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CN-121990810-A - Preparation method and application of bamboo fiber/cement radiation refrigeration composite material

CN121990810ACN 121990810 ACN121990810 ACN 121990810ACN-121990810-A

Abstract

The invention discloses a preparation method and application of a bamboo fiber/cement radiation refrigeration composite material, wherein the preparation method comprises the steps of cutting moso bamboo chips into preset sizes, sequentially carrying out acid digestion delignification, alkali liquor soaking modification and air drying treatment to obtain high-purity bamboo fibers, weighing light magnesium oxide, magnesium chloride and deionized water, mixing and stirring to obtain cement base liquid, adding polyvinyl alcohol PVA and nano titanium dioxide TiO 2 into the cement base liquid, carrying out ultrasonic dispersion and mechanical stirring uniformly to obtain radiation refrigeration cement slurry, carrying out directional arrangement on the bamboo fibers pretreated in the step S1 in a mould, pouring the radiation refrigeration cement slurry obtained in the step S2, curing in a constant temperature and humidity box, and demoulding after hydration reaction is completed to obtain radiation refrigeration cement. The invention takes bamboo fiber reinforced magnesium oxychloride cement as a matrix and combines nano refrigeration particles, thereby realizing the balance among high-efficiency radiation refrigeration performance, high mechanical strength and green environment protection of the material and meeting the passive cooling requirement of a building structure.

Inventors

  • HE SHUAIMING
  • ZHANG MEIYU
  • WU YIQIANG
  • LIN XIANXI
  • YANG ZHENKUN

Assignees

  • 中南林业科技大学

Dates

Publication Date
20260508
Application Date
20260115

Claims (10)

