Determination method of antioxidant supplement addition amount in UHMWPE fiber spinning process

Abstract

The invention relates to a method for judging the supplementary addition amount of an antioxidant in a UHMWPE (Ultra High Molecular Weight Polyethylene) fiber spinning process. The method comprises the following steps: a) determining the dissolution temperature of the antioxidant; mixing the antioxidant with the ultra-high molecular weight polyethylene and the white oil, heating to the dissolving temperature, preserving heat for a certain time, and testing the oxidation induction time to obtain the oxidation induction time; b) repeating the step a), and establishing a regression equation of the antioxidant addition amount and the oxidation induction time; and c) respectively carrying out oxidation induction time testing on white oil at different sampling points in the UHMWPE fiber spinning process and new white oil added with the antioxidant, calculating to obtain the oxidation induction time of the minimum antioxidant supplementary addition amount, and substituting the oxidation induction time into the regression equation established in the step b) to obtain the minimum antioxidant supplementary addition amount. According to the method, the regression equation of the antioxidant addition amount and the oxidation induction time is established, the supplemental addition amount of different types of antioxidants is judged by measuring the oxidation induction time and calculating the supplemental addition amount of the antioxidants, and the accuracy is high.

Description

Technical Field

[0001] The invention relates to the technical field of ultra-high molecular weight polyethylene, and more specifically to a method for determining the amount of antioxidant supplementation in a UHMWPE fiber spinning process. Background Art

[0002] The preparation of the stock solution, swelling, dissolution, extrusion and spinning of ultra-high molecular weight polyethylene (UHMWPE), especially wet spinning, requires a continuous high temperature environment combined with twin-screw extrusion, and its temperature is above the melting temperature for a long time in the presence of large shear force, because the solvent used is lower in solubility than the dry method for the raw material under low temperature conditions. Compared with general polyethylene, although UHMWPE has a high thermal melting point, its thermal degradation temperature is not much different, about 200°C; and, because the molecular chain of UHMWPE is very long, it is more susceptible to the action of heat and oxygen and breaks, resulting in a decrease in the relative molecular mass of UHMWPE, thereby affecting the performance of its product, ultra-high molecular weight polyethylene fiber. Therefore, it is of great significance to study the thermal stability of UHMWPE.

[0003] Relevant research shows that the thermal oxidation degradation of UHMWPE is mainly due to the chain-type free radical reaction initiated by the free radicals generated by the thermal decomposition of UHMWPE. Therefore, it can be inhibited by free radical capture and hydroperoxide decomposition. In the continuous exploration and development, it is found that the thermal oxidation degradation of polymers can be inhibited by adding antioxidants, which can extend the service life of polymers. Antioxidants are also called free radical chain reaction terminators. The basic functions of antioxidants are: (1) They have active hydrogen atoms that are more active than the active hydrogen atoms on the polymer chain; (2) The free radicals of antioxidants should have sufficient stability; (3) The antioxidant itself should be difficult to oxidize, otherwise it will be oxidized and will not play an antioxidant role.

[0004] There is currently no suitable method for selecting antioxidants in the preparation process of ultra-high molecular weight polyethylene fibers, and antioxidants are usually added to ultra-high molecular weight polyethylene (UHMWPE) together with ultra-high molecular weight polyethylene (UHMWPE) in a certain solvent (usually white oil in the wet method). However, since white oil is recycled, the effective ingredients of the antioxidants will remain in the recycled solvent, and the content of this ingredient cannot be determined by conventional methods. Therefore, it is easy to add excessive amounts and cause waste of antioxidants.

[0005] At present, the main methods for determining antioxidants in plastics and oil products include chromatography, infrared spectroscopy, etc. CN115684441A Liu Jidong et al. used ultrasonic extraction to prepare sample solutions, used high performance liquid chromatography to separate six phenolic antioxidants and antioxidant degradation products, and calculated the contents of six phenolic antioxidants and antioxidant degradation products in medicinal low-density polyethylene bottles by peak area according to the external standard method to achieve accurate quantification. CN108459102A Liu Ying et al. used ethanol reagent to extract and centrifuge transformer oil, and then used gas chromatography to determine the content of T501 antioxidant in the extract, that is, the content of T501 antioxidant in transformer oil. In addition, GB / T 7602 "Determination of T501 Antioxidant Content in Transformer Oil and Turbine Oil" uses an infrared spectroscopy method to determine the content of T501 (2,6-di-tert-butyl-p-cresol) antioxidant in transformer oil and turbine oil. However, through analysis, it can be seen that the detection methods provided by the above patents and standards are all methods for a specific type of antioxidant. If a different type of antioxidant is replaced, the method is not applicable. At the same time, there is currently no method for determining the amount of supplementary addition of antioxidants of different selected types, especially a test and evaluation method for the amount of supplementary addition of antioxidants for recovered solvents (white oil) in wet spinning. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a method for determining the amount of supplementary addition of antioxidant in the UHMWPE fiber spinning process. By establishing the relationship between the oxidation induction time and the amount of antioxidant added, the amount of supplementary addition of antioxidants of different selections can be determined. The method is simple, easy to operate and highly accurate.

