A method for identifying ramie fibers and mixed fibers thereof based on long-life room temperature phosphorescence

Abstract

This invention relates to a method for identifying ramie fibers and their mixed fibers based on long-lifetime room-temperature phosphorescence. The method establishes luminescence characteristic information for a lyocell fiber control sample, a ramie fiber control sample treated with a 15% NaOH solution, and a mixed fiber control sample of the two. The method acquires the fiber sample to be tested and prepares it as a test sample. The photoluminescence emission spectrum of the test sample is acquired under 365 nm excitation conditions to obtain emission peak position information. After UV excitation stops, the long-lifetime room-temperature phosphorescence decay information of the test sample is acquired to obtain lifetime information. The emission peak position information and lifetime information are compared with the corresponding information of the control sample to identify whether the fiber sample to be tested is ramie fiber or a mixture of lyocell and ramie fibers. This invention utilizes the differences in photoluminescence and long-lifetime room-temperature phosphorescence caused by changes in the crystal structure of ramie fibers for identification, providing an auxiliary detection method based on luminescence characteristics for fiber composition identification.

Description

Technical Field

[0001] This invention relates to the field of textile fiber identification technology, specifically to a method for identifying ramie fibers and their blends based on long-life room temperature phosphorescence. Background Technology

[0002] Ramie fiber, as a natural cellulose fiber, is widely used in the textile and apparel industry due to its moisture absorption, breathability, and high strength. Lyocell fiber, also a cellulose fiber, shares some similarities in appearance and physicochemical properties with natural cellulose fibers, making identification difficult during the testing of blended fibers or textile components.

[0003] Existing methods for fiber identification typically include microscopic observation, chemical dissolution, and infrared spectroscopy. Microscopic observation relies on operator experience, chemical dissolution can damage the sample, and conventional spectroscopic detection has limited ability to distinguish fibers with similar structures. Especially for ramie fibers treated with alkali and their mixtures with lyocell fibers, relying solely on single morphological features or conventional spectral peak positions is insufficient to reliably reflect differences in fiber crystallinity, crystal form changes, and luminescent properties.

[0004] Therefore, there is an urgent need for a method that can effectively identify ramie fibers and their blends with lyocell fibers by combining the differences in crystal form transformation and luminescence characteristics of ramie fibers themselves, so as to improve the accuracy and applicability of fiber identification.

[0005] A search revealed a Chinese patent document disclosing a method for identifying hemp fibers for clothing based on FTIR-ATR principal component Fisher discriminant analysis [Application No.: 202211466018.1, Publication No.: CN115861194A]. This comparative patent discloses a method that mainly includes steps such as sample division, degumming, washing, drying, pretreatment, acquisition of FTIR-ATR spectra and data processing, principal component analysis, establishment of a Fisher discriminant model, model verification, and classification and identification of hemp fibers. The technical solution involves substituting the principal component scores of the hemp fiber sample into flax, hemp, and ramie classification functions, and comparing the classification function results to determine whether the tested hemp fiber belongs to flax, hemp, or ramie.

[0006] While the comparative patent can qualitatively identify hemp fibers, distinguishing between flax, hemp, and ramie based on FTIR-ATR spectroscopy, principal component analysis, and Fisher's discriminant model, this invention does not rely on infrared absorption spectroscopy and statistical discriminant models to classify hemp fibers. Instead, it utilizes the differences in photoluminescence emission peak positions and long-lifetime room-temperature phosphorescence lifetimes caused by changes in crystallinity and crystal form after NaOH treatment to identify ramie fibers and blends of lyocell and ramie fibers. This invention uses emission peak position information under 365 nm excitation for preliminary identification, and confirms it by combining long-lifetime room-temperature phosphorescence lifetime information after UV light cessation. It can identify ramie fibers and their blends from the perspective of the fiber's own luminescence characteristics. This dual-parameter long-lifetime room-temperature phosphorescence identification method and the identification process for blends of lyocell and ramie fibers are not available in the comparative patent. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of this invention is to provide a method for identifying ramie fibers and their mixed fibers based on long-life room temperature phosphorescence.

[0008] A method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence, characterized by comprising the following steps: S1. Establish photoluminescence emission peak position information and long-lifetime room temperature phosphorescence lifetime information for lyocell fiber control samples, ramie fiber control samples, and mixed fiber control samples; S2. Obtain the fiber sample to be tested and prepare it into a test sample; S3. Acquire the photoluminescence emission spectrum of the test sample under 365 nm excitation conditions, obtain emission peak position information, and perform preliminary identification based on the emission peak position information; S4. After the ultraviolet light excitation stops, collect the long-lifetime room temperature phosphorescence decay information of the test sample to obtain lifetime information; S5. Based on the difference between the emission peak position information and lifetime information and the corresponding information of the control sample, identify whether the fiber sample to be tested is ramie fiber or a mixture of lyocell fiber and ramie fiber.

[0009] Preferably, the Lyocell fiber control sample is a Lyocell fiber sample that has not been treated with NaOH solution; The ramie fiber control sample was a ramie fiber sample treated with a 15% NaOH solution. The mixed fiber control sample was formed by mixing the lyocell fiber control sample and the ramie fiber control sample.

[0010] The above technical solution establishes a stable reference basis for the identification of ramie fibers and their mixed fibers. Using lyocell fiber samples without NaOH treatment, ramie fiber samples treated with 15% NaOH solution, and mixed fiber samples formed from the two as references provides a clear standard for comparing the photoluminescence peak positions and long-lifetime room-temperature phosphorescence lifetimes of the tested samples.

[0011] Specifically, the lyocell fiber control sample reflects the luminescence characteristics of untreated regenerated cellulose fibers, the ramie fiber control sample reflects the luminescence characteristics of natural cellulose fibers treated with conventional alkali, and the mixed fiber control sample reflects the luminescence response when the two types of fibers coexist. By setting up these three types of control samples, the detection needs for single lyocell fibers, single ramie fibers, and mixed systems of lyocell and ramie fibers can be covered respectively.

[0012] In practical applications, this control system enables the emission peak position and lifetime information of the test samples to be comparable, avoiding the problem of insufficient judgment range caused by relying on a single fiber sample as a reference, thereby improving the applicability and reliability of the identification process of ramie fiber and its blend with lyocell fiber.

