49 results about "Chitosan membrane" patented technology

The invention relates to the technical field of food packaging, and discloses a composite preservative film as well as a preparation method and application thereof. The composite preservative film comprises a pectin film layer and a chitosan film layer which are arranged up and down, the pectin film layer contains an additive, the chitosan film layer contains lignin, and the additive is anthocyanin and / or an anthocyanin silver ion compound. The method comprises the following steps that S1, under the condition that a solvent exists, pectin and an additive are mixed I, then a pectin film layer is prepared through a tape casting method, and the additive is anthocyanin and / or an anthocyanin silver ion compound; in the presence of a solvent, chitosan and lignin are mixed II, and a chitosan film layer is prepared through a tape casting method; and S2, compounding the pectin film layer and the chitosan film layer to prepare the composite preservative film. The composite preservative film has antibacterial activity on various food spoilage bacteria and is high in oxidation resistance.

The invention provides a method for preparing a chitosan fiber / membrane by dissolving chitosan with an ionic liquid, and belongs to the technical field of chitosan resource utilization. According to the invention, 1, 5-diazabicyclo [4.3. 0] nonyl-5-ene (DBN) or N-methylimidazole or N-ethylimidazole is used as a raw material to prepare a series of nitrogen heterocyclic ring ionic liquids, and the prepared ionic liquid-chitosan solution is subjected to defoaming, filtering and dry spraying-wet spinning process / tape casting to prepare the chitosan fiber / membrane. The operation method is simple and convenient, the solvent is easy to recover, and efficient dissolution of chitosan can be achieved. The tensile strength of the prepared chitosan fiber is 0.47 to 1.07 cN / dtex, and the elongation at break is 3.15 to 6.82 percent; the tensile strength of the chitosan film is 6.57 to 25.07 MPa, and the elongation at break of the chitosan film is 5.51 to 12.94 percent.

The invention discloses a green preparation method for realizing a high-performance chitosan film through pH regulation and control of a citric acid buffering agent, and belongs to the field of food packaging and high polymer materials. According to the method, a water phase separation method is adopted, a citric acid buffering agent serves as a water phase environment, and a chitosan solution is induced to be subjected to phase separation and gelation by regulating and controlling the pH value (preferably 5.0-5.5) of the citric acid buffering agent. The preparation method comprises the following specific steps: dissolving chitosan powder in an alkali urea solvent (KOH: urea: water = 7: 12: 81), inducing gelation through a citric acid buffer agent, carrying out solvent replacement through an ethanol solution, and drying and curing. According to the method, a chemical cross-linking agent does not need to be used, and the core is that a buffer system is used for regulating and controlling the phase separation process to promote aggregation among chitosan molecular chains, so that a compact physical structure network is constructed. The prepared chitosan film has excellent mechanical strength, water resistance, gas barrier property, biocompatibility and degradability, and is suitable for the fields of food, medicine packaging and the like.

The invention discloses a method for extracting and preparing angelica keiskei exosomes. The method comprises the following steps: S1, selecting an angelica keiskei sample and selecting chitosan; s2, crushing and filtering the angelica keiskei sample to obtain an extracting solution; s3, dissolving chitosan through acetic acid, forming a film through a rotary coater, and carrying out drying and heat treatment; s4, mixing the extracting solution with the dried chitosan membrane, and adsorbing the exosome through the charge effect; s5, putting the chitosan membrane into a tangential flow filtration system, collecting effluent after tangential flow filtration, and purifying the effluent; and S6, pre-freezing the purified solution, and carrying out drying treatment. The invention also discloses application of the method. The method has the beneficial effects that the angelica keiskei sample is crushed and filtered to obtain the extracting solution, then the extracting solution and the dried chitosan film are mixed at room temperature, the exosome is adsorbed through the charge effect, and the exosome is purified after being filtered by the tangential flow filtering system, so that a large amount of high-purity exosome is obtained, and the method is simple, convenient and efficient.

