CN113214549A - Natural latex/chitin nano-fiber composite membrane and preparation method thereof - Google Patents
Natural latex/chitin nano-fiber composite membrane and preparation method thereof Download PDFInfo
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- CN113214549A CN113214549A CN202110683048.7A CN202110683048A CN113214549A CN 113214549 A CN113214549 A CN 113214549A CN 202110683048 A CN202110683048 A CN 202110683048A CN 113214549 A CN113214549 A CN 113214549A
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- 239000002131 composite material Substances 0.000 title claims abstract description 108
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- GDOPTJXRTPNYNR-UHFFFAOYSA-N methyl-cyclopentane Natural products CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 claims description 4
- 244000043261 Hevea brasiliensis Species 0.000 claims description 3
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- 230000003712 anti-aging effect Effects 0.000 claims description 2
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- 230000009286 beneficial effect Effects 0.000 abstract description 2
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- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 3
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 3
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 3
- 238000007865 diluting Methods 0.000 description 3
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- 239000000126 substance Substances 0.000 description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
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- 239000004202 carbamide Substances 0.000 description 2
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- 238000004519 manufacturing process Methods 0.000 description 2
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- 241000894006 Bacteria Species 0.000 description 1
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- 238000002835 absorbance Methods 0.000 description 1
- 125000000218 acetic acid group Chemical group C(C)(=O)* 0.000 description 1
- 239000002313 adhesive film Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
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- 125000004029 hydroxymethyl group Chemical group [H]OC([H])([H])* 0.000 description 1
- 229920003052 natural elastomer Polymers 0.000 description 1
- 229920005615 natural polymer Polymers 0.000 description 1
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Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
- C08J5/18—Manufacture of films or sheets
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F6/00—Contraceptive devices; Pessaries; Applicators therefor
- A61F6/02—Contraceptive devices; Pessaries; Applicators therefor for use by males
- A61F6/04—Condoms, sheaths or the like, e.g. combined with devices protecting against contagion
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2307/00—Characterised by the use of natural rubber
- C08J2307/02—Latex
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2405/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2401/00 or C08J2403/00
- C08J2405/08—Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
Abstract
The invention discloses a natural latex/chitin nano-fiber composite membrane and a preparation method thereof, wherein a suspension of chitin nano-fibers is dispersed in a natural latex matrix according to a proportion, and the natural latex/chitin nano-fiber composite aqueous dispersion with excellent storage stability is obtained after uniform mixing and stirring; and then forming a film by a dipping, casting or suction filtration method, and further heating and vulcanizing to obtain the natural latex/chitin nano-fiber composite film with high tensile strength, good flexibility and ageing resistance. The natural latex/chitin nanofiber composite membrane related in the invention has high tensile strength and flexibility under low strain, and is more beneficial to practical application of natural latex products.
Description
[ technical field ] A method for producing a semiconductor device
The invention relates to a natural latex/chitin nanofiber composite membrane and a preparation method thereof, belonging to the field of natural high polymer materials.
[ background of the invention ]
The fresh natural latex is produced in natural rubber trees, has high elasticity, flexibility and good film forming property, and is widely applied to daily life of people.
However, in the practical application process, the following problems exist:
1. when the natural latex is used for producing a film product, the tensile strength and the tear resistance are poor, and the application of the natural latex in the high-added-value field (such as condoms/medical saccule stents and the like) of the natural latex product is greatly limited.
2. The natural latex products have poor aging resistance: the main component of the natural latex is polyisoprene, unsaturated double bonds exist, and the natural latex is easy to break under the conditions of strong light, oxygen enrichment, high temperature and high humidity to cause the aging of latex products.
3. The natural latex has poor storage stability: during the natural latex standing process, bacteria and enzyme destroy and decompose non-rubber substances (mainly protein), so that the stability of the latex is destroyed and the latex is naturally coagulated.
Chitin is a natural polymer with the world output second to cellulose, the nanofiber has the characteristics of high strength, low density and high length-diameter ratio, and meanwhile, based on the characteristics of the chitin body, the chitin nanofiber has good biocompatibility, antibacterial property and biodegradability and can be used for preparing a high-strength and biocompatible natural latex/chitin nanofiber composite membrane.