[0007] The present invention provides a method for determining the amount of antioxidant supplementation in a UHMWPE fiber spinning process, comprising the following steps:

[0008] a) determining the dissolution temperature of the antioxidant; mixing the above antioxidant with ultra-high molecular weight polyethylene and white oil, heating to the above dissolution temperature, keeping the temperature for a certain period of time, and conducting an oxidation induction time test to obtain the oxidation induction time;

[0009] b) repeating step a) to establish a regression equation between the amount of antioxidant added and the oxidation induction time;

[0010] c) The oxidation induction time of the white oil at different sampling points in the UHMWPE fiber spinning process and the new white oil with added antioxidants were tested respectively, and the oxidation induction time of the minimum antioxidant supplementation amount was calculated and substituted into the regression equation established in step b) to obtain the minimum antioxidant supplementation amount.

[0011] Preferably, the process of determining the dissolution temperature of the antioxidant in step a) is specifically as follows:

[0012] Antioxidants were added to white oil and the temperature was raised from room temperature. Through observation, it was found that the antioxidant rapidly dissolved into the white oil at a certain temperature. This temperature was determined to be the dissolution temperature of the antioxidant.

[0013] Preferably, the antioxidant added in step a) is 0.5wt% to 3wt% of the ultra-high molecular weight polyethylene; the ultra-high molecular weight polyethylene added is 6wt% to 8wt% of the white oil.

[0014] Preferably, the insulation time in step a) is 30 min to 60 min.

[0015] Preferably, after the insulation for a certain period of time in step a), a sampling needle is used to take samples into a DSC dedicated aluminum crucible under stirring conditions to perform an oxidation induction time test.

[0016] Preferably, the process of the oxidation induction time test in step a) is specifically as follows:

[0017] The sample and reference material are heated in an inert gas atmosphere at 160°C to 230°C with a gas flow rate of 2ml / min to 50ml / min. When the specified temperature is reached, the atmosphere is switched to oxygen with a flow rate of 2ml / min to 50ml / min. The sample is kept constant at this temperature until an oxidation reaction is shown on the thermal curve. The time interval from the moment oxygen begins to enter to the moment when the oxidation reaction occurs is the oxidation induction time.

[0018] Preferably, the white oil at different sampling points in step c) includes the white oil after passing through the screw and the white oil recovered by the recovery system; wherein, the oxidation induction time of the white oil after passing through the screw after adding UHMWPE in the proportion required by the process is measured to be T1; the oxidation induction time of the white oil recovered by the recovery system after adding UHMWPE in the proportion required by the process is measured to be T2; the oxidation induction time of the white oil added with antioxidant after adding UHMWPE in the proportion required by the process is measured to be T3.

[0019] Preferably, the formula calculated in step c) includes:

[0020] ΔT1=T3-T1;

[0021] ΔT2 = T1 - T2;

[0022] ΔT ≥ ΔT1 + ΔT2;

[0023] Wherein, ΔT is the oxidation induction time of the supplementary amount of antioxidant.

[0024] Preferably, the oxidation induction time of the minimum antioxidant supplementary addition amount in step c) is the oxidation induction time when ΔT=ΔT1+ΔT2.

[0025] Preferably, the step b) further comprises:

[0026] The regression equation between the addition amount of different selected antioxidants and the oxidation induction time was established to determine the anti-thermal oxidation ability of different selected antioxidants in the UHMWPE fiber spinning process.

