Rapid testing method for thermal aging failure of oil and gas pipeline anticorrosive coating material

Abstract

The invention relates to the technical field of material performance detection, in particular to a rapid testing method for thermal aging failure of an oil and gas pipeline anticorrosive coating material, which comprises the following steps: testing oxidation induction time t of a sample; respectively carrying out thermal aging with different time lengths at 150 DEG C, measuring and calculating A (tri) / A (on) and a melt index change rate, establishing a linear equation of the A (tri) / A (on), and calculating A '(tri) / A' (on) corresponding to 35% of the melt index change rate; carrying out thermo-oxidative aging on the sample at different time lengths, measuring and calculating A (tri) / A (on), and obtaining aging time t'according to A '(tri) / A' (on); carrying out oxidation induction time test on the thermally aged material to obtain a rate coefficient k; and calculating the aging time corresponding to the material failure critical point. The test method provided by the invention can rapidly characterize the thermal aging failure critical point of the anticorrosive coating material, and provides a scientific basis for development of the material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material performance detection, in particular to a rapid test method for thermal aging failure of an oil and gas pipeline anticorrosion coating material. BACKGROUND

[0002] As the core infrastructure for oil and gas transportation, the performance of the anticorrosion coating material of the oil and gas pipeline directly affects the service life and operational safety of the oil and gas pipeline. The anticorrosion coating can effectively inhibit the chemical corrosion of the metal pipeline by forming a polymer protective layer, and has an irreplaceable role in complex environments such as soil and water. However, perforation and leakage accidents caused by aging of the anticorrosion coating of underground oil and gas pipelines occur frequently every year, and huge economic losses are caused by handling corrosion problems caused by aging. Therefore, it is of great significance to develop an efficient and scientific evaluation method for the aging resistance of the anticorrosion coating material.

[0003] Polypropylene (PP) and its blended materials (such as high-density polyethylene, polyolefin elastomer, etc.) have become the mainstream material for anticorrosion coating due to their light weight, chemical corrosion resistance and easy processing. However, polypropylene material is prone to thermal aging under long-term high-temperature operating environment, which leads to molecular chain rupture, resulting in a decrease in mechanical properties and a decrease in corrosion resistance.

[0004] In ISO 21809-1:2018 "Petroleum and natural gas industries - External coatings for buried or submerged pipelines - Part 1: Polyolefin coatings", the thermal aging failure of the coating is defined as follows: at a specified temperature of 150℃±3℃, according to the design service temperature T of the material, the material is aged for (T-70)×24h, and if the melt index change rate of the material is higher than 35%, the material is considered to be failed. For example, if the design service temperature T of the material is 120℃, the material needs to be aged at 150℃±3℃ for 50 days, and the melt index change rate of the material should not be higher than 35%. Alternatively, the melt index change rate of the material exceeding 35% at the specified aging temperature can be used as the critical point of thermal failure to further evaluate the temperature aging resistance of the material, which can provide a reference for the selection and technical optimization of anticorrosion coatings under different working conditions.

[0005] However, the existing material thermal aging evaluation method is time-consuming, generally requiring several tens of days to several months, which seriously restricts the development and iteration efficiency of new materials. Therefore, it is particularly important to quickly characterize the thermal aging resistance of the material and test the critical point of thermal failure of the material.

[0006] In view of the above, the present application is proposed. SUMMARY

[0007] The application aims at a rapid test method for thermal aging failure of oil and gas pipeline anticorrosion coating material, and is based on a collaborative test method of differential scanning calorimetry (DSC) and pyrolysis gas chromatography / mass spectrometry (Py-GC / MS), which can quickly characterize the thermal aging failure critical point of the oil and gas pipeline anticorrosion coating material, and provide a scientific basis for further development and rapid iteration of the material.

[0008] In order to achieve the above-mentioned purpose of the application, the application provides a rapid test method for thermal aging failure of oil and gas pipeline anticorrosion coating material, comprising the following steps: (a) subjecting the sample of the anticorrosion coating material to be tested to thermal oxidation aging at a temperature T to obtain an oxidation induction time t; (b) subjecting at least 5 parallel samples of the anticorrosion coating material to be tested to thermal aging at different lengths of time t x in an atmosphere at 150±3℃, respectively, and measuring A(tri) / A(mon) of each of the thermal aged materials; (c) measuring the melt index of each of the thermal aged materials in step (b), and calculating the melt index change rate; establishing a linear equation of A(tri) / A(mon) and the melt index change rate of each of the thermal aged materials, and calculating A'(tri) / A'(mon) corresponding to the melt index change rate of 35% based on the linear equation; (d) subjecting at least 5 parallel samples of the anticorrosion coating material to be tested to thermal oxidation aging at different lengths of time at a temperature T, and measuring A(tri) / A(mon) of each of the thermal oxidation aged materials; establishing a 3-order polynomial equation of A(tri) / A(mon) and the thermal oxidation aging time of each of the thermal oxidation aged materials; and substituting A'(tri) / A'(mon) calculated in step (c) into the 3-order polynomial equation to obtain an aging time t'; (e) subjecting the material in step (b) to thermal oxidation aging at a temperature T for a length of time t x , to obtain an oxidation induction time t x '', and calculating a rate coefficient k according to t x / (t-t x ''); (f) taking the product of the aging time t' obtained in step (d) and the rate coefficient k obtained in step (e) as the aging time corresponding to the failure critical point of the anticorrosion coating material to be tested at a standard aging temperature; In the step (b) and the step (d), the method for calculating A(tri) / A(mon) comprises: performing Py-GC / MS test on each aged material, extracting m / z 43 ion current diagram respectively, and calculating the ratio A(tri) / A(mon) of the peak area A(tri) of the propylene trimer characteristic ion in the m / z 43 ion current diagram to the peak area A(mon) of the propylene monomer characteristic ion. The anticorrosion layer material sample comprises polypropylene and an antioxidant; the proportion of the polypropylene in the anticorrosion layer material sample is not less than 50wt%, and the proportion of the antioxidant is 0.1wt%-0.5wt%.

[0009] In the specific embodiment of the present application, the anticorrosion layer material further comprises a blending component. Further, the blending component comprises at least one of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene low-density polyethylene and polyolefin elastomer.

[0010] In the specific embodiment of the present application, the temperature T is 200-230℃.

[0011] In the specific embodiment of the present application, the oxygen flow rate in the thermal oxidation in the step (a) and the step (d) is 50-100mL / min.

[0012] In the specific embodiment of the present application, in the step (b), the thermal aging time of the materials is 2 days, 4 days, 6 days, 8 days and 10 days respectively.

