Preparation method of rice straw fiber rope

Abstract

This invention proposes a method for preparing rice straw fiber rope, belonging to the field of fiber technology. It includes: S1 Rice straw softening and regulation process: treating rice straw with a softening solvent to regulate the chemical composition and physical structure of the rice straw cell walls; S2 Separation and preparation of long rice straw fibers: using a bar coater to repeatedly roll and separate the softened rice straw along the straw radial direction to obtain long rice straw fibers with a diameter of 50-800 μm and a length of 100-500 mm; S3 Directional helical twisting process: using a twisting device to directionally twist the long rice straw fibers to obtain a helical structure, high-strength, and high-toughness rice straw fiber rope; S4 Post-treatment and curing: impregnating the rice straw fiber rope to impart various properties such as antibacterial, water-resistant, and weather-resistant properties to the helical structure and high strength and toughness of the fibers. This invention can obtain a helical structure, high strength and toughness, and biodegradable rice straw fiber rope, which can be applied in multiple fields such as industry, agriculture, medicine, and food.

Description

Technical Field

[0001] This invention relates to the field of biomass material preparation technology and high-value utilization of agricultural waste, and in particular to a method for preparing rice straw fiber rope. Background Technology

[0002] Bundling rope, a structural material widely used in industry, agriculture, and daily life, primarily functions to secure items tightly for transportation and storage. Currently, most mainstream high-strength plastic bundling ropes are processed from petrochemical raw materials such as polypropylene and polyester. However, traditional petrochemical-based plastic bundling ropes consume significant energy and have a high carbon footprint during production. They also require precise recycling after use to prevent livestock from ingesting them. Furthermore, at the end of their lifespan, they degrade into plastic fragments, causing environmental pollution and harming the ecosystem. Therefore, developing a new, environmentally friendly bundling rope material with superior strength and toughness has become an urgent practical production problem.

[0003] Rice straw, as a major residue after rice harvest, can easily lead to resource waste, environmental pollution, and farmland soil degradation if not properly disposed of. Currently, rice straw is mainly used in areas such as cellulose and hemicellulose extraction, pulping and papermaking, building materials, and biofuel conversion. However, there are no reports on processing rice straw into high-strength, high-toughness fiber materials, especially for special purposes such as binding ropes.

[0004] Rice straw contains a natural porous structure of varying sizes, allowing it to deform under external forces. This deformation reduces the fiber spacing within the rice straw cell walls, increases the fiber contact area, and enhances inter-fiber friction and stress distribution. Furthermore, the cell walls of rice straw are composed of rigid lignin, semi-rigid cellulose, and hemicellulose components. By regulating the stiffness and flexibility, the deformability of rice can be strengthened. Therefore, by altering the micro-nano structure and chemical composition of rice straw, its flexibility, plasticity, friction, and adaptability to external forces can be controlled, thereby changing stress transmission and fracture failure, and improving mechanical strength and fracture failure deformation.

[0005] This invention proposes a novel method for preparing helical, high-strength, and high-toughness fiber binding ropes using rice straw, which has significant practical implications and broad application prospects. This not only helps solve the problem of rice straw waste disposal but also provides related industries with a new, low-cost, and high-efficiency fiber binding material, promoting the resource utilization of agricultural waste and possessing high economic and social benefits. Summary of the Invention

[0006] This invention aims to provide a rice straw fiber rope and its preparation method. The core of this invention lies in:

[0007] S1. Rice straw softening process: Rice straw is treated with a softening solvent to regulate the chemical composition and physical structure of its cell walls. The softening solvent consists of one or more of the following: water, organic solvent, eutectic solvent, and Lewis base. The solid-liquid mass ratio of rice straw to the softening solvent is 1:5 to 1:100. Pre-impregnation is performed at room temperature (5-40 ℃) for 5-500 min. The straw is then transferred to a high-temperature reactor, and the treatment temperature is adjusted to 60-300 ℃, the pressure to 0.02-8.6 MPa, and the treatment time to 5-300 min. After being allowed to cool naturally, the rice straw is washed with water until neutral to obtain softened rice straw. The water includes tap water, distilled water, or deionized water. The organic solvents include one or more combinations of methanol, ethanol, acetone, γ-valerol, formic acid, acetic acid, p-toluenesulfonic acid, and oxalic acid. The eutectic solvents include one or more combinations of choline chloride system and trioctylmethylammonium chloride system. The Lewis bases include one or more combinations of ammonia, sodium hydroxide, potassium hydroxide, aluminum chloride hexahydrate, and sodium carbonate.

