阅读说明：本技术 一种基于热解原理的漆包线热解方法 (Enameled wire pyrolysis method based on pyrolysis principle ) 是由 夏志东 程浩 周炜 王晓露 郭福 王乙舒 吴玉峰 马立民 林健 于 2021-07-16 设计创作，主要内容包括：本发明公开了一种基于热解原理的漆包线热解方法,属于漆包线热解技术领域。具体包括以下步骤：步骤(1)：通过热重分析获得漆包线的热重曲线和差热重曲线,从中得出漆包线热解温度区间；步骤(2)：根据化学反应速率表达式、反应速率常数与温度的关系式和线性升温公式,结合转化率与温度之间的关系和FWO热动力学计算方法,求得漆包线热解反应活化能；步骤(3)：对漆包线进行热解,通过FTIR分析对热解固体产物进行表征；步骤(4)：通过TG-FTIR分析表征了漆包线在不同温度下热解气体产物的官能团,并以此优化热解工艺方案。(The invention discloses an enameled wire pyrolysis method based on a pyrolysis principle, and belongs to the technical field of enameled wire pyrolysis. The method specifically comprises the following steps: step (1): obtaining a thermogravimetric curve and a differential thermogravimetric curve of the enameled wire through thermogravimetric analysis, and obtaining a pyrolysis temperature interval of the enameled wire; step (2): obtaining the activation energy of the pyrolysis reaction of the enameled wire according to a chemical reaction rate expression, a relation of a reaction rate constant and temperature and a linear temperature rise formula by combining a relation between conversion rate and temperature and a FWO thermodynamic calculation method; and (3): pyrolyzing the enameled wire, and characterizing a pyrolysis solid product through FTIR analysis; and (4): the functional groups of the pyrolysis gas products of the enameled wires at different temperatures are characterized by TG-FTIR analysis, and the pyrolysis process scheme is optimized according to the functional groups.)

1. An enameled wire pyrolysis method based on a pyrolysis principle. The method is characterized by comprising the following steps:

step (1): obtaining a thermogravimetric curve and a differential thermogravimetric curve of the enameled wire through thermogravimetric analysis, and obtaining a pyrolysis temperature interval of the enameled wire;

step (2): obtaining the activation energy of the pyrolysis reaction of the enameled wire according to a chemical reaction rate expression, a relation of a reaction rate constant and temperature and a linear temperature rise formula by combining a relation between conversion rate and temperature and a FWO thermodynamic calculation method;

and (3): pyrolyzing the enameled wire, and characterizing a pyrolysis solid product through FTIR analysis;

and (4): the functional groups of the pyrolysis gas products of the enameled wires at different temperatures are characterized by TG-FTIR analysis, and the pyrolysis process scheme is optimized according to the functional groups.

2. The enamel wire pyrolysis method based on the pyrolysis principle according to claim 1, wherein the relationship between the conversion rate and the temperature in the step (2) is calculated according to the conversion rate calculation means (1),

in the formula (1), alpha is a conversion rate, and delta W is a weight loss amount when the temperature is T (t); Δ W_∞Final weight loss; the formula (1) is used to calculate the weight loss amount Δ W corresponding to the conversion rates α of 0.1 to 0.9, respectively, and then the temperature t (t) corresponding to the conversion rates α of 0.1 to 0.9 is obtained from the thermogravimetric curve.

Calculating the reciprocal of the temperature, and calculating the logarithm of the heating rate to obtain the relation between the conversion rate and the temperature;

activation energy E of the reaction in step (2)_αThe calculation formula of (2),

in the formula (2), beta is the heating rate, and the unit is ℃/min; a is a pre-exponential factor, which is a constant determined only by the nature of the reaction and independent of the reaction temperature and the concentration of the species in the system; r is a gas constant, and R is 8.314J/(mol K);t is the thermodynamic temperature.

3. The enamel wire pyrolysis method based on the pyrolysis principle according to claim 1, wherein the thermogravimetric analysis in the step (1) is as follows: under the protection of inert gas, the maximum pyrolysis temperature is set to 900 ℃, the heating rate is 5-20 ℃/min, and the heat preservation time is 30-40 min.

4. The pyrolysis-based enameled wire pyrolysis method according to claim 1, wherein the pyrolysis gas in step (3) is characterized by using TG-FTIR.