[0013] In the specific embodiment of the present application, in the step (e), the materials aged for 4 days and 8 days in the step (b) are subjected to thermal oxidation at the temperature T, to obtain the oxidation induction time t x=4 ’’ and t x=8 ’’ respectively, and the values of t x=4 / (t-t x=4 ’’) and t x=8 / (t-t x=8 ’’) are calculated respectively, and the average value is taken as the rate coefficient k.

[0014] In the specific embodiment of the present application, in the step (d), the thermal oxidation time is t / 5, 2t / 5, 3t / 5, 4t / 5 and t respectively.

[0015] In the specific embodiment of the present application, in the Py-GC / MS test, the test conditions comprise: the thermal cracking temperature is 550-650℃, and the cracking time is 10-30s.

[0016] In the embodiment of the present application, in the Py-GC / MS test, the chromatographic column type is HP-5MS; the split ratio is (100-200):1; the interface temperature is 280-300 DEG C, and the front sample port temperature is 280-300 DEG C; the GC temperature rising program is: after being kept at 40 DEG C for 2 min, being raised to 300 DEG C at 20 DEG C / min, and then being kept at 300 DEG C for 10 min.

[0017] In the embodiment of the present application, in step (c), the melt index is measured by using a melt index tester. Further, the test temperature of the melt index is 230 DEG C, and the pressure is 2.16 kg.

[0018] In the embodiment of the present application, in the m / z 43 ion current diagram, the retention time of the propylene trimer characteristic ion is 4.48 min±0.1 min, and the retention time of the propylene monomer characteristic ion is 1.69 min±0.1 min.

[0019] Compared with the prior art, the present application has the following beneficial effects: The present application cooperates with the differential scanning calorimetry and the pyrolysis gas chromatography-mass spectrometry technology to quickly characterize the thermal aging failure critical point of the oil and gas pipeline anticorrosion layer material, is accurate and efficient, and provides a scientific basis for further development and rapid iteration of the material. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0021] Figure 1 The static oxidation induction time diagram of the anticorrosion layer material provided for the embodiment of the present application is shown in FIG. 1; Figure 2 The m / z 43 ion current diagram of the anticorrosion layer material after thermal aging provided for the embodiment of the present application is shown in FIG. 2; Figure 3 The response value change diagram of the propylene monomer characteristic ion in the m / z 43 ion current diagram of the anticorrosion layer material with different aging time provided for the embodiment of the present application is shown in FIG. 3; Figure 4 The A(tri) / A(mon) value and aging time relationship diagram in the m / z 43 ion current diagram provided for the embodiment of the present application is shown in FIG. 4; Figure 5The A(tri) / A(mon) value in the m / z 43 ion flow diagram of the anticorrosion layer material with different aging time provided by the embodiment of the present application and the change rate of the melt index are related. DETAILED DESCRIPTION

[0022] The technical solutions of the present application will be described clearly and completely in combination with the drawings and specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, and are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are conventional products that can be purchased on the market.

[0023] The existing material thermal aging evaluation method takes a long time, generally several tens of days to several months, which seriously restricts the development and iteration efficiency of new materials. In view of the above problems, the present application proposes a collaborative test method based on differential scanning calorimetry (DSC) and pyrolysis gas chromatography-mass spectrometry (Py-GC / MS), taking the linear positive correlation between the ratio of propylene trimers to propylene monomers generated by the cracking of oil and gas pipeline anticorrosion coating materials under different aging degrees and the change rate of melt index as the breakthrough point, and establishing a rapid prediction model through the correlation between thermodynamic data and cracking products. By comparing the change relationship of the oxidation induction time, the critical failure points of the materials under two different aging conditions are corresponded, so that the aging time corresponding to the critical failure point of the material under the standard aging temperature of the material can be quickly estimated. Compared with the actual aging time of the material under the standard temperature, the absolute error is less than 5%, the result is accurate and reliable, which greatly shortens the time required for thermal aging failure of the material, and further significantly shortens the research and development period, and is suitable for rapid iteration of anticorrosion material development. In addition, the change relationship of the internal molecular structure corresponding to the critical failure point of the material also provides a certain basis for the development of new materials and new formulations.

[0024] The static oxidation induction time t of the anticorrosion layer material is tested by a differential scanning calorimeter, as shown in Figure 1 The melt index change rate of the anticorrosion layer material is 35%, and the corresponding DSC static high-temperature oxidation time is always between 0-t. The cracking mass spectrum m / z 43 ion flow diagram of the anticorrosion layer material after thermal aging, the response value change diagram of the propylene monomer characteristic ion in the m / z 43 ion flow diagram of the anticorrosion layer material with different aging time, and the relationship diagram of the A(tri) / A(mon) value in the m / z 43 ion flow diagram and the thermal oxygen aging time are respectively as shown in Figures 2 to 4As shown in the figure, it can be seen from the figure that the ratio of the peak area of the propylene trimer to the propylene monomer (A(tri) / A(mon)) in the m / z 43 ion flow diagram of the material cracking mass spectrum and the aging time satisfy a positive correlation nonlinear relationship; the A(tri) / A(mon) value in the m / z 43 ion flow diagram of the anticorrosive coating material of different aging time and the melt index change rate relationship diagram are as shown in the figure. Figure 5 According to the Arrhenius equation, the rate coefficient relationship under two different aging conditions is found by combining the oxidation induction time, so that the critical point of material thermal failure can be quickly characterized.

[0025] Based on this, the application provides a rapid test method for thermal aging failure of an anticorrosive coating material of an oil and gas pipeline, which comprises the following steps: (a) subjecting a sample of the anticorrosive coating material to be tested to thermal oxidation aging at a temperature T to obtain an oxidation induction time t; (b) subjecting at least 5 parallel samples of the anticorrosive coating material to be tested to thermal aging in an atmospheric atmosphere at 150±3℃ for different time t x , and measuring the A(tri) / A(mon) of each thermal aged material; (c) measuring the melt index of each thermal aged material in step (b), and calculating the melt index change rate; establishing a linear equation of the A(tri) / A(mon) and the melt index change rate of each thermal aged material, and calculating the A'(tri) / A'(mon) corresponding to the melt index change rate of 35% based on the linear equation; (d) subjecting at least 5 parallel samples of the anticorrosive coating material to be tested to thermal oxidation aging at the temperature T for different time, and measuring the A(tri) / A(mon) of each thermal oxidation aged material; establishing a 3-order polynomial equation of the A(tri) / A(mon) and the thermal oxidation aging time of each thermal oxidation aged material; substituting the A'(tri) / A'(mon) calculated in step (c) into the 3-order polynomial equation to obtain an aging time t'; (e) subjecting the material in step (b) to thermal oxidation aging at the temperature T for the time t x , and obtaining an oxidation induction time t x ''; calculating a rate coefficient k according to t x / (t-t x ''); (f) taking the product of the aging time t' obtained in step (d) and the rate coefficient k obtained in step (e) as the aging time corresponding to the failure critical point of the anticorrosive coating material to be tested at a standard aging temperature; In steps (b) and (d), the method for calculating A(tri) / A(mon) includes: performing Py-GC / MS tests on each aged material, extracting the m / z 43 ion flow map, and calculating the ratio A(tri) / A(mon) of the peak area of ​​the characteristic ions of propylene trimer to the peak area of ​​the characteristic ions of propylene monomer in the m / z 43 ion flow map. The anti-corrosion layer material sample includes polypropylene and antioxidant; in the anti-corrosion layer material sample, the proportion of polypropylene is not less than 50 wt%, and the proportion of antioxidant is 0.1 wt% to 0.5 wt%.

