A method for detecting stem content in cut tobacco based on activation energy

Abstract

This invention relates to the field of cigarette and cigarette product quality testing, and particularly to a method for detecting the stem content in tobacco shreds based on activation energy. This invention determines the stem content in tobacco shreds by calculating the correspondence between activation energy (E) and different stem contents through thermal analysis. The method provided by this invention, based on activation energy, prepares a series of tobacco shred samples with different stem contents and effectively characterizes each stage of tobacco pyrolysis using various thermal analysis techniques. It establishes a correspondence between samples with different stem contents and activation energy using thermal analysis techniques, thus establishing a method for determining the stem content in tobacco shreds. The activation energy of different pyrolysis stages of the samples is calculated using the differential conversion rate method. By establishing a mathematical model between activation energy and stem content in tobacco shreds, a more accurate quantitative analysis of stem content can be performed, providing strong support for the quality testing of tobacco shreds.

Description

Technical Field

[0001] This invention relates to the field of quality testing of cigarettes and cigarette products, and in particular to a method for detecting the stem content in tobacco shreds based on activation energy. Background Technology

[0002] Currently, there are no unified standards for the detection and evaluation of stem content in tobacco shreds, both domestically and internationally. Traditional methods primarily involve manually selecting stems, weighing them, and calculating the stem content. While simple, this method is time-consuming, susceptible to human error, and has low accuracy. Based on literature review, some methods analyze the differences in the content of chemical components such as total sugar, total alkali, chlorine, and potassium in leaf and stem shreds to establish a correlation between the stem ratio and the content of these chemical components, thereby evaluating the stem content of the sample. However, these methods are easily affected by the stability of the raw materials and the detection method, leading to poor accuracy and reproducibility.

[0003] The invention patent application with application number 201310251337.5 discloses "an evaluation method for the uniformity of blending of stems and reconstituted tobacco in cigarettes". A near-infrared spectral prediction model based on the blending ratio of stems and reconstituted tobacco was established for brand-oriented near-infrared spectroscopy. Blending of pure tobacco leaves with pure stems and pure tobacco leaves with pure reconstituted tobacco was performed in increments of 0.50%. After collecting near-infrared diffuse reflectance spectra, data preprocessing methods such as mean standardization, differentiation, and smoothing were used to establish, optimize, and validate the model. In actual testing, 100 cigarettes were selected to calculate the blending ratio.

[0004] Patent application number 201811098249.5 discloses "a method for rapidly estimating the actual proportion of stems in tobacco shreds in a cigarette." By measuring the potassium and chlorine content in the leaves and stems, the potassium and chlorine content in the blended mixture is calculated. The actual proportion of stems in the tobacco shreds is then calculated by accurately testing the potassium and chlorine content in the tobacco shreds in the cigarette, and a reliability assessment is performed. The average value is taken as the actual proportion of stems in the cigarette. This method requires no modeling, is simple and fast, and provides accurate and reliable results.

[0005] Patent application number 201310169230.6 discloses "a method for characterizing the uniformity of blending of leaf shreds, expanded tobacco shreds, and stem shreds." The method involves designing mixed tobacco shreds with different blending ratios and preparing standard samples, measuring their filling value and breakage rate; correlating the filling value and breakage rate of the blended tobacco shreds according to the blending ratio, and establishing a mathematical model using multiple linear regression; taking samples of tobacco shreds to be tested, mixing them thoroughly, and measuring their filling value and breakage rate; predicting the blending ratio based on the mathematical model, and thus characterizing the blending uniformity.

[0006] Patent application number 201710179755.6 discloses "a method for determining the uniformity of tobacco shreds, stems, and reconstituted tobacco blends." Based on the differences in cellulose and total sugar content in different tobacco blend components, the percentage content of cellulose and total sugar in each component is determined, and the blending uniformity is calculated using these differences. This method requires no modeling or the addition of external parameters and is easy to operate.

[0007] The methods for detecting stem content or evaluating blending uniformity in the aforementioned patent literature mostly rely on chemical index methods. For certain chemical components with significantly different contents in the selected stems and leaves, such as cellulose, total sugar, potassium, and chlorine, the content is determined using a continuous flow method. This method is time-consuming and its convenience needs improvement. Furthermore, these methods are easily affected by the stability of the raw materials and the detection method, leading to poor accuracy and reproducibility. Methods that use differences in leaf and stem filling values ​​and broken shred rates to determine the stem content of tobacco shreds suffer from low sensitivity and accuracy. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for detecting the stem content in tobacco shreds based on activation energy. This method studies the thermal decomposition characteristics and kinetic processes of tobacco shreds, gaining a deeper understanding of the differences in pyrolysis characteristics among tobacco shred samples with different stem contents. Based on this, by determining the correspondence between samples with different stem contents and the thermodynamic parameter activation energy, a method is established that can accurately determine the stem content in tobacco shreds to solve the problems of long time consumption, lack of convenience, and poor accuracy and reproducibility in the prior art.