For example, chinese patent No. CN106947126A discloses a high-strength and biocompatible natural latex/chitin nanofiber composite membrane, which is obtained by compounding chitin nanofibers with negative charges or weak alkalinity on the surface thereof with natural latex: the stress is improved by 3 times compared with that of a pure adhesive film, and the Young modulus is improved by 35 times.
However, in the natural latex/chitin nanofiber composite membrane prepared by the prior art, the dry weight content of the chitin nanofibers is not less than 0.1 wt%, and the higher dosage of the chitin nanofibers damages the flexibility of the natural latex product (particularly, the tensile stress under low strain is higher); on the other hand, the suspension of the chitin nano-fibers is generally low in solid content, and the natural latex is extremely easy to be excessively diluted due to the high dosage of the chitin nano-fibers, so that the dipping process is influenced; and the cost of the nano material is high, and the high compounding amount increases the cost of the final product.
In addition, the prior art can not solve the problems of poor storage stability of natural latex and poor ageing resistance of products thereof.
[ summary of the invention ]
The natural latex has poor storage stability, and the aging resistance, tensile strength and tear resistance of the product are poor, so that the application of the natural latex in the field of high added value is limited.
In the prior art, when a natural latex/chitin nano-fiber composite membrane is prepared, the content of the chitin nano-fiber is high, so that the cost is increased, the process is influenced, and the obtained composite membrane has poor flexibility. In addition, the prior art can not solve the problems of poor storage stability of natural latex and poor ageing resistance of products thereof.
In order to solve the above problems, the present invention provides a natural latex/chitin nanofiber composite membrane with high strength and good flexibility.
The invention also aims to provide a preparation method of the natural latex/chitin nanofiber composite membrane with high strength and good flexibility.
The invention also provides a method for improving the storage stability of the natural latex and the aging resistance of the product by utilizing the chitin nano-fiber.
The invention provides a preparation method of a natural latex/chitin nano-fiber composite membrane, which disperses a suspension of chitin nano-fibers in a natural latex matrix according to a proportion, and obtains a natural latex/chitin nano-fiber composite aqueous dispersion with excellent storage stability after mixing and stirring uniformly; and then forming a film by a dipping, casting or suction filtration method, and further heating and vulcanizing to obtain the natural latex/chitin nano-fiber composite film with high tensile strength, good flexibility and ageing resistance.
The invention is realized by the following technical scheme:
a preparation method of a natural latex/chitin nanofiber composite material is characterized by comprising the following steps:
1) preparing a suspension of chitin nanofibers;
2) adjusting the solid content and the pH value of the obtained suspension of the chitin nano fibers for later use;
3) uniformly mixing the suspension of the chitin nano fibers adjusted in the step 2) with natural latex under the condition of continuous stirring to obtain a composite aqueous dispersion of the natural latex/the chitin nano fibers;
4) forming the natural latex/chitin nano fiber composite suspension in the step 3) into a film in a dipping, casting or suction filtration mode, and further heating and vulcanizing to obtain the natural latex/chitin nano fiber composite film.
It is preferable that: the contents of the natural latex and the chitin nano-fiber are calculated according to the dry weight parts as follows:
99.9-99.99 wt% of natural latex
0.01-0.1 wt% of chitin nano-fiber
It is preferable that: the molecular chain of the chitin nano-fiber is provided with carboxyl, and the Zeta potential of the chitin nano-fiber suspension at the pH value of 10-11 is-30 to-60 mV.
It is preferable that: the chitin nano-fiber has a diameter of 1-5nm, a length of more than 1 μm, and a length-diameter ratio of more than 200.
It is preferable that: the raw material for preparing the chitin nano fiber is any one of shrimp shell, crab shell, insect shell, squid bone, penholder fish bone, canal worm or cuttlefish bone.
It is preferable that: the preparation method of the chitin nanofiber suspension in the step 1) is characterized in that an oxidizing reagent is adopted to oxidize chitin to obtain oxidized slurry with carboxyl on the surface, and then the oxidized slurry is crushed and peeled by using mechanical force to prepare the chitin nanofiber suspension.
It is preferable that: the chitin comprises purified chitin powder or raw materials containing chitin.
It is preferable that: the oxidizing agent is any one of a TEMPO agent or a peroxide.
