CN107899085B

CN107899085B - Preparation method of nano hydroxyapatite/PA 6 composite material

Info

Publication number: CN107899085B
Application number: CN201711235835.5A
Authority: CN
Inventors: 邱丽; 胡雅菲; 邓晓楠; 郭兴梅; 李莎; 陈永康; 杨永珍; 刘旭光
Original assignee: Taiyuan University of Technology
Current assignee: Taiyuan University of Technology
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2020-11-20
Anticipated expiration: 2037-11-30
Also published as: CN107899085A

Abstract

A method for preparing nano hydroxyapatite/PA 6 composite material comprises adding nano hydroxyapatite into polyethylene glycol ethanol solution, and dispersing to obtain hydroxyapatite dispersion; dissolving PA6 raw material in FeCl₃Precipitating in ethanol solution to obtain PA6 powder; adding PA6 powder into the nano hydroxyapatite dispersion liquid, uniformly mixing, and drying to obtain composite material powder; carrying out hot press molding on the composite material powder to prepare a nano hydroxyapatite/PA 6 composite material; or the composite material powder is firstly put into silver ion solution for dipping treatment, the dipped silver ions are reduced into nano silver, and then the nano silver is heated and pressed to form the silver/nano hydroxyapatite/PA 6 composite material. The composite material prepared by the invention has the mechanical properties required by bone repair materials such as high strength, large modulus and the like, has certain antibacterial activity and bioactivity, and can be used as a biomedical composite material to be applied to the bone repair materials.

Description

Preparation method of nano hydroxyapatite/PA 6 composite material

Technical Field

The invention belongs to the technical field of biomedical composite materials, and relates to a preparation method of a nano hydroxyapatite/PA 6 composite material, in particular to a preparation method of a silver-loaded nano hydroxyapatite/PA 6 composite material. The invention enhances the strength, the bacterial inhibition and the biocompatibility of the PA6 by silver loading and hydroxyapatite addition.

Background

The biomedical materials for bone repair mainly comprise metal materials, medical ceramic materials, biomedical composite materials and the like. Most metallic materials are strong and have a higher modulus than human bone. The titanium and the titanium alloy which are widely applied have good biocompatibility, light weight, specific gravity close to that of human bones, elastic modulus close to that of natural bones compared with other medical metals, but the cost of the titanium alloy is higher. The medical ceramic material has good stability and biocompatibility, but has high brittleness and is only suitable for bone repair in non-stress occasions.

As a good material for bone repair, the material has good stability, antibacterial activity, bioactivity and mechanical property while considering the flexibility of processing and preparation.

Compared with the prior art, the polymer material has the multifunctional property and can be modified and compounded, so that the biomedical composite material has great advantages and development potential and is widely concerned by scientific researchers.

Hydroxyapatite is the main inorganic substance constituting bones and teeth, Ca being in the molecule²⁺Can perform exchange reaction with amino acid, protein, organic acid and the like containing carboxyl, thereby having good bone conduction performance and bioactivity, forming firm bony combination with bone tissues and promoting bone growth, and being a well-known bone repair substitute material with good performance. However, due to the above properties of hydroxyapatite, it is easy to concentrate bacteria thereon, for example, in dental surgery, which often results in failure of the surgery due to lack of effective antibacterial ability. In addition, the bending strength and the compressive strength of the single hydroxyapatite material are low, so that the application range and the use value of the hydroxyapatite material as a human bone substitute are greatly limited. Therefore, in order to improve the mechanical properties of the material and enhance the bacteriostatic properties of the material, other substances need to be introduced into the hydroxyapatite so as to form a composite material meeting the requirements.

PA6, commonly known as nylon 6, is a white to light yellow opaque solid, a heat resistant thermoplastic with high hardness, good strength, and abrasion resistance. PA6 is a high molecular polymer polymerized by caprolactam, the molecular structure of the polymer contains amide groups similar to the structure of collagen, the biocompatibility is better, and a friendly interface can be provided for cells and biological tissues.

The hydroxyapatite/PA 6 composite material is widely concerned by researchers due to excellent mechanical property, biological property and good processability.