[0009] To achieve the above and other related objectives, the present invention provides a method for detecting the stem content in tobacco shreds based on activation energy. The method is characterized in that the activation energy of the tobacco to be tested is detected based on the correspondence between the stem content of the tobacco shreds and the activation energy, thereby determining the stem content in the tobacco to be tested.

[0010] The method includes the following steps:

[0011] 1) Establish a standard curve: Perform thermal analysis tests on tobacco with known stem content, and calculate the corresponding relationship between known stem content and activation energy of tobacco at a specific conversion rate using the activation energy calculation method, and establish a standard curve of stem content and activation energy at a specific conversion rate;

[0012] 2) Perform thermal analysis on the tobacco to be tested, and calculate the activation energy of the tobacco to be tested at the same conversion rate as in step 1) using the activation energy calculation method;

[0013] 3) Substitute the activation energy of the tobacco shreds to be tested obtained in step 2) into the standard curve established in step 1) to obtain the stem content in the tobacco shreds to be tested.

[0014] Preferably, the specific conversion rate is selected from any conversion rate between 50% and 60%.

[0015] This invention also provides an application of the activation energy calculation method in calculating the stem content in tobacco samples.

[0016] Preferably, the activation energy calculation method is the Friedmad method of differential iso-conversion rate.

[0017] As described above, the method for detecting stem content in tobacco shreds based on activation energy according to the present invention has the following beneficial effects:

[0018] 1. This invention prepares a series of tobacco samples with different stem contents and uses various thermal analysis techniques (thermogravimetric analysis (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), etc.) to effectively characterize the various stages of tobacco pyrolysis.

[0019] 2. This invention establishes a correspondence between samples with different stem contents and thermodynamic parameters (activation energy) using thermal analysis technology, and establishes a method for determining the stem content in tobacco shreds;

[0020] 3. This invention uses the differential conversion rate method to calculate the activation energy of the sample at different pyrolysis stages. By establishing a mathematical model of activation energy and stem content in tobacco, the stem content can be more accurately quantitatively analyzed, providing strong support for the quality detection of tobacco. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method for determining the stem content in tobacco shreds according to the present invention.

[0022] Figure 2 In Figure A, the thermogravimetric curve of pure leaf filaments was measured using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention. In Figure B, the thermogravimetric curve of pure stem filaments was measured.

[0023] Figure 3 A represents the differential thermogravimetric curves of 12% stem-leaf filaments at different heating rates, measured using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention; B represents the differential scanning calorimetry curves of 12% stem-leaf filaments at different heating rates; and C represents the conversion rate curves of 12% stem-leaf filaments at different heating rates.

[0024] Figure 4A represents the differential thermogravimetric curves of 14% stem-leaf filaments at different heating rates, measured using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention; B represents the differential scanning calorimetry curves of 14% stem-leaf filaments at different heating rates; and C represents the conversion rate curves of 14% stem-leaf filaments at different heating rates.

[0025] Figure 5 A is the differential thermogravimetric curve of 16% stem-leaf filaments at different heating rates, measured using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention; B is the differential scanning calorimetry curve of 16% stem-leaf filaments at different heating rates; C is the conversion rate curve of 16% stem-leaf filaments at different heating rates.

[0026] Figure 6 A is the differential thermogravimetric curve of 18% stem-leaf filaments at different heating rates, measured using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention; B is the differential scanning calorimetry curve of 18% stem-leaf filaments at different heating rates; C is the conversion rate curve of 18% stem-leaf filaments at different heating rates.

[0027] Figure 7 A is the differential thermogravimetric curve of 20% stem-leaf filaments at different heating rates, measured using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention; B is the differential scanning calorimetry curve of 20% stem-leaf filaments at different heating rates; C is the conversion rate curve of 20% stem-leaf filaments at different heating rates.

[0028] Figure 8 This is a mathematical model of the activation energy corresponding to different filament-doped samples with a conversion rate of 40%, as determined by the RIGAKU TG-DTA8122 synchronous thermal analyzer used in this invention.

[0029] Figure 9 The results of the actual activation energy determination of a tobacco sample with a stem content of 15% at α = 40% were obtained using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention.

[0030] Figure 10 The results of the actual activation energy measurement of a tobacco sample with a stem content of 17% at α = 40% were obtained using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention.