5. The enamel wire pyrolysis method based on the pyrolysis principle as claimed in claim 1, wherein the solid product generated after the enamel wire pyrolysis is characterized by FTIR.

Technical Field

The invention relates to the technical field of enameled wire pyrolysis, in particular to an enameled wire pyrolysis method based on a pyrolysis principle.

Background

The global copper reserves are about 7 hundred million tons, mainly concentrated in Chile, USA, King of Asia and Peru. The recovery of the waste enameled wire is used as an important supplement of the reclaimed copper resource, and the development of an efficient and environment-friendly waste enameled wire recovery method is imminent.

In the recycling of the waste enameled wires, the waste enameled wires are easily scraped off by mechanical paint scraping, so that the copper loss is serious; the laser paint removing equipment has high cost and great energy consumption; paint remover can damage underground water and atmosphere; the direct combustion method and the reverberatory furnace smelting method have the problems of high energy consumption, high labor cost, low efficiency, high pollution and the like, and are easy to generate dust, acid gas and other pollution, and the copper burning loss is 3-8 percent; the reverberatory furnace smelting method also has the problems of dioxin pollution and metal loss.

The pyrolysis depainting has the remarkable advantages of good depainting effect, high large-scale degree, low manual strength, small copper loss, small environmental pollution, high recovery efficiency, small copper loss and the like, and becomes the main depainting method for the waste enameled wire at present. However, the temperature for recovering copper from the waste enameled wire by pyrolysis on the current production line is higher, usually reaches over 900 ℃, and a strict process control route is not available, so that the pyrolysis energy consumption is higher, and the method is inconsistent with the era background of the current green development. Therefore, the development of a pyrolysis method with low energy consumption for pyrolysis paint removal is a technical problem to be solved in the field.

Disclosure of Invention

The invention aims to provide an enameled wire pyrolysis method based on a pyrolysis principle, based on the pyrolysis principle of an enameled wire, and by combining a thermogravimetric analysis, FTIR, TG-FTIR analysis and test method and a Flynn-Wall-Ozawa (FWO) pyrolysis dynamics calculation method, the efficient pyrolysis method of the enameled wire is obtained, and the effect of controlling pyrolysis products can be achieved.

In order to achieve the purpose, the invention provides the following technical scheme:

the enameled wire pyrolysis method based on the pyrolysis principle comprises the following steps:

step (1): obtaining a thermogravimetric curve and a differential thermogravimetric curve of the enameled wire through thermogravimetric analysis, and obtaining a pyrolysis temperature interval of the enameled wire;

step (2): obtaining the activation energy of the pyrolysis reaction of the enameled wire according to a chemical reaction rate expression, a relation of a reaction rate constant and temperature and a linear temperature rise formula by combining a relation between conversion rate and temperature and a FWO thermodynamic calculation method;

and (3): pyrolyzing the enameled wire, and characterizing a pyrolysis solid product through FTIR analysis;

and (4): the functional groups of the pyrolysis gas products of the enameled wires at different temperatures are characterized by TG-FTIR analysis, and the pyrolysis process scheme is optimized according to the functional groups.

According to the size of the reaction activation energy of the enameled wire, the difficulty degree of the pyrolysis reaction can be judged; the pyrolysis gas and the pyrolysis solid product of the enameled wire are characterized, and the pyrolysis degree of the organic coating of the waste enameled wire can be judged.

Preferably, the relationship between the conversion rate and the temperature in the step (2) is calculated according to the conversion rate calculation means (1),

in the formula (1), alpha is the conversion rate, W₀Is the initial weight g of the enameled wire; w_∞The final weight g of the enameled wire is obtained; w is the weight g of T (t); Δ W is the weight loss at T (t); Δ W_∞The final weight loss g; the formula (1) is used for calculating the corresponding weight loss amount delta W when the conversion rate alpha is 0.1-0.9 respectively, so that the corresponding weight loss amount delta W when the conversion rate alpha is 0.1-0.9 is obtained according to a thermogravimetric curveTemperature T (t);

calculating the reciprocal of the temperature, and calculating the logarithm of the heating rate to obtain the relation between the conversion rate and the temperature;

activation energy E of the reaction in step (2)_αThe calculation formula of (2),

in the formula (2), beta is the heating rate ℃/min; a is a pre-exponential factor; r is a gas constant, and R is 8.314J/(mol K); g (α) is a reaction kinetics function, which is an integral form of a reaction model function f (α); for the process in which only one irreversible reaction is carried out in the system, since thermogravimetric analysis is carried out in a nitrogen atmosphere, a reaction model function f (. alpha.) is used as (1-. alpha.)³Reaction kinetic functionT is the thermodynamic temperature.

