A method for predicting the life of a polyaryletherketone resin-based thermoplastic composite material

Abstract

The present invention discloses a method for predicting the service life of a polyaryletherketone resin-based thermoplastic composite material. The method includes performing a thermal aging acceleration test on a polyaryletherketone resin-based thermoplastic composite material specimen in a set thermal aging acceleration test environment; during the test, after a preset time interval, taking out the polyaryletherketone resin-based thermoplastic composite material specimen for testing and collecting the mechanical property test data of the specimen; after the thermal aging acceleration test is completed, predicting the service life of the polyaryletherketone resin-based thermoplastic composite material according to the mechanical property test data in combination with the Arrhenius equation. The test process of this method is easy to implement, the test parameters are accurately controlled, the test data is comprehensive, and the prediction result has a high credibility.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoplastic composites, and particularly relates to a method for predicting the service life of a polyaryletherketone resin-based thermoplastic composite material. Background Art

[0002] Polyaryletherketone resin-based thermoplastic composites have high specific strength, high modulus, and excellent corrosion resistance, and are becoming increasingly popular in high-tech industries such as aerospace, rail transit, and ship transportation, becoming an ideal choice to replace steel. When polyaryletherketone resin-based thermoplastic composites are in long-term service in the use environment, oxygen, moisture in the environment, and the slow chain segment relaxation of the thermoplastic resin matrix itself will all have a continuous impact on the composites, ultimately leading to the aging and degradation of the composite material properties. At present, there are few reports on the durability of polyaryletherketone resin-based thermoplastic composites in the use environment, lacking scientific and effective means for evaluating the aging degree and methods for predicting the service life, which hinders the engineering promotion and application of polyaryletherketone resin-based thermoplastic composites. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a method for predicting the service life of a polyaryletherketone resin-based thermoplastic composite material to solve the problem that there is currently a lack of scientific and effective means for evaluating the aging degree and methods for predicting the service life of polyaryletherketone resin-based thermoplastic composite materials.

[0004] A method for predicting the service life of a polyaryletherketone resin-based thermoplastic composite material provided by the present invention includes the following steps:

[0005] Suspend a batch of polyaryletherketone resin-based thermoplastic composite material specimens in different aging chambers, and heat them simultaneously to conduct a thermal accelerated aging test at different thermal accelerated aging temperatures T. The lowest temperature of the thermal accelerated aging temperature T is room temperature of 25°C;

[0006] During the test, after reaching different thermal accelerated aging times τ, take out the specimens at each thermal accelerated aging temperature T. The different thermal accelerated aging times τ are at fixed interval durations, and then measure the mechanical property data of each specimen;

[0007] Calculate the ratio of the mechanical properties of the specimens at different thermal accelerated aging temperatures T higher than room temperature to the mechanical properties of the specimens at room temperature respectively to obtain the mechanical property retention rate P of the specimens, and calculate lnP;

[0008] The relationship between the mechanical property retention rate P of the specimens and the thermal accelerated aging time τ follows the first-order kinetic reaction formula P = Be -Kτ, where B is an experimental constant and K is the thermal accelerated aging rate constant; according to this first-order kinetic reaction relationship, the relationship curve lnP-τ between lnP and τ at each thermal accelerated aging temperature T is plotted, and linear regression is performed on this relationship curve to obtain the absolute value of the slope of the function curve, that is, K; the natural exponential of the intercept of the lnP-τ function curve at each temperature is taken to obtain B;

[0009] The thermal accelerated aging rate constant K and the thermal accelerated aging temperature T obey the Arrhenius equation K = Ae -E / RT , where A is the frequency factor, R is the gas constant, and E is the apparent activation energy; according to this Arrhenius equation, the relationship curve lnK-1 / T between K and T is plotted, and linear regression is performed on this relationship curve to obtain the specific Arrhenius function of the thermal accelerated aging reaction of the specimen;

[0010] The predicted value K0 of the thermal accelerated aging rate constant of the specimen under normal temperature conditions is read from the curve of this Arrhenius function;

[0011] The average value B0 of the experimental constant B at each thermal accelerated aging temperature T is obtained;

[0012] K0 and B0 are substituted into the above first-order kinetic reaction relationship to calculate the life prediction formula of the polyaryletherketone resin-based thermoplastic composite under room temperature conditions

[0013] According to the life prediction formula, the service life of the polyaryletherketone resin-based thermoplastic composite under the mechanical property retention rate P is predicted.

[0014] Furthermore, the polyaryletherketone resin-based thermoplastic composite is composed of a resin matrix polyaryletherketone and a fiber reinforcement, where the resin matrix polyaryletherketone is any one of polyetheretherketone, polyetherketone, polyetherketoneketone, and polyetheretherketoneketone; the fiber reinforcement is any one of short carbon fibers or short glass fibers, and the volume content of the fiber reinforcement is 5%-40%, such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc.

