …, t n-1 respectively represent the performance values P1, P2, …, P obtained by solving the performance degradation curve equations with the temperatures at the 2nd, 3rd, …, nth time intervals as the isothermal aging temperatures n-1 and the time required when E a represents the activation energy of the aging reaction, and Z represents the frequency factor; Step 8: Based on the obtained environmental cumulative damage model, form an environmental effect cumulative damage curve, and determine the storage life of the material on the environmental effect cumulative damage curve according to the performance failure threshold of the polymer material.

2. The method for evaluating the shelf life of the polymer material under time-varying temperature conditions according to claim 1, characterized in that: For rubber or adhesive, the upper limit temperature of the thermal acceleration test is determined by TGA test, and the temperature corresponding to a 0.5wt% thermal weight loss is used as the set upper limit temperature of the thermal acceleration test; for plastic polymers, it is determined by DSC test, and the upper limit temperature of the thermal acceleration test is comprehensively determined according to the glass transition and melting temperature; among them, the highest temperature of the thermal acceleration test shall not exceed the upper limit temperature, and then it is decreased by 10℃ in turn to set thermal aging acceleration tests with more than 4 temperature gradients.

3. The method for evaluating the storage life of the polymer material under time-varying temperature conditions according to claim 1, wherein: Rubber materials are made into columnar compression or tensile specimens, plastic materials are made into tensile or impact specimens, and adhesive materials are made into shear specimens or peel specimens.

4. The method for evaluating the shelf life of the polymer material under time-varying temperature conditions according to claim 1, wherein: The number of performance detections under each temperature condition is not less than 8 times.

5. The method for evaluating the storage life of a polymer material under time-varying temperature conditions according to any one of claims 1-4, characterized in that: Decompose the natural environmental factor data for 1 year into 8760 continuous time value data, with each hour as the unit interval time.

6. An evaluation system for the storage life of a polymer material under time-varying temperature conditions, comprising a computer device, the computer device including a memory, a processor, and a program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, the following steps are implemented: S1: Read the input test sample material type, specification, and its performance degradation data at different aging test cycles. S2: Calculate and output the performance change rate constant of the test samples according to Equation (Ⅰ). In the formula: P is the performance at aging time t, A is the initial performance data, t is the aging time, and α is a constant. S3: Calculate and output the frequency factor Z and the apparent activation energy E of the test samples according to Equation (Ⅱ). K = Ze -E / RT ....................................(II) In the formula: R is the gas constant, T is the absolute temperature, and e is a constant. S4. Calculate and output the initial aging times \(t_1\), \(t_2\), …, \(t\) of the performance degradation curves of the test samples at the temperatures of each unit interval time according to formula (Ⅲ). n-1 ; where: Δt represents the unit interval time, E a represents the activation energy of the aging reaction, and n is the number of unit interval times; S5: In combination with the input performance degradation data and the initial aging time obtained in Step S4, construct an environmental cumulative damage model, as shown in Equation (Ⅳ). In the formula, ΔP represents the performance degradation value of the material during the evaluation period. ΔP1, ΔP2, …, ΔP n respectively represent the performance degradation value of the first time interval, the performance degradation value of the second time interval, …, the performance degradation value of the nth time interval; P0 represents the initial performance value of the material. P0′, P1′, …, P n-1 ′ represent the performance value after the first time interval, the performance degradation value after the second time interval, …, the performance degradation value after the nth time interval, respectively; P1, P2, …, P n-1 represent the initial values of the performance degradation curves at the temperatures of the second time interval after experiencing the first time interval, with the same magnitude as P0'; the initial values of the performance degradation curves at the temperatures of the third time interval after experiencing the second time interval, with the same magnitude as P1'; …; the initial values of the performance degradation curves at the temperatures of the nth time interval after experiencing the (n - 1)th time interval, with the same magnitude as P n-2 '; Δt represents the unit interval time. K0, K1, …, K n-1 represent the reaction rate constants at the temperatures of the 1st, 2nd, …, nth time intervals; t1, t2, …, t n-1 respectively represent the performance values P1, P2, …, P obtained by solving the performance degradation curve equations with the temperatures at the 2nd, 3rd, …, nth time intervals as the isothermal aging temperatures n-1 and the time required when E a represents the activation energy of the aging reaction, and Z represents the frequency factor; S6: Generate an environmental effect cumulative damage curve based on the obtained environmental cumulative damage model, input the performance failure threshold according to the polymer material, and calibrate the storage life of the material on the environmental effect cumulative damage curve.

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