[0026] In some embodiments, the anti-corrosion coating material sample includes polypropylene. Further, the proportion of polypropylene in the anti-corrosion coating material sample is not less than 50 wt%, for example, it can be a range of 50 wt%, 60 wt%, 70 wt%, 80 wt%, 90 wt%, 100 wt%, or any combination thereof.

[0027] In some embodiments, the antioxidant content in the anti-corrosion coating material sample can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or any combination thereof.

[0028] In some embodiments, the antioxidant includes at least one of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0029] In some embodiments, the anti-corrosion coating material further includes a blend component. More specifically, the blend component includes at least one selected from high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene low-density polyethylene, and polyolefin elastomers.

[0030] In some embodiments, the blending method of polypropylene and optional blending components and antioxidants in the tested anti-corrosion coating material sample is not limited, and may include: mixing the raw material components in proportion and then mixing thoroughly by internal mixing. Further, the internal mixing temperature is 230–235°C, and the internal mixing time is 5–10 minutes. This is not a limitation on the blending method of the tested anti-corrosion coating material sample, but merely an optional blending method.

[0031] In some embodiments, in step (a), the sample of the anti-corrosion coating material to be tested is subjected to thermo-oxidative aging at a temperature T to obtain the oxidation induction time t. Specifically, the thermo-oxidative aging is performed in a differential scanning calorimeter, and the temperature T for thermo-oxidative aging is 200-230°C, for example, it can be 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, or any combination thereof.

[0032] In some implementations, in step (a), at least three parallel experiments may be performed, and the average value is taken as the oxidation induction time t.

[0033] In some embodiments, during the thermo-oxidative aging in step (a), the oxygen flow rate is 50 to 100 mL / min, for example, it can be a range of 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min or any combination thereof.

[0034] In some implementations, the thermal aging in step (b) can be performed in an oven.

[0035] In some implementations, the duration of thermal aging in step (b) is 2 days, 4 days, 6 days, 8 days, and 10 days, respectively.

[0036] In some embodiments, in step (e), the materials that have been thermally aged for 4 days and 8 days in step (b) are subjected to thermo-oxidative aging at a temperature T to obtain oxidation induction time t, respectively. x=4 '' and t x=8 '', and calculate t respectively. x=4 / (tt x=4 '') and t x=8 / (tt x=8 The value of '') is then taken as the average value as the rate coefficient k.

[0037] In some embodiments, in step (c), the melt index is measured using a melt indexer. Further, the melt index is tested at a temperature of 230°C and a pressure of 2.16 kg.

[0038] In some embodiments, in step (c), the melt flow index (MI) of each of the heat-aged materials in step (b) is determined. 老化后 The melt flow index (MI) of the anti-corrosion coating material sample that was not subjected to thermal aging was compared with that of the sample under test. 初始 Compare and calculate the rate of change of melt index; where, the rate of change of melt index = (MI 老化后 -MI 初始 ) / MI 初始 ×100%.

[0039] In some implementations, in step (c), a linear equation is established with the melt index change rate of each heat-aged material as the ordinate and the A(tri) / A(mon) of each heat-aged material as the abscissa.

[0040] In some implementations, the thermo-oxidative aging of step (d) is performed in a differential scanning calorimeter.

[0041] In some implementations, the temperature T and oxygen flow rate of the thermo-oxidative aging in step (d) are the same as those in step (a).

[0042] In some implementations, the duration of thermo-oxidative aging in step (d) is t / 5, 2t / 5, 3t / 5, 4t / 5, and t, respectively. Further, the duration of thermo-oxidative aging is rounded to one decimal place according to rounding rules, and the unit is minutes (min).

[0043] In some implementations, in step (d), a third-order polynomial equation is established with A(tri) / A(mon) of each thermo-oxidative aged material as the ordinate and the thermo-oxidative aging time of each thermo-oxidative aged material as the abscissa.

[0044] In some implementations, the calculation of A(tri) / A(mon) is performed by Py-GC / MS testing in a thermal pyrolysis-gas chromatography-mass spectrometry system.

[0045] In some implementations, the test conditions in Py-GC / MS testing include: a thermal decomposition temperature of 550–650°C, specifically a range of 550°C, 580°C, 600°C, 620°C, 650°C, or any combination thereof; and a decomposition time of 10–30 s, specifically a range of 10 s, 15 s, 20 s, 25 s, 30 s, or any combination thereof.

[0046] In some implementations, the Py-GC / MS test uses an HP-5MS column; the split ratio is (100–200):1, for example, 100:1, 120:1, 150:1, 180:1, 200:1, or any combination thereof; the interface temperature is 280–300°C, for example, 280°C, 285°C, 290°C, 295°C, 300°C, or any combination thereof; and the inlet temperature is 280–300°C, for example, 280°C, 285°C, 290°C, 295°C, 300°C, or any combination thereof.

[0047] In some implementations, the GC temperature program for Py-GC / MS testing is as follows: hold at 40°C for 2 min, then increase the temperature to 300°C at a rate of 20°C / min, and then hold at 300°C for 10 min. Further, the sample mass in the Py-GC / MS testing is 0.1–0.5 mg.

[0048] For Py Parameters not mentioned in the GC / MS test are all standard parameter settings.

[0049] In some embodiments, in the m / z 43 ion chromatogram, the retention time of the characteristic ions of propylene trimer is 4.48 min ± 0.1 min, and the retention time of the characteristic ions of propylene monomer is 1.69 min ± 0.1 min.

[0050] The following embodiments further verify the accuracy and reliability of the testing method of the present invention. In the testing method of the present invention, the time parameter is converted into the value corresponding to minutes during calculation.

[0051] Example 1 This embodiment provides a rapid method for determining the thermal aging failure of anti-corrosion coating materials, including the following steps: (1) Weigh 90 parts of polypropylene material, 10 parts of high-density polyethylene and 0.2 parts of antioxidant 168 according to the weight ratio, mix them in a Harker rheometer, heat the temperature to 230℃ and mix for 5 min to obtain the anti-corrosion layer material to be tested.