The present invention provides a medical implant, comprising (a) a matrix layer comprising chitosan; and (b) a reinforcement structure comprising polymer filaments or polymer fibers, whereby the reinforcement structure is incorporated into the matrix layer. The invention further relates to the medical implant for use in the treatment of ophthalmological diseases or skin disorders. The invention finally relates to a method for producing the medical implant of the invention.

The application discloses a solid-phase preparation method of sulfonated chitosan membrane and application of the sulfonated chitosan membrane in catalytic biodiesel preparation, and the sulfonated chitosan membrane is prepared by the following steps: chitosan powder is suspended in a dispersant in which a sulfonating agent is dissolved to perform a sulfonating reaction, sulfonated chitosan powder is obtained through solid-liquid separation, the sulfonated chitosan powder is dissolved in a membrane solvent to prepare a casting membrane liquid, the casting membrane liquid is naturally cast on a glass surface to form a membrane, and the sulfonated chitosan membrane is obtained after drying and removing the membrane solvent. The sulfonated chitosan membrane is added into a mixed solution of fatty acid and methanol, and after stirring and heating for a period of time, the sulfonated chitosan membrane is taken out, and biodiesel is obtained after removing methanol from the solution. The sulfonated chitosan membrane prepared by the application has the advantages of fast mass transfer rate, high catalytic efficiency and easy separation, and under the conditions of an alcohol / oil ratio of 10:1, a reaction temperature of 65 DEG C, a catalyst dosage of 5wt%, and a reaction time of 3h, the esterification rate reaches 92.29%. Under the same conditions, the esterification rates of powdered chitosan and commercially available macroporous ion exchange resin are 57.73% and 33.0% respectively.

This invention discloses a method for preparing and applying a chitosan-nanofibrillar-based smart indicator membrane loaded with anthocyanins and alizarin. The method includes the following steps: mixing beet powder with hydrochloric acid, washing with water until neutral, and drying; adding sodium hydroxide solution, mixing and reacting, washing with water until neutral, and drying; adding sodium chlorite solution, mixing, adjusting the pH to 3-3.5, reacting, and washing with water until neutral to obtain beet fiber; adding water, homogenizing under ultra-high pressure to obtain a beet nano-suspension; adding the beet nano-suspension to a chitosan-acetic acid solution and stirring, then adding glycerol; adding pigments, mixing, and obtaining a membrane solution; ultrasonically degassing, and drying to form a membrane. This membrane, as a food preservation indicator membrane, possesses both the characteristics and functions of food preservation and indicating food freshness; using beet nanofibers as a supplementary material improves the mechanical properties of the chitosan membrane; the addition of alizarin and anthocyanin mixed pigments enriches the color changes of the indicator membrane and improves its stability.

The application belongs to the technical field of bio-based packaging materials, and particularly relates to a novel double-layer composite film and application thereof. The novel double-layer composite film comprises the following steps: reacting palmitic anhydride and carboxymethyl cellulose to obtain carboxymethyl cellulose palmitate; adding a pH-sensitive natural dye indicator to obtain carboxymethyl cellulose palmitate nanoemulsion containing a pH-sensitive substance; then loading a natural polymer material to prepare a film material; finally adding the film material to the carboxymethyl cellulose palmitate to prepare a composite film, thereby obtaining the novel double-layer composite film. The double-layer composite film can be self-emulsified without adding a surfactant, and has the ability to load functional indicator (pH-sensitive color indicator) substances; meanwhile, the barrier performance of the film material, such as a chitosan film, to water vapor and oxygen is improved, and the double-layer composite film has a very promising application in food or fruit preservation. The method provided by the application is not only green in raw materials, but also uses a flow casting method, which can be applied to industrial production and has a good application prospect.

