JP5656281B2 - Fiber discrimination method and fiber discrimination device - Google Patents

Description

  The present invention relates to a fiber identification method and a fiber identification device that identify fibers using irradiation of terahertz electromagnetic waves.

In recent years, material analysis and organic chemistry research using terahertz electromagnetic waves have attracted attention. Terahertz electromagnetic waves (1 THz = 10 ¹² Hz) are also called far-infrared light, and are electromagnetic waves of about 0.1 THz to 30 THz whose frequency region corresponds to the boundary between light and radio waves. The frequency in the terahertz band corresponds to natural vibrations in biological molecules such as proteins and polymer materials, and is expected to be applied to analysis of biological functions and molecular structures. In addition, since vibration and rotation spectra of various organic molecules classified into various proteins, lipids, and carbohydrates exist in this frequency region, application as a fingerprint spectrum for molecular identification is also expected.
Non-Patent Document 1 discloses a method for generating a broadband, high-output terahertz electromagnetic wave, and various applications using a terahertz frequency band that has been considered as an unexplored region have been studied. Terahertz electromagnetic waves have translucency depending on the substance, and also have straightness as light waves. For this reason, application to nondestructive inspection of specific substances and imaging of concealed materials is being studied.

  Here, with regard to conventional inspection methods for fibers, goat wool and wool, which are classified as animal hair among high-quality natural fibers, have a price difference of several tens of times depending on the type and quality, but the main components are very similar. Therefore, the chemical identification method cannot be used, and the identification is difficult. In particular, illegal labeling of textile products using cashmere (a kind of goat hair) has been discovered one after another, which has become a social problem. Seventy to eighty percent of the cashmere products are made in China, and the cause has not been specified except that other hair was mixed in the production process in China. This problem is becoming more serious as demand for expensive cashmere increases and balance with supply is lost, and the price of products decreases. For this reason, it is highly desirable that producers and sellers cooperate to restore consumer confidence by ensuring a reliable quality display.

For the identification of animal hair, it is necessary to identify the difference in the cuticle structure constituting the animal hair. This inspection has relied on a method of counting the form and number of fibers with a microscope performed by experts of the Hair Products Inspection Association. The time required for the inspection is one hour or more, and the cost is 20,000 to 30,000 yen. The inspection takes excessive time and manpower. Recently, in order to pass through this inspection, there are examples of melting the cuticle with chemicals and intentionally mixing animal hair that is difficult to identify.
Some research institutions have reported successful identification by DNA testing, but the amount of DNA contained in animal hair is very small, and it is effective because it can be easily broken by staining or chemical treatment. It is considered not to be an analytical tool. This situation has been a cause of widespread mislabeling of textile products.
Patent Document 1 describes a method for identifying animal hair fibers using DNA. Patent Document 2 describes a method of determining the cashmere mixture ratio in white raw hair using a cashmere dyeing apparatus.

JP 2000-210084 Japanese Patent No. 2558440

J. Phys. D: Appl. Phys. 36 (2003) 953-957

  The purpose of this application is to use terahertz spectroscopy to apply spectrum analysis of energy derived from intermolecular interactions and aggregate structures to the analysis of various fibers such as synthetic fibers, plant-derived fibers, and animal hair fibers. And In particular, in the case of animal hair fibers, a unique spectrum corresponding to the cell structure (primary structure) of cuticles and cortex and the aggregate form (higher order structure) of cells is found, and the type and quality of the fibers (animal hair) are immediately identified. For the purpose. When performing terahertz spectroscopic analysis, it is necessary to pulverize the fiber to be analyzed to a size sufficiently smaller than the wavelength of the terahertz wave to form a homogeneous powder, and then prepare an analysis pellet. As for the fiber pulverization method, the method of freeze pulverization while preventing the temperature rise accompanying pulverization is the most effective.

  In the above terahertz spectroscopic analysis, under the pulverization conditions, most samples need to be pulverized to about 10 μm. The reason is that in terahertz spectroscopic analysis, it is desired to set the analysis range from 0.1 to 10 THz, so that the wavelength is 30 μm at 10 THz. For this reason, since the sample has a size of 30 μm or more and an incident terahertz wave for spectroscopic analysis is scattered, the intensity of the terahertz wave incident on the detector is attenuated, and an accurate spectrum cannot be measured. Therefore, it is necessary to grind the sample to about 10 μm. Thus, in order to analyze the fiber, it is necessary to pulverize the fiber finer than the wavelength in the terahertz spectroscopic analysis. However, in the conventional pulverization method, considerable heat is generated during pulverization (when the fiber is pulverized). There is a problem that many fibers are denatured).