[0027] The invention provides a method for determining the amount of antioxidant supplementary addition in a UHMWPE fiber spinning process, comprising the following steps: a) determining the dissolution temperature of an antioxidant; mixing the antioxidant with ultra-high molecular weight polyethylene and white oil, heating the mixture to the dissolution temperature, keeping the mixture warm for a certain period of time, and performing an oxidation induction time test to obtain the oxidation induction time; b) repeating step a) to establish a regression equation between the amount of antioxidant addition and the oxidation induction time; c) performing oxidation induction time tests on white oil at different sampling points in the UHMWPE fiber spinning process and new white oil with added antioxidants, respectively, calculating the oxidation induction time of the minimum amount of antioxidant supplementary addition, substituting the time into the regression equation established in step b) to obtain the minimum amount of antioxidant supplementary addition. Compared with the prior art, the present invention can obtain the corresponding relationship between the required antioxidant addition amount and the oxidation induction time consumed by swelling and dissolution by establishing the relationship between the oxidation induction time and the antioxidant addition amount, and can also establish the relationship between different antioxidants and the oxidation induction time; the antioxidant selection and supplementary addition amount determination test method provided by the present invention establishes a regression equation between the antioxidant and the oxidation induction time, measures the oxidation induction time, calculates the supplementary antioxidant addition amount, and performs antioxidant selection, thereby realizing the determination of the supplementary addition amount of different selected antioxidants, and the method is simple, easy to operate, and has high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a sampling position diagram of the UHMWPE fiber spinning process in the embodiment;

[0029] Figure 2 This is a graph showing the relationship between the addition ratio of the antioxidant 1076 and the oxidation induction time in the embodiment;

[0030] Figure 3 This is a graph showing the relationship between the addition ratio of antioxidant 1790 and the oxidation induction time in the example. DETAILED DESCRIPTION

[0031] The technical solution 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 only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] The present invention provides a method for determining the amount of antioxidant supplementation in a UHMWPE fiber spinning process, comprising the following steps:

[0033] a) determining the dissolution temperature of the antioxidant; mixing the above antioxidant with ultra-high molecular weight polyethylene and white oil, heating to the above dissolution temperature, keeping the temperature for a certain period of time, and conducting an oxidation induction time test to obtain the oxidation induction time;

[0034] b) repeating step a) to establish a regression equation between the amount of antioxidant added and the oxidation induction time;

[0035] c) The oxidation induction time of the white oil at different sampling points in the UHMWPE fiber spinning process and the new white oil with added antioxidants were tested respectively, and the oxidation induction time of the minimum antioxidant supplementation amount was calculated and substituted into the regression equation established in step b) to obtain the minimum antioxidant supplementation amount.

[0036] At present, antioxidants are usually added to the solvent (usually white oil in the wet method) in a certain proportion together with ultra-high molecular weight polyethylene in the spinning process of ultra-high molecular weight polyethylene. However, since white oil is recycled, the effective components of the antioxidants will remain in the recycled solvent, and the content of this component cannot be determined by conventional methods. Therefore, it is easy to add excessive amounts and cause the waste of antioxidants. The main purpose of the present invention is to provide a method for determining and testing the amount of antioxidants added in the spinning process of UHMWPE fibers.

[0037] The present invention first determines the dissolution temperature of the antioxidant; mixes the antioxidant with ultra-high molecular weight polyethylene and white oil, heats to the dissolution temperature, keeps the temperature for a certain period of time, and performs an oxidation induction time test to obtain the oxidation induction time.

[0038] In the present invention, the process of determining the dissolution temperature of the antioxidant is preferably specifically as follows:

[0039] Antioxidants were added to white oil and the temperature was raised from room temperature. Through observation, it was found that the antioxidant rapidly dissolved into the white oil at a certain temperature. This temperature was determined to be the dissolution temperature of the antioxidant.

[0040] The present invention has no particular limitation on the type and source of the antioxidant, and commercially available antioxidants of different types well known to those skilled in the art may be used.

[0041] The present invention has no special restrictions on the sources of the ultra-high molecular weight polyethylene and white oil, and commercial products well known to those skilled in the art can be used.

[0042] In the present invention, the added amount of the antioxidant is preferably 0.5wt% to 3wt% of the ultra-high molecular weight polyethylene; the added amount of the ultra-high molecular weight polyethylene is preferably 6wt% to 8wt% of the white oil.

[0043] In the present invention, the insulation time is preferably 30 min to 60 min.

[0044] In the present invention, after the insulation for a certain period of time, preferably under stirring, a sampling needle is used to take a sample into a DSC dedicated aluminum crucible to perform an oxidation induction time test.