[0008] S2. Separation and preparation of long rice straw fibers: The softened rice straw obtained in S1 was repeatedly rolled and split along the radial direction of the straw using a wire bar coater to separate long rice straw fibers. The fibers were then placed in a constant temperature and humidity chamber to maintain a moisture content of 20% to 200%.

[0009] S3. Directional Helical Structure Twisting Process: The long rice straw fibers separated in S2 are directionally twisted using a twisting device to obtain a high-strength and high-toughness long rice straw fiber rope with a helical structure. The twisting process is set with a twist of 5~20 t / cm, a twist angle of 10°~80°, a twist coefficient of 250~400, and the twisted rice straw fiber rope has a diameter of 0.5~30 mm, a density of 0.9~1.5 g / cm³, an internal fiber orientation angle of 5°~88°, a tensile strength of 50~600 MPa, and a tensile breaking deformation rate of 10%~100%.

[0010] S4. Post-treatment and curing: The rice straw fiber rope is impregnated with a solution containing polyvinyl alcohol, soy protein isolate, chitosan, and alkali lignin polymer. The concentration of the polymer in deionized water is controlled at 0.1 wt% to 10 wt%, the impregnation temperature is controlled at 40 to 60 ℃, and the impregnation time is controlled at 1 to 6 h to ensure that the rice straw fiber rope is in full contact with the polymer. After the impregnation treatment, the rope is removed and air-dried naturally at 20 to 40 ℃ or heat-dried in an oven at 40 to 60 ℃ for 2 to 48 h.

[0011] In a further technical solution, step S1 specifically includes: softening treatment using subcritical hydrothermal methods, using water as the softening solvent, with a solid-liquid mass ratio of rice straw to the softening solvent of 1:5, pre-soaking at room temperature (5~40 ℃) for 500 min, transferring to a high-temperature reactor, adjusting the treatment temperature to 160 ℃, and treating for 90 min. The softened rice straw is measured to have a crystallinity of 28%~40%, a cellulose content of 55%~60%, a hemicellulose content of 10%~15%, a lignin content of 10%~18%, an ash content of 4%~5%, a wall thickness of 15~20 μm, a wall layer gap of 1.5~3.0 μm, and a wall layer porosity of 55%~65%.

[0012] In a further technical solution, step S1 specifically includes: softening treatment using subcritical hydrothermal methods with a solid-liquid ratio of 1:10, pre-soaking at room temperature (5~40 ℃) for 300 min, transferring to a high-temperature reactor, adjusting the treatment temperature to 200 ℃, and treating for 30 min. The softened rice straw is measured to have a crystallinity of 30%~45%, a cellulose content of 55%~60%, a hemicellulose content of 8%~12%, a lignin content of 10%~13%, an ash content of 5%~7%, a wall thickness of 13~18 μm, a wall layer gap of 2.1~3.5 μm, and a wall layer porosity of 60%~65%.

[0013] In a further technical solution, step S1 specifically includes: softening treatment using a formic acid-methanol system with a solid-liquid ratio of 1:10, pre-impregnation at room temperature (5~40 ℃) for 60 min, transferring to a high-temperature reactor, adjusting the treatment temperature to 100 ℃, treating for 40 min, washing with water until neutral, and measuring the softened rice straw to have a crystallinity of 40%~48%, a cellulose content of 55%~65%, a hemicellulose content of 2%~5%, a lignin content of 5%~10%, an ash content of 4%~5%, a wall thickness of 12~15 μm, a wall layer gap of 2.5~3.8 μm, and a wall layer porosity of 60%~65%.

[0014] In a further technical solution, step S1 specifically includes: softening treatment using a choline chloride-ethylenediamine eutectic solvent with a solid-liquid ratio of 1:30, pre-impregnation at room temperature (5~40 ℃) for 60 min, transferring to a high-temperature reactor, adjusting the treatment temperature to 120 ℃, treating for 60 min, washing with water until neutral, and measuring the softened rice straw to have a crystallinity of 45%~50%, a cellulose content of 60%~65%, a hemicellulose content of 5%~8%, a lignin content of 4%~8%, an ash content of 2%~4%, a wall thickness of 15~18 μm, a wall interlayer spacing of 2.0~3.5 μm, and a wall porosity of 55%~60%.