The invention belongs to the technical field of food packaging materials and bacteriostatic packaging films, and discloses an active packaging film capable of generating singlet oxygen bacteriostasis based on light driving, a preparation method and application of the active packaging film in fresh keeping of fruits, vegetables and edible mushrooms, and the active packaging film comprises the following steps: S1, obtaining a chitosan film solution A for later use; s2, obtaining a polyvinyl alcohol membrane solution B for later use; s3, obtaining a polyvinyl alcohol / chitosan composite membrane solution D based on food-grade nano silicon dioxide loaded sodium copper chlorophyllin; s4, preparing the bacteriostatic active packaging film, and using the bacteriostatic active packaging film in combination with blue-violet light. The antibacterial film disclosed by the invention has the advantages of high barrier property, ultraviolet-resistant optical property, strong and flexible mechanical property, good thermal stability, biodegradability and antibacterial property of CD-ROM movable product singlet oxygen (1O2). The packaging film can be used as a bio-based active package, can reduce the environmental pollution of a traditional petroleum-based packaging film, can prolong the shelf life of fruits, vegetables and edible mushrooms, and has the dual effects of environmental protection, bacteriostasis and preservation.

The utility model relates to the technical field of band-aids, and discloses a band-aid containing dehydrated gel and a chitosan protective film, which comprises a non-woven fabric body, two viscose layers and a dehydrated gel layer are arranged at the top end of the non-woven fabric body, the two viscose layers are respectively positioned on two sides of the dehydrated gel layer, and the dehydrated gel layer is positioned on the bottom end of the non-woven fabric body. A chitosan film covers the top end of the dehydrated gel layer, an anti-sticking layer is stuck to the top end of the adhesive layer, and connecting paper is fixedly connected to the corner position of the side, close to the chitosan film, of the anti-sticking layer. According to the technical scheme, through the arrangement of the connecting paper, a user can directly tear down the anti-sticking layer from the adhesive layer under the condition that the user does not make contact with the chitosan film, the user can tear down the anti-sticking layer by means of force, meanwhile, the anti-skid protruding blocks can improve the anti-skid performance of the connecting paper, the use experience of the user is improved, and the use experience of the user is improved. The practicability is high.

The present invention relates to an optical fiber sensor for detecting lead ions in industrial wastewater from battery production, which is composed of a multimode optical fiber, a coreless optical fiber, a microsphere, a chromium film, a silver film, and a modified chitosan film. The end face of the coreless optical fiber is processed into a microsphere shape, and the surface of the coreless optical fiber is successively coated with a chromium film, a silver film, and a modified chitosan film to form an optical fiber cladding. The present invention utilizes the adsorption of lead ions in industrial wastewater from battery production by the modified chitosan film, which causes a change in the refractive index of the modified chitosan film layer, and further leads to a change in the wavelength of the SPR signal loss peak. By analyzing the wavelength of the SPR signal, the detection of lead ion concentration is realized, meeting the actual requirements for the detection of heavy metal ions. The preparation method of the present invention uses simple equipment, steps, and processes, can effectively excite the SPR signal, realize the high-sensitivity and high-precision detection of lead ions, and effectively evaluate the pollution situation of lead ions in industrial wastewater from battery production.

The invention discloses functional nano zinc oxide as well as a preparation method and application thereof, and belongs to the technical field of food packaging materials and functional nano composite materials. The preparation method comprises the following steps: dissolving dialdehyde cellulose in a hydrochloric acid solution, mixing with a procyanidine solution dissolved in DMSO (Dimethylsulfoxide), heating to react, dialyzing and drying to obtain a cellulose-polyphenol graft; and uniformly mixing the cellulose-polyphenol graft aqueous solution with a zinc nitrate aqueous solution, adjusting the pH value, carrying out a hydrothermal reaction, carrying out centrifugal separation, washing the precipitate, and drying to obtain the functional zinc oxide nanoparticles. Through an aldehyde cellulose-polyphenol grafting strategy, the particle size controllability and dispersity of ZnO nano particles are improved, the ZnO nano particles are endowed with higher specific surface area and functionality, and after the ZnO nano particles are loaded to a chitosan film, the oxidation resistance, antibacterial property and mechanical strength of the film are remarkably enhanced.