  An object of the present invention is to provide a highly reliable fiber discrimination method and a fiber discrimination apparatus that can perform pulverization of fibers to be identified without alteration in the preparation of a measurement sample, and can reliably identify the fibers. It is to be.

  For the problem that heat is generated when fibers are pulverized, which is a conventional defect, and many fibers are altered (caused by local thermal damage when fibers are pulverized) In the present application, the following solution was used. That is, in the present invention, the fiber is frozen and pulverized to eliminate heat denaturation that occurs in the fiber during pulverization.

A specific procedure for pulverizing fibers in the present invention will be described below.
The fibers to be identified are placed in a stainless steel grinding jar (50 ml) together with several stainless steel balls, immersed in liquid nitrogen for about 10 minutes, and cooled to 77K. Thereafter, the pulverization jar is immediately attached to the pulverizer and pulverized at a predetermined frequency for a predetermined time.
The grinding conditions are carried out in two stages.
1st stage: Ball diameter 25mmφ 1 sample and grinding at 20Hz for 2 minutes 2nd stage: Ball diameter 10mmφ 10 pieces (or 12mmφ8 pieces) + sample at 30Hz for 2 minutes Grinding device is ball mill (Retsch) Manufactured by MM400).

The crushed sample is vacuum-dried and then mixed with polyethylene powder to produce pellets. The pellet is placed in an analyzer and analyzed.
A specific procedure will be described below.
The freeze-ground sample is vacuum dried, weighed, and mixed with polyethylene powder to a predetermined concentration (5-7 wt%). For mixing, rub in a mortar or place in a sealed container (threaded test tube) and mix with a rotary stirrer. A predetermined amount of the mixed powder sample is weighed (300-350 mg) and pressed with a press machine to form a disk-shaped wedge-shaped pellet having a diameter of 20 mm. To do. The wedge-shaped pellet has an angle of 2 °, which is empirically suitable. If it is not wedge-shaped, there is a phenomenon that the terahertz light incident on the front and back surfaces of the pellet interferes and an accurate spectrum cannot be obtained. This pellet is set in a terahertz spectrometer, and a transmission spectrum analysis at 0.1-10 THz is performed.
Here, the polyethylene powder weight concentration is changed so that the fiber detection sensitivity can be obtained. When the polyethylene powder weight concentration is 3-10 wt%, the detection sensitivity is high, and 5-7 wt% is particularly suitable for analysis. This is the same trend for all types of fibers.

The invention according to claim 1 freezes the fiber to be identified and the means for pulverizing the fiber to be differentiated, pulverizes the fiber to be identified to a particle size of 10 μm or less by the pulverizing means, The ground fiber and polyethylene powder are mixed to prepare a sample, the sample is irradiated with electromagnetic waves, the frequency of the electromagnetic waves is swept within a frequency range of 0.1 THz to 10 THz, and the sample is transmitted. The fiber discrimination method is characterized in that the component of the fiber held inside the sample is analyzed by measuring the transmission intensity of the electromagnetic wave and obtaining the transmission spectrum.

  The invention according to claim 2 is characterized in that the fiber is identified by identifying an absorption band of a natural frequency corresponding to a specific component contained in the fiber in the sample from the transmission spectrum. It is.

The invention according to claim 3 is the fiber discrimination method characterized in that the pulverizing means is a ball mill.
The invention according to claim 4, wherein the fibers, after being frozen, a fiber discriminating method characterized in that it is comminuted to a particle size up to 10μm or less.

  The invention according to claim 4 is the fiber identification method, wherein the fiber is frozen at a temperature of 77K or less.

The invention according to claim 4 is the fiber discrimination method characterized in that the weight concentration of the fiber with respect to the sample is in the range of 3 wt% to 10 wt%.

The invention according to claim 5 is the fiber discrimination method characterized in that the sample is a wedge-shaped pellet, and the angle between the front surface and the back surface of the wedge-shaped pellet is 2 °.