It is preferable that: the mechanical force comprises ultrasound, ball milling, high shearing, high pressure homogenization and high pressure water jet.
It is preferable that: the natural latex is pre-vulcanized natural latex, and comprises fresh natural latex derived from hevea trees or concentrated natural latex, and is pre-vulcanized by adopting a vulcanization system consisting of a vulcanizing agent, an accelerator and an activator, an anti-aging agent and a stabilizer.
It is preferable that: the dry rubber content of the natural rubber latex is 60 wt%.
It is preferable that: the solid content of the adjusted chitin nano-fiber suspension in the step 2) is 0.04-0.1 wt%, and the pH value is 10-11.
Preferably, the mixing and stirring in the step 3) is performed under a continuous stirring condition, wherein the stirring speed is 200-2000r/min, the stirring time is 5-120min, and the temperature is 10-40 ℃.
Preferably, the vulcanization in the step 4) is heating vulcanization, and the heating vulcanization is either or both of vacuum drying and forced air drying.
Preferably, the temperature of the vulcanization in step 4) is 80-110 ℃ and the time is 0.5-2 h.
Preferably, the dipping film formation in the step 4) is to use different dipping dies to pull the natural latex/chitin nanofiber composite aqueous dispersion into a film.
Preferably, the step 4) of casting to form a film refers to pouring the natural latex/chitin nanofiber composite aqueous dispersion into a mold, and forming the film at the temperature of 25-60 ℃.
Preferably, the film formation by suction filtration in the step 4) refers to vacuum filtration of the natural latex/chitin nanofiber composite aqueous dispersion under a flow field condition.
Preferably, the dry glue content of the natural latex/chitin nano-fiber composite aqueous dispersion is 24-60 wt%, and the processing process of the natural latex is not influenced.
Preferably, the natural latex/chitin nano-fiber composite aqueous dispersion has excellent storage stability, can keep the stability of the natural latex, is naturally stored for more than 6 months, has mechanical stability of not less than 650 seconds and has a volatile fatty acid value of less than 0.06 percent.
Preferably, the tensile strength of the natural latex/chitin nano-fiber composite membrane is 20-40 MPa. Particularly, when the dry weight content of the chitin nano fibers in the composite film is 0.01-0.05 wt%, the 100% stress at definite elongation is 0.5-0.7MPa, and the 500% stress at definite elongation is 1.0-1.3MPa, so that the flexibility of the natural latex film under low strain is maintained.
Preferably, the natural latex/chitin nanofiber composite membrane has excellent aging resistance, and after aging for 72 hours at 70 ℃, the tensile strength retention rate is 70-150%, the tensile elongation retention rate is 70-110%, and the 100% stress retention rate at definite elongation is 90-120%.
The invention also relates to the application of the natural latex/chitin nano-fiber composite material in the field of condoms.
The invention also relates to the application of the natural latex/chitin nanofiber composite material in the field of medical balloon materials.
The invention also relates to the application of the natural latex/chitin nano-fiber composite material in the fields of tissue engineering, regenerative medicine and medical scaffold materials.
By adopting the technical scheme, the invention has the following advantages:
1. the surface of the chitin nanofiber has negative charges; and has a length of more than 1 μm, a diameter of 1-5nm and an aspect ratio of more than 200.
In order to ensure good dispersion of the chitin nano-fibers in the natural latex, the suspension of the chitin nano-fibers is diluted to 0.04-0.1 wt% of solid content before use, and the pH value is adjusted to 10-11.
The chitin nano-fiber has an ultra-high length-diameter ratio and good dispersion, so that a cross-linked network and multiple stress transfer points which are uniformly distributed are more easily formed in a natural latex product, and the aim of enhancing the natural latex product can be achieved under an ultra-low use amount (accounting for 0.01-0.1 wt% of the dry weight of latex); meanwhile, under low strain, the nano-fibers with ultrahigh length-diameter ratio in the natural latex product are in a coiled state, and the filler network is softer and looser, so that the flexibility of the product is not influenced.
Therefore, the natural latex/chitin nanofiber composite membrane related in the invention has high tensile strength and flexibility under low strain, and is more beneficial to practical application of natural latex products.