[0013] Preferably, the ramie fiber control sample is prepared by the following steps: Ramie fibers were placed in a 15% NaOH solution and soaked at 25°C for 8 hours. After soaking, the ramie fibers are rinsed with deionized water until the pH value of the ramie fibers is about 7.0. The rinsed ramie fibers were then vacuum dried at 40 °C to obtain the ramie fiber control sample.

[0014] The above technical solution enables the acquisition of ramie fiber reference samples with stable processing conditions and well-defined crystal structures. Treating ramie fibers in a 15% NaOH solution alters their crystal structure, resulting in luminescent characteristics suitable for identification.

[0015] Specifically, soaking at 25 ℃ for 8 hours allows the NaOH solution to fully act on the ramie fibers, promoting a transformation of the crystal structure in their crystalline regions. Subsequent rinsing with deionized water until the pH is approximately 7.0 reduces the impact of residual alkali on subsequent spectroscopic tests. Finally, vacuum drying at 40 ℃ removes moisture under relatively mild conditions, maintaining sample stability. This process ensures good reproducibility for the ramie fiber control samples.

[0016] In practical applications, this preparation method can provide a stable sample basis for subsequent photoluminescence emission peak position testing and long-lifetime room temperature phosphorescence lifetime testing, so that different batches of ramie fiber control samples maintain a relatively consistent processing state, which facilitates comparison and identification with the fiber samples to be tested.

[0017] Preferably, the mixed fiber control sample is formed by cutting and mixing the lyocell fiber control sample and the ramie fiber control sample; The mass ratio of the lyocell fiber control sample to the ramie fiber control sample is selected from at least one of 1:1, 1:3, 1:5, 3:1 and 5:1.

[0018] The above technical solution enables the establishment of a control system for lyocell fiber and ramie fiber with different mixing ratios. By cutting and mixing lyocell fiber control samples and ramie fiber control samples, and setting multiple mass ratios, the luminescence characteristics of the two types of fibers coexisting under different content relationships can be simulated.

[0019] Specifically, the shredding process allows for a more uniform distribution of lyocell and ramie fibers during mixing, reducing test bias caused by fiber length or localized aggregation. Mass ratios of 1:1, 1:3, 1:5, 3:1, and 5:1 can cover different scenarios, such as high ramie fiber content, high lyocell fiber content, and similar content of both, providing a more comprehensive reference range for the mixed fiber control samples.

[0020] In practical applications, by establishing a control sample with the above mixing ratio, the mixed fibers to be tested can find a closer reference when comparing the 365 nm photoluminescence emission peak position and the long-lifetime room temperature phosphorescence lifetime, thereby improving the ability to identify mixed fibers of lyocell and ramie.

[0021] Preferably, when establishing the photoluminescence emission peak position information and the long-lifetime room-temperature phosphorescence lifetime information, X-ray diffraction tests are also performed on the ramie fiber control sample. The total integrated area Sp of the crystalline region and the integrated area IA of the amorphous region are obtained from the X-ray diffraction curve, and the crystallinity CrI% of the ramie fiber control sample is calculated according to the following formula: Where Sp is the total integral area of ​​the crystalline region and IA is the integral area of ​​the amorphous region.

[0022] The above technical solution allows for the incorporation of ramie fiber crystallinity variations into the luminescence characteristic analysis of control samples. By using X-ray diffraction testing and calculating the crystallinity CrI%, the structural parameters of the ramie fiber control samples can be obtained, providing a basis for explaining the differences in photoluminescence emission peak positions and long-lifetime room-temperature phosphorescence lifetimes.

[0023] Specifically, X-ray diffraction patterns can reflect the distribution of crystalline and amorphous regions in ramie fibers. By obtaining the total integrated area Sp of the crystalline regions and the integrated area IA of the amorphous regions, and calculating the crystallinity according to CrI% = Sp / (Sp + IA) × 100%, the changes in the crystalline structure of ramie fibers under different treatment conditions can be quantified. This crystallinity information can be correlated with subsequent emission peak position and lifetime information, illustrating the relationship between sample structural changes and luminescence behavior.

[0024] In practical applications, the introduction of crystallinity calculation can avoid making empirical judgments based solely on spectral results, and provide structural parameters to support the luminescence characteristics of ramie fiber control samples, thereby improving the technical integrity of the identification method and the rationality of the result interpretation.

[0025] Preferably, when establishing the photoluminescence emission peak position information and the long-lifetime room temperature phosphorescence lifetime information, the crystal structure of the ramie fiber control sample is determined based on the characteristic diffraction peaks of cellulose type I and cellulose type II. The characteristic diffraction peaks of cellulose type I correspond to diffraction angles 2θ of 14.9°, 16.5° and 22.7°, and the characteristic diffraction peaks of cellulose type II correspond to diffraction angles 2θ of 12.1°, 20.1° and 22°. The crystallinity CrI%, crystal structure, photoluminescence emission peak position information, and long-lifetime room temperature phosphorescence lifetime information are used as the corresponding information of the ramie fiber control sample for comparison with the corresponding information of the test sample.

[0026] The above technical solution can further determine the crystal structure of ramie fiber control samples and correlate crystal form changes with luminescence characteristics. By identifying the characteristic diffraction peaks of cellulose type I and cellulose type II, it can be determined whether ramie fibers undergo a crystal form transformation after NaOH treatment, thus providing a clearer structural basis for subsequent identification.

[0027] Specifically, cellulose type I and cellulose type II exhibit different characteristic diffraction peak positions in their X-ray diffraction patterns. Based on the characteristic peaks with diffraction angles of 2θ of 14.9°, 16.5°, and 22.7°, the cellulose type I structure can be identified; based on the characteristic peaks with diffraction angles of 2θ of 12.1°, 20.1°, and 22°, the cellulose type II structure can be identified. Using crystallinity (CrI%), crystal structure, photoluminescence emission peak positions, and long-lifetime room-temperature phosphorescence lifetime as corresponding information for ramie fiber control samples provides a more complete basis for comparing the tested samples based on both structure and luminescence.

[0028] In practical applications, this method can not only determine whether the sample exhibits the luminescent characteristics of ramie fibers, but also help determine whether it has a crystal state corresponding to that of ramie fibers treated with NaOH, thereby improving the reliability of the identification results of ramie fibers and their mixed fibers.