[0031] Figure 11The results of the actual activation energy measurement of a tobacco sample with a stem content of 19% at α = 40% were obtained using the RIGAKU TG-DTA8122 synchronous thermal analyzer from Japan in this invention.

[0032] Figure 12 The thermogravimetric curves of leaf filaments and stem filaments were measured using the SDT-Q600 thermal analyzer in this invention.

[0033] Figure 13 In Figure A, the thermogravimetric curve of the leaf filaments was measured using the SDT-Q600 thermal analyzer in this invention; in Figure B, the thermogravimetric curve of the stem filaments was measured.

[0034] Figure 14 In this invention, A is the differential thermogravimetric curve of pure leaf filaments measured using the SDT-Q600 thermal analyzer; B is the differential scanning calorimetry curve of pure leaf filaments; and C is the conversion rate curve of pure leaf filaments at different heating rates.

[0035] Figure 15 In Figure A, the differential thermogravimetric curve of pure stem fibers measured using the SDT-Q600 thermal analyzer in this invention is shown; in Figure B, the differential scanning calorimetry curve of pure stem fibers is shown; and in Figure C, the conversion rate curve of pure stem fibers at different heating rates is shown.

[0036] Figure 16 A is the thermogravimetric curve of 5% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 5% stem-leaf filaments; C is the differential scanning calorimetry curve of 5% stem-leaf filaments at different heating rates; D is the conversion rate curve of 5% stem-leaf filaments at different heating rates.

[0037] Figure 17 A is the thermogravimetric curve of 10% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 10% stem-leaf filaments; C is the differential scanning calorimetry curve of 10% stem-leaf filaments at different heating rates; D is the conversion rate curve of 10% stem-leaf filaments at different heating rates.

[0038] Figure 18 A is the thermogravimetric curve of 15% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 15% stem-leaf filaments; C is the differential scanning calorimetry curve of 15% stem-leaf filaments at different heating rates; D is the conversion rate curve of 15% stem-leaf filaments at different heating rates.

[0039] Figure 19A is the thermogravimetric curve of 20% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 20% stem-leaf filaments; C is the differential scanning calorimetry curve of 20% stem-leaf filaments at different heating rates; D is the conversion rate curve of 20% stem-leaf filaments at different heating rates.

[0040] Figure 20 A is the thermogravimetric curve of 25% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 25% stem-leaf filaments; C is the differential scanning calorimetry curve of 25% stem-leaf filaments at different heating rates; D is the conversion rate curve of 25% stem-leaf filaments at different heating rates.

[0041] Figure 21 A is the thermogravimetric curve of 30% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 30% stem-leaf filaments; C is the differential scanning calorimetry curve of 30% stem-leaf filaments at different heating rates; D is the conversion rate curve of 30% stem-leaf filaments at different heating rates.

[0042] Figure 22 A is the thermogravimetric curve of 35% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 35% stem-leaf filaments; C is the differential scanning calorimetry curve of 35% stem-leaf filaments at different heating rates; D is the conversion rate curve of 35% stem-leaf filaments at different heating rates.

[0043] Figure 23 A is the thermogravimetric curve of 40% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 40% stem-leaf filaments; C is the differential scanning calorimetry curve of 40% stem-leaf filaments at different heating rates; D is the conversion rate curve of 40% stem-leaf filaments at different heating rates.

[0044] Figure 24 A is the thermogravimetric curve of 45% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 45% stem-leaf filaments; C is the differential scanning calorimetry curve of 45% stem-leaf filaments at different heating rates; D is the conversion rate curve of 45% stem-leaf filaments at different heating rates.

[0045] Figure 25A is the thermogravimetric curve of 50% stem-leaf filaments measured using the SDT-Q600 thermal analyzer in this invention; B is the differential thermogravimetric curve of 50% stem-leaf filaments; C is the differential scanning calorimetry curve of 50% stem-leaf filaments at different heating rates; D is the conversion rate curve of 50% stem-leaf filaments at different heating rates.

[0046] Figure 26 This is a mathematical model of the activation energy corresponding to different filament-doped samples at different conversion rates, as determined by the SDT-Q600 thermal analyzer in this invention.

[0047] Figure 27 In this invention, A represents the thermogravimetric curve of 14% stem-leaf filaments measured on a RIGAKU TG-DTA8122 instrument after the sample tested in the SDT-Q600 instrument was placed back in the instrument; B represents the differential thermogravimetric curve of 14% stem-leaf filaments; C represents the differential scanning calorimetry curve of 14% stem-leaf filaments at different heating rates; and D represents the conversion rate curve of 14% stem-leaf filaments at different heating rates.