2. Based on the method, the prepared natural latex film breaks through the limit thickness and is 10 mu m at the lowest while ensuring the strength and the flexibility under low strain, and the application of the natural latex film in the high-added-value field (such as condoms/medical saccule stents and the like) of natural latex products is greatly widened.
3. The extremely low usage amount does not influence the processing technology performance of the natural latex (the solid content/viscosity of the composite aqueous dispersion and other parameters are controllable), and the usage cost of the nano material is reduced; the conventional filler cannot achieve the purpose of reinforcing the natural latex product under the condition of extremely low addition amount.
4. The chitin nanofiber can interact with non-rubber substances on the surfaces of natural latex particles, damage of the non-rubber substances is protected, and storage stability of the natural latex composite aqueous dispersion and ageing resistance of the composite film are improved. In addition, based on the characteristics (biocompatibility, antibacterial property and the like) of the chitin nano-fiber, the chitin nano-fiber can effectively reduce the cytotoxicity of the natural latex film.
5. The production process of the natural latex/chitin nanofiber composite material is environment-friendly, the product performance is excellent, the defect that the existing nanomaterial reinforces the natural latex is overcome, and the natural latex/chitin nanofiber composite material has a very wide actual application prospect.
[ description of the drawings ]
FIG. 1 is a stress-strain curve of a natural latex composite membrane added with different amounts of chitin nanofibers;
FIG. 2 is a stress-strain curve of an aged natural latex composite film added with different amounts of chitin nanofibers;
FIG. 3 is a transmission electron microscope photograph of a section of a natural latex composite membrane compounded with 0.01 wt% chitin nanofibers;
FIG. 4 is a stress-strain curve of natural latex/chitin nanofiber composite membranes of different thicknesses;
FIG. 5 is a photograph of a natural latex/chitin nanofiber composite aqueous dispersion left at room temperature for 10 months;
FIG. 6 shows the UV absorbance of the surface surviving cells of the natural latex composite membrane added with different chitin nanofiber contents.
Table 1 shows the parameters and properties of the composites in the examples and comparative examples.
[ detailed description of the invention ]
The technical solution of the present invention is further illustrated below with reference to specific examples, but the scope of the present invention is not limited thereto.
Example 1
Weighing 4g of squid bones in a beaker, adding 80g of deionized water, crushing by using a crusher, then adding 2mol/L of ammonium persulfate, and magnetically stirring for 5 hours at 60 ℃ to oxidize hydroxymethyl on chitin molecular chains in the squid bones into carboxyl. After the reaction was completed, excess ammonium persulfate was washed off by filtration to obtain a neutral slurry (solid content 5 wt%). And (3) putting 10g of slurry into a beaker, adding 198g of deionized water, adjusting the pH to 10 by using 1mol/L NaOH solution, and performing ultrasonic treatment for 15min to obtain a transparent chitin nanofiber suspension with the solid content of 0.2 wt%. The suspension of chitin nano-fibers with the solid content of 0.2 wt% is diluted to 0.08 wt% by deionized water, and the pH value is adjusted to 10.5 by using 1mol/L NaOH solution, and the zeta potential of the obtained suspension of chitin nano-fibers is-55 mV, the diameter is 1-5nm, and the length is a few microns. And uniformly mixing the suspension of the chitin nano fibers and natural latex with the dry glue content of 60 wt% according to the corresponding proportion that the dry glue content of the chitin nano fibers in the composite film is 0.03 wt% to obtain natural latex/chitin nano fiber composite aqueous dispersion, wherein the dry glue content in the composite aqueous dispersion is 49 wt%. Diluting the composite material by using deionized water until the dry glue content is 38 wt%, directly dipping the composite material into a film (a common dipping mode of a condom is adopted, a mold is not dipped with a coagulant), dipping three layers, heating the composite material at 90 ℃ for 30min, and demoulding to obtain the natural latex-chitin nanofiber film with the thickness of 45 microns. The mechanical properties of the prepared natural latex/chitin nanofiber membrane are shown in figure 1 and table 1. After the composite film is placed in an oven at 70 ℃ and aged for 72 hours, the strength retention rate of the composite film is 130%, the tensile elongation retention rate is 89%, and the 100% stress retention rate at definite elongation is 105% (fig. 2). FIG. 6 shows that the cytotoxicity is reduced compared with that of natural latex film, and the material is suitable for condoms, medical saccule stents and the like.