[0029] Preferably, in step S4, at least one lifetime component and its corresponding proportional parameter are obtained based on the long-lifetime room temperature phosphorescence decay information, and the average long-lifetime room temperature phosphorescence lifetime of the test sample is calculated based on the lifetime component and its corresponding proportional parameter. In step S5, the average long-lifetime room temperature phosphorescence lifetime of the test sample is compared with the average long-lifetime room temperature phosphorescence lifetime of the control sample to confirm the identification result of the fiber sample to be tested.

[0030] The above technical solution allows for further confirmation of the fiber sample under test using long-lifetime room-temperature phosphorescence decay information. Compared to using only emission peak information for judgment, introducing the average long-lifetime room-temperature phosphorescence lifetime increases the identification dimension and improves the ability to distinguish ramie fibers and their mixed fibers.

[0031] Specifically, long-lifetime room-temperature phosphorescence decay information can include one or more lifetime components. Different lifetime components and their proportional parameters can reflect the decay behavior of different emission centers in the sample. By calculating the average long-lifetime room-temperature phosphorescence lifetime using the lifetime components and corresponding proportional parameters, the complex decay process can be transformed into a lifetime index that is easy to compare. Comparing this average lifetime with the average lifetime of the control sample can confirm the preliminary identification results obtained from the photoluminescence emission peak position.

[0032] In practical applications, this lifetime verification step can reduce the possibility of misjudgment caused by near emission peak positions or test fluctuations, and transform the identification process from judging a single spectral peak position to judging both emission peak position and lifetime information, thereby improving the stability of the identification results.

[0033] Preferably, in step S5, the difference in photoluminescence emission peak position and the difference in long-lifetime room temperature phosphorescence lifetime caused by the transformation of cellulose type I to cellulose type II in ramie fibers are used as the identification criteria. When the emission peak position information and average long-life room temperature phosphorescence lifetime of the test sample both correspond to the ramie fiber control sample, the fiber sample to be tested is determined to be ramie fiber. When the emission peak position information and average long-life room temperature phosphorescence lifetime of the test sample both correspond to the mixed fiber control sample, the test fiber sample is determined to be a mixed fiber of lyocell fiber and ramie fiber.

[0034] The above technical solution allows us to use the differences in luminescence caused by the crystal form transformation of ramie fibers as a basis for identification. After the transformation from cellulose type I to cellulose type II in ramie fibers, the photoluminescence emission peak position and long-lifetime room temperature phosphorescence lifetime will change. Therefore, we can use these differences to determine whether the sample to be tested is ramie fiber or a mixed fiber containing ramie fiber.

[0035] Specifically, when the emission peak position information and average long-lifetime room temperature phosphorescence lifetime of the test sample correspond to those of the ramie fiber control sample, it indicates that the test sample has the luminescence characteristics of ramie fiber and can be identified as ramie fiber; when the emission peak position information and average long-lifetime room temperature phosphorescence lifetime of the test sample correspond to those of the mixed fiber control sample, it indicates that the test sample simultaneously exhibits the luminescence response of the mixed system of lyocell fiber and ramie fiber and can be identified as a mixed fiber containing ramie fiber.

[0036] In practical applications, this judgment method can combine the changes in ramie fiber crystal form, photoluminescence peak position, and long-lifetime room temperature phosphorescence lifetime, so that the identification process has clear structural and optical basis, and is especially suitable for the auxiliary identification of mixed samples of lyocell fiber and ramie fiber.

[0037] Compared with the prior art, the present invention has the following advantages: 1. This invention utilizes the changes in crystal structure and corresponding luminescence differences in ramie fibers after NaOH treatment for identification, rather than solely relying on fiber morphology observation or differences in chemical dissolution. By using the photoluminescence emission peak position under 365 nm excitation as a preliminary judgment criterion, combined with the long-lifetime room-temperature phosphorescence lifetime for confirmation, the differences between ramie and lyocell fibers can be reflected from the perspective of optical response, providing a clearer technical basis for the identification process.

[0038] 2. This invention, by setting up lyocell fiber control samples, ramie fiber control samples, and mixed fiber control samples, allows the emission peak position and lifetime information of the sample to be tested to be compared with the corresponding references. This method can not only be used to determine whether the sample to be tested contains ramie fiber, but also to assist in the identification of lyocell fiber and ramie fiber mixed systems, which is beneficial to improving the applicability of fiber component identification. Attached Figure Description

[0039] Figure 1 The ¹³C NMR spectrum of RA-0; Figure 2 X-ray diffraction data of RA series samples and schematic diagram of O atom interactions in cellulose type I and cellulose type II; Figure 3 Photographs of the RA series samples under different ultraviolet light and confocal micrographs of RA-0; Figure 4 Excitation spectra of RA series samples at different emission peaks and emission spectra of samples at different excitation peaks; Figure 5 The excitation spectra of the RA series samples at an emission wavelength of 425 nm and the emission spectra under different excitation conditions are shown. Figure 6 The graph shows the relationship between quantum yield, crystallinity, and crystal form of the RA series samples. Figure 7 Delayed emission photographs of RA series samples after UV irradiation was stopped; Figure 8 Long-lifetime room-temperature phosphorescence spectra of RA series samples under different excitation conditions; Figure 9 The CIE color coordinate trajectory diagrams corresponding to the long-lifetime room temperature phosphorescence spectra of the RA series samples under different excitation conditions are shown. Figure 10 Long-lifetime room-temperature phosphorescence lifetime diagram for RA series samples; Figure 11 A graph showing the relationship between long-lifetime room temperature phosphorescence lifetime and crystallinity and cellulose type II content of RA series samples; Figure 12 SEM and EDX-Mapping analysis images of RA samples with different crystallinity; Figure 13 SEM images and EDX-Mapping analysis diagrams of RA samples with different crystallinity; Figure 14 Anti-counterfeiting encryption effect diagrams for RA fiber combinations with different crystallinity and crystal structure; Figure 15 This is a schematic flowchart of the method for identifying ramie fibers and their mixed fibers based on long-life room temperature phosphorescence according to the present invention. Figure 16 This diagram illustrates the preparation and identification of CLY-0, RA-15, and their mixed fiber control samples. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. All equivalent substitutions, improvements, and variations made within the spirit and principles of the present invention should fall within the scope of protection of the present invention.