[0048] Figure 28 In this invention, A represents the thermogravimetric curve of 18% stem-leaf filaments measured on a RIGAKU TG-DTA8122 instrument after the sample tested in the SDT-Q600 instrument was placed back in the instrument; B represents the differential thermogravimetric curve of 18% stem-leaf filaments; C represents the differential scanning calorimetry curve of 18% stem-leaf filaments at different heating rates; and D represents the conversion rate curve of 18% stem-leaf filaments at different heating rates. Detailed Implementation

[0049] This invention provides a method for detecting the stem content in tobacco shreds based on activation energy. The method involves determining the stem content in the tobacco shreds by detecting the activation energy of the tobacco shreds to be tested based on the correspondence between the stem content and activation energy.

[0050] Furthermore, the method includes the following steps:

[0051] 1) Establish a standard curve: Perform thermal analysis tests on tobacco with known stem content, calculate the relationship between known stem content and activation energy at a specific conversion rate using the activation energy calculation method, and establish a standard curve between stem content and activation energy at a specific conversion rate.

[0052] 2) Perform thermal analysis on the tobacco to be tested, and calculate the activation energy of the tobacco to be tested at the same conversion rate as in step 1) using the activation energy calculation method;

[0053] 3) Substitute the activation energy of the tobacco shreds to be tested obtained in step 2) into the standard curve established in step 1) to obtain the stem content in the tobacco shreds to be tested.

[0054] Further, the establishment of the standard curve in step 1) includes the following steps: 1a) establishing the conversion rate curve of tobacco with known stem content at different heating rates through thermal analysis test; 1b) establishing the activation energy correlation curve of tobacco with known stem content based on the conversion rate curve; and 1c) establishing the standard curve based on the activation energy correlation curve.

[0055] Further, in step 1a), the thermal analysis test is selected from one or more of thermogravimetric analysis (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermal expansion method (DIL), thermomechanical method (TMA), or dynamic thermomechanical method. Preferably, the thermal analysis test is one or more of thermogravimetric analysis, differential thermal analysis, or differential scanning calorimetry.

[0056] Further, the method for establishing the activation energy correlation curve in step 1b) is as follows: multiply the value of a specific conversion rate and temperature after differentiation in the conversion rate curve by the heating rate, take the logarithm of the product as the ordinate ln(β(dα / dT)) of the activation energy correlation curve, and take the reciprocal of the temperature in the conversion rate curve as the abscissa 1 / T of the activation energy correlation curve, thereby obtaining the activation energy correlation curve.

[0057] Further, in step 1c), a standard curve of filament content-activation energy is established using the known filament content from step 1b) as the abscissa and the activation energy calculated from the corresponding activation energy correlation curve as the ordinate.

[0058] Furthermore, step 1) thermal analysis testing includes one or more of the following steps: sample pretreatment, standard sample preparation, and sample thermal analysis.

[0059] The sample pretreatment involves selecting leaf filaments and / or stem filaments of a known formula and baking them separately in an oven. The baking temperature is 70-90℃. Preferably, the baking temperature is 80℃. The baking time is 1-3 hours. Preferably, the baking time is 2 hours. After baking, the moisture content of the leaf filaments or stem filaments is between 4% and 12%. Preferably, the moisture content of the leaf filaments or stem filaments is 6-10%. The leaf filaments or stem filaments are leaves or powder. Preferably, the leaf filaments or stem filaments are powder. The particle size of the powder can pass through a 38-42 mesh standard sieve. Preferably, the standard sieve has a mesh size of 40.

[0060] The standard sample is prepared by uniformly mixing stem powder and leaf powder in a certain proportion to form a standard sample with a known stem content. The proportion is one or more of the following: stem powder accounts for 1%-5%, 5-12%, 12-14%, 14-16%, 18%-20%, 20%-25%, 25%-30%, 30%-50%, or 50%-70% of the total weight of the stem-leaf powder mixture. Preferably, the proportion is one or more of the following: stem powder accounts for 12%-14%, 14%-16%, or 18%-20% of the total weight of the stem-leaf powder mixture.

[0061] The thermal analysis of the sample includes one or more of the following steps:

[0062] a) Place the standard sample into the sample pool of the testing instrument;

[0063] b) Start the carrier gas purging process. The carrier gas is a mixture of oxygen and inert gas.

[0064] c) Set the heating rate and heat the sample; record the thermal analysis data.

[0065] d) Calculate the activation energy corresponding to a specific conversion rate based on the sample thermal analysis data recorded in step c);

[0066] e) Perform steps a), b), c), and d) on the standard samples with different stem contents.

[0067] Further, in step a), the mass of the standard sample is 2-13 mg. Preferably, the mass of the standard sample is 5-10 mg. The detection instrument is selected from one or more of thermogravimetric analyzer, differential thermal analyzer, thermomechanical analyzer, or differential scanning calorimeter. Preferably, the detection instrument is selected from thermogravimetric analyzer and / or differential thermal analyzer.