The existing preparation method of the hydroxyapatite/PA 6 composite material which is relatively environment-friendly is to dissolve PA6 with a complexing agent and then prepare the composite material by a solvent precipitation method. CN 105031720A discloses a nano hydroxyapatite-polyamide medical composite material and a preparation method thereof, which is to obtain hydroxyapatite dispersion liquid by ultrasonically dispersing nano hydroxyapatite powder in ethanol solution containing polyethylene glycol, add high-strength PA into CaCl-containing solution₂Heating and dissolving the anhydrous ethanol solution, then dropwise adding an ethanol water solution to obtain a polyamide solution, then adding the hydroxyapatite dispersion liquid into the polyamide solution, adding water, stirring to separate out powder, and carrying out solid-liquid separation to obtain the nano hydroxyapatite-polyamide medical composite material. The PA6 is dissolved by adopting calcium chloride as a complexing agent, the dissolving speed is slow, the time consumption is long, the efficiency is low, and the potential safety hazard of overnight dissolution is large.

The other preparation method of the hydroxyapatite/PA 6 composite material which is relatively commonly used is an extrusion injection molding method, but the fluidity of the composite material prepared by the method is deteriorated along with the increase of the content of the hydroxyapatite in the matrix, so that the method is only suitable for preparing the composite material with less filler content or good filler fluidity.

Xulihua et al, vol.29, No. 2 (73-78) of composite materials, provide a method for preparing multi-walled carbon nanotubes/PA 6 composites by dissolving PA6 in formic acid, adding modified multi-walled carbon nanotubes thereto, and evaporating at 70 ℃ until most of the formic acid is volatilized. The strong corrosivity and toxicity of formic acid in the method can cause certain harm and pollution to experimenters and the environment.

Meanwhile, bacterial infections associated with the implantation of bone repair replacement materials have been widespread. When the bone repair material is implanted into a bone defect, free bacteria are easy to adhere to the surface of the material (particularly to the bone defect repair treatment in osteomyelitis with high bacteria concentration) and grow and propagate on the material, so that the operation fails. The current common solution is to add antibiotics to the material to play an antibacterial role. However, long-term use of antibiotics can cause drug resistance of bacteria, and the slow release capacity of the antibiotics is poor, so that the bacteria cannot resist the bacteria for a long time.

The introduction of the excellent broad-spectrum antibacterial agent nano silver into the material to destroy the growth of microorganisms is an effective means for avoiding the infection caused by the implanted material and providing long-term antibacterial protection for the biological material.

In Vol.20, 2 nd volume of powder metallurgy materials science and engineering, Lu Shi Qiang et al adopts a liquid-phase chemical reduction method, uses polyvinyl alcohol as a dispersing agent, sodium borohydride as a reducing agent and silver nitrate as a precursor to prepare silver powder with a particle size of about 120 nm. The chemical reduction method leads the prepared nano silver to have higher impurity content due to the introduction of a reducing agent, a dispersing agent and the like.

Disclosure of Invention

The invention aims to provide a preparation method of a nano hydroxyapatite/PA 6 composite material, and the composite material prepared by the method has excellent mechanical property and certain bioactivity.

The nano-hydroxyapatite/PA 6 composite material is a biological composite material prepared by taking PA6 as a base material, adding nano-hydroxyapatite and carrying out hot press molding. In the composite material prepared by the invention, the content of the nano-hydroxyapatite is 30-50 wt%, and the balance is PA 6.

The preparation method of the nano hydroxyapatite/PA 6 composite material comprises the steps of adding nano hydroxyapatite into a polyethylene glycol ethanol solution and dispersing to obtain a hydroxyapatite dispersion liquid; dissolving PA6 raw material in FeCl₃Precipitating in ethanol solution to obtain PA6 powder; adding PA6 powder into the nano hydroxyapatite dispersion liquid, uniformly mixing, and drying to obtain composite material powder; and carrying out hot press molding on the composite material powder to prepare the nano hydroxyapatite/PA 6 composite material.

In the preparation method, the nano hydroxyapatite used as the raw material is hydroxyapatite with the particle size of 30-80 nm.