[0052] (2) Weigh three portions of the anti-corrosion material to be tested, each weighing 10 to 15 mg, and place them in a differential scanning calorimeter to test the static oxidation induction time. Take the average of the three test results and determine the oxidation induction time as 41.2 min. The aging temperature is 220℃ and the oxygen flow rate is 50 mL / min.

[0053] (3) Five 10g portions of the anti-corrosion coating material to be tested were weighed in parallel and placed in an oven at 150℃ in an atmospheric atmosphere for 2, 4, 6, 8 and 10 days of aging, respectively. Then, the aged materials were tested by Py-GC / MS. The m / z 43 ion chromatograms were extracted. The peak areas A(mon) and A(tri) were obtained by integrating the peaks with retention times of 1.69 min (corresponding to the characteristic ion of propylene monomer) and 4.48 min (corresponding to the characteristic ion of propylene trimer). Then, A(tri) / A(mon) was calculated.

[0054] (4) The melt index of the aged material and the unaged anti-corrosion layer material in step (3) was measured using a melt index meter. The melt index test temperature was 230℃ and the pressure was 2.16kg. The melt index change rate was calculated. Then, the melt index change rate of each heat-aged material was used as the ordinate and the corresponding A(tri) / A(mon) of each heat-aged material was used as the abscissa. Linear fitting was performed to obtain the linear equation y = 0.396x -1.424. Then, the melt index change rate of the failure critical point of 35% was substituted into the linear equation to obtain the corresponding A'(tri) / A'(mon) = 4.48.

[0055] (5) Five parallel portions of the anti-corrosion coating material to be tested, each weighing 10–15 mg, were placed in a differential scanning calorimeter with an oxygen flow rate of 50 mL / min. The materials were aged at 220℃ for 8.2 min, 16.5 min, 24.7 min, 33.0 min, and 41.2 min, respectively. The aged materials were then subjected to Py-GC / MS testing. m / z 43 ion chromatograms were extracted, and peak areas A(mon) and A(tri) were obtained by integrating the peaks at retention times of 1.69 min (corresponding to propylene monomer characteristic ions) and 4.48 min (corresponding to propylene trimer characteristic ions). A(tri) / A(mon) was then calculated. Using A(tri) / A(mon) as the ordinate and the aging time as the abscissa, a third-order polynomial was fitted, yielding the third-order polynomial equation y = 0.00007x. 3 - 0.0026x 2 + 0.0256x + 3.5792. Then, substituting A'(tri) / A'(mon)=4.48 into the third-order polynomial equation, we obtain the critical failure time t'=36.7min for the thermo-oxidative aging material in the differential scanning calorimeter.

[0056] (6) The oxidation induction time of the materials aged for 4 days and 8 days in step (3) was tested according to the conditions in step (2) to obtain their respective oxidation induction times t. x=4 ''=37.7min and t x=8 =34.8min, then calculate t respectively. x=4 / (tt x=4 '')=4d / (41.2min-37.7min) and t x=8 / (tt x=8 = 8d / (41.2min-34.8min), and take the average of the two as the temperature rate coefficient k, which is 1723.

[0057] (7) The product of the critical failure time t'=36.7min obtained in step (5) and the rate coefficient k=1723 obtained in step (6) is 63234.1min, which is approximately 43.9 days after conversion. This is the aging time corresponding to the critical failure point (melt index change rate of 35%) of the anti-corrosion layer material under test at the standard aging temperature (150℃).

[0058] The Py-GC / MS test conditions for steps (3) and (5) in this embodiment include: The thermal pyrolysis temperature was set to 600℃, and the pyrolysis time was 10s. The column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, increased to 300℃ at a rate of 20℃ / min, and then held at 300℃ for 10 min. The split ratio was 100:1. The interface temperature was 300℃, and the inlet temperature was 300℃.

[0059] The 43.9 days obtained by the test method in this embodiment is compared with the actual aging failure time of 45.2 days of the anti-corrosion coating material under test in this embodiment. The method error is -2.88%, and the result is accurate and reliable.

[0060] Example 2 This embodiment provides a rapid method for determining the thermal aging failure of anti-corrosion coating materials, including the following steps: (1) Weigh 87 parts of polypropylene material, 13 parts of linear low-density polyethylene and 0.28 parts of antioxidant 1010 according to the weight ratio, mix them in a Harker rheometer, heat the temperature to 230℃ and mix for 5 min to obtain the anti-corrosion layer material to be tested.

[0061] (2) Weigh three portions of the anti-corrosion material to be tested, each weighing 10 to 15 mg, and place them in a differential scanning calorimeter to test the static oxidation induction time. Take the average of the three test results and determine the oxidation induction time as 52.9 min. The aging temperature is 220℃ and the oxygen flow rate is 50 mL / min.

[0062] (3) Five 10g portions of the anti-corrosion coating material to be tested were weighed in parallel and placed in an oven at 150℃ in an atmospheric atmosphere for 2, 4, 6, 8 and 10 days of aging, respectively. Then, the aged materials were tested by Py-GC / MS. The m / z 43 ion chromatograms were extracted. The peak areas A(mon) and A(tri) were obtained by integrating the peaks with retention times of 1.69 min (corresponding to the characteristic ion of propylene monomer) and 4.48 min (corresponding to the characteristic ion of propylene trimer). Then, A(tri) / A(mon) was calculated.

[0063] (4) The melt index of the aged material and the unaged anti-corrosion layer material in step (3) was measured using a melt index meter. The melt index test temperature was 230℃ and the pressure was 2.16kg. The melt index change rate was calculated. Then, the melt index change rate of each heat-aged material was used as the ordinate and the corresponding A(tri) / A(mon) of each heat-aged material was used as the abscissa. Linear fitting was performed to obtain the linear equation y = 0.492x -1.771. Then, the melt index change rate of the failure critical point of 35% was substituted into the linear equation to obtain the corresponding A'(tri) / A'(mon) = 4.31.

[0064] (5) Five parallel portions of the anti-corrosion coating material to be tested, each weighing 10–15 mg, were placed in a differential scanning calorimeter with an oxygen flow rate of 50 mL / min. The materials were aged at 220℃ for 10.6 min, 21.2 min, 31.7 min, 42.3 min, and 52.9 min, respectively. The aged materials were then subjected to Py-GC / MS testing. m / z 43 ion chromatograms were extracted, and peak areas A(mon) and A(tri) were obtained by integrating the peaks at retention times of 1.69 min (corresponding to propylene monomer characteristic ions) and 4.48 min (corresponding to propylene trimer characteristic ions). A(tri) / A(mon) was then calculated. Using A(tri) / A(mon) as the ordinate and the aging time as the abscissa, a third-order polynomial was fitted, yielding the third-order polynomial equation y = 0.00004x. 3 - 0.0021x 2 + 0.0290x + 3.5681. Then, substituting A'(tri) / A'(mon)=4.31 into the third-order polynomial equation, we obtain the critical failure time t'=45.5min for the thermo-oxidative aging material in the differential scanning calorimeter.