[0068] Further, in step b), the inert gas is selected from nitrogen. The proportion of inert gas in the mixed air is 75%-85%. Preferably, the proportion of inert gas in the mixed air is 79.5%-80.5%. The total flow rate of the carrier gas purging gas is 80 ml / min-450 ml / min. Preferably, the total flow rate is 90 ml / min-410 ml / min.

[0069] Further, in step c), the heating rate is selected from one or more of 5℃ / min-10℃ / min, 10℃ / min-15℃ / min, 15℃ / min-20℃ / min, 20℃ / min-40℃ / min, or 40℃ / min-60℃ / min. Preferably, the heating rate is selected from one or more of 5℃ / min-10℃ / min, 10℃ / min-15℃ / min, or 15℃ / min-20℃ / min. The temperature range is 15℃-1000℃. Preferably, the temperature range is 25℃-800℃.

[0070] Further, the specific conversion rate in step d) is selected from one or more of 10%-20%, 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, 70%-80%, or 80%-90%. Preferably, the specific conversion rate is any conversion rate of 50%-60%.

[0071] Furthermore, the mathematical model is a linear regression model. The linear regression model uses the doping content of the stem fibers as the abscissa and the activation energy as the ordinate.

[0072] This invention also provides an application of the activation energy calculation method in calculating the stem content in tobacco samples.

[0073] The activation energy is an inherent property of matter, representing the minimum energy required for reactant molecules to achieve effective collisions; it is an apparent concept. The activation energy calculation method is selected from one or more of the following: the differential isoconversion method (Friedman method), the Achar-Brindley method, the Piloyan-Ryabchihov method, the Freeman-Carroll method, the Anderson-Freeman method, the Vachuska-Voboril method, the Starink method, the Rogers method, the Rogers-Smith method, the Rogers-Morris method, the Borham-Olson method, or the Borchardt-Daniels method. Preferably, the activation energy calculation method is the Friedman method.

[0074] The activation energy calculation method described above does not require prior knowledge of the mechanistic function to obtain the activation energy (E) value, and can obtain the relationship between activation energy and reaction progress (E ~ conversion rate (α)). By selecting a certain α value, a set of dα / dT and T data corresponding to that α value can be obtained from the α ~ instantaneous temperature (T) curves for different heating rates (β). Substituting these values ​​into the logarithm of both sides and rearranging the equation, we obtain a constant α. In this case, the first two terms on the right side of the equation are constants, and E can be calculated from the slope.

[0075]

[0076] Where β is the heating rate in the thermal analysis of tobacco, dα is the derivative of the tobacco conversion rate, dT is the derivative of the reaction temperature, A is the frequency factor, f(α) is the reaction mechanism function, E is the activation energy, R is the gas constant, and T is the reaction temperature. Then, an activation energy correlation curve is plotted with 1 / T as the abscissa and ln[β(dα / dT)] as the ordinate.

[0077] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0078] Example 1: Determination of activation energy of stem-leaf filament samples using a Rigaku TG-DTA8122 simultaneous thermal analyzer (Japan)

[0079] 1. Experimental Samples

[0080] Samples of Grade A: pure leaf filaments, pure stem filaments, and mixed samples of stem filaments and leaf filaments in different proportions (physically stirred and uniformly mixed).

[0081] 2. Testing conditions

[0082] Instrument: RIGAKU TG-DTA8122 simultaneous thermal analyzer (Japan)

[0083] Carrier gas: a nitrogen-oxygen mixture of air (20.1% oxygen + 79.9% nitrogen) mixed in proportion, with a total flow rate maintained at 400 mL / min;

[0084] Temperature range: room temperature (25℃) — 800℃;

[0085] Heating rate: 10℃ / min, 15℃ / min, 20℃ / min;

[0086] 3. Detection method:

[0087] The thermal analysis of the sample includes one or more of the following steps:

[0088] f) Place the standard sample into the sample cell of the testing instrument;

[0089] g) Start the carrier gas purging process. The carrier gas is a mixture of oxygen and inert gas.

[0090] h) Set the heating rate and heat the sample; record the thermal analysis data.

[0091] i) Calculate the activation energy corresponding to a specific conversion rate based on the sample thermal analysis data recorded in step c);

[0092] j) Perform steps a), b), c), and d) on the standard samples with different stem contents.