Furthermore, the nano hydroxyapatite can be prepared by the following method: dropwise adding 0.3mol/L diammonium hydrogen phosphate solution into 0.5mol/L calcium nitrate solution with the same volume, controlling the pH value of the solution to be 10-12, stirring and reacting at the constant temperature of 45-55 ℃ for 3-4 h, adding polyethylene glycol with the volume 0.5-1 time of that of the generated hydroxyapatite, standing and precipitating for 24h, carrying out suction filtration and washing to be neutral, drying and grinding, and roasting at the temperature of 650-750 ℃ for 3-6 h to obtain the nano hydroxyapatite.

Preferably, the nano hydroxyapatite is dispersed in a polyethylene glycol ethanol solution with the volume percentage of 20-40%.

Wherein, the molecular weight of the used polyethylene glycol is less than or equal to 8000.

More preferably, 0.25-0.4 g of nano hydroxyapatite is added and dispersed in 1ml of polyethylene glycol ethanol solution.

Furthermore, after the nano hydroxyapatite powder is added into the polyethylene glycol ethanol solution, the nano hydroxyapatite powder can be rapidly and uniformly dispersed in the polyethylene glycol ethanol solution by adopting an ultrasonic treatment method.

In the production method of the present invention, PA6 as another raw material should be used as a dried raw material. Specifically, the PA6 used in the invention needs to be dried in vacuum for not less than 12 hours at 100-120 ℃ in advance.

The invention adopts FeCl₃The dissolving of PA6 by ethanol solution is based on the fact that iron ions are easily coordinated with carbonyl oxygen in PA6, which should form hydrogen bonds with amino groups, so as to weaken the hydrogen bonding between PA6 segments and promote the dissolution. Compared with other complexing agents, the method provided by the invention has the advantages that the dissolution rate and the solubility are obviously improved, and the potential safety hazard caused by overlong dissolution time is avoided. Moreover, tests prove that the functional group and the structure of the PA6 powder obtained after dissolution by the method are not obviously changed, which indicates that the original structure of PA6 is not damaged by the dissolution method.

Further, FeC for dissolving PA6 according to the inventionl₃In ethanol solution, FeCl is preferred₃The molar ratio of the alcohol to the ethanol is 1: 5-6.

More further, the FeCl of the present invention₃The optimal amount of the ethanol solution should satisfy the amount of the added PA6 and FeCl₃The mass ratio of the ethanol solution is 1: 12.5-13.5.

More preferably, the present invention adds said PA6 to FeCl₃After the ethanol solution is added, the mixture can be heated to 65-75 ℃ and stirred to promote dissolution.

Further, the ethanol aqueous solution to be re-precipitated from PA6 in the present invention is preferably an ethanol aqueous solution having a volume ratio of 1: 1 to 3. The invention controls the slow dropwise addition of the ethanol water solution into FeCl dissolved with PA6₃In the ethanol solution, PA6 precipitated slowly.

And (3) drying the separated PA6 after centrifugal separation to obtain PA6 powder meeting the requirements of preparing the composite material. Furthermore, the centrifugal rate is preferably 3000-4000 r/min, and the centrifugation is carried out for 9-12 times, 10-15 min each time.

The method specifically comprises the step of carrying out hot pressing on the composite material powder at 190-230 ℃ and 5-10 MPa to obtain a molding material.

The invention provides a typical hot press forming process: preheating a hot-pressing forming machine to 190-230 ℃, putting the mould added with the composite material powder into the hot-pressing forming machine, closing the mould, preheating for 25-30 min, then carrying out hot pressing for 10-15 min under the pressure of 5-10 MPa, keeping the pressure, cooling to normal temperature, releasing pressure, and taking out the formed material.

The preferred hot press molding machine is a flat vulcanizing machine, and of course, other hot press molding equipment such as an extruder, an injection molding machine and the like can be adopted to obtain the nano hydroxyapatite/PA 6 composite material by hot pressing under appropriate conditions.

