Method for measuring length of cotton linter fiber

Abstract

The invention discloses a method for measuring the length of cotton linter fibers, which comprises the following steps of: soaking with anhydrous alcohol and a sodium hydroxide solution, dyeing with Congo red for pretreatment, diluting with distilled water, arranging a sample on a glass slide coated with glycerol for sample preparation, imaging through a microscope, automatically tracking and calculating through a computer, and counting the number of fibers at each length level. According to the method, the defects that a traditional hand pulling method is inaccurate in measurement and the length of fibers with the length of 8 mm or below is difficult to measure can be overcome, meanwhile, the method has good substitutability for the traditional hand pulling method and a roller method, and the method is suitable for short-fiber cotton linter products with large fiber length distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber length measurement methods, and specifically relates to a method for measuring the length of cotton linter fibers. Background Art

[0002] Cotton linter is a by-product of cotton. With the development of economy and technology, cotton linter is no longer just a by-product of cotton. Its extensive functional roles have made it an indispensable basic material in industries such as chemical fiber, papermaking, and cotton cellulose, and it is even the most basic material for military explosives, rocket propellants, food and medicine, and new energy batteries. The fiber length and distribution of cotton linter are key technical properties of cotton linter. The fiber length distribution is directly related to the batching and process reactions in the processing and production process of cotton linter.

[0003] At present, the fiber length of cotton linter is classified and graded based on 13 mm. For a long time, in actual production, the fiber length of cotton linter has been measured with reference to GB / T19617, that is, the hand-stretching and ruler-measuring method for measuring the fiber length of cotton is used. This method is applicable to the detection of fiber lengths of 28 mm and above. However, for cotton linter fibers with a benchmark of 13 mm, a large proportion of the lengths are distributed below 8 mm. It is very difficult to manually comb the fibers, and the measurement accuracy is poor. At the same time, it is also difficult to obtain an accurate fiber length distribution through measurement, which makes it difficult for industries that have requirements for fiber length, including the refined cotton industry, to control the quality of cotton linter raw materials in actual production, especially affecting the process of developing and producing high-end products such as high-viscosity and military products that are urgently needed in the cotton cellulose industry in China. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for measuring the length of cotton linter fibers to solve the deficiencies in the background art.

[0005] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0006] A method for measuring the length of cotton linter fibers, the measurement method comprising the following steps:

[0007] Step 1: Take fiber samples from multiple points in different parts of the cotton linter, soak them successively with anhydrous alcohol and sodium hydroxide solution to break the influence of the cutin membrane and primary cell wall, and then pre-treat the fibers with Congo red solution for staining to facilitate microscopic observation;

[0008] Step 2: Dilute the fiber samples with distilled water and take samples from multiple points. Spread all the taken fibers on a glass slide coated with glycerin, and use a dissecting needle to arrange them evenly to prevent overlap;

[0009] Step 3: Place the prepared slide on the stage of the microscope, select an appropriate objective lens magnification, adjust the microscope focus to obtain a clear image, and the morphological image of the measured fiber can be observed through the microscope eyepiece and on the display screen connected to the digital imaging system. Use a paper fiber measuring instrument to divide each fiber into multiple straight segments along the fiber direction. The computer automatically tracks, calculates, and counts the number of fibers at each length level, and finally obtains the average length and distribution information of the sample fibers.

[0010] Preferably, fiber samples are taken from multiple points of cotton linters, including the following steps: Take fiber samples from multiple points of different parts of cotton linters, tear the fiber samples into thin slices, remove obvious large non-fiber substances, and take two fiber samples, each weighing 1 g.

[0011] Preferably, the pretreatment of dyeing the fiber sample includes the following steps:

[0012] Soak the fiber sample in absolute alcohol for 1 minute, stir continuously with a glass rod during soaking, take out the sample, and squeeze out the alcohol.

[0013] Soak it in a sodium hydroxide solution with a mass concentration of 17.5 ± 0.5% for 5 minutes, stir continuously with a glass rod during soaking, transfer the fiber sample to a copper wire mesh, rinse it with distilled water until the pH of the eluate is 7, and squeeze out the excess water.

[0014] Put the fiber sample into a boiling Congo red staining solution with a mass concentration of 1%, boil for 10 minutes, then filter out the fiber sample and wash it with distilled water to remove the staining solution.