[0065] (6) The oxidation induction time of the materials aged for 4 days and 8 days in step (3) was tested according to the conditions in step (2) to obtain their respective oxidation induction times t. x=4 ''=49.6min and t x=8 ''=46.2min, then calculate t respectively x=4 / (tt x=4 '')=4d / (52.9min-49.6min) and t x=8 / (tt x=8 =8d / (52.9min-46.2min), and then take the average of the two as the temperature rate coefficient k, which is 1732.

[0066] (7) The product of the critical failure time t'=45.5min obtained in step (5) and the rate coefficient k=1732 obtained in step (6) is 78806min, which is approximately 54.7 days after conversion. This is the aging time corresponding to the critical failure point (melt index change rate of 35%) of the anti-corrosion layer material under test at the standard aging temperature (150℃).

[0067] The Py-GC / MS test conditions for steps (3) and (5) in this embodiment include: The thermal pyrolysis temperature was set to 600℃, and the pyrolysis time was 10s. The column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, increased to 300℃ at a rate of 20℃ / min, and then held at 300℃ for 10 min. The split ratio was 100:1. The interface temperature was 300℃, and the inlet temperature was 300℃.

[0068] The 54.7 days obtained by the test method in this embodiment is compared with the actual aging failure time of 56.5 days of the anti-corrosion coating material under test in this embodiment. The method error is -3.19%, and the result is accurate and reliable.

[0069] Example 3 This embodiment provides a rapid method for determining the thermal aging failure of anti-corrosion coating materials, including the following steps: (1) Weigh 75 parts of polypropylene material, 25 parts of metallocene low-density polyethylene and 10760.15 parts of antioxidant according to the weight ratio, mix them in a Harker rheometer, heat the temperature to 230℃ and mix for 5 min to obtain the anti-corrosion layer material to be tested.

[0070] (2) Weigh three portions of the anti-corrosion material to be tested, each weighing 10 to 15 mg, and place them in a differential scanning calorimeter to test the static oxidation induction time. Take the average of the three test results and determine the oxidation induction time as 31.1 min. The aging temperature is 220℃ and the oxygen flow rate is 50 mL / min.

[0071] (3) Five 10g portions of the anti-corrosion coating material to be tested were weighed in parallel and placed in an oven at 150℃ in an atmospheric atmosphere for 2, 4, 6, 8 and 10 days of aging, respectively. Then, the aged materials were tested by Py-GC / MS. The m / z 43 ion chromatograms were extracted. The peak areas A(mon) and A(tri) were obtained by integrating the peaks with retention times of 1.69 min (corresponding to the characteristic ion of propylene monomer) and 4.48 min (corresponding to the characteristic ion of propylene trimer). Then, A(tri) / A(mon) was calculated.

[0072] (4) The melt index of the aged material and the unaged anti-corrosion layer material in step (3) was measured using a melt index meter. The melt index test temperature was 230℃ and the pressure was 2.16kg. The melt index change rate was calculated. Then, the melt index change rate of each heat-aged material was used as the ordinate and the corresponding A(tri) / A(mon) of each heat-aged material was used as the abscissa. Linear fitting was performed to obtain the linear equation y = 0.411x -1.479. Then, the melt index change rate of the failure critical point of 35% was substituted into the linear equation to obtain the corresponding A'(tri) / A'(mon) = 4.45.

[0073] (5) Five parallel portions of the anti-corrosion coating material to be tested, each weighing 10–15 mg, were placed in a differential scanning calorimeter with an oxygen flow rate of 50 mL / min. The materials were aged at 220℃ for 6.2 min, 12.4 min, 18.7 min, 24.9 min, and 31.1 min, respectively. The aged materials were then subjected to Py-GC / MS testing. m / z 43 ion chromatograms were extracted, and peak areas A(mon) and A(tri) were obtained by integrating the peaks at retention times of 1.69 min (corresponding to propylene monomer characteristic ions) and 4.48 min (corresponding to propylene trimer characteristic ions). A(tri) / A(mon) was then calculated. Using A(tri) / A(mon) as the ordinate and the aging time as the abscissa, a third-order polynomial was fitted, yielding the third-order polynomial equation y = 0.0002x. 3 - 0.0056x 2 + 0.0438x + 3.5513. Then, substituting A'(tri) / A'(mon)=4.45 into the third-order polynomial equation, we obtain the critical failure time t'=26.2min for the thermo-oxidative aging material in the differential scanning calorimeter.

[0074] (6) The oxidation induction time of the materials aged for 4 days and 8 days in step (3) was tested according to the conditions in step (2) to obtain their respective oxidation induction times t. x=4 ''=27.9min and t x=8 =24.5min, then calculate t respectively. x=4 / (tt x=4 '')=4d / (31.1min-27.9min) and t x=8 / (tt x=8 =8d / (31.1min-24.5min), and then take the average of the two as the temperature rate coefficient k, which is 1773.

[0075] (7) The product of the critical failure time t'=26.2min obtained in step (5) and the rate coefficient k=1773 obtained in step (6) is 46452.2min, which is about 32.3 days after conversion. This is the aging time corresponding to the critical failure point (melt index change rate of 35%) of the anti-corrosion layer material under the standard aging temperature (150℃).

[0076] The Py-GC / MS test conditions for steps (3) and (5) in this embodiment include: The thermal pyrolysis temperature was set to 600℃, and the pyrolysis time was 10s. The column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, increased to 300℃ at a rate of 20℃ / min, and then held at 300℃ for 10 min. The split ratio was 100:1. The interface temperature was 300℃, and the inlet temperature was 300℃.

[0077] The 32.3 days obtained by the test method in this embodiment is compared with the actual aging failure time of 30.9 days of the anti-corrosion coating material to be tested in this embodiment. The method error is 4.53%, and the result is accurate and reliable.

[0078] Example 4 This embodiment provides a rapid method for determining the thermal aging failure of anti-corrosion coating materials, including the following steps: (1) Weigh 80 parts of polypropylene material, 10 parts of linear low-density polyethylene, 10 parts of polyolefin elastomer and 0.2 parts of antioxidant 168 according to the weight ratio, mix them in a Hack rheometer, heat the temperature to 230℃ and mix for 5 min to obtain the anti-corrosion layer material to be tested.

[0079] (2) Weigh three portions of the anti-corrosion material to be tested, each weighing 10 to 15 mg, and place them in a differential scanning calorimeter to test the static oxidation induction time. Take the average of the three test results and determine the oxidation induction time as 40.3 min. The aging temperature is 220℃ and the oxygen flow rate is 50 mL / min.