[0041] This invention provides a method for identifying ramie fibers and their mixed fibers based on long-lifetime room-temperature phosphorescence. The method is based on the changes in crystallinity and crystal form of ramie fibers after treatment with NaOH solution, and the resulting differences in photoluminescence emission peak positions and long-lifetime room-temperature phosphorescence lifetimes. By establishing luminescence characteristic information for lyocell fiber control samples, ramie fiber control samples, and mixed fiber control samples, the method identifies the fiber samples to be tested.

[0042] Specifically, this invention uses a lyocell fiber sample that has not been treated with NaOH solution as a lyocell fiber control sample, and a ramie fiber sample treated with a 15% NaOH solution as a ramie fiber control sample. The two are then mixed in different mass ratios to form a mixed fiber control sample. During identification, the photoluminescence emission spectrum of the fiber sample under 365 nm excitation conditions is first collected to obtain emission peak position information, which is then used for preliminary identification. Then, after stopping ultraviolet light excitation, the long-lifetime room-temperature phosphorescence decay information of the fiber sample is collected to obtain lifetime information, which is used to confirm the preliminary identification results.

[0043] This invention mainly utilizes the differences in luminescence behavior corresponding to changes in the crystal structure of ramie fibers for identification, which can reduce the reliance on fiber morphology observation, chemical solubility, or conventional infrared absorption peaks. This method is particularly suitable for the identification of ramie fibers and blends of lyocell and ramie fibers.

[0044] (1) Confirmation of the basic structure of ramie fiber The ramie fiber used in this invention is a natural cellulose fiber. To confirm the structural basis of ramie fiber, the ramie fiber sample RA-0, which was not treated with NaOH solution, was subjected to component analysis, molecular weight testing, and solid-state ¹³C NMR spectroscopy.

[0045] The cellulose, hemicellulose, and lignin contents of RA-0 were 75.9%, 11.6%, and 2.5%, respectively, indicating that RA-0 has a high cellulose content; its mass-average molecular weight was 2.201 × 10⁻⁶. 5 g / mol, with a number average molecular weight of 9.443 × 10⁻⁶ g / mol. 4 g / mol, with a polydispersity index of 2.33.

[0046] like Figure 1 As shown in the solid-state ¹³C NMR spectrum of RA-0, all characteristic peaks can be attributed to cellulose structures, thus proving that RA-0 is a cellulose fiber. This result indicates that the ramie fiber studied in this invention has a typical cellulose structural basis, and its molecular structure contains a large number of hydroxyl groups, providing structural conditions for the subsequent formation of hydrogen bonds, oxygen atom interactions, and cluster emission centers.

[0047] (2) Preparation of ramie fiber samples treated with different NaOH To obtain ramie fiber samples with different crystallinity and crystal structures, ramie fibers were immersed in NaOH solutions with mass fractions of 0%, 5%, 10%, 15%, 20%, and 30% for 8 hours at 25 °C. After immersion, the ramie fibers were rinsed with deionized water until the pH value was approximately 7.0, and then dried in a vacuum oven at 40 °C to obtain samples RA-0, RA-5, RA-10, RA-15, RA-20, and RA-30, respectively.

[0048] Among them, RA-15 is a ramie fiber sample treated with a 15% NaOH solution. Lyocell fiber usually does not require NaOH treatment, while ramie fiber is usually mercerized with a 15% NaOH solution before being made into fabric. Therefore, this invention uses untreated Lyocell fiber samples CLY-0 and RA-15 as the main control system.

[0049] (3) Crystallinity and crystal structure analysis X-ray diffraction tests were performed on the RA series samples, and the XRD curves were fitted using MDI Jade 6.0 software to obtain the crystalline diffraction peaks and amorphous peaks corresponding to the characteristic peaks of cellulose fibers. Based on the total integrated area Sp of the crystalline region and the integrated area IA of the amorphous region, the crystallinity CrI% of the ramie fiber samples was calculated using the following formula: Where Sp is the total integral area of ​​the crystalline region and IA is the integral area of ​​the amorphous region.

[0050] Meanwhile, the crystal structure of the RA series samples was determined based on the characteristic diffraction peaks of cellulose type I and cellulose type II. The diffraction angles 2θ corresponding to the characteristic diffraction peaks of cellulose type I were 14.9°, 16.5°, and 22.7°; the diffraction angles 2θ corresponding to the characteristic diffraction peaks of cellulose type II were 12.1°, 20.1°, and 22°.

[0051] The crystallinity, cellulose type II content, and quantum yield of the RA series samples are shown in Table 1 below: sample NaOH mass fraction CrI% Cellulose type II content QY / 312 nm RA-0 0 73.57% 0 3.46% RA-5 5% 66.03% 0 7.58% RA-10 10% 68.58% 34.82% 8.40% RA-15 15% 58.23% 100% 6.19% RA-20 20% 57.80% 100% 6.05% RA-30 30% 56.28% 100% 5.52% like Figure 2As shown, the X-ray diffraction characteristics of the RA series samples changed after treatment with NaOH solutions of different mass fractions. Combined with the table above, it can be seen that with increasing NaOH mass fraction, the crystal form of the RA sample's crystalline region gradually transformed from cellulose type I to cellulose type II. The cellulose type II content in RA-0 and RA-5 was 0%, in RA-10 it was 34.82%, and in RA-15, RA-20, and RA-30 it was 100%. Therefore, RA-15 can be used as a control sample for ramie fiber after complete conversion to cellulose type II.

[0052] Figure 2 The differences in O atom interactions between cellulose type I and cellulose type II were also revealed. The different intramolecular and intermolecular oxygen atom interactions between cellulose type I and cellulose type II affect the hydrogen bond network and the degree of electron delocalization between cellulose chains, thus influencing the formation of cluster emission centers. This structural difference provides a structural basis for the different photoluminescence characteristics and long-lifetime room-temperature phosphorescence lifetimes of the RA series samples.

[0053] (4) Photoluminescence phenomenon and spectral characteristics To investigate the photoluminescence properties of the RA series samples, RA-0, RA-5, RA-10, RA-15, RA-20 and RA-30 were observed under ultraviolet light at 254 nm, 312 nm and 365 nm, respectively.

[0054] like Figure 3 As shown, all six RA samples exhibited blue-green light emission under ultraviolet light irradiation at 254 nm, 312 nm, and 365 nm, but there were differences in the emission color and intensity among the different samples. Figure 3 The confocal microscopy images of RA-0 under 405 nm and 488 nm laser excitation are also shown. RA-0 shows a change from blue light to green light under different excitation wavelengths, indicating that RA fiber has wavelength-dependent photoluminescence characteristics.