[0015] In a further technical solution, step S1 specifically includes: softening and deligninating the rice straw using a trioctylmethylammonium chloride-ammonium chloride eutectic solvent and peroxy acid, with a solid-liquid ratio of 1:20. The straw is pre-impregnated in the trioctylmethylammonium chloride-ammonium chloride eutectic solvent at room temperature (5~40 ℃) for 60 min, then transferred to a high-temperature reactor. The treatment temperature is adjusted to 80 ℃, and the treatment time is 180 min. The straw is washed with water until neutral, and then delignin is assisted by peroxy acid. After washing with water until neutral, the softened rice straw is measured to have a crystallinity of 45%~55%, a cellulose content of 75%~85%, a hemicellulose content of 2%~5%, a lignin content of 1%~6%, an ash content of 1%~4%, a wall thickness of 12~15 μm, a wall interlayer spacing of 3.0~4.5 μm, and a wall porosity of 65%~70%.

[0016] In a further technical solution, step S1 specifically includes: softening and deligninating the rice straw using sodium hydroxide, sodium sulfite, and peracetic acid, with a solid-liquid ratio of 1:20. The straw is pre-impregnated in sodium hydroxide solution at room temperature (5-40 °C) for 120 min, then transferred to a high-temperature reactor. The treatment temperature is adjusted to 80 °C, and the treatment time is 60 min. After washing with water until neutral, the straw undergoes complete delignination using peracetic acid. After washing with water until neutral, the softened rice straw is found to have a crystallinity of 45%-60%, a cellulose content of 90%-95%, a hemicellulose content of 1%-4%, a lignin content of 0%-2%, an ash content of 0-1%, a wall thickness of 10-12 μm, a wall layer gap of 2.5-4.5 μm, and a wall layer porosity of 70%-75%.

[0017] The advantages of the method for preparing rice straw fiber rope of the present invention compared with the prior art are as follows:

[0018] 1. This invention utilizes a softening agent to treat rice straw, thereby regulating the lignin content in the cell walls of rice straw and reducing the rigidity of the rice straw. This makes the rice straw easier to bend and twist during twisting, thus forming a spiral structure. At the same time, by regulating the cellulose content in the rice straw, the hydrogen bond strength between rice straw fibers can be enhanced, promoting tight fiber bonding during later twisting.

[0019] 2. This invention uses a bar coater to roll back and forth along the radial direction of softened rice straw, utilizing the contact and frictional shear stress between the coil and the rice straw to promote the effective separation of straw deformation and long fibers. Furthermore, the diameter of the separated fibers can be controlled by adjusting the coil diameter and coil gap of the bar coater.

[0020] 3. This invention employs a twisting process to directionally assemble separated long rice straw fibers. Through physical interweaving, winding, and friction, a helical structure is formed, enhancing the interlocking degree of the fibers and resulting in more uniform stress transmission, enabling the helical fibers to withstand greater external stress. Simultaneously, under tension, the unwinding and fiber slippage help delay breakage, thus providing a simple and efficient way to prepare high-strength, high-strength fiber ropes. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a method for preparing rice straw fiber rope according to the present invention;

[0023] Figure 2 The images shown are physical samples and scanning electron microscope images of rice straw obtained using different softening processes according to this invention. Figure 2 In the image, 'a' and 'e' are the original physical image and scanning electron microscope image of rice straw, respectively. Figure 2 In the figures, b and f are actual images and scanning electron microscope images of rice straw after hydrothermal treatment in the first embodiment. Figure 2 c and g in the figure are the physical image and scanning electron microscope image of partially deligninated rice straw in the third embodiment; Figure 2 (d and g in the text refer to the actual images and scanning electron microscope images of the fully delignin-treated rice straw from the sixth embodiment).

[0024] Figure 3 The spiral structure and high-strength, high-toughness rice straw fiber rope are described in the first embodiment of the present invention.

[0025] Figure 4 The XRD diffraction patterns of rice straw using different softening processes in this invention are shown below (a is the original rice straw, b is the hydrothermal rice straw of the first embodiment, c is the partially deligninized rice straw of the third embodiment, and d is the fully deligninized rice straw of the sixth embodiment).

[0026] Figure 5 The following are infrared spectra of rice straw produced using different softening processes according to the present invention (a is the original rice straw, b is the hot water rice straw of the first embodiment, c is the partially deligated rice straw of the third embodiment, and d is the fully deligated rice straw of the sixth embodiment). Specific implementation methods

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, the preparation method of a rice straw fiber rope according to the first embodiment 1 of the present invention includes the following steps:

[0029] S1 Rice Straw Softening Process: Subcritical hydrothermal softening was used, with water as the softening solvent. The solid-liquid mass ratio of rice straw to softening solvent was 1:5. Pre-soaking was performed at room temperature (5-40 ℃) for 500 min. The straw was then transferred to a high-temperature reactor, and the treatment temperature was adjusted to 160 ℃ for 90 min. The softened rice straw exhibited a crystallinity of 28%-40%, a cellulose content of 55%-60%, a hemicellulose content of 10%-15%, a lignin content of 10%-18%, an ash content of 4%-5%, a wall thickness of 15-20 μm, a wall interlayer spacing of 1.5-3.0 μm, and a wall porosity of 55%-65%.