Example 2:
the kind, amount and process flow of the used materials are the same as those of example 1, except that chitin powder derived from shrimp shells and crab shells is used as the raw material. The preparation method of the chitin powder comprises the following steps: grinding shrimp shell and crab shell into powder by using a grinder, soaking the powder in 0.1mol/L diluted HCl solution for 12 hours at room temperature, washing the powder by using distilled water, soaking the powder in 0.1mol/L NaOH solution for 12 hours, washing the powder by using deionized water, and then washing the powder by using 0.3 wt% of NaClO2Removing pigment from the solution, and drying to obtain chitin powder with acetyl degree of 95% derived from shrimp shell and crab shell. 4g of chitin powder is added into 3mol/L ammonium persulfate solution and stirred magnetically for 20h at 60 ℃. The pH value is adjusted to 10.5 by using 1mol/L NaOH solution, and the Zeta potential of the obtained chitin nano-fiber suspension is-50 mV, the diameter is 1-5nm, and the length is a plurality of micrometers. The properties of the prepared natural latex/chitin nanofiber composite are shown in Table 1. After the composite film is placed in an oven at 70 ℃ and aged for 72 hours, the strength retention rate of the composite film is maintainedThe tensile elongation is 150%, the retention rate of tensile elongation is 100%, and the retention rate of 100% stress at definite elongation is 110%. Is suitable for materials such as condoms, medical saccule stents and the like.
Example 3:
the kind, amount and process flow of the materials used were the same as those of example 2, except that 1g of chitin powder was dispersed in 99.0g of 1mol/L TEMPO reagent (TEMPO: NaClO)2In a molar ratio of 1: 10: 100) magnetically stirring at 80 ℃ for 4h, washing to neutral, adjusting pH, and peeling with a high-pressure homogenizer to obtain the chitin nanofiber suspension. The Zeta potential of the obtained chitin nano-fiber suspension is-52 mV, the diameter is 1-5nm, and the length is several micrometers. The properties of the prepared natural latex/chitin nanofiber composite are shown in Table 1. After the composite film is placed in an oven at 70 ℃ for aging for 72 hours, the strength retention rate of the composite film is 148%, the tensile elongation retention rate is 105%, and the 100% stress retention rate at definite elongation is 102%. Is suitable for materials such as condoms, medical saccule stents and the like.
Example 4:
the kind, amount and process flow of the used materials are the same as those of example 1, except that the compounding amount of the chitin nano-fibers is 0.01 t%. The properties of the prepared natural latex/chitin nanofiber composite material are shown in figure 1 and table 1. After the composite film is placed in an oven at 70 ℃ and aged for 72 hours, the strength retention rate of the composite film is 140%, the tensile elongation retention rate is 90%, and the 100% stress retention rate at definite elongation is 102% (fig. 2). In addition, from the projection electron microscope photograph of the ultrathin section of the composite film, the chitin nanofibers are uniformly dispersed in the natural latex film (fig. 3). FIG. 6 shows that the cytotoxicity is reduced compared with that of natural latex film, and the material is suitable for condoms, medical saccule stents and the like.
Example 5:
the kind, amount and process flow of the used materials are the same as those of example 1, except that the compounding amount of the chitin nano-fibers is 0.05 wt%. The properties of the prepared natural latex/chitin nanofiber composite material are shown in figure 1 and table 1. After the composite film is placed in an oven at 70 ℃ and aged for 72 hours, the strength retention rate of the composite film is 80%, the tensile elongation retention rate is 85%, and the 100% stress retention rate at definite elongation is 110% (fig. 2). FIG. 6 shows that the cytotoxicity is reduced compared with that of natural latex film, and the material is suitable for condoms, medical saccule stents and the like.
Example 6
The kind, amount and process flow of the used materials are the same as those of example 1, except that the compounding amount of the chitin nano-fibers is 0.1 wt%. The properties of the prepared natural latex/chitin nanofiber composite material are shown in figure 1 and table 1. After the composite film is placed in an oven at 70 ℃ and aged for 72 hours, the strength retention rate of the composite film is 85%, the tensile elongation retention rate is 75%, and the 100% stress retention rate at definite elongation is 115% (fig. 2). FIG. 6 shows that the cytotoxicity is lower than that of the natural latex film, and the film is more hard to handle due to more improved strength under low strain, so that the film is more suitable for materials such as medical gloves.