The invention according to claim 6 measures an electromagnetic wave generating means for generating an electromagnetic wave having a frequency of 0.1 THz to 10 THz to irradiate a sample including a fiber to be identified, and a transmission intensity of the electromagnetic wave transmitted through the sample including the fiber. The sample is a fiber discrimination device comprising: a sample that is subjected to freezing of the fiber to be identified and the ball mill, and then pulverized to a particle size of 10 μm or less by a ball mill, and the pulverized fiber and polyethylene powder are It is formed by mixing, the sample is a wedge-shaped pellet, and the angle between the front surface and the back surface of the wedge-shaped pellet is 2 °.

According to the invention of claim 1, it can be pulverized without causing alteration of the fiber to be distinguished,
The pulverized fiber and polyethylene powder are mixed to prepare a sample, and the fiber can be stably identified by a terahertz spectrometer.
According to the invention of claim 2, the fiber is identified by identifying the absorption band of the natural frequency corresponding to the specific component contained in the fiber in the sample from the transmission spectrum of the sample measured by the terahertz spectrometer. can do.
According to the invention of claim 6, since the sample is a wedge-shaped pellet and the angle between the front surface and the back surface of the wedge-shaped pellet is 2 °, the transmission spectrum with a stable terahertz spectrometer can be measured.

  According to the present invention, there is provided a highly reliable fiber discrimination method and fiber discrimination apparatus that can pulverize fibers to be identified without alteration in the preparation of a measurement sample, and that can reliably identify the fibers. it can.

It is a block diagram of the terahertz spectrometer of the present invention. It is a figure of the wedge-shaped pellet used by this invention. 2A is a top view, and FIG. 2B is a cross-sectional view taken along line AA in FIG. It is a micrograph of the pulverized fiber It is a measurement result of the transmission spectrum of various synthetic fibers. It is a measurement result of the transmission spectrum of various plant origin fibers. It is a measurement result of the transmission spectrum of various animal hair fibers. It is the result of having measured the transmission spectrum about the sample of 15% of silk + 85% of wool, 100% of silk, and 100% of wool. It is the result of having compared the transmission spectrum of the sample which passed through the degreasing | defatting, the bleaching, and the dyeing | staining process with the raw | natural hair of merino wool which has not performed degreasing etc. at all.

  The present invention is characterized in that the fiber to be identified is frozen and pulverized to eliminate heat denaturation that occurs in the fiber during pulverization, the fiber to be differentiated is frozen, pulverized, and the pulverized fiber A sample is prepared by mixing with polyethylene powder, the sample is irradiated with an electromagnetic wave, the frequency of the electromagnetic wave is swept within a frequency range of 0.1 THz to 10 THz, and the transmission intensity of the electromagnetic wave transmitted through the sample is determined. It is a fiber discrimination method characterized by analyzing a fiber component held in the sample by measuring and obtaining a transmission spectrum.

  In this application, terahertz spectroscopic analysis is used, and spectral analysis of energy derived from intermolecular interactions and aggregate structures is applied to animal hair analysis. That is, an object is to find a unique spectrum corresponding to the cell structure (primary structure) of cuticles and cortex and the aggregated form (higher order structure) of cells, and to immediately identify the type and quality of animal hair. When performing terahertz spectroscopic analysis, it is necessary to pulverize the fiber to be analyzed to a size sufficiently smaller than the wavelength of the terahertz wave, to make a homogeneous powder, and to prepare an analysis pellet. Uses a method of freeze pulverization while preventing a temperature rise associated with pulverization, that is, a method of freezing and pulverization.

The advantages of freezing the fiber are as follows. Regarding the nature and application fields of the terahertz school, there has been an example of transcribing the fabric and imaging secret objects. There are few examples of analyzing the fibers themselves. In order to analyze the fiber, it is necessary to pulverize the fiber finer than the wavelength. However, considerable heat is generated during the pulverization (local heat damage occurs when the fiber is pulverized), and many fibers are It will be altered. For this reason, the heat denaturation which arises in a fiber at the time of a grinding | pulverization can be eliminated by freezing and grinding | pulverizing.
FIG. 3 is a photomicrograph of the crushed fiber

  Further, the present invention provides an electromagnetic wave generating means for generating an electromagnetic wave having a frequency of 0.1 THz to 10 THz, which is applied to a sample including a fiber to be identified, and a detection for measuring the transmission intensity of the electromagnetic wave transmitted through the sample including the fiber. In the fiber discrimination apparatus, the sample is a wedge-shaped pellet, and the angle between the front surface and the back surface of the wedge-shaped pellet is 2 °. Here, the sample is formed by freezing a fiber to be identified and then pulverizing, and mixing the pulverized fiber and polyethylene powder.