[0015] Preferably, the preparation of the fiber sample slide includes the following steps: Add the washed fiber sample to a beaker containing 1 L of distilled water, stir evenly, pick up the fibers with tweezers under stirring, take samples from multiple points, and absorb the excess water with filter paper. Apply an appropriate amount of glycerin on the slide, arrange all the taken fibers on the slide, and use a dissecting needle to arrange the fibers evenly to prevent overlap. Cover the slide with a cover glass and set it aside for use.

[0016] Preferably, the microscopic length measurement of the fiber sample includes the following steps: Use a calibrated Olympus microscope to measure the fiber morphology, use a magnification of 2 times, adjust the microscope focus to make the image clearly presented on the computer display screen. The number of fibers that can be observed in each slide is 300 - 500, and use a paper fiber measuring instrument to set the limit value of the fine fibers of the measured fiber to 0.2 - 0.5 mm.

[0017] Preferably, through a paper fiber measuring instrument, depict the fiber skeleton structure, and use the mouse to divide the fiber into multiple straight segments along the fiber direction on the display screen to measure the fiber length at each length level l i in and count the number of roots n i, calculate the length-weight average fiber length and coefficient of variation of the fibers, and draw a length frequency diagram.

[0018] Preferably, after both fiber specimens are measured, the relative error of the length-weight average fiber length results of the two parallel fiber specimens should not exceed ±2%.

[0019] Preferably, calculate the length-weight average fiber length and coefficient of variation of the fibers through formulas (1)-(4), and calculate and draw the fiber length frequency diagram through formulas (5)-(6).

[0020] Number average fiber length L

[0021]

[0022] Assume that the fibers have the same thickness, and the length-weight average fiber length L′

[0023]

[0024] The coefficient of variation CV value is calculated by formulas (3)-(4).

[0025]

[0026] The percentage content f of the number of fibers in each stage in the length frequency diagram i Calculated by formula (5).

[0027]

[0028] Assume that each fiber has the same thickness, and the length-weight percentage content f′ of the fibers in each stage i Calculated by formula (6).

[0029]

[0030] In the formula:

[0031] n i —— The number of fibers in the i-th stage;

[0032] l i —— The median value of the fiber length in the i-th stage, in millimeters (mm);

[0033] s —— Standard deviation, in millimeters (mm);

[0034] ∑n i —— The total number of fibers in each stage;

[0035] ∑n i l i —— The total fiber length value in each stage, in millimeters (mm).

[0036] The technical effects that can be achieved by the present invention adopting the above technical solution: The cotton linter fiber sample is soaked successively in anhydrous alcohol and sodium hydroxide solution. After breaking the influence of the cutin membrane and the primary wall, the fiber sample is pre-stained with Congo red solution. Then, the fiber sample is diluted with distilled water and sampled at multiple points. All the taken fibers are spread out on a glass slide coated with glycerol, and are arranged evenly with a dissecting needle to prevent overlapping. The prepared glass slide is placed on the stage of a microscope, and the microscope focus is adjusted to make the image clear. Each fiber is divided into multiple straight segments along the fiber direction, and a computer automatically tracks and counts the number of fibers in each length level to obtain the fiber length and distribution information. This measurement method is applicable to the measurement of the fiber length in the full length range of 0 - 14.5 mm and the distribution with a class interval of 0.5 mm, which can make up for the defect that the traditional hand-stretching method is difficult to measure the fiber length of 8 mm and below. At the same time, for the cotton linter fibers with a length of 8 mm and above, its measurement results have good substitutability for both the traditional hand-stretching method and the roller method. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0038] Figure 1 It is a partial microscopic view of the fiber sample in the present invention;

[0039] Figure 2 It is a distribution diagram of the quantity and length-weight percentage of each level of fiber in the present invention;

[0040] Figure 3 It is a comparison diagram of the fiber length distribution results of more than 8 mm in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0042] A method for measuring the length of cotton linter fibers, the measurement method comprising the following steps:

[0043] Step 1: Take fiber samples from different parts of the cotton linter at multiple points, tear the fiber samples into thin slices, and remove obvious large non-fiber substances. A total of two fiber samples are taken, each weighing 1 g.

[0044] The dyeing pretreatment of the fiber sample includes the following steps:

[0045] Soak the fiber sample in about 40 ml of absolute alcohol for 1 minute, continuously stir with a glass rod during soaking, take out the sample, and squeeze out the alcohol.

[0046] Soak it in about 40 ml of sodium hydroxide solution with a mass concentration of 17.5 ± 0.5% for 5 minutes, continuously stir with a glass rod during soaking, transfer the fiber sample to a copper wire mesh, and rinse it with distilled water until the pH of the rinsing liquid is 7, then squeeze out the excess water.