[0055] Further photoluminescence spectra of the RA series samples were collected at different excitation and emission wavelengths. For example... Figure 4As shown, the RA series samples exhibit significant excitation and emission dependence. The main excitation peak of RA-0 is located at 258 nm, while the main excitation peaks of RA-5, RA-10, RA-15, RA-20, and RA-30 are located near 263 nm, 262 nm, 262 nm, 263 nm, and 263 nm, respectively. Under 254 nm excitation conditions, the main emission peaks of RA-0, RA-5, RA-10, RA-15, RA-20, and RA-30 are at 461 nm, 450 nm, 438 nm, 438 nm, 445 nm, and 450 nm, respectively. The variations in peak position and intensity in the excitation and emission spectra of different samples indicate that different crystallinity and crystal structures can cause differences in the luminescence centers of the RA samples.

[0056] like Figure 5 As shown, at an emission wavelength of 425 nm, the relative intensities of the excitation peaks near 260 nm and 360 nm differ among the RA series samples, indicating that the excitation responses of the RA samples vary under different processing conditions. The RA series samples all exhibit certain differences in emission peak position and emission intensity under excitation at 254 nm, 312 nm, and 365 nm. Specifically, under 312 nm excitation, a significant blue shift occurs in the emission peaks from RA-0 to RA-20, indicating that changes in crystallinity and crystal form may affect the photoluminescence behavior of the RA samples.

[0057] This invention uses the photoluminescence emission peak position under 365 nm excitation as a preliminary identification criterion. The 365 nm excitation condition matches commonly used ultraviolet detection conditions, and the RA series samples and CLY-0 / RA-15 hybrid fibers can show comparable differences in emission peak positions under this excitation condition. Therefore, it can be used to make a preliminary judgment on the fiber samples to be tested.

[0058] (5) Relationship between crystallinity, crystal structure and quantum yield The quantum yield of the RA series samples is related to crystallinity and crystal structure, but it is not determined by crystallinity alone.

[0059] like Figure 6 As shown, RA-0 has the highest crystallinity (73.57%) among the RA series samples, but its crystallinity (QY) is only 3.46%, which is relatively low. RA-10 has a crystallinity of 68.58%, with a cellulose type II content of 34.82%, exhibiting a mixed crystal form of cellulose type I and cellulose type II, and a QY of 8.40%. RA-15 has a cellulose type II content of 100% and a QY of 6.19%.

[0060] The above results indicate that the photoluminescence intensity of the RA sample is not determined solely by crystallinity, but is influenced by both crystallinity and crystal structure. Mixed crystal forms may be beneficial for improving quantum yield, while RA-15, completely converted to cellulose type II, exhibits more prominent long-lifetime room-temperature phosphorescence characteristics. These results provide experimental basis for selecting RA-15 as the control sample for ramie fiber in this invention.

[0061] (6) Long-lifetime room temperature phosphorescence phenomenon and lifetime characteristics After UV irradiation was stopped, all RA series samples exhibited green delayed luminescence, and RA samples with different crystallinity and crystal structure had different p-RTP delay times.

[0062] like Figure 7 As shown, delayed emission was observed in all RA series samples after irradiation with 254 nm, 312 nm, and 365 nm ultraviolet light was stopped under atmospheric conditions. However, the duration of delayed emission varied among different samples after irradiation with different ultraviolet lights. Among them, the delayed emission time was longer after irradiation with 312 nm ultraviolet light, indicating that the long-lifetime room temperature phosphorescence of the RA series samples also has an excitation wavelength dependence.

[0063] Further p-RTP spectra of the RA series samples under different excitation conditions were collected. For example... Figure 8 As shown, the long-lifetime room-temperature phosphorescence emission of the RA series samples exhibits a significant excitation dependence. With increasing excitation wavelength, the p-RTP emission peak gradually redshifts. For example, the emission peak of RA-0 under 274 nm excitation is at 468 nm, but redshifts to 510 nm when the excitation wavelength increases to 334 nm; similarly, the emission peak of RA-15 under 274 nm excitation is at 468 nm, but redshifts to 504 nm when the excitation wavelength increases to 334 nm. This result indicates that emission centers with different emission capabilities exist within the RA series samples.

[0064] like Figure 9 As shown, the CIE color coordinate trajectories corresponding to the p-RTP spectra of the RA series samples change under different excitations. Taking RA-0 as an example, its CIE coordinates are (0.2128, 0.3036) under 254 nm excitation, (0.2581, 0.432) under 312 nm excitation, and (0.324, 0.4278) under 365 nm excitation. With the increase of excitation wavelength, the emission color gradually changes from the blue-green region to the green region, further proving that the p-RTP emission of the RA series samples is excitation-dependent.

[0065] The p-RTP lifetime test results of the RA series samples are shown in Table 2: sample τ1 / ms A1 / % τ2 / ms A2 / % τ3 / ms A3 / % Mean lifetime τ / ms RA-0 0.73 23.34 4.37 30.15 18.73 46.51 10.20 RA-5 0.84 16.18 8.35 37.62 51.58 46.19 27.06 RA-10 0.90 19.27 11.34 38.19 75.63 42.55 36.68 RA-15 1.55 16.35 14.49 41.55 86.07 41.92 42.35 RA-20 0.95 20.52 11.22 41.37 71.24 38.11 31.99 RA-30 0.76 19.73 9.61 40.40 60.92 39.87 28.32 like Figure 10 As shown, RA samples treated with different NaOH mass fractions exhibited different p-RTP lifetimes. RA-15 had the longest average lifetime of 42.35 ms, while RA-0 had a shorter average lifetime of 10.20 ms. This result indicates that the crystal form transformation induced by NaOH treatment affects the long-lifetime room-temperature phosphorescence emission capability of RA samples, with the cellulose type II structure being more conducive to sustained p-RTP emission.

[0066] like Figure 11 As shown, the p-RTP lifetime of the RA series samples does not simply increase with increasing crystallinity. RA-0 has the highest crystallinity but the shortest p-RTP lifetime; RA-15 has lower crystallinity than RA-0 and RA-10, but its cellulose type II content reaches 100%, and it has the longest average lifetime. This result indicates that the cellulose type II structure has a more significant impact on the p-RTP lifetime of RA samples than crystallinity alone.