This invention discloses a topologically oriented cyclodextrin / chitosan composite membrane, its preparation method, and its applications, belonging to the field of bio-based nanomaterials technology. Using α-cyclodextrin and polyethylene glycol (PEG) as raw materials, this invention prepares topologically oriented cyclodextrin-PEG "ring-slippery" nanoparticles (TNPs). TNPs, as green and biodegradable nanoparticles, fill the chitosan network matrix, enhancing hydrogen bonding interactions with chitosan molecules and improving the mechanical properties of the chitosan membrane. This method not only uses simple raw materials and is easy to implement, but also effectively improves the mechanical strength of the chitosan composite membrane, effectively overcoming the problem of poor mechanical strength in existing chitosan composite membranes, and providing a simple and effective approach for practical production.

The invention provides chitosan-coated zeolite with liquid blocking and ventilating functions as well as a preparation method and application thereof, and relates to the technical field of enhanced mass transfer of equipment for adsorption heat exchange. According to the invention, a film coating technology and an adsorption technology are combined, the surface of 13X zeolite is coated with a layer of liquid-resistant breathable film-chitosan film, and vinyl trimethoxy silane is adopted to carry out chemical crosslinking on the chitosan film, so that the pore size and distribution of the chitosan film are regulated and controlled, and liquid free water in a system is regulated and controlled. The coated zeolite prepared by the invention has excellent liquid resistance, reduces the content of free water in a bed layer so as to enhance the overall performance and efficiency of a system, and is more suitable for being applied to a direct contact type adsorption heat pump system.

The invention discloses a chitosan / diatomite coated biochar-based slow release fertilizer and a preparation method and application thereof, and the preparation method comprises the following steps: firstly, mixing biochar, urea and corn starch according to a specific ratio, granulating to prepare a fertilizer core, and then carrying out coating treatment on the fertilizer core by taking a chitosan solution / diatomite as a coating liquid. By adding the diatomite, the mechanical property and swelling property of the chitosan film are improved, and the chitosan film, the diatomite and the biochar have a synergistic effect to delay nutrient release. The fertilizer is simple in preparation process, low in cost and environment-friendly, can remarkably improve the nutrient utilization rate and the crop yield, has the effect of improving saline-alkali soil, and is suitable for green development of agriculture.

The preparation method comprises the following steps: S1, adding a certain amount of tin-doped indium oxide and carbon nanotubes into an aqueous solution containing aniline and hydrochloric acid, carrying out ultrasonic dispersion for 1-2 hours, then adding ammonium persulfate, and carrying out a reaction for a certain time, so as to obtain a solution A; centrifuging, washing and drying to obtain polyaniline modified carbon nanotubes and tin-doped indium oxide particles; s2, mixing polyaniline modified tin-doped indium oxide, carbon nanotubes, chitosan, acetic acid, citric acid and distilled water, mechanically stirring and uniformly dispersing, then performing ultrasonic treatment to remove bubbles, pouring a film forming solution into a polytetrafluoroethylene mold for tape casting, and then putting the film forming solution into a drying oven for treatment to obtain the antibacterial flame-retardant infrared stealth functional chitosan film. According to the invention, by means of the synergistic effect among the carbon nanotubes, the tin-doped indium oxide, the polyaniline and the chitosan, the chitosan film has extremely low infrared emissivity, and a good infrared stealth effect is achieved.

The present application discloses a chitosan porous membrane and its preparation method and application. The present application utilizes the processes of electrospinning, urushiol cross-linking, and swelling to prepare a porous chitosan membrane with a nanoscale pore structure. By introducing oligomeric urushiol, a structure is constructed with chitosan molecules that are easily soluble in a swelling agent solution as the main chain and acid-resistant and hydrophobic polymeric urushiol as the cross-linking bridge. This allows for slow and controllable swelling of chitosan nanofibers, solving the problem of precise and effective control of the pore size and structure of the chitosan membrane. Furthermore, the nanofiber swelling process is utilized to transform the disordered stacked nanofiber precursors formed by electrospinning into a cross-fused continuous network, thereby forming a continuous porous membrane with high strength.