[0015] Furthermore, the specimen is suspended freely in different aging chambers, so that it can be ensured that the splines do not interfere with each other and can all be fully heated by hot air.

[0016] Further, after the specimens are suspended in different aging chambers, laminar-flow air heating is adopted, so that the air flowing through the heating chamber can maintain a laminar flow state, with a uniform and stable flow rate, which is convenient to control, and the reliability of the experiment is improved. The air flow rate for laminar-flow air heating is 0.5 - 2 m / s, such as 0.5 m / s, 1 m / s, 1.5 m / s, 2 m / s, etc. If the flow rate is too fast, the hot air will not be in sufficient contact with the sample bars, and the suspended sample bars will be blown and shaken, interfering with the progress of the experiment; if the flow rate is too slow, the hot air will accumulate at the blower, and will not disperse in time, causing local heat concentration at the blower outlet that cannot be dissipated, posing a fire hazard.

[0017] Further, the thermal accelerated aging test is carried out at different thermal accelerated aging temperatures T. In addition to the normal temperature of 25 °C, the thermal accelerated aging temperature T also includes several equally spaced temperature values in the range of 40 - 200 °C, such as 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, etc.; the different thermal accelerated aging temperatures T higher than the normal temperature refer to several equally spaced temperature values in the range of 40 - 200 °C, such as 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, etc. If it is lower than 40 °C, the change of material properties with the extension of time is not obvious, and the effect of thermal accelerated aging cannot be achieved.

[0018] Further, the fixed interval duration is 1 - 3 days, such as 1 day, 2 days, 3 days, etc.

[0019] Further, the mechanical property data is bending strength data or notched impact strength data.

[0020] Further, the multi-point sampling method is adopted to measure the mechanical property data of each specimen. The steps include: for each thermal accelerated aging temperature and thermal accelerated aging time, measure the mechanical properties of several specimens, and calculate the average value as the mechanical property data of the specimen under the current thermal accelerated aging temperature and thermal accelerated aging time.

[0021] Further, for the life prediction formula data transformation is carried out to obtain the transformation formula According to this transformation formula, predict the service life of the polyaryletherketone resin-based thermoplastic composite material under the mechanical property retention rate P.

[0022] The beneficial technical effects achieved by the present invention are:

[0023] (1) In the prior art, no thermal accelerated aging test was found for thermoplastic composites based on polyaryletherketone resin. The present invention uniquely proposes a thermal accelerated aging test for thermoplastic composites based on polyaryletherketone resin. In the thermal accelerated aging test of thermoplastic composites based on polyaryletherketone resin, the inventors found that the mechanical property retention rate P of the specimens of thermoplastic composites based on polyaryletherketone resin and the thermal accelerated aging time τ obey the first-order kinetic reaction relationship P = Be -Kτ . The thermal accelerated aging test of the present invention can perform thermal accelerated aging treatment on thermoplastic composites based on polyaryletherketone resin more scientifically, quantitatively, efficiently, and accurately.

[0024] (2) When analyzing the data based on the thermal accelerated aging test, the present invention can effectively predict the service life of thermoplastic composites based on polyaryletherketone resin by combining the first-order kinetic reaction relationship with the Arrhenius equation. The present invention provides an evaluation method for the durability of thermoplastic composites based on polyaryletherketone resin in the use environment, effectively promoting the engineering popularization and application of this material, with obvious technical advantages and promising economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] By referring to the following drawings, the exemplary embodiments of the present invention can be more fully understood:

[0026] Figure 1 is a flowchart of the method for predicting the life of thermoplastic composites based on polyaryletherketone resin according to an embodiment of the present invention;

[0027] Figure 2 is a digital photo of the flexural strength specimen of T700 / PEEK thermoplastic composite according to an embodiment of the present invention;

[0028] Figure 3 is a schematic diagram of the aging test process of the laminar air heating specimen according to an embodiment of the present invention;

[0029] Figure 4 is the lnP-τ relationship curve of T700 / PEEK thermoplastic composite at different thermal accelerated aging temperatures;

[0030] Figure 5 is the lnK-1 / T relationship curve of T700 / PEEK thermoplastic composite. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of 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 fall within the scope of protection of the present invention.