The derivation process of formula (2) in step 2 is as follows:

according to the chemical reaction rate expression (3),

simultaneous reaction rate constant with temperature (4),

obtaining a dynamic calculation mode (5),

in the formulas (3) to (5), α is the conversion rate; t is time in min; t is the thermodynamic temperature; k (T) is the chemical reaction rate constant; f (a) is a reaction model function, f (alpha) ═ 1-alpha³(ii) a A is a pre-exponential factor; e_αIs the activation energy of the reaction; r is a gas constant, and R is 8.314J/(mol K);

root of successorAccording to the linear temperature-increasing formula T ═ T₀The + β t is differentiated to dT ═ β dT, and the formula (6) is obtained by bringing the formula (5),

beta in the formula (6) is the heating rate ℃/min;

deriving based on the formula to obtain formula (7),

p (u) in the formula (7) is a temperature integral function;

combined with FWO thermodynamic calculation method, according to a temperature integration function lgP (u) approximatively-2.315-0.4567 u, andbringing into availability:

according to the formulaIn the formulaIs a fixed value, and therefore the reciprocal (1/T) of the temperature is taken as the abscissa and the logarithm of the temperature rise rate (lg beta) is taken as the ordinate, to obtain a graph of the temperature rise rate versus the temperature at different conversions, the slope of the corresponding line at different conversions being equal toWhere R is 8.314J/(mol · K), the pyrolysis activation energy can be solved accordingly.

Preferably, the thermogravimetric analysis in step (1) is performed by the following specific method: under the protection of inert gas, the maximum pyrolysis temperature is set to 900 ℃, the heating rate is 5-20 ℃/min, and the heat preservation time is 30-40 min.

Preferably, the pyrolysis gas in step (3) is characterized by TG-FTIR.

Preferably, the solid product generated during pyrolysis can be characterized by FTIR.

The main pyrolysis temperature interval of the enameled wire can be obtained through analysis according to the TG-DTG curve, pyrolysis is carried out in the temperature interval, the pyrolysis efficiency can be improved to the maximum extent, and the energy consumption is reduced. And simultaneously, whether the enameled wire is pyrolyzed completely at the temperature is known according to the infrared analysis result of the pyrolysis solid product at 900 ℃ of the enameled wire.

The surface coating of the enameled wire mainly comprises wire enamels such as polyester enamel, polyurethane enamel and the like, and the wire enamels generally comprise corresponding binder resin, a halogen-containing combustion improver and a brightener; the polyester paint mainly comprises polyethylene glycol terephthalate COC₆H₄COOCH₂CH₂O, polybutylene terephthalate [ C ]₁₂H₁₂O₄]_nPolyarylate [ C ]₂₇H₂₄O₆]_nThe main component of the polyurethane paint is polyurethane (C)₁₀H₈N₂O₂·C₆H₁₄O₃)_nThe pyrolysis gas mainly comprises phenols, various aromatic hydrocarbons, ketones, alcohols and aldehydes; the pyrolysis solid product is composed of carbon black and organic compounds such as alkane, alkene, alcohol, ketone, aldehyde, aromatic compounds and the like.

The invention has the following beneficial technical effects:

according to the invention, the pyrolysis temperature suitable for pyrolysis of various enameled wires is selected, and the activation energy required by the enameled wire pyrolysis reaction is calculated, so that the effects of accelerating the reaction rate and reducing the energy input in the pyrolysis recovery are achieved. Meanwhile, the invention achieves the purpose of optimizing the pyrolysis process scheme by representing the functional groups of the pyrolysis gas products and analyzing the change of the functional groups of the pyrolysis products in the temperature rising process.