[0067] Therefore, in this invention, the long-lifetime room-temperature phosphorescence lifetime information of the sample under test can serve as a basis for confirming the preliminary identification results of the 365 nm photoluminescence emission peak position. Compared with judging solely based on the photoluminescence emission peak position, further introducing p-RTP lifetime information can improve the reliability of the identification results.

[0068] (7) Surface morphology and elemental analysis To eliminate the interference of residual sodium ions or other exogenous ions after NaOH treatment on the interpretation of the luminescence behavior of the RA series samples, the RA series samples were observed by scanning electron microscopy and elemental analysis by EDX-Mapping.

[0069] like Figure 12 As shown, the RA fibers are relatively uniform in size, with a diameter of approximately 40 μm. With increasing NaOH mass fraction, the fiber surface gradually becomes rougher from the relatively smooth surface of RA-0. Meanwhile, EDX-Mapping analysis results show that the surface of the RA sample is mainly composed of C and O elements, indicating that the basic composition of the RA sample is still dominated by cellulose-related C and O elements.

[0070] like Figure 13 As shown, the surface roughness of RA samples varies under different NaOH treatment conditions; meanwhile, the contents of other elements besides C and O in the RA samples are low. Combined with the elemental content test results, it can be seen that the Na content in the RA series samples is almost zero, indicating that the cleaning process has essentially removed the metal ions from the RA surface.

[0071] The specific results are shown in Table 3: sample C / wt% O / % Na / % RA-0 62.0 37.9 0.1 RA-5 58.4 41.5 0.0 RA-10 61.2 38.6 0.4 RA-15 59.8 39.9 0.2 RA-20 57.0 42.9 0.2 RA-30 59.0 40.8 0.1 The results above indicate that the differences in photoluminescence and p-RTP of the RA series samples mainly stem from changes in crystallinity, crystal structure, and inter-chain interactions of cellulose, rather than differences caused by residual metal ions.

[0072] (8) Mechanism and theoretical explanation of CTE Ramie fiber contains a large number of hydroxyl groups, enabling abundant hydrogen bonds and interactions between oxygen atoms within the cellulose molecular chains. According to the CTE mechanism, these interactions—including hydroxyl groups, hydrogen bonds, and oxygen atoms—can lead to electron delocalization and the formation of cluster emission centers. Different degrees of crystallinity, crystal structures, and arrangements of cellulose molecular chains result in variations in the size, spatial arrangement, and emission capacity of these cluster emission centers, thus altering the photoluminescence peak position and p-RTP lifetime.

[0073] During NaOH treatment, the crystalline structure of ramie fibers changes, with cellulose type I gradually transforming into cellulose type II. The intramolecular and intermolecular interactions between oxygen atoms in cellulose type I and cellulose type II differ, and this difference affects the formation of cluster emission centers. RA-15 contains 100% cellulose type II, and its average p-RTP lifetime is 42.35 ms, indicating that the cellulose type II structure promotes long-lifetime room-temperature phosphorescence emission.

[0074] Furthermore, coupled trimer and coupled hexamer models of cellulose type I and cellulose type II were constructed based on the smallest structural unit D-Cbs of cellulose, and the orbitals, energy levels, and SOC constants were obtained through conformational optimization and TD-DFT calculations. By comparing the emission capabilities and phosphorescence emission tendencies of different coupling structures, the influence of different crystal structures on photoluminescence and long-lifetime room-temperature phosphorescence emission behavior can be explained. The coupled D-Cbs hexamer exhibits a larger redshift emission and is more favorable for phosphorescence emission compared to the coupled D-Cbs trimer.

[0075] Therefore, this invention combines the crystallinity, crystal structure, photoluminescence emission peak position, and long-lifetime room temperature phosphorescence lifetime of ramie fiber as the technical basis for identifying ramie fiber and its mixed fibers.

[0076] (9) Criteria for identifying mixed fibers In actual production, lyocell fibers typically do not require NaOH treatment, while ramie fibers are usually mercerized with a 15% NaOH solution before being made into fabric. Therefore, this invention selects the untreated lyocell fiber sample CLY-0 and the ramie fiber sample RA-15 treated with a 15% NaOH solution as the main control samples.

[0077] CLY-0 and RA-15 samples were shredded and mixed to prepare five mixed fiber control samples with CLY-0:RA-15 mass ratios of 1:1, 1:3, 1:5, 3:1, and 5:1. By comparing the photoluminescence and p-RTP properties of these mixed fibers under the same conditions, preliminary identification was made by the peak position of the photoluminescence emission spectrum under 365 nm excitation, and the mixed fibers were effectively identified by their long lifetime characteristics.

[0078] like Figure 15 As shown, the identification method of the present invention includes: establishing luminescence characteristic information of lyocell fiber control samples, ramie fiber control samples, and mixed fiber control samples; obtaining the fiber sample to be tested and preparing it into a test sample; acquiring the photoluminescence emission spectrum of the test sample under 365nm excitation conditions and obtaining emission peak position information; acquiring the long-lifetime room temperature phosphorescence decay information of the test sample after ultraviolet light excitation stops and obtaining lifetime information; and identifying whether the fiber sample to be tested is ramie fiber or a mixed fiber of lyocell fiber and ramie fiber based on the difference between the emission peak position information and lifetime information and the corresponding information of the control sample.

[0079] like Figure 16 As shown, CLY-0 is a lyocell fiber sample without NaOH treatment, and RA-15 is a ramie fiber sample treated with a 15% NaOH solution. CLY-0 and RA-15 were shredded and mixed at mass ratios of 1:1, 1:3, 1:5, 3:1, and 5:1 to obtain five mixed fiber control samples. By comparing the emission peak positions of the test sample and the above control samples under 365 nm excitation and the long-lifetime room-temperature phosphorescence lifetime after UV excitation was stopped, it can be determined whether the test sample belongs to a mixture of lyocell and ramie fibers.

[0080] The above-described technical solution enables the identification of ramie fibers and blends of lyocell and ramie fibers. This method utilizes the differences in luminescence caused by variations in the crystallinity and crystal form of ramie fibers themselves, without relying on complex chemical dissolution processes or solely on morphological observation or subjective experience.