[0045] In the present invention, the process of the oxidation induction time test is preferably specifically as follows:

[0046] The sample and reference material are heated in an inert gas atmosphere at 160°C to 230°C and a gas flow rate of 2ml / min to 50ml / min. When the specified temperature is reached, the atmosphere is switched to oxygen at a flow rate of 2ml / min to 50ml / min. The sample is kept constant at this temperature until an oxidation reaction is shown on the thermal curve. The time interval from the moment when oxygen begins to enter to the moment when the oxidation reaction occurs is the oxidation induction time.

[0047] More preferably:

[0048] The sample and reference material are heated in an inert gas atmosphere at 190°C to 200°C with a gas flow rate of 22ml / min to 30ml / min. When the specified temperature is reached, the atmosphere is switched to oxygen with a flow rate of 22ml / min to 30ml / min. The sample is kept constant at this temperature until an oxidation reaction is shown on the thermal curve. The time interval from the moment oxygen begins to enter to the moment when the oxidation reaction occurs is the oxidation induction time (the larger the value, the stronger the antioxidant capacity of the antioxidant).

[0049] In the present invention, the inert gas is preferably nitrogen.

[0050] Afterwards, the above step a) is repeated to establish a regression equation between the amount of antioxidant added and the oxidation induction time, thereby obtaining the relationship between the oxidation induction time and the amount of antioxidant added to UHMWPE.

[0051] Finally, the present invention tests the oxidation induction time of white oil at different sampling points in the UHMWPE fiber spinning process and the new white oil with added antioxidants, calculates the oxidation induction time of the minimum antioxidant supplementation amount, substitutes it into the regression equation established in step b), and obtains the minimum antioxidant supplementation amount.

[0052] In the present invention, the white oil at different sampling points preferably includes white oil after passing through the screw and white oil recovered by the recovery system; wherein, the oxidation induction time of the white oil after passing through the screw is measured to be T1 after adding UHMWPE in the proportion required by the process; the oxidation induction time of the white oil recovered by the recovery system is measured to be T2 after adding UHMWPE in the proportion required by the process; the oxidation induction time of the white oil added with antioxidant is measured to be T3 after adding UHMWPE in the proportion required by the process.

[0053] In the present invention, the calculation formula preferably includes:

[0054] ΔT1=T3-T1;

[0055] ΔT2 = T1 - T2;

[0056] ΔT ≥ ΔT1 + ΔT2;

[0057] Wherein, ΔT is the oxidation induction time of the supplementary amount of antioxidant.

[0058] In the present invention, when ΔT≥ΔT1+ΔT2, the amount of antioxidant added can meet the requirements of the process.

[0059] In the present invention, the oxidation induction time of the minimum antioxidant supplementary addition amount is preferably the oxidation induction time when ΔT=ΔT1+ΔT2; therefore, when ΔT is substituted into the linear regression equation established in step b), the addition ratio M (%) of the antioxidant to UHMWPE is obtained, and finally the minimum antioxidant supplementary addition amount is calculated.

[0060] In the present invention, the step b) preferably further comprises:

[0061] The regression equation between the addition amount of different selected antioxidants and the oxidation induction time was established to determine the anti-thermal oxidation ability of different selected antioxidants in the UHMWPE fiber spinning process.

[0062] The invention provides a method for determining the amount of antioxidant supplementary addition in a UHMWPE fiber spinning process, comprising the following steps: a) determining the dissolution temperature of an antioxidant; mixing the antioxidant with ultra-high molecular weight polyethylene and white oil, heating the mixture to the dissolution temperature, keeping the mixture warm for a certain period of time, and performing an oxidation induction time test to obtain the oxidation induction time; b) repeating step a) to establish a regression equation between the amount of antioxidant addition and the oxidation induction time; c) performing oxidation induction time tests on white oil at different sampling points in the UHMWPE fiber spinning process and new white oil with added antioxidants, respectively, calculating the oxidation induction time of the minimum amount of antioxidant supplementary addition, substituting the time into the regression equation established in step b) to obtain the minimum amount of antioxidant supplementary addition. Compared with the prior art, the present invention can obtain the corresponding relationship between the required antioxidant addition amount and the oxidation induction time consumed by swelling and dissolution by establishing the relationship between the oxidation induction time and the antioxidant addition amount, and can also establish the relationship between different antioxidants and the oxidation induction time; the antioxidant selection and supplementary addition amount determination test method provided by the present invention establishes a regression equation between the antioxidant and the oxidation induction time, measures the oxidation induction time, calculates the supplementary antioxidant addition amount, and performs antioxidant selection, thereby realizing the determination of the supplementary addition amount of different selected antioxidants, and the method is simple, easy to operate, and has high accuracy.