[0030] S2 The softened rice straw from step S1 is processed using a wire bar coater, and then rolled and separated into fibers along its radial direction. Based on the gap depth and the number of rolling cycles, long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm are obtained. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0031] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 5 t / cm and the twist angle is 10°. The resulting rice straw cellulose rope has a diameter of 0.5~5 mm, a density of 1.2~1.5 g / cm³, a twist coefficient of 280~320, and a fiber orientation angle of 20°~25°.

[0032] S4 involves impregnating twisted rice straw fiber ropes with a 0.1 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled within the range of 40 ℃, and the duration is 6 h. After removal, the ropes are dried in a 40 ℃ oven for 12 h. Figure 2 and 3 As shown, after rice straw is softened, it can be separated into long fibers, which are then twisted in a specific direction to form long ropes with good winding and bending properties.

[0033] Second embodiment 2:

[0034] S1 Rice Straw Softening Process: Subcritical hydrothermal softening is used for softening treatment with a solid-liquid ratio of 1:10. Pre-soaking is performed at room temperature (5-40 ℃) for 300 min, followed by transfer to a high-temperature reactor. The treatment temperature is adjusted to 200 ℃, and the treatment time is 30 min. The softened rice straw exhibits a crystallinity of 30%-45%, a cellulose content of 55%-60%, a hemicellulose content of 8%-12%, a lignin content of 10%-13%, an ash content of 5%-7%, a wall thickness of 13-18 μm, a wall interlayer spacing of 2.1-3.5 μm, and a wall porosity of 60%-65%.

[0035] S2 The softened rice straw from step S1 is processed using a wire bar coater, and then rolled and separated into fibers along its radial direction. Based on the gap depth and the number of rolling cycles, long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm are obtained. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0036] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 10 t / cm and the twist angle is 20°. The resulting rice straw cellulose rope has a diameter of 1~8 mm, a density of 1.4~1.6 g / cm³, a twist coefficient of 270~320, and a fiber orientation angle of 30°~60°.

[0037] S4 involves impregnating twisted rice straw fiber ropes with a 1 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled at 50 ℃ for 3 h, followed by drying in a 60 ℃ oven for 6 h.

[0038] Third embodiment 3:

[0039] S1 Rice Straw Softening Process: A formic acid-methanol system was used for softening treatment with a solid-liquid ratio of 1:10. Pre-soaking was performed at room temperature (5-40℃) for 60 min. The straw was then transferred to a high-temperature reactor, and the treatment temperature was adjusted to 100℃ for 40 min. After washing with water until neutral, the softened rice straw exhibited a crystallinity of 40%-48%, a cellulose content of 55%-65%, a hemicellulose content of 2%-5%, a lignin content of 5%-10%, an ash content of 4%-5%, a wall thickness of 12-15 μm, a wall interlayer spacing of 2.5-3.8 μm, and a wall porosity of 60%-65%.

[0040] S2 The softened rice straw from step S1 is processed using a wire bar coater, and then rolled and separated into fibers along its radial direction. Based on the gap depth and the number of rolling cycles, long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm are obtained. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0041] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 10 t / cm and the twist angle is 20°. The resulting rice straw cellulose rope has a diameter of 1~8 mm, a density of 1.2~1.4 g / cm³, a twist coefficient of 300~350, and a fiber orientation angle of 40°~65°.

[0042] S4 involves impregnating twisted rice straw fiber ropes with a 5 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled at 60 ℃ for 1 h, followed by drying in a 60 ℃ oven for 8 h.

[0043] Fourth Example 4:

[0044] S1 Rice Straw Softening Process: A choline chloride-ethylenediamine eutectic solvent was used for softening treatment at a solid-liquid ratio of 1:30. Pre-soaking was performed at room temperature (5~40 ℃) for 60 min, followed by transfer to a high-temperature reactor. The treatment temperature was adjusted to 120 ℃, and the treatment time was 60 min. The straw was then washed with water until neutral. The softened rice straw exhibited a crystallinity of 45%~50%, a cellulose content of 60%~65%, a hemicellulose content of 5%~8%, a lignin content of 4%~8%, an ash content of 2%~4%, a wall thickness of 15~18 μm, a wall interlayer spacing of 2.0~3.5 μm, and a wall porosity of 55%~60%.