[0081] Specifically, this invention uses the photoluminescence emission peak position under 365 nm excitation as a preliminary identification criterion and the long-lifetime room-temperature phosphorescence lifetime after ultraviolet light cessation as a confirmation criterion. Since RA-15 contains 100% cellulose type II and its average p-RTP lifetime is significantly longer than that of RA-0, the long-lifetime room-temperature phosphorescence characteristic can enhance the reliability of the identification of ramie fibers and their blends.

[0082] (10) Visual aids like Figure 14As shown, patterned combinations of RA fibers with different crystallinity and crystal structure can form blue-green luminescent patterns under 254 nm ultraviolet light irradiation. When the ultraviolet light is turned off, the pattern changes from blue to green and gradually disappears over time. This result demonstrates that RA fibers with different crystallinity and crystal structure exhibit visible differences in delayed luminescence, and also proves the observability of p-RTP emission differences in RA samples from an application perspective.

[0083] In practical applications, the delayed luminescence phenomenon of the sample after the ultraviolet light is removed can be observed with the naked eye or recorded by photograph. Then, the sample can be confirmed and judged by combining the photoluminescence emission peak position under 365 nm excitation and the long-lifetime room temperature phosphorescence lifetime test results. This visualization method can serve as an auxiliary observation means for the identification method of this invention.

[0084] Example 1: Identification of ramie fiber samples using the method of the present invention This embodiment uses ramie fibers treated with a 15% NaOH solution as the sample to be tested.

[0085] Take one sample of the fiber to be tested, cut it into pieces, and prepare the test sample. Take another sample of Lyocell fiber, CLY-0, which has not been treated with NaOH solution, as a Lyocell fiber control sample; take a ramie fiber sample, RA-15, which has been treated with 15% NaOH solution by mass, as a ramie fiber control sample.

[0086] RA-15 was prepared by the following steps: ramie fibers were placed in a 15% NaOH solution and soaked at 25 °C for 8 hours; after soaking, they were rinsed with deionized water until the pH value was about 7.0; and then dried in a vacuum oven at 40 °C to obtain the RA-15 sample.

[0087] The test sample, CLY-0 control sample, and RA-15 control sample were placed under the same testing conditions, and photoluminescence emission spectra were collected under 365 nm excitation to obtain the emission peak position information of each sample. The emission peak position information of the test sample was compared with that of the CLY-0 control sample and the RA-15 control sample.

[0088] If the emission peak position information of the sample to be tested corresponds to that of the RA-15 control sample, but is different from that of the CLY-0 control sample, then the sample to be tested is preliminarily identified as a ramie fiber sample.

[0089] Subsequently, the sample to be tested was excited with ultraviolet light, and after the ultraviolet light excitation was stopped, the long-lifetime room temperature phosphorescence decay information of the sample was collected to obtain its average long-lifetime room temperature phosphorescence lifetime. This average lifetime was compared with the average lifetime of the RA-15 control sample. The average p-RTP lifetime of the RA-15 sample was 42.35 ms, while that of the RA-0 sample was 10.20 ms, showing a significant difference. If the average lifetime information of the sample to be tested corresponds to that of the RA-15 control sample, then the sample to be tested is confirmed to be ramie fiber.

[0090] In this embodiment, the photoluminescence emission peak position under 365 nm excitation is used for preliminary identification, and the long-lifetime room temperature phosphorescence lifetime is used to confirm the identification result, thereby avoiding the error that may be caused by relying on a single spectral peak position for judgment.

[0091] Example 2: Identification of mixed fibers of lyocell and ramie using the method of the present invention. This embodiment illustrates the process of identifying a mixture of lyocell and ramie fibers using the method of the present invention.

[0092] Take lyocell fiber sample CLY-0 that has not been treated with NaOH solution, and ramie fiber sample RA-15 that has been treated with 15% NaOH solution. CLY-0 and RA-15 samples were cut into small pieces and mixed together to prepare five groups of mixed fiber control samples with CLY-0:RA-15 mass ratios of 1:1, 1:3, 1:5, 3:1 and 5:1 respectively.

[0093] Take a sample of the mixed fiber to be tested, cut it into pieces, and prepare the test sample. Place the test sample and five groups of mixed fiber control samples under the same test conditions, and collect photoluminescence emission spectra under 365 nm excitation conditions to obtain the emission peak position information of the test sample and each mixed fiber control sample.

[0094] The emission peak position information of the sample to be tested was compared with the emission peak position information of five groups of mixed fiber control samples. If the emission peak position information of the sample to be tested corresponds to one of the mixed fiber control samples, the sample to be tested was preliminarily identified as a mixture of lyocell fiber and ramie fiber.

[0095] Subsequently, the sample to be tested was excited with ultraviolet light, and after the ultraviolet light excitation was stopped, the long-lifetime room-temperature phosphorescence decay information of the sample was collected to obtain the average long-lifetime room-temperature phosphorescence lifetime of the sample. The average lifetime of the sample to be tested was compared with the average lifetime of five groups of mixed fiber control samples. If the emission peak position information and average lifetime information of the sample to be tested correspond to the same group of mixed fiber control samples, the sample to be tested was confirmed to be a mixture of lyocell fiber and ramie fiber.

[0096] This embodiment demonstrates the application of the present invention to hybrid fibers. First, the emission peak position information under 365 nm excitation is used to determine whether the sample possesses the characteristics of CLY-0 / RA-15 hybrid fibers, and then confirmation is made through long-lifetime room-temperature phosphorescence lifetime. This method can be used for the auxiliary identification of lyocell and ramie fiber hybrid systems.

[0097] Example 3: Using the method of the present invention to assist in determining the treatment status of ramie fibers This embodiment illustrates the process of using the method of the present invention to assist in judging the processing status of ramie fibers.

[0098] The ramie fiber sample to be tested was cut into pieces to prepare the test sample. Separately, RA-0, RA-5, RA-10, RA-15, RA-20, and RA-30 were taken as control samples for the treatment state. RA-0, RA-5, RA-10, RA-15, RA-20, and RA-30 were obtained by treating ramie fiber with NaOH solutions of 0%, 5%, 10%, 15%, 20%, and 30% by mass, respectively.

[0099] Under the same test conditions, photoluminescence emission spectra of the test sample and control samples under each treatment state were measured under 365 nm excitation to obtain emission peak position information. Then, the test sample and control samples under each treatment state were excited by ultraviolet light, and long-lifetime room temperature phosphorescence decay information was collected after ultraviolet light excitation was stopped to obtain average lifetime information.