[0080] (3) Five 10g portions of the anti-corrosion coating material to be tested were weighed in parallel and placed in an oven at 150℃ in an atmospheric atmosphere for 2, 4, 6, 8 and 10 days of aging, respectively. Then, the aged materials were tested by Py-GC / MS. The m / z 43 ion chromatograms were extracted. The peak areas A(mon) and A(tri) were obtained by integrating the peaks with retention times of 1.69 min (corresponding to the characteristic ion of propylene monomer) and 4.48 min (corresponding to the characteristic ion of propylene trimer). Then, A(tri) / A(mon) was calculated.

[0081] (4) The melt flow index of the aged material and the unaged anti-corrosion layer material in step (3) was measured using a melt flow index meter. The melt flow index test temperature was 230℃ and the pressure was 2.16kg. The melt flow index change rate was calculated. Then, the melt flow index change rate of each heat-aged material was used as the ordinate and the corresponding A(tri) / A(mon) of each heat-aged material was used as the abscissa. A linear fit was performed, and the linear equation was obtained as y = 0.357x -1.285. Then, the melt flow index change rate of the failure critical point of 35% was substituted into the linear equation to obtain the corresponding A'(tri) / A'(mon) = 4.58.

[0082] (5) Five parallel portions of the anti-corrosion coating material to be tested, each weighing 10–15 mg, were placed in a differential scanning calorimeter with an oxygen flow rate of 50 mL / min. The materials were aged at 220℃ for 8.1 min, 16.1 min, 24.2 min, 32.2 min, and 40.3 min, respectively. The aged materials were then subjected to Py-GC / MS testing. m / z 43 ion chromatograms were extracted, and peak areas A(mon) and A(tri) were obtained by integrating the peaks at retention times of 1.69 min (corresponding to propylene monomer characteristic ions) and 4.48 min (corresponding to propylene trimer characteristic ions). A(tri) / A(mon) was then calculated. Using A(tri) / A(mon) as the ordinate and the aging time as the abscissa, a third-order polynomial was fitted, yielding the third-order polynomial equation y = 0.00003x. 3 + 0.00004x 2 - 0.0030x + 3.5508. Then, substituting A'(tri) / A'(mon)=4.58 into the third-order polynomial equation, we obtain the critical failure time t'=33.1min for the material undergoing thermo-oxidative aging in the differential scanning calorimeter.

[0083] (6) The oxidation induction time of the materials aged for 4 days and 8 days in step (3) was tested according to the conditions in step (2) to obtain their respective oxidation induction times t. x=4 ''=37.0min and t x=8 =33.5min, then calculate t respectively. x=4 / (tt x=4 '')=4d / (40.3min-37.0min) and t x=8 / (tt x=8 =8d / (40.3min-33.5min), and then take the average of the two as the temperature rate coefficient k, which is 1720.

[0084] (7) The product of the critical failure time t'=33.1min obtained in step (5) and the rate coefficient k=1720 obtained in step (6) is 56932min, which is about 39.5 days after conversion. This is the aging time corresponding to the critical failure point (melt index change rate of 35%) of the anti-corrosion layer material under the standard aging temperature (150℃).

[0085] The Py-GC / MS test conditions for steps (3) and (5) in this embodiment include: The thermal pyrolysis temperature was set to 600℃, and the pyrolysis time was 10s. The column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, increased to 300℃ at a rate of 20℃ / min, and then held at 300℃ for 10 min. The split ratio was 100:1. The interface temperature was 300℃, and the inlet temperature was 300℃.

[0086] The 39.5 days obtained by the test method in this embodiment is compared with the actual aging failure time of 40.2 days of the anti-corrosion coating material to be tested in this embodiment. The method error is -1.74%, and the result is accurate and reliable.

[0087] Example 5 This embodiment provides a rapid method for determining the thermal aging failure of anti-corrosion coating materials, including the following steps: (1) Weigh 78 parts of polypropylene material, 22 parts of linear low-density polyethylene, 0.2 parts of antioxidant 1010 and 0.2 parts of antioxidant 168 according to the weight ratio, mix them in a Harker rheometer, heat the temperature to 230℃ and mix for 5 minutes to obtain the anti-corrosion layer material to be tested.

[0088] (2) Weigh three portions of the anti-corrosion material to be tested, each weighing 10 to 15 mg, and place them in a differential scanning calorimeter to test the static oxidation induction time. Take the average of the three test results and determine the oxidation induction time as 36.9 min. The aging temperature is 230℃ and the oxygen flow rate is 50 mL / min.

[0089] (3) Five 10g portions of the anti-corrosion coating material to be tested were weighed in parallel and placed in an oven at 150℃ in an atmospheric atmosphere for 2, 4, 6, 8 and 10 days of aging, respectively. Then, the aged materials were tested by Py-GC / MS. The m / z 43 ion chromatograms were extracted. The peak areas A(mon) and A(tri) were obtained by integrating the peaks with retention times of 1.69 min (corresponding to the characteristic ion of propylene monomer) and 4.48 min (corresponding to the characteristic ion of propylene trimer). Then, A(tri) / A(mon) was calculated.

[0090] (4) The melt index of the aged material and the unaged anti-corrosion layer material in step (3) was measured using a melt index meter. The melt index test temperature was 230℃ and the pressure was 2.16kg. The melt index change rate was calculated. Then, the melt index change rate of each heat-aged material was used as the ordinate and the corresponding A(tri) / A(mon) of each heat-aged material was used as the abscissa. Linear fitting was performed to obtain the linear equation y = 0.684x -2.461. Then, the melt index change rate of the failure critical point of 35% was substituted into the linear equation to obtain the corresponding A'(tri) / A'(mon) = 4.11.

[0091] (5) Five parallel portions of the anti-corrosion coating material to be tested, each weighing 10–15 mg, were placed in a differential scanning calorimeter with an oxygen flow rate of 50 mL / min. The materials were aged at 230℃ for 7.4 min, 14.8 min, 22.1 min, 29.5 min, and 36.9 min, respectively. The aged materials were then subjected to Py-GC / MS testing. m / z 43 ion chromatograms were extracted, and peak areas A(mon) and A(tri) were obtained by integrating the peaks at retention times of 1.69 min (corresponding to propylene monomer characteristic ions) and 4.48 min (corresponding to propylene trimer characteristic ions). A(tri) / A(mon) was then calculated. Using A(tri) / A(mon) as the ordinate and the aging time as the abscissa, a third-order polynomial was fitted, yielding the third-order polynomial equation y = 0.0001x. 3 - 0.0036x 2 + 0.0337x + 3.5722. Then, substituting A'(tri) / A'(mon)=4.11 into the third-order polynomial equation, we obtain the critical failure time t'=30.7min for the material undergoing thermo-oxidative aging in the differential scanning calorimeter.