Furthermore, the composite material powder can be placed in a silver ion solution for impregnation treatment, the impregnated silver ions are reduced into nano silver, and then the nano silver is heated and pressed to form the silver/nano hydroxyapatite/PA 6 composite material. In the composite material, the content of nano hydroxyapatite is 30-50 wt%, the content of nano silver is 0.1-0.65 wt%, and the balance is PA 6.

The invention preferably adopts silver nitrate as a silver source, and the nano hydroxyapatite/PA 6 composite material powder is soaked in silver nitrate aqueous solution in equal volume. During the impregnation process, silver ions are associated with amino groups in PA6, and the association can effectively help the nano silver to be uniformly dispersed.

The invention preferably adopts a plasma-assisted reduction method to reduce silver ions to obtain the nano silver. The plasma equipment can enable high-energy electron excited material surface groups or water molecules to generate high-energy free radicals under high pressure, and silver ions are reduced by utilizing the strong reducibility of the free radicals.

Specifically, the plasma-assisted reduction is to dry the composite material powder impregnated with the silver ion solution, and then reduce the silver ions for 1 hour by using plasma equipment with power of 600-700W in an inert gas environment.

The silver/nano-hydroxyapatite/PA 6 composite material prepared by the method not only has the mechanical properties required by bone repair materials such as high strength, large modulus and the like, but also has certain antibacterial activity and bioactivity. The composite material can be used as a biomedical composite material with excellent performance and can be applied to bone repair materials.

The invention firstly adopts FeCl₃The ethanol solution is used for dissolving the PA6, so that the defects of long time consumption, large potential safety hazard of overnight dissolution and low efficiency of dissolving PA6 by using calcium chloride as a complexing agent are overcome, the harm to experimenters and the pollution to the environment caused by using strong corrosive and toxic solvents such as formic acid are avoided, more importantly, the obtained PA6 powder is mixed with the nano-hydroxyapatite, the uniform dispersion of the nano-hydroxyapatite is obviously improved, and the composite material has stable biological activity and biocompatibility.

Secondly, the invention loads nano silver into the composite material. Due to the characteristics of broad spectrum and durability and no drug resistance, the silver is used as a common antibacterial agent, can effectively avoid the infection problem caused by the implantation of the bone repair material into the body, and relieves the pain of patients.

Meanwhile, silver nitrate is used as a silver source, silver ions in the silver source can be associated with amino groups in PA6, the dispersion of the silver ions can be promoted to a certain extent, and the silver nitrate is reduced by adopting plasma auxiliary reduction equipment, so that the method is short in time consumption, small in pollution, simple to operate, environment-friendly and efficient.

Finally, the molded composite material is prepared by adopting a hot-press molding method, so that the dispersity and the bonding capacity of the filler in PA6 can be increased, the uniform mixing of several substances is realized, and the performance of the composite material is more stable.

Drawings

FIG. 1 shows the XRD comparison patterns of PA6 raw material and PA6 powder.

FIG. 2 shows FT-IR comparison spectra of PA6 starting material and PA6 powder.

FIG. 3 is FT-IR comparison spectra of PA6 powder, nano hydroxyapatite and nano hydroxyapatite/PA 6 composite material.

Fig. 4 is a DSC diagram of the nano hydroxyapatite/PA 6 composite material.

Fig. 5 is a comparison graph of storage modulus of PA6 raw material, PA6 powder and nano hydroxyapatite/PA 6 composite material formed by hot pressing.

Fig. 6 is an XRD comparison pattern of the nano hydroxyapatite/PA 6 and silver/nano hydroxyapatite/PA 6 composite material.

Fig. 7 is a FT-IR comparison spectrum of the nano hydroxyapatite/PA 6 and silver/nano hydroxyapatite/PA 6 composite material.

Fig. 8 is a comparison of UV-vis absorption spectra of nano hydroxyapatite/PA 6 and silver/nano hydroxyapatite/PA 6 composite.

Detailed Description

The following examples are only preferred embodiments of the present invention and are not intended to limit the present invention in any way. Various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Example 1.