Drawings

FIG. 1 is a thermogravimetric-infrared coupled spectrum of a polyester enameled wire pyrolysis gas product;

FIG. 2 is a thermogravimetric-infrared coupled spectrum of a polyurethane enameled wire pyrolysis gas product;

FIG. 3 is a thermogravimetric-infrared combined spectrum of a pyrolysis gas product of a polyesterimide enameled wire;

FIG. 4 is a thermogravimetric curve and a differential thermogravimetric curve of the polyester enameled wire in example 1 when the temperature rise rate is 10 ℃/min;

FIG. 5 is a thermogravimetric plot and a differential thermogravimetric plot of the polyurethane enameled wire of example 2 at a temperature rise rate of 10 deg.C/min;

FIG. 6 is a thermogravimetric curve and a differential thermogravimetric curve of a polyesterimide enameled wire in example 3 at a temperature rise rate of 10 ℃/min;

FIG. 7 is a thermogravimetric graph of the polyester enameled wire in example 1 at different temperature rising rates;

FIG. 8 is a thermogravimetric plot of the polyurethane enameled wire of example 2 at different temperature rise rates;

FIG. 9 is a thermogravimetric graph of a polyesterimide enameled wire according to example 3 at different temperature rise rates;

FIG. 10 is a graph of the pyrolysis conversion rate of the polyester enameled wire according to example 1 as a function of temperature;

FIG. 11 is a graph of pyrolysis conversion versus temperature for the polyurethane enameled wire of example 2;

FIG. 12 is a graph of the pyrolysis conversion rate of the polyesterimide enameled wire according to example 3 with respect to temperature;

FIG. 13 is a reaction activation energy of pyrolysis of a polyester enameled wire according to example 1;

FIG. 14 is the reaction activation energy for pyrolysis of the polyurethane enameled wire of example 2;

FIG. 15 is the reaction activation energy of pyrolysis of the polyesterimide enameled wire in example 3;

FIG. 16 is an infrared spectrum of a pyrolyzed solid product of a polyester enameled wire in example 1;

FIG. 17 is a chart of the infrared spectrum of the solid product of the polyurethane enameled wire pyrolysis in example 2;

FIG. 18 is an infrared spectrum of a pyrolyzed solid product of a polyesterimide enameled wire in example 3.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

Step 1: setting the maximum pyrolysis temperature to 900 ℃, respectively raising the temperature to 900 ℃ at the heating rates of 5 ℃/min, 10 ℃/min and 20 ℃/min, keeping the temperature for 30min, and obtaining a thermogravimetric curve (TG) and a differential thermal gravimetric curve (DTG) of the polyester enameled wire by using a thermogravimetric analysis method so as to obtain a pyrolysis temperature interval of the polyester enameled wire; meanwhile, the reciprocal of the temperature is solved, and the logarithm of the heating rate is solved, so that the relation between the conversion rate and the temperature can be obtained;

step 2: further analyzing the thermogravimetric curve of the polyester enameled wire, and calculating activation energy required by pyrolysis reaction by combining Flynn-Wall-Ozawa (FWO) thermodynamic calculation methods according to formulas such as a chemical reaction rate expression and the like to obtain the average pyrolysis activation energy of the polyester enameled wire of 296.9 KJ/mol;

and step 3: pyrolyzing a polyester enameled wire at the pyrolysis temperature of 900 ℃ in a nitrogen atmosphere at the heating rate of 10 ℃/min, after pyrolysis is finished, carrying out vibration treatment on the enameled wire, collecting a pyrolysis solid product of an organic coating of the enameled wire, and carrying out Fourier infrared spectroscopy (FTIR) analysis on the pyrolysis solid product to obtain that the pyrolysis solid product mainly comprises carbon black and organic compounds such as alkane, alkene, alcohol, ketone, aldehyde and aromatic compounds;

and 4, step 4: TG-FTIR analysis of polyester enameled wires resulted in FIG. 1, from which it can be seen that the pyrolysis gas product of polyester enameled wires mainly contains C-O, C-H, -OH, C-O-C, -CH₂and-CH₃An isofunctional group;

and 5: and (3) according to the average activation energy obtained in the step (2) and the analysis result of the pyrolysis gas product in the step (4), for the polyester enameled wire, the enameled wire can stay for 11min at 420 ℃ in the temperature raising process, then the enameled wire is continuously raised to 900 ℃ and is kept for 30min, complete pyrolysis is ensured, and the surface pyrolysis solid product is more easily removed to obtain high-purity copper.