[0047] Put the fiber sample into about 100 ml of boiling congo red solution with a mass concentration of 1%, boil for 10 minutes, then filter out the fiber sample and wash the dyeing solution with distilled water.

[0048] Step 2: Prepare the fiber sample for microscopy, including the following steps: Add the washed fiber sample to a beaker containing 1 L of distilled water, stir evenly, pick up the fiber with forceps under stirring, take multiple samples, and blot the excess water with filter paper. Apply an appropriate amount of glycerin on the glass slide, arrange all the fibers taken on the glass slide, and use a dissecting needle to arrange the fibers evenly to prevent overlap. Cover the glass slide with a coverslip and set it aside for use.

[0049] Step 3: Measure the length of the fiber sample under a microscope, including the following steps: Use a calibrated Olympus OLYMPUS microscope for fiber morphology determination. The microscope uses a magnification of 2 times. Adjust the microscope focus so that the image is clearly presented on the computer display screen. As Figure 1 shown, the number of fiber roots that can be observed in each glass slide is about 300. Set the limit value of the fine fibers of the measured fibers to 0.4 mm through a papermaking fiber measuring instrument. This papermaking fiber measuring instrument is produced by Zhuhai Hualun Papermaking Technology Co., Ltd.

[0050] Through the papermaking fiber measuring instrument, depict the fiber skeleton structure, use the mouse to divide the fiber into multiple straight lines along the fiber direction on the display screen to measure the fiber length l i in each length class and count the number of roots n i , calculate the length-weight average fiber length and coefficient of variation of the fiber, and draw a length frequency diagram. Measure both samples of the fiber. The relative error of the length-weight average fiber length results of the two parallel fiber samples should not exceed ±2%.

[0051] Calculate the length-weight average fiber length and coefficient of variation of the fiber through formulas (1)-(4), and calculate and draw the fiber length frequency diagram through formulas (5)-(6).

[0052] Number average fiber length L

[0053]

[0054] Assume that the fiber thickness is uniform, and the length-weight average fiber length L′

[0055]

[0056] The coefficient of variation CV value is calculated by formulas (3)-(4)

[0057]

[0058] The percentage content f of the number of fibers in each grade in the length frequency diagram i is calculated by formula (5)

[0059]

[0060] Assume that each fiber has a uniform thickness, and the length-weight percentage content f′ of the fibers in each grade i is calculated by formula (6)

[0061]

[0062] Randomly select the results of a certain sample measurement for data processing demonstration. All results are shown in Table 1. Taking the median value of the length interval as the abscissa and the 3rd column and the 8th column in Table 1 as the ordinates to plot a graph, we can obtain the Figure 2 fiber length frequency diagram of this sample as shown. At the same time, according to formulas (1)-(4), the length-weight average fiber length and the coefficient of variation of the sample are calculated to be 8.76 mm and 27.2% respectively.

[0063] Table 1 Data processing data table of a certain sample

[0064]

[0065] In addition, to compare the differences between the measurement method established in this application and the traditional method, 18 experimental samples were randomly selected from the same batch of short cotton lint fiber samples, and each sample was divided into three equal parts. One part was used for the hand-tearing method, one part was used for the roller method, and one part was used for the method established in this application. However, considering that it is difficult to sample fibers below 8 mm by the hand-tearing method and the roller method, only the short cotton lint samples above 8 mm combed out were measured. The results of the method established in this application and the roller method are the average values of two measurements. All results are shown in Table 2.

[0066] Table 2 Result comparison of three testing methods

[0067]

[0068] As can be seen from the data in Table 2, the results of the established method are close to those of the other two methods, and the relative error of the average value is within 12%. The standard deviation result of the established method is significantly smaller than that of the hand-stretching method, indicating that the established method has better stability. Through correlation analysis, the linear relationship between the results of the hand-stretching and ruler-measuring method and the method established in this application is: y = 1.938x - 7.867, and the correlation coefficient r = 0.861. The linear relationship between the results of the roller method and the method established in this application is y = 0.883x + 1.753, and the correlation coefficient r = 0.975. This shows that the established method has good substitutability for both the hand-stretching and ruler-measuring method and the roller method under ideal conditions. Compared with the hand-stretching and ruler-measuring method, the results are closer to those of the roller method. Further, Figure 3 The distribution frequency results of different length intervals between the roller method and the established method were compared, indicating that the results are relatively close. The above shows that for cotton linter fibers with a length of 8 mm or more, the measurement results of the established method have good substitutability for both the traditional hand-stretching method and the roller method. This method is applicable to the distribution measurement of fiber length in the full length interval of 0 - 14.5 mm and the group distance of 0.5 mm.