[0045] S2 The softened rice straw from step S1 is processed using a wire bar coater, and then rolled and separated into fibers along its radial direction. Based on the gap depth and the number of rolling cycles, long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm are obtained. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0046] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 20 t / cm and the twist angle is 80°. The resulting rice straw cellulose rope has a diameter of 2~10 mm, a density of 1.4~1.5 g / cm³, a twist coefficient of 300~350, and a fiber orientation angle of 20°~25°.

[0047] S4 involves impregnating twisted rice straw fiber ropes with a 10 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled at 60 ℃ for 3 h, followed by drying in a 60 ℃ oven for 8 h.

[0048] Fifth Example 5:

[0049] S1 Rice Straw Softening Process: Trioctylmethylammonium chloride-ammonium chloride eutectic solvent and peroxy acid are used for softening and delignin treatment. The solid-liquid ratio is 1:20. Pre-impregnation with trioctylmethylammonium chloride-ammonium chloride eutectic solvent is carried out at room temperature (5-40 ℃) for 60 min. The straw is then transferred to a high-temperature reactor, and the treatment temperature is adjusted to 80 ℃ for 180 min. After washing with water until neutral, delignin is assisted by peroxy acid. After washing with water until neutral, the softened rice straw is found to have a crystallinity of 45%-55%, a cellulose content of 75%-85%, a hemicellulose content of 2%-5%, a lignin content of 1%-6%, an ash content of 1%-4%, a wall thickness of 12-15 μm, a wall interlayer spacing of 3.0-4.5 μm, and a wall porosity of 65%-70%.

[0050] S2 The softened rice straw from step S1 is processed using a wire bar coater, and then rolled and separated into fibers along its radial direction. Based on the gap depth and the number of rolling cycles, long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm are obtained. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0051] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 20 t / cm and the twist angle is 80°. The resulting rice straw cellulose rope has a diameter of 2~10 mm, a density of 1.3~1.5 g / cm³, a twist coefficient of 330~360, and a fiber orientation angle of 60°~80°.

[0052] S4 involves impregnating twisted rice straw fiber ropes with a 10 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled at 60 ℃ for 3 h, followed by drying in a 60 ℃ oven for 8 h.

[0053] Sixth Example 6:

[0054] S1 Rice Straw Softening Process: Sodium hydroxide, sodium sulfite, and peracetic acid are used for softening and delignin treatment at a solid-liquid ratio of 1:20. The straw is pre-impregnated in sodium hydroxide solution at room temperature (5-40 ℃) for 120 min, then transferred to a high-temperature reactor. The treatment temperature is adjusted to 80 ℃ for 60 min. After washing with water until neutral, peracetic acid is used for complete delignin treatment. The softened rice straw has a crystallinity of 45%-60%, a cellulose content of 90%-95%, a hemicellulose content of 1%-4%, a lignin content of 0%-2%, an ash content of 0-1%, a wall thickness of 10-12 μm, a wall layer gap of 2.5-4.5 μm, and a wall layer porosity of 70%-75%.

[0055] S2 The softened rice straw from step S1 is processed using a wire bar coater, and then rolled and separated into fibers along its radial direction. Based on the gap depth and the number of rolling cycles, long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm are obtained. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0056] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 10 t / cm and the twist angle is 50°. The resulting rice straw cellulose rope has a diameter of 1~6 mm, a density of 0.9~1.3 g / cm³, a twist coefficient of 330~360, and a fiber orientation angle of 30°~60°.

[0057] S4 involves impregnating twisted rice straw fiber ropes with an 8 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled at 60 ℃ for 3 h, followed by drying in a 60 ℃ oven for 8 h.

[0058] Comparative Example 1: Original rice straw

[0059] Untreated rice straw was found to contain 30%–40% cellulose, 20%–30% hemicellulose, 10%–20% lignin, 5%–15% ash (3%–12% silicon), 30%–40% porosity, 10–25 μm wall thickness, 1.5–4 μm wall interlayer spacing, 40%–50% wall porosity, and 25%–40% crystallinity. Single rice straw was used as a control.

[0060] Comparative Example 2: Raw rice straw was directly twisted into rope

[0061] S1 untreated rice straw was found to have the following contents: cellulose content 30%–40%, hemicellulose content 20%–30%, lignin content 10%–20%, ash content 5%–15% (silicon content 3%–12%), porosity 30%–40%, wall thickness 10–25 μm, wall interlayer spacing 1.5–4 μm, wall porosity 40%–50%, and crystallinity 25%–40%.