50mL of absolute ethanol is added into a three-neck flask, the mixture is heated to 65 ℃, and 23g of FeCl is added₃And stirring to dissolve. 5g of PA6 which had previously been dried at 100 ℃ for 12 hours under vacuum were addedAfter the pellets were completely dissolved, an aqueous ethanol solution (V) was slowly dropped into the three-necked flask_Ethanol∶V_{Water (W)}= 1: 3) until the PA6 powder was completely precipitated. Stirring is continued for 3h while keeping the temperature, and the mixture is centrifugally washed for ten times for 15min each time by using an ethanol aqueous solution at the rotating speed of 3500 r/min. The powder was filtered off with suction, dried at 100 ℃ for 12h and ground to give PA6 powder.

The PA6 raw material and the PA6 powder prepared in the example are respectively taken and added into a die for cold press molding. Preheating a lower plate of a flat vulcanizing machine to 190 +/-3 ℃, preheating an upper plate to 220 +/-3 ℃, putting the die into the flat vulcanizing machine, preheating for 25min, boosting to 9-10 MPa, keeping the temperature and pressure for 10min, stopping heating, keeping the pressure and cooling for 25min, and taking out to obtain a molding material of a PA6 raw material and PA6 powder.

FIG. 1 shows the PA6 feedstock and FeCl used in this example₃XRD pattern of PA6 powder prepared from ethanol solution, where curve 1 is PA6 starting material and curve 2 is PA6 powder.

As can be seen from fig. 1, the alpha crystal form characteristic absorption peaks of PA6 appear at 2 θ =20.12 ° and 23.79 ° respectively, the gamma crystal form characteristic absorption peak of PA6 appears at 2 θ =21.53 °, and the PA6 raw material corresponds to the characteristic absorption peak of the powder, which proves that FeCl is used as the raw material₃The PA6 powder prepared by dissolving the ethanol solution does not change the crystal structure.

FIG. 2 shows the PA6 feedstock and FeCl used in this example₃FT-IR spectrum of PA6 powder prepared from ethanol solution, where curve 1 is PA6 feedstock and curve 2 is PA6 powder.

It can be seen that the characteristic absorption peak of PA6, 1640cm, also appears in curve 2 compared to curve 1^-1Is located at 3437cm as carbonyl stretching vibration peak^-1Is positioned at 2958cm of an amino stretching vibration peak^-1And a methylene stretching vibration peak is shown. Comparing

curves

1 and 2, it is illustrated with FeCl₃The functional groups of the PA6 powder prepared by dissolving in ethanol solution are not destroyed, and few new functional groups are generated.

Example 2.

Adding 3.4mL of PEG400 into 7mL of ethanol, dissolving uniformly, adding 3.4289g of nano-hydroxyapatite into the solution, and performing ultrasonic dispersion for 1 h. Adding 8g of the PA6 powder prepared in example 1 into the dispersion, stirring and mixing uniformly, washing with an ethanol water solution, and drying to obtain nano hydroxyapatite/PA 6 composite material powder.

Taking nano hydroxyapatite/PA 6 composite material powder, adding into a mould, and cold-pressing and molding. Preheating a lower plate of a flat vulcanizing machine to 190 +/-3 ℃, preheating an upper plate to 220 +/-3 ℃, putting the die into the flat vulcanizing machine, preheating for 25min, boosting to 9-10 MPa, keeping the temperature and pressure for 10min, stopping heating, keeping the pressure and cooling for 25min, and taking out to obtain the nano-hydroxyapatite/PA 6 composite molding material.

Fig. 3 shows FT-IR spectra of the raw PA6 powder, nano-hydroxyapatite, and nano-hydroxyapatite/PA 6 composite powder prepared in this example, wherein curve 1 is nano-hydroxyapatite, curve 2 is PA6 powder, and curve 3 is nano-hydroxyapatite/PA 6 composite.

As can be seen from curve 3, the nano-hydroxyapatite 1051cm in curve 1^-1Phosphoric acid group stretching vibration absorption peak and 3425cm^-1The hydroxyl stretching vibration peak of (2) still exists in the composite material. At the same time, 1640cm in the composite material^-1Carbonyl stretching vibration peak of 3305cm^-1(2935 cm) of the peak of amino group stretching vibration^-1The methylene stretching vibration peak of (a) is not significantly shifted compared to the PA6 powder of curve 2. This shows that the composite material has the characteristic peaks of hydroxyapatite and PA 6.