Example 7
The kind, amount and process flow of the used materials are the same as example 1, except that the pH value of the suspension of the chitin nano-fibers is adjusted to 11 by using 1mol/L NaOH solution before the suspension is compounded with the natural latex, and the Zeta potential of the obtained suspension of the chitin nano-fibers is-50 mV. The prepared natural latex/chitin nanofiber composite material has the properties shown in Table 1, has good biocompatibility, and is suitable for materials such as condoms, medical saccule stents and the like.
Example 8
The kind, amount and process flow of the used materials are the same as example 1, except that before the suspension of the chitin nano-fibers is compounded with the natural latex, 1mol/L NaOH solution is used for adjusting the pH value to 10, and the Zeta potential of the obtained suspension of the chitin nano-fibers is-50 mV. The prepared natural latex/chitin nanofiber composite material has the properties shown in Table 1, has good biocompatibility, and is suitable for materials such as condoms, medical saccule stents and the like.
Example 9
The kind, amount and process flow of the used materials are the same as example 1, except that deionized water is used to adjust the solid content of the suspension of the chitin nano fibers to 0.1 wt% before the suspension of the chitin nano fibers is compounded with natural latex, and the Zeta potential of the obtained chitin nano fiber suspension is-55 mV. The prepared natural latex/chitin nanofiber composite material has the properties shown in Table 1, has good biocompatibility, and is suitable for materials such as condoms, medical saccule stents and the like.
Example 10
The kind, amount and process flow of the used materials are the same as example 1, except that deionized water is used to adjust the solid content of the suspension of the chitin nano fibers to 0.06 wt% before the suspension of the chitin nano fibers is compounded with natural latex, and the Zeta potential of the obtained chitin nano fiber suspension is-55 mV. The prepared natural latex/chitin nanofiber composite material has the properties shown in Table 1, has good biocompatibility, and is suitable for materials such as condoms, medical saccule stents and the like.
Example 11
The kind, amount and process flow of the used materials are the same as example 1, except that deionized water is used to adjust the solid content of the suspension of the chitin nano fibers to 0.04 wt% before the suspension of the chitin nano fibers is compounded with natural latex, and the Zeta potential of the obtained chitin nano fiber suspension is-55 mV. The prepared natural latex/chitin nanofiber composite material has the properties shown in Table 1, has good biocompatibility, and is suitable for materials such as condoms, medical saccule stents and the like.
Example 12
The types, the using amounts and the process flow of the used materials are the same as those of the example 1, the difference is that two layers are directly dipped to form a film, the performance of the prepared natural latex/chitin nanofiber film is shown in figure 4 and table 1, the prepared natural latex/chitin nanofiber film has good biocompatibility, and the natural latex/chitin nanofiber film is suitable for materials such as condoms, medical saccule stents and the like.
Comparative example 1
The chitin powder was prepared as in example 5. The chitin powder is dispersed in 2.5mol/L KOH and 0.67mol/L urea aqueous solution to obtain chitin solution with mass fraction of 1 wt%. The chitin solution is self-assembled by a dialysis mode to prepare the alkalescent chitin nano-fiber suspension, and the obtained chitin nano-fiber has the diameter of 20nm and the length of several microns. The solid content of the suspension of the chitin nano-fibers is adjusted to be 0.45 wt% before use, and the pH value is 7. Compounding the suspension of the chitin nano fibers with natural latex with the dry glue content of 60 wt% according to the condition that the chitin nano fibers account for 2 wt% of the dry weight of the natural latex, wherein the dry glue content of the obtained composite material is 16 wt%. Because the content of the dry glue is too low, the film can not be peeled off after being directly immersed into three layers, and the method is not suitable for film materials such as condoms. The natural latex/chitin nano-fiber composite membrane is obtained by heating at 90 ℃ for 30min after casting and membrane forming, the thickness of the composite membrane is 500 mu m, the tensile strength is 13MPa, the elongation at break is 630%, the 100% stress at definite elongation is 5.2MPa (the 100% stress at definite elongation of the natural latex membrane with the membrane thickness of 500 mu m is 0.8MPa and is improved by 550%), and the 500% stress at definite elongation is 8.2MPa (the 500% stress at definite elongation of the natural latex membrane with the membrane thickness of 500 mu m is 1.3MPa and is improved by 530%). The composite membrane under low strain has high strength, and the membrane is hard and is not suitable for materials such as medical gloves, medical saccules and the like.