[0092] (6) The oxidation induction time of the materials aged for 4 days and 8 days in step (3) was tested according to the conditions in step (2) to obtain their respective oxidation induction times t. x=4 ''=35.3min and t x=8 =33.8min, then calculate t respectively. x=4 / (tt x=4 '')=4d / (36.9min-35.3min) and t x=8 / (tt x=8 '')=4d / (36.9min-33.8min), and then take the average of the two as the temperature rate coefficient k, which is 3658.

[0093] (7) The product of the critical failure time t'=30.7min obtained in step (5) and the rate coefficient k=3658 obtained in step (6) is 112300.6min, which is approximately 78.0 days. This is the aging time corresponding to the critical failure point (melt flow index change rate of 35%) of the anti-corrosion layer material under test at the standard aging temperature (150℃).

[0094] The Py-GC / MS test conditions for steps (3) and (5) in this embodiment include: The thermal pyrolysis temperature was set to 600℃, and the pyrolysis time was 10s. The column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, increased to 300℃ at a rate of 20℃ / min, and then held at 300℃ for 10 min. The split ratio was 100:1. The interface temperature was 300℃, and the inlet temperature was 300℃.

[0095] The 78.0 days obtained by the test method in this embodiment is compared with the actual aging failure time of 75.4 days of the anti-corrosion coating material under test in this embodiment. The method error is 3.45%, and the result is accurate and reliable.

[0096] Example 6 This embodiment provides a rapid method for determining the thermal aging failure of anti-corrosion coating materials, including the following steps: (1) Weigh 100 parts of polypropylene material and 0.25 parts of antioxidant 168 according to the weight ratio, mix them in a Hack rheometer, heat the temperature to 230℃, and mix for 5 minutes to obtain the anti-corrosion layer material to be tested.

[0097] (2) Weigh three portions of the anti-corrosion material to be tested, each weighing 10 to 15 mg, and place them in a differential scanning calorimeter to test the static oxidation induction time. Take the average of the three test results and determine the oxidation induction time as 47.4 min. The aging temperature is 220℃ and the oxygen flow rate is 50 mL / min.

[0098] (3) Five 10g portions of the anti-corrosion coating material to be tested were weighed in parallel and placed in an oven at 150℃ in an atmospheric atmosphere for 2, 4, 6, 8 and 10 days of aging, respectively. Then, the aged materials were tested by Py-GC / MS. The m / z 43 ion chromatograms were extracted. The peak areas A(mon) and A(tri) were obtained by integrating the peaks with retention times of 1.69 min (corresponding to the characteristic ion of propylene monomer) and 4.48 min (corresponding to the characteristic ion of propylene trimer). Then, A(tri) / A(mon) was calculated.

[0099] (4) The melt index of the aged material and the unaged anti-corrosion layer material in step (3) was measured using a melt index meter. The melt index test temperature was 220℃ and the pressure was 2.16kg. The melt index change rate was calculated. Then, the melt index change rate of each heat-aged material was used as the ordinate and the corresponding A(tri) / A(mon) of each heat-aged material was used as the abscissa. Linear fitting was performed to obtain the linear equation y = 0.343x -1.235. Then, the melt index change rate of the failure critical point of 35% was substituted into the linear equation to obtain the corresponding A'(tri) / A'(mon) = 4.62.

[0100] (5) Five parallel portions of the anti-corrosion coating material to be tested, each weighing 10–15 mg, were placed in a differential scanning calorimeter with an oxygen flow rate of 50 mL / min. The materials were aged at 220℃ for 9.5 min, 19.0 min, 28.4 min, 37.9 min, and 47.4 min, respectively. The aged materials were then subjected to Py-GC / MS testing. m / z 43 ion chromatograms were extracted, and peak areas A(mon) and A(tri) were obtained by integrating the peaks at retention times of 1.69 min (corresponding to propylene monomer characteristic ions) and 4.48 min (corresponding to propylene trimer characteristic ions). A(tri) / A(mon) was then calculated. Using A(tri) / A(mon) as the ordinate and the aging time as the abscissa, a third-order polynomial was fitted, yielding the third-order polynomial equation y = 0.00006x. 3 - 0.0026x 2 + 0.0303x + 3.5793. Then, substituting A'(tri) / A'(mon)=4.62 into the third-order polynomial equation, we obtain the critical failure time t'=41.3min for the material undergoing thermo-oxidative aging in the differential scanning calorimeter.

[0101] (6) The oxidation induction time of the materials aged for 4 days and 8 days in step (3) was tested according to the conditions in step (2) to obtain their respective oxidation induction times t. x=4 ''=44.1min and t x=8 =40.8min, then calculate t respectively. x=4 / (tt x=4 '')=4d / (47.4min-44.1min) and t x=8 / (tt x=8 =8d / (47.4min-40.8min), and then take the average of the two as the temperature rate coefficient k, which is 1745.

[0102] (7) The product of the critical failure time t'=41.3min obtained in step (5) and the rate coefficient k=1745 obtained in step (6) is 72068.5min, which is about 50.0 days after conversion. This is the aging time corresponding to the critical failure point (melt index change rate of 35%) of the anti-corrosion layer material under the standard aging temperature (150℃).

[0103] The Py-GC / MS test conditions for steps (3) and (5) in this embodiment include: The thermal pyrolysis temperature was set to 600℃, and the pyrolysis time was 10s. The column type was HP-5MS, and the GC temperature program was: 40℃ for 2 min, increased to 300℃ at a rate of 20℃ / min, and then held at 300℃ for 10 min. The split ratio was 100:1. The interface temperature was 300℃, and the inlet temperature was 300℃.

[0104] The 50.0 days obtained by the test method in this embodiment is compared with the actual aging failure time of 52.3 days of the anti-corrosion coating material to be tested in this embodiment. The method error is -4.40%, and the result is accurate and reliable.

[0105] Comparative Example 1 Comparative Example 1 uses the same determination method as Example 1, except that the amount of antioxidant used in step (1) is different, resulting in different test results. The specific differences are as follows.

[0106] In step (1) of Comparative Example 1, the amount of antioxidant 168 used was 0.03 parts; In step (2) of Comparative Example 1, the oxidation induction time was 4.6 min; In step (4) of Comparative Example 1, the obtained linear equation is y = 0.250x -0.899; the corresponding A'(tri) / A'(mon) = 5.00; In step (5) of Comparative Example 1, the aging times were 0.9 min, 1.8 min, 2.8 min, 3.7 min, and 4.6 min, respectively; the critical failure time t' of the thermo-oxidative aging material obtained by differential scanning calorimetry was 4.2 min. In step (6) of Comparative Example 1, the obtained temperature rate coefficient k is 1980; In step (7) of Comparative Example 1, the product of the critical failure time t'=4.2min of the thermo-oxidative aging material and the rate coefficient k=1980 obtained in step (6) is 8316min, which is approximately 5.8 days after conversion.