FIG. 1 is a block diagram of a terahertz spectrometer 10 of the present invention. The terahertz spectrometer 10 includes an electromagnetic wave oscillator 1, a detector 4, and a signal processing unit 5. A sample 3 to be measured is placed on the optical axis 2 between the oscillator 1 and the detector 4. The electromagnetic wave that has passed through the sample 3 is detected by the detector 4, and the detection signal is processed by the signal processing unit 5. The drive mechanism 6 is necessary when positioning the sample 3 or scanning the sample 3 to obtain transmission imaging.
The analysis point of the sample 3 is determined on the optical axis 2 by movement / adjustment in a plane perpendicular to the optical axis 2. As the detector 4, a pyroelectric detector having a wide wavelength sensitivity characteristic, a bolometer, or the like is used. The signal detected by the detector is processed and stored as spectrum information by the signal processing unit 5.
As the electromagnetic wave oscillator 1, for example, a differential frequency terahertz wave generator using a GaP crystal is used. When a LiNbO 3 crystal is used instead of the GaP crystal, a terahertz electromagnetic wave of 0.7 THz to 2.5 THz can be obtained by difference frequency generation or parametric oscillation. Furthermore, as the electromagnetic wave oscillator 1, a Gunn diode, a tannet diode, a resonant tunnel diode, or an electronic device such as a p-type germanium laser or a quantum cascade laser can be used. By using these oscillators, electromagnetic waves in the frequency range of 0.1 THz to 30 THz can be used.
In the apparatus of this example, an electromagnetic wave having a frequency range of 0.4 to 6.2 THz was used.
FIG. 2 is a diagram of a wedge-shaped pellet 31 used in the present invention. 2A is a top view, and FIG. 2B is a cross-sectional view taken along line AA in FIG. The wedge-shaped pellet 31 has an outer diameter D of 20 mm, a thickness t of about 1 mm, and an angle α formed by the front surface 32a and the back surface 32b is 2 °. The wedge-shaped pellet 31 is arranged as the sample 3 of the terahertz spectrometer 10 shown in FIG.
Thus, the angle of the wedge-shaped pellet 31 is suitably 2 °. If it is not wedge-shaped, there is a phenomenon that the terahertz light incident on the front and back surfaces of the pellet interferes and an accurate spectrum cannot be obtained.

(Example 1) (Identification of various synthetic fibers)
FIG. 4 shows measurement results of transmission spectra of various synthetic fibers.
Different spectra were obtained for chemical fibers (nylon 6, nylon 66, polyester, acrylic, rayon, etc.) by performing terahertz spectroscopy on freeze-ground fibers. Nylon fabric of unknown composition was analyzed and confirmed to be nylon 66 from the spectral pattern.
Each dough containing 100% was freeze-ground and used as a measurement sample.
As described in paragraphs 0011 and 0012, these samples were prepared by freezing the fibers, pulverizing them, and mixing them with polyethylene powder to form wedge-shaped pellets for concentration measurement shown in FIG.

As shown in FIG. 4, there is a broad absorption band near 5.5 THz for polyertel and around 4 THz for acrylic. In contrast, nylon 6 is 2
Absorption peaks characteristic of THz and 3.1 THz and nylon 3.3 at 2, 3.3 and 5.1 TH have been confirmed. Nylon 6 and nylon 66 are considered to be difficult to discriminate because their spectra are very similar to each other by the infrared spectroscopy that has been conventionally used. In this case, terahertz spectroscopic analysis has found not only the identification of synthetic fibers with different molecular structures such as polyester and acrylic, but also a case where mutations in the molecular form and crystal structure of nylon can be detected with high sensitivity.

(Example 2) (Identification of natural fibers derived from various plants)
FIG. 5 shows measurement results of transmission spectra of various plant-derived fibers.
Terahertz analysis of plant-derived natural fibers was performed, and the spectral differences of cotton, flax (linen), ramie (ramie), and cannabis (hemp) were confirmed. It was shown that the structural difference of cellulose (crystal) of natural fibers derived from various plants can be detected by terahertz spectroscopy.
Each dough containing 100% was freeze-ground and used as a measurement sample.
As described in paragraphs 0011 and 0012, these samples were prepared by freezing the fibers, pulverizing them, and mixing them with polyethylene powder to form wedge-shaped pellets for concentration measurement shown in FIG.