  1. 1. The preparation method of the bamboo fiber/cement radiation refrigeration composite material is characterized by comprising the following steps of: s1, pretreatment of bamboo fibers: Cutting moso bamboo chips into preset sizes, and sequentially performing acid digestion delignification, alkali liquor soaking modification and air drying treatment to obtain high-purity bamboo fibers; s2, preparing magnesium oxychloride cement matrix slurry: weighing light magnesium oxide, magnesium chloride and deionized water, mixing and stirring to obtain cement base liquid, adding polyvinyl alcohol PVA and nano titanium dioxide TiO 2 into the cement base liquid, performing ultrasonic dispersion, and mechanically stirring uniformly to obtain radiation refrigeration cement slurry; s3, directional pouring and curing: And (3) directionally arranging the bamboo fibers pretreated in the step (S1) in a mould, pouring the radiation refrigeration cement slurry prepared in the step (S2), placing the radiation refrigeration cement slurry in a constant temperature and humidity box for solidification, and demoulding after hydration reaction is completed to obtain the radiation refrigeration cement.
  2. 2. The method for preparing a bamboo fiber/cement radiation refrigerating composite material according to claim 1, wherein in the step S1, the preset dimensions of bamboo chips cut are 1mm x 20mm x 80mm.
  3. 3. The preparation method of the bamboo fiber/cement radiation refrigeration composite material is characterized by comprising the specific processes of preparing an acidic solution, preparing a certain amount of 1.5 wt-percent sodium chlorite solution, adding an acetic acid solution to adjust the pH value to 4.6, uniformly mixing, putting a certain amount of natural bamboo wood into the mixed solution, immersing the bamboo chips in the acidic solution, boiling for 6 hours at 100 ℃, taking out the bamboo chips after boiling, repeatedly cleaning the bamboo chips with deionized water for more than 3 times, and soaking for 30 minutes each time until the pH value of a cleaning liquid is neutral.
  4. 4. The preparation method of the bamboo fiber/cement radiation refrigeration composite material is characterized by comprising the following steps of preparing a sodium hydroxide solution with the mass concentration of 1wt.% in the step S1, immersing delignified bamboo chips in the sodium hydroxide solution, standing for 15 hours at room temperature, taking out the bamboo chips after immersion, washing the bamboo chips with deionized water until no alkaline residue exists, manually stripping hemicellulose and other components, reserving a plurality of long fibers, and then drying the long fibers by blasting at the room temperature for 8 hours, wherein the water content of the bamboo fibers is controlled to be less than or equal to 5%.
  5. 5. The preparation method of the bamboo fiber/cement radiation refrigeration composite material according to claim 1 is characterized in that in the step S2, weighing light magnesium oxide, magnesium chloride and deionized water according to a mol ratio of MgO to MgCl 2 :H 2 O of 5:1:13, mixing and stirring to prepare cement-based liquid, adding polyvinyl alcohol PVA accounting for 1% of the mass of the cement-based liquid and nano titanium dioxide TiO 2 accounting for 10% of the mass of the magnesium oxide; the light magnesium oxide has the activity of 65%, the ignition loss of less than or equal to 6.0%, the magnesium chloride is anhydrous magnesium chloride, the purity of more than or equal to 99%, the particle size of nano titanium dioxide is 20-50 nm, the crystal form is anatase, the purity of more than or equal to 99.5%, the polymerization degree of polyvinyl alcohol is 1700-1800, and the alcoholysis degree of more than or equal to 99%.
  6. 6. The preparation method of the bamboo fiber/cement radiation refrigeration composite material according to claim 1 is characterized in that in the step S2, a certain amount of PVA is firstly dispersed in deionized water, a certain amount of the solution is taken, a certain amount of magnesium chloride is dispersed in the solution, stirring is carried out for 5min at a rotating speed of 500r/min until the magnesium chloride is completely dissolved, then light magnesium oxide with a corresponding mass is added, stirring is carried out for 5min at a rotating speed of 700r/min, cement-based liquid is prepared, nano TiO 2 with a mass of 10% MgO is added, mechanical stirring is carried out for 5min at a rotating speed of 800r/min again, ultrasonic dispersion is carried out for 30min at a power of 300W and a frequency of 40kHz, and uniform particle aggregation-free slurry is ensured.
  7. 7. The method for preparing the bamboo fiber/cement radiation refrigeration composite material according to claim 1, wherein in the step S3, the bamboo fiber/cement radiation refrigeration composite material is placed in a constant temperature and humidity box with the temperature of 25 ℃ and the humidity of 60% for curing for 24 hours, and demoulding is carried out after the hydration reaction for 72 hours, so that the radiation refrigeration cement is obtained; The solar reflectivity of the radiation refrigeration cement is more than or equal to 90% within the range of 0.25-2.5 mu m, the infrared emissivity of the radiation refrigeration cement is more than or equal to 99% within the range of 2.5-16 mu m, the bending strength is 176+/-18 MPa, and the passive cooling effect lower than the environment temperature by 5-10 ℃ can be realized in the outdoor environment.
  8. 8. The method for preparing the bamboo fiber/cement radiation refrigeration composite material according to claim 1, wherein in the step S3, the bamboo fibers are arranged in a directional mode in a mold, wherein the bamboo fibers are paved in parallel along the length direction of the mold, the paving layer number is adjusted according to the thickness of the mold, and the volume fraction of the bamboo fibers is 3% -7% of the total mass of the composite material.
  9. 9. The method for preparing the bamboo fiber/cement radiation refrigeration composite material according to claim 1, wherein in the step S3, the curing process is divided into two stages, namely, a first stage of standing and curing, standing for 12 hours in a constant temperature and humidity box after pouring is completed, enabling slurry to be primarily solidified, a second stage of curing and curing, maintaining the constant temperature and humidity condition for 24/48/72 hours, detecting the surface hardness of the material every 8 hours, and finishing curing when the Shore hardness is more than or equal to 80D.
  10. 10. The application of cement obtained by the preparation method of the bamboo fiber/cement radiation refrigeration composite material in the aspects of building outer walls, roof panels, road pavement surfaces or traffic signal lamp shells according to claims 1-9 is characterized in that components with different shapes are prepared by adjusting the sizes of the dies, and the application is suitable for various chemical engineering demands.