[0063] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0064] Example

[0065] (1) Add an antioxidant to white oil and raise the temperature from room temperature. Through observation, it is found that the antioxidant rapidly dissolves into the white oil at a certain temperature. This temperature is determined to be the dissolution temperature of the antioxidant.

[0066] (2) UHMWPE was added to white oil at an addition amount of 7 wt% of UHMWPE, and the addition amount of antioxidant relative to UHMWPE was 0.5 wt% to 3 wt%. The oil was heated to the dissolution temperature of the antioxidant in step (1), and kept warm for 45 min. Under stirring conditions, a sampling needle was used to take samples into a DSC special aluminum crucible for oxidation induction time test.

[0067] (3) The sample and reference material are heated at 195°C and a gas flow rate of 26 ml / min in an inert gas (nitrogen) atmosphere. When the specified temperature is reached, the atmosphere is switched to oxygen at a flow rate of 26 ml / min. The sample is kept constant at this temperature until an oxidation reaction is shown on the thermal curve. The time interval from the moment when the oxygen flow begins to enter to the moment when the oxidation reaction occurs is the oxidation induction period. The longer the oxidation induction period, the stronger the antioxidant capacity of the antioxidant.

[0068] (4) Repeat the above steps (1), (2), and (3) to conduct experiments with different antioxidant and UHMWPE addition amounts; establish a regression equation for the antioxidant addition amount and the oxidation induction time, and obtain the relationship between the oxidation induction period and the antioxidant and UHMWPE addition amount.

[0069] (5) See Figure 1 As shown, at sampling point 1, the white oil after passing through the screw is taken out, UHMWPE is added according to the proportion required by the process, and the oxidation induction time T1 is calculated according to the method of step (3); at sampling point 2, the white oil recovered by the recovery system is taken out, UHMWPE is added according to the proportion required by the process, and the oxidation induction time T2 is calculated according to the method of step (3); the addition ratio of the existing added antioxidant to UHMWPE is known to be ɑwt%, and the antioxidant and UHMWPE are added to the new white oil according to the addition ratio of ɑwt% to the new white oil, and the oxidation induction time T3 is calculated according to the method of step (3).

[0070] (6) Define ΔT1=T3-T1, and obtain ΔT1, ΔT2=T1-T2. When ΔT≥ΔT1+ΔT2, the antioxidant supplement amount can meet the process requirements. When ΔT=ΔT1+ΔT2=T3-T2, the added amount at this time is the minimum antioxidant supplement amount. Therefore, when it is substituted into the linear regression equation of step (4), the addition ratio M (wt%) of antioxidant to UHMWPE is obtained, and finally the minimum antioxidant supplement amount is calculated.

[0071] The specific experimental data are as follows:

[0072] Experiment 1:

[0073] According to Table 1 below, the regression equation between the amount of antioxidant 1076 added and the oxidation induction time is established as follows: Figure 2 get:

[0074] y=2.98x+1 (1);

[0075] x=(y-1) / 2.98 (2);

[0076] Substituting ΔT=y in Table 2 into equation (2), we obtain the antioxidant supplementation ratio M=0.85wt%.

[0077] Table 1 Relationship between antioxidant addition amount and oxidation induction time

[0078] Antioxidant 1076 / UHMWPE (%) Oxidation induction time (min) 0.5 2.39 0.67 2.89 1 3.87 1.67 6.32 2 7.25 2.5 8.36 3.33 10.74

[0079] Table 2 Oxidation induction time and antioxidant supplementation amount

[0080]

[0081] Experiment 2:

[0082] According to Table 3 below, the regression equation between the amount of antioxidant 1790 added and the oxidation induction time was established. Figure 3 get:

[0083] y = 7.87x + 4.18 (1);

[0084] x = (y - 4.18) / 7.87 (2);

[0085] Substituting ΔT=y in Table 4 into equation (2), we obtain the antioxidant supplementation ratio M=0.40wt%.