The invention belongs to the technical field of fruit and vegetable fresh-keeping, and particularly relates to a fruit and vegetable fresh-keeping agent and a preparation method and application thereof. The invention provides a fruit and vegetable fresh-keeping agent. The fruit and vegetable fresh-keeping agent comprises the following components in percentage by volume of a solvent: 1%-4% of chitosan, 1%-5% of acetic acid, 0.5%-1.2% of glycerol and 0.2%-0.5% of bacteriostatic plant hydrolat. Wherein the chitosan can form a layer of colorless and transparent protective film on the surfaces of fruits and vegetables to prolong the after-ripening period of the fruits and vegetables, the chitosan has a good effect of inhibiting and killing bacteria, and the acetic acid can promote dissolution of the chitosan, so that the chitosan is easy to form a film on the surfaces of the fruits and vegetables after being dissolved; glycerol can maintain the stability of the chitosan film; the bacteriostatic plant hydrolat has a bacteriostatic effect and can kill microorganisms on fruits and vegetables. Results of the embodiment show that the fruit and vegetable fresh-keeping agent can effectively reduce the rotting rate of fruits and vegetables in the fresh-keeping process.

This invention provides a method for preparing a chitosan membrane, the chitosan membrane prepared by this method, and its applications. The method includes the following steps: S1: mixing chitosan, acid, C1-C6 monohydric alcohol, pore-forming agent, metal salt, and water to obtain a casting solution; S2: placing the casting solution on a carrier to obtain a carrier loaded with the chitosan membrane; S3: immersing the carrier loaded with the chitosan membrane sequentially in an alkaline solution and water to separate the chitosan membrane from the carrier. The chitosan membrane of this invention has a strong resistance to strong alkalis. When used as an anion exchange membrane material in fuel cells, it has advantages such as high specific power, rapid start-up, non-corrosiveness, low reaction temperature, and low oxidant requirement.

The invention relates to the technical field of biological catalysis, in particular to a preparation method and application of a co-immobilized enzyme based on macroporous resin adsorption-chitosan membrane coating, and the preparation method mainly comprises the following steps: pretreating resin, adding glucose oxidase and catalase, fully adsorbing, and coating with a chitosan membrane to obtain the co-immobilized enzyme, the method can be used for producing gluconic acid. The co-immobilized enzyme prepared by the invention has the characteristics of adaptation to low-pH production, high enzyme activity retention rate and the like.

The present invention discloses a polyethylene filter membrane for homogenizing bags and a preparation method thereof, relating to the field of new materials technology. The polyethylene filter membrane for homogenizing bags produced in the present invention is made by attaching a modified phospholipid to a composite polyethylene filter membrane. The composite polyethylene filter membrane is formed by laminating an irradiated polyethylene filter membrane with a thiol chitosan membrane, thereby enhancing the mechanical properties of the filter membrane. The modified phospholipid is obtained by first epoxidizing soybean phospholipid and then reacting it with a terpolymer through a ring-opening reaction. The terpolymer is obtained by introducing hydroxyl-terminated polybutadiene to both ends of polyvinyl alcohol. The epoxy rings on the epoxidized soybean phospholipid can undergo a ring-opening reaction with the terpolymer, introducing both hydroxyl groups and amphiphilic long chains of the terpolymer, thereby improving the hydrophilicity of the filter membrane and enhancing its stability.

This invention relates to the field of fruit preservation technology and discloses a method for preserving mangoes containing chitosan, a eutectic solvent, and EGC. The method includes the following steps: adding chitosan to an acetic acid solution and heating and stirring in a water bath to obtain a chitosan film solution; pre-dispersing and wetting epigallocatechin in a eutectic solvent, then adding it to the aforementioned chitosan film solution and stirring at room temperature to obtain a modified chitosan composite film solution; selecting undamaged mangoes, washing and air-drying their surface moisture, immersing them in the modified chitosan composite film solution to evenly coat the surface with the film solution, removing them and air-drying them naturally, repeating the aforementioned immersion and air-drying process, and finally storing the dried mangoes in an indoor environment for preservation. This invention utilizes a eutectic solvent to solve the problem of easy aggregation of polyphenolic active substances, forming a uniform and continuous semi-permeable membrane on the mango peel, limiting moisture loss, achieving slow release of antioxidant components, and significantly extending the mango's shelf life.