[0062] S3 The rice straw in S1 is directionally twisted using a manual twisting device. The twist is 20t / cm and the twist angle is 60°. The resulting rice straw cellulose rope has a diameter of 4~10 mm, a density of 1.2~1.5 g / cm³, a twist coefficient of 260~300, and a fiber orientation angle of 60°~80°.

[0063] Comparative Example 3: Preparation of Rice Straw Fiber Rope After Natural Composting and Softening

[0064] S1 uses rice straw as raw material and is softened by natural composting with a solid-liquid ratio of 1:10. After composting at room temperature (5~40 ℃) for 10 days, the softened rice straw was found to have a crystallinity of 20%~30%, a cellulose content of 30%~45%, a hemicellulose content of 10%~15%, a lignin content of 9%~18%, an ash content of 4~12%, a wall thickness of 12~14 μm, a wall layer gap of 2.0~3.0 μm, and a wall layer porosity of 55%~65%.

[0065] S2 The rice straw from step S1 is processed using a wire bar coater, and the straw is rolled back and forth along its radial direction to separate it into long rice straw fibers with a diameter of 100~2000 μm and a length of 100~500 mm according to the gap depth and the number of rolling times. The fibers are then placed in a constant temperature and humidity chamber to maintain a moisture content of 20%~200%.

[0066] S3 The rice straw long fibers prepared in S2 are directionally twisted using a manual twisting device. The twist is 20 t / cm and the twist angle is 60°. The resulting rice straw cellulose rope has a diameter of 4~10 mm, a density of 1.2~1.5 g / cm³, a twist coefficient of 260~300, and a fiber orientation angle of 60°~80°.

[0067] S4 involves impregnating twisted rice straw fiber ropes with a 1 wt% polyvinyl alcohol / soy protein isolate / chitosan / alkali lignin solution. The impregnation temperature is controlled within the range of 40 ℃ for 6 h, and the ropes are then dried in a 40 ℃ oven for 12 h.

[0068] Test Example 1

[0069] The physical samples and microstructures of the original rice straw, hydrotreated rice straw (first embodiment), partially deligated rice straw (third embodiment), and fully deligated rice straw (sixth embodiment) of this invention were characterized, and the results are shown in [the table below]. Figure 2 .

[0070] The testing method is as follows: The microscopic morphology of rice straw before and after treatment was observed using a scanning electron microscope (SEM).

[0071] like Figure 2 As shown, Figure a is a picture of the original rice straw, and Figure e is a microscopic morphology diagram of Figure a. Figure b is a picture of the rice straw softened by subcritical hydrothermal treatment, and Figure f is a microscopic morphology diagram of Figure b, i.e., the picture after softening treatment using subcritical hydrothermal treatment in the first embodiment. Figure c is a picture of the partially deligated rice straw, and Figure g is a microscopic morphology diagram of Figure c, i.e., the picture after softening treatment in the third embodiment. Figure d is a picture of the fully deligated rice straw, and Figure g is a microscopic morphology diagram of Figure d, i.e., the picture after softening treatment in the sixth embodiment. (Comparison) Figure 2 As shown in a~d, after softening treatment, the color of rice straw changes from dark to light to white. This is because the lignin content in the rice straw gradually decreases. (Comparison) Figure 2 As can be seen from e~g, with the removal of lignin components from rice straw, the surface of rice straw becomes smoother and fibrillation increases.

[0072] Test Example 2

[0073] The rice straw obtained in Examples 1-6 and Comparative Example 3 of this invention was subjected to determination of cellulose, hemicellulose, lignin content, and crystallinity. The results are shown in Tables 1 and 2. Figure 4 .

[0074] The testing methods are as follows: the contents of cellulose, hemicellulose and lignin were determined by NREL method; the crystallinity of rice straw before and after treatment was calculated by measuring the XRD diffraction peak intensity of rice straw.

[0075] Table 1. Cellulose, hemicellulose, lignin content and crystallinity of raw rice straw compared with those obtained after softening treatment in the examples and comparative examples.