Example 2

Step 1: setting the highest pyrolysis temperature to 900 ℃, respectively raising the temperature to 900 ℃ at the heating rates of 5 ℃/min, 10 ℃/min and 20 ℃/min, keeping the temperature for 30min, and obtaining a thermogravimetric curve (TG) and a differential thermal gravimetric curve (DTG) of the polyurethane enameled wire by using a thermogravimetric analysis method so as to obtain a pyrolysis temperature interval of the polyurethane enameled wire; meanwhile, the reciprocal of the temperature is solved, and the logarithm of the heating rate is solved, so that the relation between the conversion rate and the temperature can be obtained;

step 2: further analyzing the thermogravimetric curve of the polyurethane enameled wire, calculating the activation energy required by the pyrolysis reaction according to formulas such as a chemical reaction rate expression and the like and by combining a Flynn-Wall-Ozawa (FWO) thermodynamic calculation method, and obtaining the average pyrolysis activation energy of the polyurethane enameled wire to be 194.2 kJ/mol;

and step 3: pyrolyzing the polyurethane enameled wire at 900 ℃ in a nitrogen atmosphere at a heating rate of 10 ℃/min, after pyrolysis is finished, carrying out vibration treatment on the enameled wire, collecting a pyrolysis solid product of an organic coating of the enameled wire, and carrying out Fourier infrared spectroscopy (FTIR) analysis to obtain that the pyrolysis solid product mainly comprises carbon black and organic compounds such as alkane, alkene, alcohol, ketone, aldehyde and aromatic compounds;

and 4, step 4: TG-FTIR analysis of the polyurethane enameled wire resulted in FIG. 2, and it can be seen from FIG. 2 that the pyrolysis gas product of polyurethane enameled wire mainly contains C-O, C-H, -OH, -CH₂、-CH₃And N-H functional groups;

and 5: and (3) combining the average activation energy obtained in the step (2) and the analysis result of the pyrolysis gas product in the step (4), aiming at the polyurethane enameled wire, keeping the polyurethane enameled wire at 285 ℃ for 12-18min in the temperature raising process, then continuously raising the temperature to 800 ℃ and preserving the temperature for 30min, ensuring complete pyrolysis, and removing the surface pyrolysis solid product more easily to obtain high-purity copper.

Example 3

Step 1: step 1: setting the maximum pyrolysis temperature to 900 ℃, respectively raising the temperature to 900 ℃ at the heating rates of 5 ℃/min, 10 ℃/min and 20 ℃/min, keeping the temperature for 30min, and obtaining a thermogravimetric curve (TG) and a differential thermal gravimetric curve (DTG) of the polyester-imide paint by using a thermogravimetric analysis method so as to obtain a pyrolysis temperature interval of the polyester enameled wire; meanwhile, the reciprocal of the temperature is solved, and the logarithm of the heating rate is solved, so that the relation between the conversion rate and the temperature can be obtained;

step 2: further analyzing the thermogravimetric curve of the polyesterimide enameled wire, calculating the activation energy required by the pyrolysis reaction according to formulas such as a chemical reaction rate expression and the like and by combining a Flynn-Wall-Ozawa (FWO) thermodynamic calculation method, and obtaining the average pyrolysis activation energy of the polyesterimide enameled wire to be 275.8 KJ/mol;

and step 3: pyrolyzing a polyesterimide enameled wire at the pyrolysis temperature of 900 ℃ in a nitrogen atmosphere at the heating rate of 10 ℃/min, after pyrolysis is finished, carrying out vibration treatment on the enameled wire, collecting a pyrolysis solid product of an organic coating of the enameled wire, and carrying out Fourier infrared spectroscopy (FTIR) analysis on the pyrolysis solid product to obtain that the pyrolysis solid product mainly comprises organic compounds such as alkane, alkene, alcohol, ketone, aldehyde and aromatic compounds;

and 4, step 4: TG-FTIR analysis of the polyesterimide enameled wire is shown in FIG. 3, and it can be seen from FIG. 3 that the pyrolysis gas product of the polyesterimide enameled wire mainly contains-OH, N-H, C-H, C ═ O, -CH₃C-O-C, and a benzene ring;

and 5: and (3) according to the average activation energy obtained in the step (2) and the analysis result of the pyrolysis gas product in the step (4), the polyesterimide enameled wire can stay for 11min at 420 ℃ in the temperature raising process, then the temperature is continuously raised to 900 ℃ and is kept for 30min, complete pyrolysis is ensured, and the surface pyrolysis solid product is more easily removed to obtain high-purity copper.