It is a terahertz spectrum of rayon which is a plant-derived fiber and a cellulose regenerated fiber. As plant-derived fibers, measurement examples of cotton, hemp (cannabis), linen (flax), and ramie (cannabis) are shown. Most of the constituents of cotton are made of linear polymer cellulose with D-glucose bonded, and the cellulose structure is a structure in which crystalline and amorphous structures are arranged. It is known that the structure is over 80%. Hemp has different fiber forms depending on the type, and in addition to the cellulose structure, it contains many impurities such as pectic substances that adhere the fibers.

  As shown in FIG. 5, the terahertz spectrum of various fibers can be considered to reflect the crystal form of cellulose. The hemp, linen, and ramie spectra are similar to the cotton spectra expected to have high crystal purity, but the absorption peaks around 3.2 and 5.2 THz are different. This seems to reflect the cellulose crystal form of the plant as a raw material. On the other hand, rayon, which is a regenerated fiber, shows a completely different spectrum. Rayon is made from wood pulp and the like, and uses a method in which fibers are melted and spun. Therefore, it is considered that the crystal structure of cellulose is altered or almost disappeared. From these results, it is expected that terahertz spectroscopic analysis can identify each fiber type with high sensitivity also for identifying fiber derived from plants.

(Example 3) (Identification of various animal hair fibers)
FIG. 6 shows measurement results of transmission spectra of various animal hair fibers.
We have also found differences in the terahertz absorption spectrum of goat wool cashmere, which is a high-grade animal hair fiber, and various purebred wool, camel and rabbit animal hair, and silk. It was also possible to identify the wool of extremely fine wool (merino, sheep) and yak (cow), which are very similar in nature to cashmere, which is a problem in the industry.
Each dough containing 100% was freeze-ground and used as a measurement sample.
As described in paragraphs 0011 and 0012, these samples were prepared by freezing the fibers, pulverizing them, and mixing them with polyethylene powder to form wedge-shaped pellets for concentration measurement shown in FIG.

As shown in FIG. 6, it is a terahertz spectrum of cashmere (goat wool), merino (wool), and yak (cow wool). Each animal used pure washed animal hair as a sample, but for cashmere, considering the possibility of other animal hair being mixed, additional measurements were taken for different sources (cashmere No. .2).
For convenience, the vertical axis (transmittance) in FIG. 6 is a logarithmic display for easy identification of the spectrum. Merino is a kind of wool that is difficult to distinguish from cashmere because the diameter of hair is 16-18μm, the thinnest fiber among wool, and almost the same as cashmere fiber (11-18μm). Yak's delicate underhair is one of animal hairs that are difficult to distinguish from cashmere because the scale shape of the hair surface is similar to that of cashmere. The terahertz spectrum of these animal hairs is observed at 3.9 THz for Merino species, 5.2 and 5.7 THz for yaks, and 4.7 and 5.7 THz for cashmere. It was confirmed that different spectra were shown.

  Animal hair is composed of almost 100% protein and is composed of cuticles, hair pulp, and cortical cells (cortex). Cortex is composed of spindle-shaped cells, accounting for nearly 90% of all animal hair. In terahertz spectroscopic analysis, it is considered that the vibration mode caused by the coupling of the cortex structure or the hydrogen bond between molecules is detected, and the difference depending on the animal hair type is detected.

In order to measure the mixture ratio of cashmere and the like, a method of counting the form and number of fibers with a microscope performed by an expert has been used. In this method, the specific fiber is identified from the cuticle scale shape on the mirror surface of the finely cut fiber, the number of the specific fiber in the cut fiber is counted, and the mixing ratio is obtained by statistical processing. I went. In this method, the key is how to identify specific fibers efficiently. However, the reliability of the inspection itself fluctuates because the scale shape is lost due to chemical treatment, or other types of fibers with very similar scale shapes are mixed. is there. In this application, the following test was implemented regarding the measurement of mixed use rate. FIG. 7 shows the results of measuring samples of 15% silk + 85% wool, 100% silk and 100% wool in view of the fact that many products in which silk is mixed with cashmere and wool are produced.
In the 100% silk sample, a significant absorption peak is observed around 3.5 THz, while in wool, absorption peaks are observed around 5.3 and 5.7 THz. For 15% silk + 85% wool (Silk mixed wool in the figure), an absorption peak is observed around 4.2 THz. This means a shift in absorption peak caused by the addition and averaging of the spectra of silk and wool due to the mixing of silk and wool. By measuring the magnitude of this shift, the fiber mixture ratio can be obtained. Similar measurement results are observed when cashmere is used instead of wool.