[0076] Sample Name Cellulose hemicellulose Lignin Crystallinity Original rice straw 30%~40% 20%~30% 10%~20% 25%~40% The first embodiment is rice straw after softening treatment. 55%~60% 10%~15% 10%~18% 28%~40% The second embodiment is rice straw after softening treatment. 55%~60% 8%~12% 10%~13% 30%~45% The third embodiment is rice straw after softening treatment. 55%~65% 2%~5% 5%~10% 40%~48% Fourth embodiment: softened rice straw 60%~65% 5%~8% 4%~8% 45%~50% Fifth embodiment: softened rice straw 75%~85% 2%~5% 1%~6% 48%~55% Sixth embodiment: softened rice straw 90%~95% 1%~4% 0%~2% 45%~60% Comparative Example 3: Softened rice straw 30%~45% 10%~15% 9%~18% 20%~30%

[0077] Table 1 shows that after softening treatment in Examples 1-6, hemicellulose and lignin in rice straw were removed to varying degrees, and the crystallinity of rice straw increased with the increase of cellulose content. This indicates that the softening process can regulate the chemical composition and microstructure of rice straw, thereby altering its mechanical properties. In Comparative Example 3, during the natural composting process, some of the cellulose in the rice straw was degraded by microorganisms, resulting in a decrease in crystallinity. Because the molecular chains in the crystalline regions are highly ordered, they provide high tensile strength through strong intermolecular forces (such as van der Waals forces and hydrogen bonds). Therefore, the crystal structure can effectively withstand and disperse applied stress, and fibers with higher crystallinity have better tensile strength. Figure 4 It can be seen that as hemicellulose and lignin components in rice straw are removed, the peak intensities of rice straw near 15.8 and 22.3 are higher, indicating that different softening treatments can adjust the chemical composition and crystallinity of rice straw.

[0078] Test Example 3

[0079] Fourier transform infrared spectroscopy was performed on the original rice straw, hydrotreated rice straw (first embodiment), partially deligated rice straw (third embodiment), and fully deligated rice straw (sixth embodiment) of this invention. The results are shown in […]. Figure 5 .

[0080] The test method is as follows: the potassium bromide pellet method was used to determine the thickness of rice straw in the 500-4000 cm³ range. -1 Absorption spectrum at [location].

[0081] like Figure 5 As shown, the wave number is 3423 cm⁻¹. -1 and 2916 cm -1 The peaks are generated by CH from hydroxyl, methyl, and methylene groups, respectively. The intensity of these characteristic peaks increases after different softening treatments, indicating that the structure of the rice straw is disrupted after softening treatment, exposing more cellulose. At 1733 cm⁻¹ -1 and 1625 cm -1 The absorption peak at 1515 cm⁻¹ corresponds to the stretching vibration of the conjugated carbonyl and carboxyl groups at C=O. -1 The typical absorption peak at this point mainly originates from the stretching vibration of the conjugated carbon groups in lignin. As the lignin content decreases, the intensity decreases, and in fully deligninized rice straw, this peak disappears.

[0082] Test Example 4

[0083] The mechanical properties of the rice straw fiber ropes prepared in Examples 1-6 and Comparative Examples 1-3 of this invention were tested, and the results are shown in Tables 2 and 3.

[0084] The test method is as follows: referring to national standards GB / T 14344-2022 and GB / T 1447-2005, the tensile properties of rice straw fiber ropes were tested on a benchtop electronic universal testing machine.

[0085] Table 2. Tensile property tests of nanofiber flexible membranes and helical long fibers in the comparative examples.

[0086] sample Preparation process Crystallinity (%) Tensile strength (MPa) Elongation at break (%) Comparative Example 1 Original rice straw 30 20~30 5~10 Comparative Example 2 Original rice straw twisted fiber rope 30 45~60 3~8 Comparative Example 3 Naturally fermented and softened rice straw twisted into fiber rope 28 70~80 10~15

[0087] As shown in Table 2, in Comparative Example 1, the tensile strength of the untwisted raw rice straw was 20-30 MPa, and the elongation at break was 5%-10%. After twisting treatment (Comparative Example 2), the tensile strength increased to 45-60 MPa, and the elongation at break decreased to 3%-8%. This indicates that twisting treatment can improve the mechanical strength of rice straw by forming a helical structure. In Comparative Example 3, the internal chemical composition and microstructure of rice straw changed after natural composting and softening treatment. Although the crystallinity decreased slightly, the tensile strength of the fiber rope increased to 70-80 MPa after twisting. This is because the internal structure of rice straw changed after softening treatment, increasing its flexibility and plasticity, altering the stress transmission of rice straw, and thus increasing its mechanical properties.