Fig. 4 shows DSC crystallization curve spectra of the raw PA6 powder and the prepared nano-hydroxyapatite/PA 6 composite powder used in this example. Wherein curve 1 is PA6 powder and curve 2 is nano hydroxyapatite/PA 6 composite material.

Generally speaking, the crystallinity is an expression of mechanical properties of materials, and the larger the crystallinity is, the more regular and compact the arrangement of the polymer chain segments is, and the better the mechanical properties are.

As can be seen from the figure, the crystallization temperature of the nano hydroxyapatite/PA 6 composite material powder is higher than that of the raw material PA6 powder, which shows that the addition of the nano hydroxyapatite plays a role in heterogeneous nucleation and can promote the crystallization of the material at a higher temperature.

Furthermore, the crystallinity of the nano-hydroxyapatite/PA 6 composite materialX _tCan be calculated by the following formula.

Wherein:ΔH _m ^*is the heat of fusion when the polymer is completely crystalline (100%),ΔH _mthe actual melting heat obtained by measuring and solving the peak area of the composite material under the equipment condition,θis the mass percentage of the nano hydroxyapatite in the composite material.

In particular of the polymer PA6ΔH _m ^*188J/g, the heat of fusion of the PA6 powder was 66.14J/g, the heat of fusion of the nano-hydroxyapatite/PA 6 composite was 51.59J/g, the crystallinity of the PA6 powder was 35.18% and the crystallinity of the composite was 39.20% as calculated by the above formula, according to DSC curves and software.

Fig. 5 shows the dynamic mechanical analysis maps of different materials. In the figure, curve 1 is the storage modulus of the raw material PA6 after hot press molding, and curve 2 is FeCl₃The storage modulus of the PA6 powder dissolved in the ethanol solution after hot press molding is shown in curve 3, which is the storage modulus of the nano hydroxyapatite/PA 6 composite material after hot press molding. It can be seen from the figure that the storage modulus of curve 3 is the highest, because the hydroxyl group of the nano-hydroxyapatite itself can form a hydrogen bond with the amino group in the PA6 chain segment, the interface acting force of the nano-hydroxyapatite and PA6 is enhanced, so that the stress dispersion and transfer are effectively performed, the performances of the nano-hydroxyapatite and PA6 are effectively combined, and the mechanical property of the composite material is significantly improved.

Example 3.

0.012g of silver nitrate was weighed and dissolved in 3mL of water to prepare a silver nitrate solution. 3g of the nano-hydroxyapatite/PA 6 composite powder prepared in example 2 was weighed, and the silver nitrate solution was added to just infiltrate the nano-hydroxyapatite/PA 6 composite powder with the solution, and the same volume of impregnation was performed.

And uniformly stirring the soaked materials, drying the materials in a vacuum drying oven for 24 hours in a dark place, putting the materials into a plasma device, introducing argon, treating the materials for 1 hour under the condition of the power of 600W to reduce silver ions into nano silver, and drying the nano silver ions to obtain silver/nano hydroxyapatite/PA 6 composite material powder.

Adding a certain amount of silver/nano hydroxyapatite/PA 6 composite material powder into a mould for cold press molding. Simultaneously preheating a lower plate of the flat vulcanizing machine to 190 +/-3 ℃, preheating an upper plate to 220 +/-3 ℃, and putting the die into the flat vulcanizing machine for preheating; after 25min, increasing the pressure to 9-10 MPa, and keeping the temperature and the pressure for 10 min; stopping heating, maintaining the pressure, cooling for 25min, and taking out the molding material after cooling.

Fig. 6 shows XRD patterns of the nano-hydroxyapatite/PA 6 and silver/nano-hydroxyapatite/PA 6 composite materials. Curve 1 is nano-hydroxyapatite/PA 6, and curve 2 is silver/nano-hydroxyapatite/PA 6. As can be seen from the figure, when no nano-silver is added, PA6 exists in two crystal forms, namely, an α crystal form (2 θ =19.97 °, 23.98 °) and a γ crystal form (2 θ =21.40 °), and after silver nitrate is added and plasma equipment is used for treatment, the crystal form of PA6 is also transformed into an α crystal form (2 θ =20.26 °, 23.97 °) with more stable performance, and a characteristic absorption peak of nano-silver (2 θ =38.16 °) is generated at the same time. This shows that the addition of nano silver can rearrange the chain segment of PA6 to become a more stable alpha crystal form.