Comparative example 2
The types, the amounts and the process flows of the used materials are the same as those of the comparative example 1, except that the solid content of the suspension of the chitin nano-fibers is adjusted to 0.08 wt% and the pH value is 10.5 before use. Compounding the suspension of chitin nano fiber with natural latex with dry glue content of 60 wt% in the content of chitin nano fiber of 0.03 wt%, and obtaining the composite material with the properties shown in Table 1. At an extremely low compounding amount, the chitin nano-fibers regenerated by dissolving with the alkali urea have no reinforcing effect on the natural latex film.
Comparative example 3
The kind, amount and process flow of the used materials were the same as those of example 1, except that the pH of the suspension of chitin nanofibers was not adjusted to 7.3 before use. The suspension of the chitin nano-fibers is in a gel state, the composite material has the aggregation of the chitin nano-fibers, the film forming property is slightly poor, the performance of the obtained composite film is shown in table 1, and the reinforcing effect on a natural latex film is poor.
Comparative example 4
The types, amounts and process flows of the materials used were the same as in example 1, except that the solid content of the suspension of chitin nanofibers was not adjusted before use. The suspension of the chitin nano-fibers is in a gel state, the composite material has the aggregation of the chitin nano-fibers, the film forming property is slightly poor, the performance of the obtained composite film is shown in table 1, and the reinforcing effect on a natural latex film is poor.
Comparative example 5
Diluting natural latex with dry glue content of 60 wt% to 38 wt%, directly soaking to form three layers, and heating at 90 deg.C for 30min to obtain natural latex film with thickness of 35-46 μm. Natural latex films are not uniform in thickness and have low strength and limited applications (table 1 and fig. 2). In addition, after being hermetically placed for 10 months together with the composite aqueous dispersions of examples 1, 8 and 9, it was found that the stability of the natural latex was improved as the amount of the chitin nanofibers was increased (fig. 5), and fig. 6 shows that the cytotoxicity of the natural latex film was high.
Comparative example 6
Diluting natural latex with dry glue content of 60 wt% to 38 w%, directly soaking two layers to form a film, and heating at 90 deg.C for 30min to obtain the natural latex film. Because of the thin thickness and the low strength, the demoulding can not be finished.
Comparative example 7
The natural latex with the dry glue content of 60 wt% is cast into a film, and then the film is heated for 30min at 90 ℃ to obtain the natural latex film, wherein the film thickness is 500 mu m, the tensile strength is 18MPa, the elongation at break is 1000%, the 100% stress at definite elongation is 0.8MPa, and the 500% stress at definite elongation is 1.3 MPa. TABLE 1 comparison of composite film Performance of examples and comparative examples
Claims (10)
1. A preparation method of a natural latex/chitin nanofiber composite membrane is characterized by comprising the following steps: dispersing the suspension of the chitin nano-fibers in a natural latex matrix according to a proportion, and mixing and stirring uniformly to obtain a natural latex/chitin nano-fiber composite aqueous dispersion; and then forming a film, heating and vulcanizing to obtain the natural latex/chitin nano-fiber composite film.
2. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 1, wherein: the method comprises the following steps:
1) preparing a suspension of chitin nanofibers;
2) adjusting the solid content and the pH value of the obtained suspension of the chitin nano fibers for later use;
3) uniformly mixing the suspension of the chitin nano fibers adjusted in the step 2) with natural latex under the condition of continuous stirring to obtain a composite aqueous dispersion of the natural latex/the chitin nano fibers;
4) forming the natural latex/chitin nano-fiber composite aqueous dispersion in the step 3) into a film in a dipping, casting or suction filtration mode, and further heating and vulcanizing to obtain the natural latex/chitin nano-fiber composite film.
3. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 1 or 2, wherein: the contents of the natural latex and the chitin nano fiber are as follows according to dry weight parts:
99.9-99.99 wt% of natural latex
0.01-0.1 wt% of chitin nano-fiber.
4. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 1 or 2, wherein: the molecular chain of the chitin nano-fiber is provided with carboxyl, and the Zeta potential of the chitin nano-fiber suspension at the pH value of 10-11 is-30 to-60 mV;
it is preferable that: the diameter of the chitin nano-fiber is 1-5nm, the length is more than 1 μm, and the length-diameter ratio is more than 200;
it is preferable that: the raw material for preparing the chitin nano fiber is any one of shrimp shell, crab shell, insect shell, squid bone, penholder fish bone, canal worm or cuttlefish bone.
5. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 2, wherein: the preparation method of the chitin nanofiber suspension in the step 1) is characterized in that an oxidizing reagent is adopted to oxidize chitin to obtain oxidized slurry with carboxyl on the surface, and then the oxidized slurry is crushed and peeled by mechanical force to obtain the chitin nanofiber suspension;
preferably, the chitin comprises purified chitin powder or raw materials containing chitin;
preferably, the oxidizing agent is any one of a TEMPO agent or a peroxide;
preferably, the mechanical force comprises ultrasound, ball milling, high shear, high pressure homogenization, high pressure water jet.
6. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 1 or 2, wherein: the natural latex is pre-vulcanized natural latex, and comprises fresh natural latex derived from hevea trees or concentrated natural latex, and is pre-vulcanized by adopting a vulcanization system consisting of a vulcanizing agent, an accelerator and an activator, an anti-aging agent and a stabilizer;
it is preferable that: the dry rubber content of the natural rubber latex is 60 wt%.
7. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 2, wherein: the solid content of the adjusted chitin nano-fiber suspension in the step 2) is 0.04-0.1 wt%, and the pH value is 10-11;
preferably, the step 3) of uniformly mixing and stirring means that the mixing of the suspension of the chitin nanofibers and the natural latex is performed under the condition of continuous stirring, the stirring speed is 200-2000r/min, the stirring time is 5-120min, and the temperature is 10-40 ℃;
preferably, the vulcanization in the step 4) is heating vulcanization, and the heating vulcanization is either or both of vacuum drying and forced air drying;
preferably, the temperature of the vulcanization in step 4) is 80-110 ℃ and the time is 0.5-2 h.
Preferably, the dipping film formation in the step 4) refers to a film formation by pulling in a natural latex/chitin nanofiber composite aqueous dispersion by using different dipping dies;
preferably, the step 4) of casting the film is that the natural latex/chitin nanofiber composite aqueous dispersion is poured into a mould and the film is formed at the temperature of 25-60 ℃;
preferably, the film formation by suction filtration in the step 4) refers to vacuum filtration of the natural latex/chitin nanofiber composite aqueous dispersion under a flow field condition.
8. The method for preparing the natural latex/chitin nanofiber composite membrane according to claim 1 or 2, wherein: the dry glue content of the natural latex/chitin nano fiber composite aqueous dispersion is 24-60 wt%;
the natural latex/chitin nano-fiber composite aqueous dispersion has excellent storage stability, can keep the stability of the natural latex, can be naturally stored for more than 6 months, has mechanical stability of not less than 650 seconds and has a volatile fatty acid value of less than 0.06 percent.
9. A composite membrane prepared by the method of any of claims 1 to 8, wherein: when the content of the chitin nano-fiber in the composite membrane is 0.01-0.05 wt%, the 100% stress at definite elongation of the natural latex/chitin nano-fiber composite membrane is 0.5-0.7MPa, and the 500% stress at definite elongation is 1.0-1.3MPa, so that the flexibility of the natural latex membrane under low strain is maintained; the tensile strength of the natural latex/chitin nanofiber composite membrane is 20-40 MPa; after aging for 72 hours at 70 ℃, the retention rate of tensile strength is 70-150%, the retention rate of elongation at break is 70-110%, and the retention rate of 100% stress at definite elongation is 90-120%.
10. The use of the composite film according to claim 9 in the fields of condoms, medical balloon materials, tissue engineering, regenerative medicine, and medical scaffold materials.
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