The application discloses a preservative film liquid, a preservative film and a preparation method and application thereof in berry preservation, and relates to the technical field of food preservation. The preservative film liquid comprises a self-assembled nanoparticle with a melatonin core and a PEG-40 hydrogenated castor oil shell and a chitosan dispersion liquid, wherein the mass ratio of the PEG-40 hydrogenated castor oil to the melatonin is 0.25:1.2-1.6. The application also provides a preparation method of the preservative film liquid, a preservative film prepared by the preservative film liquid and application thereof in berry preservation. The application loads the melatonin in the chitosan film and overcomes the negative influence of the melatonin on the performance of the chitosan film material, so that the preservative film has good mechanical performance, barrier performance and continuous preservation function, and has important significance for the preservation of perishable foods such as berries.

The invention belongs to the technical field of fresh-keeping materials, and particularly relates to a pumpkin carbon dot / chitosan composite film as well as a preparation method and application thereof. The preparation method of the composite membrane comprises the following steps: dissolving chitosan in an acetic acid solution to obtain a chitosan acetic acid solution; dissolving the pumpkin carbon dots in deionized water to obtain a pumpkin carbon dot aqueous solution; and blending and stirring the chitosan acetic acid solution, the pumpkin carbon dot aqueous solution and glycerol, casting in a mold, and drying to form a film. According to the method, the pumpkin flesh is used as a raw material, the raw material is wide in source and convenient to process, the pumpkin flesh is easily decomposed into a small-molecule carbon precursor in the carbonization process, in addition, the pumpkin flesh can directly form the nitrogen-doped carbon dots, no additional nitrogen source needs to be added, and the fluorescence quantum yield is increased; the problems that a single chitosan film is high in brittleness and insufficient in water resistance are solved, a degradable packaging material with ultraviolet blocking and high toughness is provided, and meanwhile good visible light transparency is kept.

The invention discloses a lignin nanoparticle-perilla essential oil Pickering emulsion / chitosan composite membrane as well as a preparation method and application thereof. The composite membrane comprises a chitosan matrix and lignin nanoparticle-perilla essential oil Pickering emulsion uniformly dispersed in the chitosan matrix, the emulsion is prepared by mixing perilla essential oil with the volume fraction of 30% and lignin nanoparticle suspension with the mass concentration of 0.25%-1.00% according to the volume fraction of 10%-50%, and the Pickering emulsion and a chitosan solution are compounded according to the mass ratio of 2%-8% and then cast into a film. The composite film effectively solves the problems that the perilla essential oil is easy to volatilize and oxidize and the chitosan film is poor in mechanical property and barrier property, has excellent tensile strength, elongation at break, hydrophobicity, antioxidant activity and antibacterial property, and can realize slow release of the perilla essential oil; the packaging material can be widely applied to the field of fresh-keeping and antibacterial packaging materials for perishable fruits (such as strawberries).

The application discloses a preparation method of a glucose oxidase sensor with a porous structure outer membrane, and steps of the method comprise the following steps: a chitosan outer membrane is prepared on the surface of a glucose oxidase sensor assembly; solid particles of salt are added into a pre-solidified PDMS solution, ultrasonic mixing is performed to obtain a salt-PDMS mixed solution, the salt-PDMS mixed solution is dropped into a groove, and air in the groove is extracted by vacuum; then the glucose oxidase sensor assembly with the chitosan outer membrane is immersed into the salt-PDMS mixed solution in the groove, and the glucose oxidase sensor assembly is taken out and solidified repeatedly for multiple times until a PDMS outer membrane with a set thickness is formed on the chitosan membrane layer; and then the salt particles in the PDMS outer membrane are dissolved by deionized water to obtain the glucose oxidase sensor with the porous structure outer membrane. The sensor prepared by the method has chitosan and PDMS with the porous structure as outer membrane materials, the preparation method is simple, and product quality control is convenient.