[0107] The 5.8 days obtained by the test method of Comparative Example 1 was compared with the actual aging failure time of 8.9 days of the anti-corrosion coating material to be tested in this comparative example. The method error was -34.8%, and the estimated result had a large error with the actual result.

[0108] Comparative Example 2 Comparative Example 2 uses the same testing method as Example 1, except that the amount of polypropylene material and high-density polyethylene used in step (1) is different, resulting in different test results. The specific differences are as follows.

[0109] In step (1) of Comparative Example 2, there are 30 parts of polypropylene material and 70 parts of high-density polyethylene. In step (4) of Comparative Example 2, the melt index change rate of each heat-aged material is used as the vertical axis and the corresponding A(tri) / A(mon) of each heat-aged material is used as the horizontal axis for linear fitting. The two do not satisfy the linear relationship and cannot be used for subsequent calculation and evaluation.

[0110] Comparative Example 3 Comparative Example 3 uses the same determination method as Example 1, except that the thermal decomposition temperature is different in the Py-GC / MS test conditions of steps (3) and (5).

[0111] In the Py-GC / MS test conditions of Comparative Example 3, the thermal decomposition temperature was 450℃.

[0112] In steps (3) and (5) of Comparative Example 3, the m / z 43 ion chromatogram was extracted. Due to the low pyrolysis temperature, the pyrolysis process and mechanism changed, and the retention time shifted. The retention times of 1.69 min and 4.48 min could not correspond to the characteristic ions of propylene monomer and propylene trimer, so A(mon) / A(tri) could not be calculated.

[0113] This invention is based on a synergistic testing method combining DSC and Py-GC / MS. Taking the linear positive correlation between the ratio of propylene trimers to propylene monomers produced by the cracking of anti-corrosion coatings for oil and gas pipelines under different aging conditions and the rate of change of melt flow index as a starting point, a rapid prediction model is established through the correlation between thermodynamic data and cracking products. By comparing the changes in oxidation induction time, the critical failure points of materials under two different aging conditions are correlated, thereby quickly estimating the aging time corresponding to the material's critical failure point at the standard aging temperature. Compared with the actual aging time of the material at the standard temperature, the absolute error is less than 5%, and the results are accurate and reliable. This significantly shortens the time required for thermal aging failure of materials, thereby significantly shortening the R&D cycle and making it suitable for the rapid iteration of anti-corrosion material development.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rapid test method for thermal aging failure of anti-corrosion coating materials for oil and gas pipelines, characterized in that, Includes the following steps: (a) The anti-corrosion material sample to be tested is subjected to thermo-oxidative aging at temperature T to obtain the oxidation induction time t; (b) At least five parallel samples of the anti-corrosion coating material to be tested were subjected to different durations (t) in an atmospheric atmosphere at 150±3℃. x The thermal aging was carried out, and the A(tri) / A(mon) ratio of each thermally aged material was calculated. (c) Determine the melt index of each heat-aged material in step (b) and calculate the melt index change rate; establish a linear equation between A(tri) / A(mon) and the melt index change rate of each heat-aged material, and calculate A'(tri) / A'(mon) corresponding to a melt index change rate of 35% based on the linear equation. (d) Perform thermo-oxidative aging on at least 5 parallel samples of the anti-corrosion coating material to be tested at temperature T for different durations, and calculate A(tri) / A(mon) for each thermo-oxidative aged material; establish a third-order polynomial equation between A(tri) / A(mon) for each thermo-oxidative aged material and the thermo-oxidative aging time; substitute A'(tri) / A'(mon) calculated in step (c) into the third-order polynomial equation to obtain the aging time t'; (e) The t that has been heat-aged in step (b) x The material was subjected to thermo-oxidative aging at temperature T to obtain the oxidation induction time t. x '', according to t x / (tt x The rate coefficient k is calculated. (f) The product of the aging time t' obtained in step (d) and the rate coefficient k obtained in step (e) is taken as the aging time corresponding to the failure critical point of the anti-corrosion coating material under standard aging temperature. In steps (b) and (d), the method for calculating A(tri) / A(mon) includes: performing Py-GC / MS tests on each aged material, extracting the m / z 43 ion flow map, and calculating the ratio A(tri) / A(mon) of the peak area of ​​the characteristic ions of propylene trimer to the peak area of ​​the characteristic ions of propylene monomer in the m / z 43 ion flow map. The anti-corrosion layer material sample includes polypropylene and an antioxidant; in the anti-corrosion layer material sample, the proportion of polypropylene is not less than 50 wt%, and the proportion of antioxidant is 0.1 wt% to 0.5 wt%.

2. The test method according to claim 1, characterized in that, The anti-corrosion layer material also includes blended components; The blend component includes at least one of high-density polyethylene, low-density polyethylene, linear low-density polyethylene, metallocene low-density polyethylene, and polyolefin elastomer.

3. The test method according to claim 1, characterized in that, It has at least one of the following characteristics: (1) The temperature T is 200-230℃; (2) In the thermo-oxidative aging process of steps (a) and (d), the oxygen flow rate is 50-100 mL / min.

4. The test method according to claim 1, characterized in that, In step (b), the duration of the thermal aging is 2 days, 4 days, 6 days, 8 days, and 10 days, respectively.

5. The test method according to claim 1, characterized in that, In step (e), the materials that have been thermally aged for 4 days and 8 days in step (b) are subjected to thermo-oxidative aging at a temperature T to obtain the oxidation induction time t. x=4 '' and t x=8 '', and calculate t respectively x=4 / (tt x=4 '') and t x=8 / (tt x=8 The average value of '') is taken as the rate coefficient k.

6. The test method according to claim 1, characterized in that, In step (d), the durations of the thermo-oxidative aging are t / 5, 2t / 5, 3t / 5, 4t / 5, and t, respectively.

7. The test method according to claim 1, characterized in that, The Py-GC / MS test conditions include a thermal decomposition temperature of 550–650°C and a decomposition time of 10–30 s.

8. The test method according to claim 1, characterized in that, In the Py-GC / MS test, the column type was HP-5MS; the split ratio was (100~200):1; the interface temperature was 280~300℃; and the inlet temperature was 280~300℃. The GC heating program is as follows: hold at 40℃ for 2 min, then increase the temperature to 300℃ at a rate of 20℃ / min, and then hold at 300℃ for 10 min.

9. The test method according to claim 1, characterized in that, In step (c), the melt index is measured using a melt indexer; the test temperature for the melt index is 230℃ and the pressure is 2.16kg.

10. The test method according to claim 1, characterized in that, In the m / z 43 ion chromatogram, the retention time of the characteristic ion of propylene trimer was 4.48 min ± 0.1 min, and the retention time of the characteristic ion of propylene monomer was 1.69 min ± 0.1 min.

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