[0069] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to the specific embodiments only. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for measuring the length of cotton linters, characterized in that: The determination method comprises the following steps: Step 1, taking fiber samples from different parts of cotton linters, soaking them in anhydrous alcohol and sodium hydroxide solution in turn to break the cuticle and primary wall, and then pre-staining the fibers with Congo red for easy microscopic observation; Step 2: Dilute the fiber with distilled water and take samples at multiple points. Arrange all the fibers on a glass slide coated with glycerol and arrange them evenly with a dissecting needle to prevent overlap. Step 3, place the prepared slide on the stage of the microscope, select the appropriate objective lens magnification, adjust the focal length of the microscope to make the image clear, and the morphological image of the measured fiber can be observed in the microscope eyepiece and the display screen connected to the digital imaging system. Each fiber is subdivided into multiple straight lines along the fiber direction through computer software. The computer automatically tracks, calculates and counts the number of fibers at each level of length, and finally obtains the average fiber length and distribution information.

2. The method for measuring the length of cotton linters according to claim 1, characterized in that: In the step 1, fiber samples are collected from multiple points at different locations of the cotton linters, the fiber samples are torn into thin slices, and obviously large pieces of non-fiber matter are removed. Two fiber samples are collected, each weighing 1 g.

3. The method for measuring the length of cotton linters according to claim 2, characterized in that: In the step 1, the fiber is soaked in anhydrous alcohol for 1 minute, and is constantly stirred with a glass rod during soaking. The sample is taken out, the alcohol is squeezed out, and the fiber is soaked in a sodium hydroxide solution with a mass concentration of 17.5±0.5% for 5 minutes, and is constantly stirred with a glass rod during soaking. The fiber is transferred to a copper wire mesh, rinsed with distilled water until the pH value of the eluate is 7, and excess water is squeezed out. The fiber is placed in a boiling Congo red staining solution with a mass concentration of 1%, boiled for 10 minutes, and then the fiber is filtered out, and the staining solution is washed with distilled water.

4. The method for measuring the length of cotton linters according to claim 3, characterized in that: In the step 2, the washed fibers are added to a beaker containing 1 L of distilled water and stirred evenly. The fibers are clamped with tweezers while stirring, and samples are taken at multiple points. Excess water is absorbed with filter paper, and a proper amount of glycerin is applied on a glass slide. All the taken fibers are arranged on the glass slide, and the fibers are arranged evenly with a dissecting needle to prevent overlapping. The glass slide with the arranged fibers is covered with a cover glass for later use.

5. The method for measuring the length of cotton linters according to claim 4, characterized in that: In step 3, a glass slide is placed on a microscope stage, an appropriate objective lens magnification is selected, and the focal length of the microscope is adjusted so that the image is clearly presented on the computer display screen. The number of observable fibers in each glass slide is 300 to 500. The fine fiber limit value of the measured fibers is set between 0.2 mm and 0.5 mm using a paper fiber measuring instrument.

6. The method for measuring the length of cotton linters according to claim 5, characterized in that: The fiber skeleton structure is depicted by the paper fiber measuring instrument. The fiber is subdivided into multiple straight lines along the fiber direction on the display screen with the mouse to measure the length of each level l i The fiber length in and count its number n i , calculate the fiber length-weight average fiber length and coefficient of variation, and draw a length-frequency graph.

7. The method for measuring the length of cotton linters according to claim 6, characterized in that: Two fiber samples are measured separately, and the relative error of the length-weight average fiber length results of the two parallel fiber samples should not exceed ±2%.

8. A method for measuring the length of cotton linters according to claim 6 or 7, characterized in that: The fiber length-weight average fiber length and coefficient of variation are calculated according to formulas (1)-(4), and the frequency of its length is calculated by formulas (5)-(6) and a frequency distribution diagram is plotted. Number average fiber length L Assuming that the fiber thickness is uniform, the length-weight average fiber length L′ The coefficient of variation CV value is calculated by formula (3)-(4) The percentage of fibers in each level in the length-frequency diagram f i Calculated by formula (5) Assuming that each fiber has the same thickness, the length-weight percentage of each grade of fiber is f′ i Calculated by formula (6) Where: n i ——The number of fibers at level i; l i ——median value of the length of the i-th grade fiber, in millimeters (mm); s——standard deviation, in millimeters (mm); ∑n i ——Total number of fibers at each level; ∑n i l i ——Total length of fibers of each grade, in millimeters (mm).

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