From example 1, it can be seen that the pyrolysis product of polyester enameled wire mainly contains C-O, C-H, -OH, C-O-C and-CH₂、-CH₃And benzene ring and the like, and the peak value of the functional group generated by pyrolysis gradually increases with the increase of the pyrolysis temperature and reaches the maximum value at about 400 ℃. When the pyrolysis temperature is further increased, the peak of C-H gradually decreases to disappear, and C ═ O, -CH₂And other peaks are gradually reduced, which indicates that the generation rate of the product is fastest at about 400 ℃, and the TG-DTG curve and the FTIR analysis result are combined, and the temperature is kept for 30min at 400 ℃ and then heated to 900 ℃ to ensure complete pyrolysis.

From example 2, it can be seen that the gas product of pyrolysis of polyurethane enameled wires mainly contains C-O, C-H, -OH, -CH₂、-CH₃And N-H, the peak value of the functional group generated by pyrolysis gradually increases with the increase of the pyrolysis temperature and reaches the maximum value between 300 ℃ and 400 ℃. When the pyrolysis temperature is further increased, the peaks of C ═ O and C-H functional groups basically disappear, which indicates that the product generation rate is fastest around 300-400 ℃, and the TG-DTG curve and FTIR analysis result are combined, and the temperature is kept for 30min at 300 ℃ and then heated to 900 ℃ to ensure the pyrolysis is complete.

From example 3, it can be seen that the pyrolysis gas product of the polyesterimide enameled wire mainly contains-OH, N-H, C-H, C ═ O, -CH₂C-O-C and benzene ring. The peak value of each functional group gradually increases with the increase of the pyrolysis temperature, and the peak value of each functional group reaches the maximum value between 400 ℃ and 500 ℃. With further increase in the pyrolysis temperature, C ═ O and-CH₂The peak value of the functional groups is gradually reduced, which indicates that the product generation rate is fastest at about 400-500 ℃, and the TG-DTG curve and the FTIR analysis result are combined, and the temperature is kept at 300 ℃ for 30min and then heated to 900 ℃ to ensure complete pyrolysis.

FIG. 4 is a thermogravimetric curve and a differential thermogravimetric curve of the polyester enameled wire in example 1 when the temperature rise rate is 10 ℃/min, and as can be seen from FIG. 4, the pyrolysis temperature interval of the polyester enameled wire is 334-487 ℃, and the maximum pyrolysis rate corresponding temperature is 420 ℃;

FIG. 5 is a thermogravimetric curve and a differential thermogravimetric curve of the polyurethane enameled wire in example 2 at a temperature rise rate of 10 ℃/min, and it can be seen from FIG. 5 that the pyrolysis temperature range of the polyurethane enameled wire is 144-724 ℃, and the maximum pyrolysis rate corresponding temperature is 286 ℃;

FIG. 6 is a thermogravimetric curve and a differential thermogravimetric curve of the polyesterimide enameled wire in example 3 at a temperature rise rate of 10 ℃/min, and as can be seen from FIG. 6, the pyrolysis temperature interval of the polyesterimide enameled wire is 337-513 ℃, and the maximum pyrolysis rate corresponding temperature is 417 ℃;

fig. 7 is a thermogravimetric graph of the polyester enameled wire in example 1 at different temperature rising rates.

FIG. 8 is a thermogravimetric plot of the polyurethane enameled wire of example 2 at different temperature rise rates.

FIG. 9 is a thermogravimetric graph of a polyesterimide enameled wire according to example 3 at different temperature rising rates.

FIG. 10 is a graph of the pyrolysis conversion rate of the polyester enameled wire according to example 1 as a function of temperature.

FIG. 11 is a graph of pyrolytic conversion versus temperature for the polyurethane enameled wire of example 2.

FIG. 12 is a graph of the pyrolysis conversion rate of the polyesterimide enameled wire according to example 3 as a function of temperature.

Fig. 13 is a reaction activation energy of pyrolysis of the polyester enameled wire according to example 1.

FIG. 14 is the reaction activation energy for pyrolysis of the polyurethane enameled wire of example 2.

Fig. 15 is a reaction activation energy of pyrolysis of the polyesterimide enameled wire of example 3.

Fig. 16 is an infrared spectrum of a pyrolyzed solid product of a polyester enameled wire in example 1.

FIG. 17 is an infrared spectrum of a solid product of the polyurethane enameled wire pyrolysis of example 2.

FIG. 18 is an infrared spectrum of a pyrolyzed solid product of a polyesterimide enameled wire in example 3.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.