[0093] 4. Experimental Results and Analysis

[0094] (1) Comparison of TG curves

[0095]

[0096]

[0097] The TG curves of the stem and leaf samples reveal that the weight loss rates are highest in stages III and VI during the tobacco weight loss process. The thermal decomposition processes in stages III and IV differ significantly between pure stem and leaf samples, with stems also exhibiting a weight loss stage VI. These differences further indicate a significant difference in the kinetic behavior of thermal decomposition between leaf and stem samples; and the kinetic behavior of the stem-leaf mixture sample falls between that of leaf and stem samples.

[0098] (2) Calculation and comparison of activation energy E

[0099] ①12% stem-leaf fibers:

[0100] from Figure 3 According to AC, for 12% stem-leaf filaments: when α = 40%, the fitting slope is -12.94, and the activation energy E = 108 KJ / mol obtained by testing and calculation.

[0101] ②14% stem-leaf fibers:

[0102] from Figure 4 According to AC, for 14% stem-leaf filaments: when α = 40%, the fitting slope is -15.9, and the activation energy E = 132 KJ / mol obtained by testing and calculation.

[0103] ③ 16% stem-leaf filaments:

[0104] from Figure 5 According to AC, for 16% stem-leaf filaments: when α = 40%, the fitting slope is -19.7, and the activation energy E = 164 KJ / mol obtained by testing and calculation.

[0105] ④18% stem-leaf fibers:

[0106] from Figure 6According to AC, for 18% stem-leaf filaments: when α = 40%, the fitting slope is -22.18, and the activation energy E = 185 KJ / mol is obtained through testing and calculation.

[0107] ⑤ 20% stem-leaf fibers:

[0108] from Figure 7 According to AC, for a 20% stem-leaf filament ratio: when α = 40%, the fitting slope is -25.78, and the activation energy E = 215 KJ / mol obtained by testing and calculation.

[0109] (3) Establish a mathematical model for the doping content of stem fibers.

[0110] from Figure 8 As can be seen from the figure, the activation energy E values ​​of different filament doped samples (12%-20%) at different α=40% were calculated. By comparison, it was found that the filament doping content and the activation energy E have a good linear correspondence. The linear relationship between the filament doping content and the activation energy E is shown in the figure below: y=13.35x-52.8,R=-0.99847.

[0111] (4) Model Performance Verification

[0112] Thermal analysis tests were performed on tobacco samples with stem contents of 15%, 17%, and 19%, respectively. The activation energy E was calculated and substituted into the above linear relationship for verification.

[0113] from Figure 9 As can be seen from the data, for a tobacco sample with a stem content of 15%, when α = 40%, the fitting slope is -18.39, and the activation energy E = 153 KJ / mol is obtained by testing and calculation; the activation energy E = 148 KJ / mol is obtained from the linear relationship y = 13.35x - 52.8.

[0114] from Figure 10 As can be seen from the data, for a tobacco sample with a stem content of 17%, when α = 40%, the fitting slope is -21.29, and the activation energy E = 177 KJ / mol obtained by testing and calculation is obtained; the activation energy E = 174 KJ / mol obtained from the linear relationship y = 13.35x - 52.8 is obtained.

[0115] from Figure 11 As can be seen from the data, for a tobacco sample with a stem content of 19%, when α = 40%, the fitting slope is -24.18, and the activation energy E = 201 KJ / mol is obtained by testing and calculation; the activation energy E = 201 KJ / mol is obtained from the linear relationship y = 13.35x - 52.8.

[0116] Example 2: Determination of activation energy of stem-leaf filament samples using the SDT-Q600 thermal analyzer.

[0117] 1. Test sample

[0118] Samples of Grade B, consisting of pure leaf filaments, pure stem filaments, and mixed samples of stem filaments and leaf filaments in different proportions (physically stirred to achieve uniform mixing).

[0119] 2. Testing conditions

[0120] Instrument Name: SDT-Q600 Thermal Analyzer

[0121] Carrier gas: a nitrogen-oxygen mixture of air (20.1% oxygen + 79.9% nitrogen) mixed in proportion, with a total flow rate of 100 mL / min;

[0122] Temperature range: room temperature (25℃) — 800℃;

[0123] Heating rate: 10℃ / min, 15℃ / min, 20℃ / min;

[0124] 3. Detection method:

[0125] The thermal analysis of the sample includes one or more of the following steps:

[0126] a) Place the standard sample into the sample pool of the testing instrument;

[0127] b) Start the carrier gas purging process. The carrier gas is a mixture of oxygen and inert gas.

[0128] c) Set the heating rate and heat the sample; record the thermal analysis data.

[0129] d) Calculate the activation energy corresponding to a specific conversion rate based on the sample thermal analysis data recorded in step c);

[0130] e) Perform steps a), b), c), and d) on the standard samples with different stem contents.