FIG. 7 is an FT-IR spectrum of a composite material of nano hydroxyapatite/PA 6 and silver nitrate/nano hydroxyapatite/PA 6 which is not reduced yet. Curve 1 is nano hydroxyapatite/PA 6, and curve 2 is silver nitrate/nano hydroxyapatite/PA 6. Curve 2 in the figure is 3300cm^-1An amino group absorption peak appears. Silver ions in silver nitrate/nano-hydroxyapatite/PA 6 can react with-NH₂and-NH, which leads to a broadening of the peak shape, indirectly indicating the presence of silver in the system.

Fig. 8 shows the UV-vis absorption spectrum of the composite material of nano hydroxyapatite/PA 6 and silver/nano hydroxyapatite/PA 6, curve 1 is nano hydroxyapatite/PA 6, and curve 2 is silver/nano hydroxyapatite/PA 6. As can be seen from the curve 2, a characteristic absorption peak of the nano-silver with narrow peak width and small absorption wavelength appears at 403 nm. Generally, the peak position of the absorption peak is related to the particle size, and the larger the difference in particle size range is, the wider the full width at half maximum of the absorption peak is. The particle size of the nano silver is about 30-40 nm under the same absorption wavelength. Therefore, the characteristic absorption peak position and peak shape of the nano-silver in the curve 2 indicate that the prepared nano-silver has narrow particle size distribution and smaller particle size to a certain extent. The smaller the particle size of the nano silver is, the higher the surface energy is, and the stronger the bacteriostasis is.

Claims

1. A preparation method of a nano-hydroxyapatite/PA 6 composite material comprises the steps of adding nano-hydroxyapatite into a polyethylene glycol ethanol solution for dispersion to obtain a hydroxyapatite dispersion solution, wherein the content of the nano-hydroxyapatite in the composite material is 30-50 wt%, and the balance is PA 6; according to PA6 with FeCl₃The mass ratio of the ethanol solution is 1: 12.5-13.5, and the PA6 raw material is dissolved in FeCl₃FeCl with ethanol in a molar ratio of 1: 5-6₃In the ethanol solution, precipitating with an ethanol water solution with the volume ratio of 1: 1-3 to obtain PA6 powder; adding PA6 powder into the nano hydroxyapatite dispersion liquid, uniformly mixing, and drying to obtain composite material powder; and carrying out hot press molding on the composite material powder to prepare the nano hydroxyapatite/PA 6 composite material.

2. The preparation method of claim 1, wherein the obtained composite material powder is firstly put into a silver ion solution for dipping treatment, the dipped silver ions are reduced into nano silver, and then the nano silver is subjected to hot press molding to prepare the silver/nano hydroxyapatite/PA 6 composite material, wherein the composite material contains 30-50 wt% of nano hydroxyapatite, 0.1-0.65 wt% of nano silver and the balance of PA 6.

3. The method according to claim 1 or 2, wherein the nano-hydroxyapatite has a particle size of 30 to 80 nm.

4. The method according to claim 1 or 2, wherein the volume percentage of the polyethylene glycol ethanol solution is 20-40%, and the molecular weight of the polyethylene glycol used is not more than 8000.

5. The method according to claim 1 or 2, wherein 0.25 to 0.4g of nano-hydroxyapatite is added and dispersed in 1mL of the polyethylene glycol ethanol solution.

6. The method according to claim 1 or 2, wherein the hot press molding is performed by hot pressing the composite powder at 190 to 230 ℃ and 5 to 10MPa in a hot press molding machine.

7. The preparation method according to claim 2, wherein the composite material powder impregnated with the silver ion solution is dried by a plasma-assisted reduction method, and then reduced for 1 hour by a plasma device with power of 600-700W in an inert gas environment.