[0086] Table 3 Relationship between antioxidant addition amount and oxidation induction time

[0087] Antioxidant 1790 / UHMWPE (%) Oxidation induction time (min) 0.5 7.52 0.67 9.53 1 12.83 1.67 17.24 2 19.87 2.5 23.64 3.33 30.63

[0088] Table 4 Oxidation induction time and antioxidant supplementation amount

[0089]

[0090] In summary, the present invention can obtain the corresponding relationship between the required antioxidant addition amount and the oxidation induction time consumed by swelling and dissolution by establishing the relationship between the oxidation induction time and the antioxidant addition amount, and can also establish the relationship between different antioxidants and the oxidation induction time; the antioxidant selection and supplementary addition amount determination test method provided by the present invention, by establishing a regression equation between the antioxidant and the oxidation induction time, by measuring the oxidation induction time, calculating the supplementary antioxidant addition amount, and performing antioxidant selection, realizes the determination of the supplementary addition amount of different selected antioxidants, and the method is simple, easy to operate, and has high accuracy.

[0091] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for determining the amount of antioxidant supplementation in a UHMWPE fiber spinning process, comprising the following steps: a) determining the dissolution temperature of the antioxidant; mixing the above antioxidant with ultra-high molecular weight polyethylene and white oil, heating to the above dissolution temperature, keeping the temperature for a certain period of time, and conducting an oxidation induction time test to obtain the oxidation induction time; b) repeating step a) to establish a regression equation between the amount of antioxidant added and the oxidation induction time; c) The oxidation induction time of the white oil at different sampling points in the UHMWPE fiber spinning process and the new white oil with added antioxidants were tested respectively, and the oxidation induction time of the minimum antioxidant supplementation amount was calculated and substituted into the regression equation established in step b) to obtain the minimum antioxidant supplementation amount.

2. The determination method according to claim 1, characterized in that: The process of determining the dissolution temperature of the antioxidant in step a) is specifically as follows: Antioxidants were added to white oil and the temperature was raised from room temperature. Through observation, it was found that the antioxidant rapidly dissolved into the white oil at a certain temperature. This temperature was determined to be the dissolution temperature of the antioxidant.

3. The determination method according to claim 1, characterized in that: In step a), the amount of the antioxidant added is 0.5wt% to 3wt% of the ultra-high molecular weight polyethylene; the amount of the ultra-high molecular weight polyethylene added is 6wt% to 8wt% of the white oil.

4. The determination method according to claim 1, characterized in that: The insulation time in step a) is 30 min to 60 min.

5. The determination method according to claim 1, characterized in that: After the insulation for a certain period of time in step a), a sample is taken into a DSC special aluminum crucible using a sampling needle under stirring to carry out an oxidation induction time test.

6. The determination method according to claim 1, characterized in that: The process of the oxidation induction time test in step a) is specifically as follows: The sample and reference material are heated in an inert gas atmosphere at 160°C to 230°C with a gas flow rate of 2ml / min to 50ml / min. When the specified temperature is reached, the atmosphere is switched to oxygen with a flow rate of 2ml / min to 50ml / min. The sample is kept constant at this temperature until an oxidation reaction is shown on the thermal curve. The time interval from the moment oxygen begins to enter to the moment when the oxidation reaction occurs is the oxidation induction time.

7. The determination method according to claim 1, characterized in that: The white oil at different sampling points in step c) includes the white oil after passing through the screw and the white oil recovered by the recovery system; wherein, the oxidation induction time of the white oil after passing through the screw after adding UHMWPE in the proportion required by the process is measured to be T1; the oxidation induction time of the white oil recovered by the recovery system after adding UHMWPE in the proportion required by the process is measured to be T2; the oxidation induction time of the new white oil added with antioxidant after adding UHMWPE in the proportion required by the process is measured to be T3.

8. The determination method according to claim 7, characterized in that: The formula calculated in step c) includes: ΔT1=T3-T1; ΔT2 = T1 - T2; ΔT ≥ ΔT1 + ΔT2; Wherein, ΔT is the oxidation induction time of the supplementary amount of antioxidant.

9. The determination method according to claim 8, characterized in that: The oxidation induction time of the minimum antioxidant supplementation amount in step c) is the oxidation induction time when ΔT=ΔT1+ΔT2.

10. The determination method according to any one of claims 1 to 9, characterized in that: The step b) further comprises: The regression equation between the addition amount of different selected antioxidants and the oxidation induction time was established to determine the anti-thermal oxidation ability of different selected antioxidants in the UHMWPE fiber spinning process.

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