[0131] 4. Results and Analysis

[0132] (1) Comparison of TG curves

[0133]

[0134] from Figure 12 and Figure 13 The TG and α-T curves of the stem and leaf samples in AB show that the curves of pure stem and leaf samples differ significantly at α = 60%, 70%, and 80%. To ensure reasonableness, we performed kinetic calculations for α = 30%–80%.

[0135] (2) Activation energy calculation and comparison

[0136] ① Pure leaf fibers:

[0137] from Figure 14 According to AC, the activation energies of pure leaf filaments calculated at different conversion rates are shown in the table below.

[0138] Activation energy of pure leaf filaments at different conversion rates

[0139]

[0140] ② Pure stems and shreds:

[0141] from Figure 15 As shown in AC, the activation energies of pure filaments at different conversion rates are as follows: (see table below).

[0142] Activation energy of pure filaments at different conversion rates

[0143]

[0144] ③5% stem-leaf filaments:

[0145] from Figure 16 According to AD, the activation energies of 5% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0146] Activation energy calculated for 5% stem-leaf filaments at different conversion rates

[0147]

[0148] ④10% stem-leaf fibers:

[0149] from Figure 17 According to AD, the activation energies of 10% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0150] Activation energy calculated for 10% stem-leaf filaments at different conversion rates

[0151]

[0152] ⑤ 15% stem-leaf fibers:

[0153] from Figure 18 According to AD, the activation energies of 15% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0154] Activation energy calculated for 15% stem-leaf filaments at different conversion rates

[0155]

[0156] ⑥ 20% stem-leaf fibers:

[0157] from Figure 19According to AD, the activation energies of 20% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0158] Activation energy calculated for 20% stem-leaf filaments at different conversion rates

[0159]

[0160] ⑦ 25% stem-leaf fibers:

[0161] from Figure 20 According to AD, the activation energies of 25% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0162] Activation energy calculated for 25% stem-leaf filaments at different conversion rates

[0163]

[0164] ⑧ 30% stem-leaf fibers:

[0165] from Figure 21 According to AD, the activation energies of 30% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0166] Activation energy calculated for 30% stem-leaf filaments at different conversion rates

[0167]

[0168] ⑨ 35% stem-leaf fibers:

[0169] from Figure 22 According to AD, the activation energies of 35% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0170] Activation energy calculated for 35% stem-leaf filaments at different conversion rates

[0171]

[0172] ⑩ 40% stem-leaf fibers:

[0173] from Figure 23 According to AD, the activation energies of 40% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0174] Activation energy calculated for 40% stem-leaf filaments at different conversion rates

[0175]

[0176] ⑪ 45% stem-leaf fibers:

[0177] from Figure 24 According to AD, the activation energies of 45% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0178] Activation energy calculated for 45% stem-leaf filaments at different conversion rates

[0179]

[0180] ⑫ 50% stem-leaf fibers:

[0181] from Figure 25 According to AD, the activation energies of 50% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0182] Activation energy calculated for 50% stem-leaf filaments at different conversion rates

[0183]

[0184] (3) Establish a mathematical model for the doping content of stem fibers.

[0185] The activation energy (E) values ​​of different stem-doped samples at different α (30%–80%) were calculated. Comparison revealed a good linear correlation between the stem-doping content and the activation energy (E) when α = 60%. This corresponds to the previous analysis showing significant differences in the TG curves of stem and leaf samples when α = 60%, indicating that a relationship can be established between E at α = 60% and the doping content. The linear relationship between stem-doping content and activation energy (E) is shown below. Figure 26 As shown: (y = 2.41x + 86.13, R = 0.99456).

[0186] Example 3: Comparative Analysis of Cross-Detection between SDT-Q600 and RIGAKU TG-DTA8122 Instruments

[0187] The samples tested in the SDT-Q600 instrument were retested and compared in the RIGAKU TG-DTA8122 instrument.

[0188] (1) Calculation and comparison of activation energy

[0189] ①14% stem-leaf fibers:

[0190] from Figure 27 According to AD, the activation energies of 14% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0191] Activation energy calculated for 14% stem-leaf filaments at different conversion rates

[0192]

[0193] When α = 60%, the actual activation energy E = 115 KJ / mol obtained by testing and calculation, while the theoretical activation energy E = 120 KJ / mol obtained from the linear relationship y = 2.41x + 86.13 for the 14% stem-leaf sample.

[0194] ②18% stem-leaf fibers:

[0195] from Figure 28 According to AD, the activation energies of 18% stem-leaf filaments calculated at different conversion rates are shown in the table below.

[0196] Activation energy calculated for 18% stem-leaf filaments at different conversion rates

[0197]

[0198] When α = 60%, the actual activation energy E = 127 KJ / mol obtained by testing and calculation, while the theoretical activation energy E = 130 KJ / mol obtained from the linear relationship y = 2.41x + 86.13 for the 18% stem-leaf sample.