[0100] The emission peak position and average lifetime information of the sample to be tested were compared with the corresponding information of RA-0, RA-5, RA-10, RA-15, RA-20, and RA-30, respectively. If the emission peak position and average lifetime information of the sample to be tested both correspond to RA-15, then the ramie fiber sample to be tested is judged to have the luminescence characteristics corresponding to ramie fiber treated with 15% NaOH.

[0101] In this embodiment, the average p-RTP lifetime of RA-15 is 42.35 ms, that of RA-10 is 36.68 ms, that of RA-20 is 31.99 ms, that of RA-30 is 28.32 ms, and that of RA-0 is 10.20 ms. These differences in lifetime can help determine whether the processing state of the ramie fiber sample being tested is close to that of RA-15.

[0102] This embodiment illustrates that the present invention can not only be used for the identification of ramie fibers and mixed fibers, but also to assist in determining whether ramie fibers have luminescent characteristics corresponding to conventional mercerizing treatment.

[0103] Example 4: Visual Assisted Identification Using the Method of the Invention This embodiment is used to illustrate that the long-lifetime room temperature phosphorescence difference upon which the present invention is based can be observed with the aid of visualization.

[0104] RA fiber samples with different crystallinity and crystal structure were taken and combined according to a predetermined pattern. The luminescence state of the combined pattern was observed under 254nm ultraviolet light irradiation. The results showed that the combined pattern could exhibit a blue-green luminescence effect.

[0105] After stopping the 254 nm ultraviolet light irradiation, the delayed emission state of the combined pattern was observed again. When the ultraviolet light was turned off, the pattern changed from blue to green and gradually disappeared over time. This phenomenon demonstrates that RA fibers with different crystallinities and crystal structures exhibit visible differences in delayed emission.

[0106] This embodiment can be used as an auxiliary application of the identification method of the present invention. In actual identification, the delayed emission phenomenon of the sample after the ultraviolet light stops can be observed or recorded by the naked eye or by taking pictures. Then, the sample can be confirmed and judged by combining the photoluminescence emission peak position under 365 nm excitation and the long-lifetime room temperature phosphorescence lifetime test results.

[0107] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0108] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0109] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence, characterized in that: Includes the following steps: S1. Establish photoluminescence emission peak position information and long-lifetime room temperature phosphorescence lifetime information for lyocell fiber control samples, ramie fiber control samples, and mixed fiber control samples; S2. Obtain the fiber sample to be tested and prepare it into a test sample; S3. Acquire the photoluminescence emission spectrum of the test sample under 365 nm excitation conditions, obtain emission peak position information, and perform preliminary identification based on the emission peak position information; S4. After the ultraviolet light excitation stops, collect the long-lifetime room temperature phosphorescence decay information of the test sample to obtain lifetime information; S5. Based on the difference between the emission peak position information and lifetime information and the corresponding information of the control sample, identify whether the fiber sample to be tested is ramie fiber or a mixture of lyocell fiber and ramie fiber.

2. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 1, characterized in that: The Lyocell fiber control sample was a Lyocell fiber sample that had not been treated with NaOH solution. The ramie fiber control sample was a ramie fiber sample treated with a 15% NaOH solution. The mixed fiber control sample was formed by mixing the lyocell fiber control sample and the ramie fiber control sample.

3. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 2, characterized in that: The ramie fiber control sample was prepared through the following steps: Ramie fibers were placed in a 15% NaOH solution and soaked at 25°C for 8 hours. After soaking, the ramie fibers are rinsed with deionized water until the pH value of the ramie fibers is about 7.

0. The rinsed ramie fibers were then vacuum dried at 40 °C to obtain the ramie fiber control sample.

4. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 2, characterized in that: The mixed fiber control sample was formed by cutting and mixing the lyocell fiber control sample and the ramie fiber control sample; The mass ratio of the lyocell fiber control sample to the ramie fiber control sample is selected from at least one of 1:1, 1:3, 1:5, 3:1 and 5:

1.

5. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 1, characterized in that: In establishing the photoluminescence emission peak position information and long-lifetime room-temperature phosphorescence lifetime information, X-ray diffraction tests were also performed on the ramie fiber control sample. The total integrated area Sp of the crystalline region and the integrated area IA of the amorphous region were obtained from the X-ray diffraction curves, and the crystallinity CrI% of the ramie fiber control sample was calculated according to the following formula: Where Sp is the total integral area of ​​the crystalline region and IA is the integral area of ​​the amorphous region.

6. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 5, characterized in that: When establishing the photoluminescence emission peak position information and long-lifetime room temperature phosphorescence lifetime information, the crystal structure of the ramie fiber control sample was determined based on the characteristic diffraction peaks of cellulose type I and cellulose type II. The characteristic diffraction peaks of cellulose type I correspond to diffraction angles 2θ of 14.9°, 16.5° and 22.7°, and the characteristic diffraction peaks of cellulose type II correspond to diffraction angles 2θ of 12.1°, 20.1° and 22°. The crystallinity CrI%, crystal structure, photoluminescence emission peak position information, and long-lifetime room temperature phosphorescence lifetime information are used as the corresponding information of the ramie fiber control sample for comparison with the corresponding information of the test sample.

7. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 1, characterized in that: In step S4, at least one lifetime component and its corresponding scaling parameter are obtained based on the long-lifetime room temperature phosphorescence decay information, and the average long-lifetime room temperature phosphorescence lifetime of the test sample is calculated based on the lifetime component and its corresponding scaling parameter. In step S5, the average long-lifetime room temperature phosphorescence lifetime of the test sample is compared with the average long-lifetime room temperature phosphorescence lifetime of the control sample to confirm the identification result of the fiber sample to be tested.

8. The method for identifying ramie fibers and their blends based on long-life room-temperature phosphorescence according to claim 6, characterized in that: In step S5, the difference in photoluminescence emission peak position and the difference in long-lifetime room temperature phosphorescence lifetime caused by the transformation of cellulose type I to cellulose type II in ramie fibers are used as the identification criteria. When the emission peak position information and average long-life room temperature phosphorescence lifetime of the test sample both correspond to the ramie fiber control sample, the fiber sample to be tested is determined to be ramie fiber. When the emission peak position information and average long-life room temperature phosphorescence lifetime of the test sample both correspond to the mixed fiber control sample, the test fiber sample is determined to be a mixed fiber of lyocell fiber and ramie fiber.

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