[0032] Specifically, as Figure 1 shown, this embodiment specifically discloses a method for predicting the lifespan of a polyaryletherketone resin-based thermoplastic composite material, and its steps include:

[0033] 1. Prepare 640 bending strength specimens of the polyaryletherketone resin-based thermoplastic composite material. The resin matrix is selected as polyetheretherketone, and the fiber reinforcement is selected as chopped T700-grade carbon fiber. The fiber volume content is 30%, that is, this polyaryletherketone resin-based thermoplastic composite material is specifically a T700 / PEEK thermoplastic composite material, as Figure 2 shown;

[0034] 2. Suspend all the T700 / PEEK thermoplastic composite material specimens in a free state in an aging chamber, and use laminar air heating with an air flow rate of 0.5 m / s, as Figure 3 shown;

[0035] 3. Adjust the heating temperatures to 25°C, 60°C, 70°C, 80°C, 90°C, and 100°C respectively for thermal accelerated aging tests;

[0036] 4. During the test, at fixed time intervals of every 2 days, that is, when the specified time nodes of 2 days, 4 days, 6 days, 8 days, 10 days, 12 days, 14 days, 16 days, 18 days, 20 days, 22 days, 24 days, 26 days, 28 days, 30 days, and 32 days are reached respectively, take out the T700 / PEEK thermoplastic composite material specimens at each temperature, measure the bending strength of 5 specimens, and calculate the average value as the bending strength data of the T700 / PEEK thermoplastic composite material at this temperature and this time interval; among them, the bending strength of the specimens at room temperature of 25°C is 325.4 Mpa, and the bending strength of the specimens at other temperatures is shown in Table 1 below.

[0037] Table 1 Bending strength of specimens at each accelerated aging temperature and time

[0038]

[0039] 5. Calculate the ratio of the flexural strength of the T700 / PEEK thermoplastic composite at 60°C, 70°C, 80°C, 90°C, and 100°C to the flexural strength of the T700 / PEEK thermoplastic composite at 25°C, and denote it as the flexural strength retention rate P of the T700 / PEEK thermoplastic composite;

[0040] 6. Take the natural logarithm of the mechanical property retention rate P of the T700 / PEEK thermoplastic composite, and denote it as lnP;

[0041] 7. Plot the relationship curve lnP-τ between the natural logarithm lnP of the mechanical property retention rate of the T700 / PEEK thermoplastic composite and the thermal accelerated aging time τ at each temperature, as Figure 4 shown;

[0042] 8. The mechanical property retention rate P of the T700 / PEEK thermoplastic composite follows a first-order kinetic reaction relationship with the thermal accelerated aging time τ, as shown in the following equation:

[0043] P = Be -Kτ

[0044] where B is the experimental constant and K is the rate constant;

[0045] 9. Perform linear regression on the relationship curve lnP-τ at each temperature, and denote the absolute value of the slope of the function curve as the thermal accelerated aging reaction rate constant K of the T700 / PEEK thermoplastic composite at each temperature, which is listed in Table 2;

[0046] 10. Take the natural exponential of the intercept of the lnP-τ function curve at each temperature, and denote it as the experimental constant B, which is listed in Table 2;

[0047] Table 2 Linear regression parameters of the lnP-τ function curve at each temperature

[0048] Fitting parameter 60℃ 70℃ 80℃ 90℃ 100℃ K 0.00108 0.00187 0.00378 0.00689 0.01272 B 1.0064 1.0002 1.0019 1.0011 1.0066

[0049] 11. The aging rate constant K of the T700 / PEEK thermoplastic composite follows the Arrhenius equation with the aging temperature T, as shown in the following equation:

[0050] K = Ae -E / RT

[0051] where A is the frequency factor, R is the gas constant (take 8.314 J·K -1 mol -1 ), T is the aging temperature, and E is the apparent activation energy;

[0052] 12. Take the natural logarithm of the thermal accelerated aging reaction rate constant K of the T700 / PEEK thermoplastic composite, and denote it as lnK;

[0053] 13. Take the reciprocal of the thermal accelerated aging temperature T, denoted as 1 / T;

[0054] 14. Plot the relationship curve lnK - 1 / T between the logarithm of the thermal accelerated aging reaction rate constant lnK of the T700 / PEEK thermoplastic composite and the reciprocal of the thermal accelerated aging temperature 1 / T, as Figure 5 shown;

[0055] 15. Perform linear regression on the relationship curve lnK - 1 / T to obtain the specific Arrhenius function for the thermal accelerated aging reaction of the thermoplastic composite sample, which is lnK = 16.37 - 7746.94 / T;

[0056] 16. Read the predicted value of the thermal accelerated aging rate constant of the T700 / PEEK thermoplastic composite sample at room temperature (when T = 298.15K) from the function curve, which is 6.68×10 -5 , denoted as K0;

[0057] 17. Take the average value of the experimental constant B at each temperature to obtain 1.0032, denoted as B0;

[0058] 18. Substitute the values of K0 and B0 into the first-order kinetic reaction relationship equation between the mechanical property retention rate P of the T700 / PEEK thermoplastic composite and the thermal accelerated aging time τ to obtain the life prediction formula for the polyaryletherketone resin-based thermoplastic composite at room temperature, as shown in the following formula:

[0059]

[0060] 19. Perform mathematical transformation on this formula, as shown in the following formula:

[0061]

[0062] Given a mechanical property retention rate P, the service life τ of the polyaryletherketone resin-based thermoplastic composite at this mechanical property retention rate P can be predicted through the formula after mathematical transformation. For example, given P0 = 0.75, the service life τ0 of the polyaryletherketone resin-based thermoplastic composite calculated from the formula is 11.92 years. The prediction result is consistent with the actual statistical result.