[0199] In this example, the 14% stem-leaf and 18% stem-leaf samples, which had previously been tested in the RIGAKU TG-DTA8122 instrument, showed activation energy values ​​calculated from the previously derived linear relationship (y = 2.41x + 86.13) when tested in the SDT-Q600 thermal analyzer. These values ​​were close to the actual values ​​of the samples. Therefore, the 14% stem-leaf and 18% stem-leaf samples also conformed to the previous conclusions, further verifying the accuracy of the linear relationship. This indicates that the relationship between the activation energy of the sample and the stem doping content is independent of the testing instrument.

[0200] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0201] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for detecting the stem content in tobacco shreds based on activation energy, characterized in that, The method involves determining the stem content in the tobacco shreds by detecting the activation energy of the shredded tobacco shreds based on the correlation between the stem content and activation energy. The method includes the following steps: 1) Establish a standard curve: Perform thermal analysis tests on tobacco with known stem content, calculate the relationship between known stem content and activation energy at a specific conversion rate using the activation energy calculation method, and establish a standard curve between stem content and activation energy at a specific conversion rate. 2) Perform thermal analysis on the tobacco to be tested, and calculate the activation energy of the tobacco to be tested at the same conversion rate as in step 1) using the activation energy calculation method; 3) Substitute the activation energy of the tobacco shreds obtained in step 2) into the standard curve established in step 1) to obtain the stem content in the tobacco shreds; Step 1) of establishing the standard curve includes the following steps: 1a) Establish conversion rate curves of tobacco with known stem content at different heating rates through thermal analysis tests; 1b) Establish an activation energy correlation curve for tobacco with known stem content based on the conversion rate curve; 1c) Establish a standard curve based on the activation energy correlation curve.

2. The method according to claim 1, characterized in that, The calculation formula for the activation energy calculation method is as follows: , where β is the heating rate in the thermal analysis test of tobacco, dα is the derivative of the tobacco conversion rate in the thermal analysis test of tobacco, dT is the derivative of the reaction temperature in the thermal analysis test of tobacco, A is the frequency factor in the thermal analysis test of tobacco, f(a) is the reaction mechanism function in the thermal analysis test of tobacco, E is the activation energy of tobacco in the thermal analysis test of tobacco, R is the gas constant, and T is the reaction temperature in the thermal analysis test of tobacco.

3. The method according to claim 1, further comprising one or more of the following features: A) The thermal analysis test described in step 1a) is selected from one or more of thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry, thermal expansion method, thermomechanical method or dynamic thermomechanical method; B) The method for establishing the activation energy correlation curve in step 1b) is as follows: Multiply the differentiated value of a specific conversion rate and temperature in the conversion rate curve by the heating rate. Use the logarithm of the product as the ordinate of the activation energy correlation curve, ln(β(dα / dT)), and use the reciprocal of the temperature in the conversion rate curve as the abscissa of the activation energy correlation curve, 1 / T, thereby obtaining the activation energy correlation curve. ; C) Step 1c) Establish a standard curve using the known filament content from step 1b) as the x-axis and the activation energy calculated from the corresponding activation energy correlation curve as the y-axis.

4. The method according to claim 1, wherein the thermal analysis test in step 1) includes one or more of the steps of sample pretreatment, standard sample preparation, and sample thermal analysis.

5. The method according to claim 4, characterized in that, The sample pretreatment involves baking the known formula leaf filaments and / or stem filaments until the moisture content of the leaf filaments or stem filaments is 6-10%.

6. The method according to claim 5, characterized in that, The leaf filaments or stem filaments are in powder form.

7. The method according to claim 1, characterized in that, In step 1a), the heating rate is selected from any one or more ranges of 5℃ / min-10℃ / min, 10℃ / min-15℃ / min, or 15℃ / min-20℃ / min; and / or, the heating temperature range is 25℃-800℃.

8. The method according to claim 1, characterized in that, The specific conversion rate in step 1) is selected from any conversion rate between 50% and 60%.

9. The method according to claim 1, characterized in that, In step 1), the standard curve is obtained through a linear regression model.

10. An application of an activation energy calculation method in calculating the stem content in tobacco samples, characterized in that, The activation energy calculation method is selected from one or more of the Friedman method, Achar-Brindley method, Piloyan-Ryabchihov method, Freeman-carroll method, Anderson-Freeman method, Vachuska-Voboril method, Starink method, Rogers method, Rogers-Smith method, Rogers-Morris method, Borham-Olson method, or Borchardt-Daniels method.

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