Example 4
In order to pass through the conventional inspection of counting the form and number of fibers with a microscope performed by a skilled worker, examples of melting animal hair cuticles with chemicals and examples of stretching fibers have occurred as new tricks . In such a case, it is possible to make a discrimination by the terahertz test of the present invention.
When wool is dyed, the cuticle is damaged by a degreasing process, a bleaching process, and coloring with a metal-containing dye or an acid dye. FIG. 8 shows the result of spectral comparison between a merino wool that has not been subjected to any degreasing treatment or the like and a sample that has undergone the degreasing, bleaching, and dyeing steps. From this result, it is understood that the absorption around 3.9 THz peculiar to Merino species is observed in all samples. Absorption peaks are also observed in the vicinity of 5 THz in the dyed black color, but the spectrum characterizing the merino species is retained. From this, it can be seen that even if the cuticle is damaged or disappears, according to the method of the present invention, the fiber type can be identified.
The terahertz spectroscopic analysis is considered to detect the binding state of cortex, which occupies most of animal hair (90% or more), and it shows that even when the cuticle is dissolved with a chemical, no large spectral change occurs.

  In the present invention, in various fibers such as synthetic fibers, plant fibers, and animal fibers in which terahertz spectrum analysis is applied to various fiber analyses, differences in the polymer structure or crystal structure of fibers, cell structures (primary structures), and cells It has been found that a unique spectrum corresponding to the set form (higher order structure) of appears. Since the present invention makes it possible to identify animal hair seed fibers that are problematic due to, for example, cashmere camouflage, there is great potential for application as a basic technique that leads to new fiber inspection techniques.

DESCRIPTION OF SYMBOLS 1 Electromagnetic wave oscillator 2 Optical axis 3 Measurement sample 31 Wedge-shaped pellet 32a Front surface 32b of wedge-shaped pellet 4 Back surface of wedge-shaped pellet 4 Detector 5 Signal processing part 6 Drive mechanism 10 Terahertz spectrometer

Claims (7)

Freezing the fiber to be identified and the means for pulverizing the fiber to be identified,
Pulverizing the fiber to be identified by the pulverizing means to a particle size of 10 μm or less ,
Mix the pulverized fiber and polyethylene powder to make a sample,
The sample is irradiated with electromagnetic waves, and the frequency of the electromagnetic waves is swept within a frequency range of 0.1 THz to 10 THz,
A fiber discrimination method characterized in that a component of a fiber held inside the sample is analyzed by measuring a transmission intensity of an electromagnetic wave transmitted through the sample and obtaining a transmission spectrum. 2. The fiber identification method according to claim 1, wherein the fiber is specified by identifying an absorption band of a natural frequency corresponding to a specific component contained in the fiber in the sample from the transmission spectrum. 3. The fiber identification method according to claim 1, wherein the pulverizing means is a ball mill. 4. The fiber identification method according to claim 1, wherein the fiber is frozen at a temperature of 77K or less. Weight concentration with respect to the sample of the fibers, according to claim 1 to 4 fiber differentiation method wherein a range from 3 wt% of 10 wt%. The sample, and a wedge-shaped pellet, a front and back of the angle of the wedge-shaped pellet, fiber discrimination method of claims 1 to 5 further characterized in that the 2 °. An electromagnetic wave generating means for generating an electromagnetic wave having a frequency of 0.1 THz to 10 THz to irradiate a sample including a fiber to be identified;
A fiber discrimination device comprising detection means for measuring the transmission intensity of electromagnetic waves that pass through a sample containing the fiber,
The sample is formed by freezing the fiber to be identified and the ball mill, pulverized to a particle size of 10 μm or less with a ball mill, and mixing the pulverized fiber and polyethylene powder.
The sample is a wedge-shaped pellet, and an angle between the front surface and the back surface of the wedge-shaped pellet is 2 °.

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