Description

Preparation method and application of bamboo fiber/cement radiation refrigeration composite material Technical Field The invention relates to the technical field of building functional materials, in particular to a preparation method and application of a bamboo fiber/cement radiation refrigeration composite material. Background The cooling takes an indispensable important role in a plurality of key fields of human production and life, for example, the energy-saving field of buildings can reduce the energy consumption of air conditioners, the field of road engineering can relieve the high-temperature aging of road surfaces in summer, the cooling of industrial facilities can ensure the stable operation of equipment and the like. The passive radiation cooling technology with the passive cooling capability has become a research hot spot in the fields of material science and engineering in recent decades by virtue of the energy saving and ecological friendly characteristics of no extra power consumption and zero carbon emission. The radiation cooling material has the core advantages of being capable of displaying high solar reflectivity in a solar spectrum (0.3-2.5 microns) range and effectively blocking solar radiation heat absorption, meanwhile, having ultra-high emissivity in an atmospheric window infrared region (8-13 microns), and being capable of efficiently transmitting heat energy on the surface of the material to a space with the temperature close to absolute zero degree in a thermal radiation mode, thereby realizing a spontaneous cooling effect without external energy driving and providing a green solution for solving the high temperature problem of various scenes. To date, researchers have developed extensive research for radiation-cooled materials, covering various types of photonic crystal films, silica aerogels, ceramic matrix composites, porous polymer films, and the like. Although the existing radiation cooling material has shown better cooling efficiency in laboratory environment (partial material can realize cooling effect lower than 5-10 ℃ in environment temperature), two key bottlenecks still exist and need to be broken through when the radiation cooling material is applied to large-scale infrastructures of buildings, roads and the like, including: (1) The preparation process and environmental protection bottleneck is that the traditional radiation cooling materials (such as photon films and ceramic composite materials) generally need complex preparation processes, such as high-temperature sintering, precise coating, nanoparticle in-situ synthesis and the like, the production process has high energy consumption and high cost, the large-scale production requirements required by infrastructure construction are difficult to meet, meanwhile, most synthetic radiation cooling materials depend on nonrenewable petrochemical raw materials or toxic and harmful chemical reagents, the production and the discarding processes of the radiation cooling materials are easy to pollute the environment, Therefore, development of a novel radiation cooling material which has a simple preparation process, low energy consumption, is environment-friendly and can be produced in a large scale becomes a core requirement for pushing the technical land infrastructure field. (2) The performance suitability is bottleneck, namely, the infrastructure such as buildings and roads has strict requirements on the mechanical properties (such as compressive strength, flexural strength, wear resistance and durability) of materials, but the existing radiation cooling materials (such as porous polymer films and aerogels) generally have the problems of low mechanical strength, easiness in breakage, poor compatibility with matrix materials and the like, and cannot be directly applied to cement-based infrastructures (such as concrete building outer walls and cement pavements) as structural materials or functional coatings. In addition, cement-based materials as building materials with the greatest global usage have the problems of high heat conductivity coefficient and rapid rise of surface temperature caused by easy absorption of solar radiation in summer, but have long lacked an adaptive radiation cooling solution. Therefore, development of radiation-cooled cement materials that have both excellent radiation cooling efficiency and mechanical properties satisfying infrastructure requirements, and are highly compatible with cement-based materials, has become an urgent need to solve the high temperature problem of the infrastructure. In summary, aiming at the technical problems in the prior art, the method for preparing the composite cement material with high-efficiency radiation refrigeration performance and excellent mechanical strength is provided, which is a technical problem to be solved by the technicians in the field. Disclosure of Invention In view of the above, the invention provides a preparation method and application of a bamboo