[0088] Table 3 Tensile property test of rice straw fiber rope in the examples

[0089] sample Preparation process Crystallinity (%) Tensile strength (MPa) Elongation at break (%) First Embodiment Subcritical hydrothermal softening of long rice straw fibers (160℃, 90 min) 30 30~60 30~100 Second Embodiment Subcritical hydrothermal softening of long rice straw fibers (200℃, 30 min) 35 50~70 50~200 Third Embodiment Formic acid / methanol softening of long rice straw fibers (100℃, 40 min) 42 60~100 80~300 Fourth embodiment Choline chloride-ethylenediamine softening of long rice straw fibers (120℃, 60 min) 48 65~120 80~310 Fifth Embodiment Trioctylmethylammonium chloride-ammonium chloride-assisted peroxyacid softening of long rice straw fibers (80℃, 180 min). 53 60~140 50~310 Sixth Embodiment Sodium hydroxide-sodium sulfite-assisted peroxyacid softening of long rice straw fibers (80℃, 60 min) 58 80~240 60~330

[0090] As shown in Table 3, rice straw was treated using various processes. By controlling the chemical composition and crystallinity of the straw and adding twisting treatment to improve the bonding strength of the fibers, a spiral structure rice straw packing rope with high strength and high toughness was obtained.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing rice straw fiber rope, characterized in that, Includes the following steps: S1. Rice straw softening process: Rice straw is treated with softening solvents to regulate the chemical composition and physical structure of the cell walls of rice straw; In step S1, the specific steps include: softening treatment using a formic acid-methanol system with a solid-liquid ratio of 1:10, pre-impregnation at room temperature (5-40℃) for 60 min, transferring to a high-temperature reactor, adjusting the treatment temperature to 100℃, treatment time for 40 min, washing with water until neutral, and measuring the softened rice straw to have a crystallinity of 40%-48%, a cellulose content of 55%-65%, a hemicellulose content of 2%-5%, a lignin content of 5%-10%, an ash content of 4%-5%, a wall thickness of 12-15 μm, a wall interlayer spacing of 2.5-3.8 μm, and a wall porosity of 60%-65%. Alternatively, step S1 specifically includes: softening and deligninating using a trioctylmethylammonium chloride-ammonium chloride eutectic solvent and peroxy acid, with a solid-liquid ratio of 1:20; pre-impregnating with the trioctylmethylammonium chloride-ammonium chloride eutectic solvent at room temperature (5-40 °C) for 60 min; transferring to a high-temperature reactor; adjusting the treatment temperature to 80 °C; treating for 180 min; washing with water until neutral; and then using peroxy acid to assist in delignination. After washing with water until neutral, the softened rice straw is measured to have a crystallinity of 45%-55%, a cellulose content of 75%-85%, a hemicellulose content of 2%-5%, a lignin content of 1%-6%, an ash content of 1%-4%, a wall thickness of 12-15 μm, a wall interlayer spacing of 3.0-4.5 μm, and a wall porosity of 65%-70%. S2. Separation and preparation of long rice straw fibers: The softened rice straw obtained in S1 was repeatedly rolled and split along the radial direction of the straw using a bar coater to separate long rice straw fibers. The fibers were then placed in a constant temperature and humidity chamber to maintain a moisture content of 20% to 200%. The bar coater was made of marble, stainless steel, copper, or alloy, with a length of 200 to 800 mm, a bar diameter of 5.6 to 9.52 mm, a coil diameter of 9.72 to 14.34 mm, and a coil gap of 100 to 1000 μm. The separated long rice straw fibers had a diameter of 50 to 800 μm and a length of 100 to 500 mm. S3. Directional Helical Structure Twisting Process: The long rice straw fibers separated in S2 are directionally twisted using a twisting device to obtain a high-strength and high-toughness long rice straw fiber rope with a helical structure. The twisting process is set with a twist of 5~20 t / cm, a twist angle of 10°~80°, a twist coefficient of 250~400, and the twisted rice straw fiber rope has a diameter of 0.5~30 mm, a density of 0.9~1.5 g / cm³, an internal fiber orientation angle of 5°~88°, a tensile strength of 50~600 MPa, and a tensile breaking deformation rate of 10%~100%. S4. Post-treatment and curing: The rice straw fiber rope is impregnated with a polymer solution including polyvinyl alcohol, soy protein isolate, chitosan and alkali lignin. The concentration of the polymer in deionized water is controlled at 0.1 wt%~10 wt%, the impregnation temperature is controlled at 40~60 ℃, and the impregnation time is controlled at 1~6 h to ensure that the rice straw fiber rope is in full contact with the polymer. After the impregnation treatment, the rope is removed and air-dried naturally at 20~40 ℃ or heat-dried in an oven at 40~60 ℃ for 2~48 h.

Images