[0063] Although the present invention has been disclosed as above with embodiments, it is not intended to limit the present invention. Any appropriate modification or equivalent replacement of the technical solutions of the present invention by those of ordinary skill in the art shall be covered by the protection scope of the present invention, and the protection scope of the present invention shall be subject to that defined by the claims.

Claims

1. A method for predicting the life of a polyaryletherketone resin-based thermoplastic composite material, characterized in that The steps include: Suspend a batch of polyaryletherketone resin-based thermoplastic composite specimens in different aging chambers, and heat them simultaneously. Conduct a thermal accelerated aging test at different thermal accelerated aging temperatures T. The lowest temperature of the thermal accelerated aging temperature T is room temperature 25°C. In addition to room temperature 25°C, the thermal accelerated aging temperature T also includes several equidistant temperature values in the range of 40 - 200°C; the polyaryletherketone resin-based thermoplastic composite is composed of a resin matrix of polyaryletherketone and a fiber reinforcement. Among them, the resin matrix of polyaryletherketone is any one of polyetheretherketone, polyetherketone, polyetherketoneketone, and polyetheretherketoneketone; the fiber reinforcement is any one of short carbon fibers or short glass fibers, and the volume content of the fiber reinforcement is 5% - 40%; During the test, after reaching different thermal accelerated aging times τ, take out the specimens at each thermal accelerated aging temperature T. The different thermal accelerated aging times τ have a fixed interval duration, and then measure the mechanical property data of each specimen; Calculate the ratio of the mechanical properties of the specimen at different thermal accelerated aging temperatures T above normal temperature to the mechanical properties of the specimen at normal temperature respectively. The different thermal accelerated aging temperatures T above normal temperature refer to several arithmetic temperature values in the range of 40 - 200 °C, obtain the mechanical property retention rate P of the specimen, and calculate ln P ; The retention rate P of the mechanical properties of the specimen and the thermal accelerated aging time τ obey the first-order kinetic reaction relationship , where B is an experimental constant, K is the thermal accelerated aging rate constant; according to this first-order kinetic reaction relationship, the relationship curve of ln P versus τ at each thermal accelerated aging temperature T, ln P -τ, is plotted, and linear regression is performed on this relationship curve to obtain the absolute value of the slope of the function curve, which is K ; the natural exponent of the intercept of the ln P -τ function curve at each temperature is obtained, which is B ; The thermal acceleration aging rate constant K and the thermal acceleration aging temperature T obey the Arrhenius equation , where A is the frequency factor, R is the gas constant, E is the apparent activation energy; according to this Arrhenius equation, the relationship curve between K and T ln K- 1 / T is plotted, and linear regression is performed on this relationship curve to obtain the specific Arrhenius function of the thermal acceleration aging reaction of the specimen; Read the predicted value of the thermal accelerated aging rate constant of the specimen under normal temperature conditions from the curve of this Arrhenius function K 0; For the experimental constants at each thermal accelerated aging temperature T B Calculate the average value B 0; Substitute K 0 and B 0 into the above first-order kinetic reaction relationship formula, and the life prediction formula of the polyaryletherketone resin-based thermoplastic composite material under room temperature conditions is calculated ; According to the service life prediction formula, predict the service life of the polyaryletherketone resin-based thermoplastic composite material when the mechanical property retention rate P is as follows.

2. The method according to claim 1, characterized in that, Suspend the specimens in different aging chambers in a free state.

3. The method according to claim 1, wherein After the specimens are suspended in different aging chambers, use laminar flow air heating. The air flow rate for laminar flow air heating is 0.5 - 2 m / s.

4. The method according to claim 1, characterized in that The fixed interval duration is 1 - 3 days.

5. The method according to claim 1, characterized in that The mechanical property data are flexural strength data or notched impact strength data.

6. The method according to claim 1, characterized in that Use the multi-point sampling method to measure the mechanical property data of each specimen. The steps include: for each thermal accelerated aging temperature and thermal accelerated aging time, measure the mechanical properties of several specimens, and calculate the average value as the mechanical property data of the specimen at the current thermal accelerated aging temperature and thermal accelerated aging time.

7. The method according to claim 1, wherein For the service life prediction formula perform data transformation to obtain a transformation formula , and predict the service life of the polyaryletherketone resin-based thermoplastic composite material under the mechanical property retention rate P according to this transformation formula.

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