The anti-inflammatory and healing-promoting chitosan dressing comprises a porous hydrophobic chitosan membrane and a bionic microneedle contact layer on the surface of the porous hydrophobic chitosan membrane, the pore diameter of the porous hydrophobic chitosan membrane is 20-50 microns, and the density of the bionic microneedle contact layer is 100-1000 needles / cm. The bionic microneedle contact layer is formed on the surface of the porous hydrophobic chitosan membrane and is in full contact with the surface of a wound, meanwhile, penetrating through a cuticle necrotic in the wound is enhanced, the drug delivery capacity is enhanced, and finally the anti-inflammatory and healing-promoting effects are achieved. The chitosan film with the porous structure provides air permeability / liquid absorption capacity, is made of the same material as the microneedle, has biocompatibility, hemostasis and antibacterial property, can load drugs, and prevents the microneedle from being broken during storage or use.

The invention discloses a fresh-keeping packaging film with antioxidant and antibacterial functions, which at least comprises three layers of chitosan films and three layers of sodium alginate-linalool layer films, and the chitosan films and the sodium alginate-linalool layer films are alternately assembled. The chitosan film is formed by pouring and drying an equivalent amount of chitosan film-forming solution with the mass concentration of 1.5% g / mL, and the sodium alginate-linalool layer film is formed by pouring and drying an equivalent amount of sodium alginate-linalool film-forming solution. The preservative film disclosed by the invention is applied to strawberry packaging and fresh keeping, not only has a longer strawberry fresh-keeping period (the normal-temperature fresh-keeping period is prolonged to 8 days from the original 4 days), but also has better antibacterial property and oxidation resistance, and the loss of strawberry weight, soluble solids, titratable acid and hardness is remarkably reduced; the preparation method is simple, electrostatic assembly is easy, the cost is low, and large-scale popularization is easy.

This invention relates to a method for preparing an expanded perlite-fly ash composite thermal insulation material, belonging to the field of thermal insulation material technology. The method includes the following steps: coating the surface of expanded perlite with polystyrene and acrylic acid via emulsion polymerization to obtain modified expanded perlite; coating the surface of the modified expanded perlite with a chitosan film to obtain a composite material; modifying fly ash with a silane coupling agent to obtain modified fly ash; and crosslinking the modified fly ash and the composite material with glutaraldehyde to obtain the expanded perlite-fly ash composite thermal insulation material. In this invention, coating the surface of expanded perlite with polystyrene and acrylic acid increases its water resistance and strength, improving its thermal insulation properties. Then, coating with a chitosan film and crosslinking with the modified fly ash increases the bonding force between the expanded perlite and the fly ash, and also improves the adsorption capacity for heavy metal ions leached from the fly ash, thus improving the overall performance of the composite thermal insulation material.

The application discloses a preparation method of a high-toughness chitosan-based intelligent film with preservation and visual monitoring of fish freshness, which comprises the following steps: firstly, co-coating curcumin and quercetin into zein and chondroitin sulfate to obtain nanoparticles with a core-shell structure; secondly, adding the nanoparticles into a chitosan acetic acid solution; thirdly, adding a plasticizer glycerol, stirring, ultrasonic degassing, and then obtaining a film-forming solution; and finally, drying the film-forming solution at a certain temperature to form the intelligent film. The application creatively co-embeds natural indicators curcumin and quercetin with excellent antioxidant properties to obtain nanoparticles with a core-shell structure, the incorporation of the nanoparticles effectively improves the physical properties and biological activity of the chitosan film, the visual intelligent indicator film is sensitive to the response of the change of the pH value in the environment, can accurately feed back the freshness information of fish and meat food, and is expected to be applied to real-time monitoring of food freshness.