Functional powder and preparation method thereof, and polyvinyl alcohol composite material and preparation method thereof

Abstract

The invention provides functional powder and a preparation method thereof, and a polyvinyl alcohol composite material and a preparation method thereof, and belongs to the technical field of polymer films. The functional powder provided by the invention comprises polydopamine modified boron nitride and silicon dioxide loaded on the polydopamine modified boron nitride. The polydopamine modified boron nitride is adopted, so that the compatibility of the inorganic filler boron nitride and the polyvinyl alcohol is improved, the agglomeration of the boron nitride is avoided, and the heat-conducting property and the mechanical property of the polyvinyl alcohol composite material are further improved; meanwhile, silicon dioxide is loaded on polydopamine modified boron nitride, so that the mechanical property of the polyvinyl alcohol composite material can be improved; the functional powder provided by the invention is relatively good in heat conductivity coefficient, and can be used as a good heat-conducting filler to fill a matrix, so that the crystallinity of polyvinyl alcohol can be improved, the scattering of phonons can be reduced, and the heat transfer efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer films, and in particular relates to a functional powder and a preparation method thereof and a polyvinyl alcohol composite material and a preparation method thereof. Background Art

[0002] Polyvinyl alcohol (PVA) has good film-forming properties, significant chemical resistance and good thermal stability. It is widely used in packaging, electronics and film industries, but has poor thermal conductivity (thermal conductivity <0.4Wm -1 ·K -1 ).

[0003] At present, the main method for improving the thermal conductivity of polyvinyl alcohol composites is to add boron nitride, but the addition of boron nitride will lead to uneven dispersion in the polyvinyl alcohol matrix, resulting in reduced thermal conductivity and mechanical properties of polyvinyl alcohol. Therefore, how to improve boron nitride to improve the dispersibility of boron nitride in the polyvinyl alcohol matrix, thereby improving the thermal conductivity and mechanical properties of polyvinyl alcohol composites has become a technical problem that needs to be solved in this field. Summary of the invention

[0004] The purpose of the present invention is to provide a functional powder and a preparation method thereof and a polyvinyl alcohol composite material and a preparation method thereof. The functional powder provided by the present invention can be uniformly dispersed in a polyvinyl alcohol matrix, thereby improving the thermal conductivity and mechanical properties of the polyvinyl alcohol composite material.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a functional powder, comprising polydopamine-modified boron nitride and silicon dioxide loaded on the polydopamine-modified boron nitride.

[0007] Preferably, the preparation method of the polydopamine-modified boron nitride comprises:

[0008] The buffer, dopamine hydrochloride, solvent and surfactant-modified boron nitride are mixed and modified to obtain polydopamine-modified boron nitride.

[0009] Preferably, the mass of the dopamine hydrochloride is 30-60% of the mass of the boron nitride.

[0010] Preferably, the modification temperature is 75-85° C., and the modification time is 20-28 h.

[0011] The present invention also provides a method for preparing the functional powder described in the above technical solution, comprising:

[0012] The polydopamine-modified boron nitride, a surfactant, an inorganic solvent and a silicon source are mixed, and gelled and dried in sequence to obtain a functional powder.

[0013] Preferably, the mass of the silicon source is 200-500% of the mass of the polydopamine-modified boron nitride.

[0014] Preferably, the mass ratio of the silicon source to the surfactant is (4-6):1.

[0015] The present invention also provides a polyvinyl alcohol composite material, the components of which include the functional powder described in the above technical solution or the functional powder prepared by the preparation method described in the above technical solution and polyvinyl alcohol.

[0016] Preferably, the mass of the functional powder is 0.1-2.0% of the mass of polyvinyl alcohol.

[0017] The present invention also provides a method for preparing the polyvinyl alcohol composite material described in the above technical solution, comprising:

[0018] Functional powder, polyvinyl alcohol and an inorganic solvent are mixed and molded to obtain a polyvinyl alcohol composite material.

[0019] The present invention provides a functional powder, including polydopamine-modified boron nitride and silicon dioxide loaded on the polydopamine-modified boron nitride. The present invention adopts polydopamine-modified boron nitride to improve the compatibility of inorganic filler boron nitride and polyvinyl alcohol, thereby avoiding the agglomeration of boron nitride, thereby improving the thermal conductivity and mechanical properties of the polyvinyl alcohol composite material; at the same time, silicon dioxide is loaded on the polydopamine-modified boron nitride, which can improve the mechanical properties of the polyvinyl alcohol composite material; in addition, the functional powder provided by the present invention itself has a good thermal conductivity coefficient, and as a good thermal conductive filler filled inside the matrix, it can improve the crystallinity of polyvinyl alcohol, reduce the scattering of phonons, and improve the heat transfer efficiency; and the functional powder has a large specific surface area, which is conducive to interaction with the surrounding matrix, and can also act as a heterogeneous nucleating agent in the crystallization process of polyvinyl alcohol, thereby improving the mechanical properties of the polyvinyl alcohol composite material. The experimental results show that the polyvinyl alcohol composite material prepared by the functional powder provided by the present invention has a tensile strength of 56.5-68.5 MPa, an elongation at break of 103.2-126.3%, a Young's modulus of 1.35-2.11 GPa, and an in-plane thermal conductivity of 1.854-2.320 Wm -1 ·K -1 . BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The in-plane thermal conductivity and thermal conductivity growth rate curves of the polyvinyl alcohol composite films prepared in Examples 2 to 6 and Comparative Example 1;

[0021] Figure 2The surface temperature changes of the polyvinyl alcohol composite films prepared in Examples 2 to 6 and Comparative Example 1 when heated by the same heat source for the same duration;

[0022] Figure 3 It is a function curve of the surface temperature of the polyvinyl alcohol composite film prepared in Examples 2 to 6 and Comparative Example 1 changing with time when the same heat source is used for the same heating time. DETAILED DESCRIPTION

[0023] The invention provides a functional powder, comprising polydopamine-modified boron nitride and silicon dioxide loaded on the polydopamine-modified boron nitride.

[0024] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0025] The functional powder provided by the present invention includes polydopamine-modified boron nitride. The present invention adopts polydopamine-modified boron nitride to improve the compatibility of inorganic filler boron nitride and polyvinyl alcohol, thereby avoiding the agglomeration of boron nitride, and further improving the thermal conductivity and mechanical properties of the polyvinyl alcohol composite material.

[0026] In the present invention, the preparation method of the polydopamine-modified boron nitride preferably comprises:

[0027] The buffer, dopamine hydrochloride, solvent and surfactant-modified boron nitride are mixed and modified to obtain polydopamine-modified boron nitride.

[0028] In the present invention, the buffer is preferably Tris-HCl powder. The present invention has no particular limitation on the particle size of the buffer, and any buffer known to those skilled in the art can be used.

[0029] In the present invention, the solvent is preferably an inorganic solvent; the inorganic solvent is preferably deionized water.

[0030] In the present invention, the mass ratio of the solvent to the buffer is preferably (1400-1600): 1. As an embodiment, the mass ratio of the solvent to the buffer may be 1500:1.

[0031] In the present invention, the surfactant in the surfactant-modified boron nitride is preferably sodium cholate and / or sodium dodecyl sulfate. The surfactant-modified boron nitride of the present invention can improve the dispersibility of boron nitride in polyvinyl alcohol.

[0032] In the present invention, the preparation method of the surfactant-modified boron nitride preferably comprises the following steps:

[0033] The surfactant solution and the boron nitride are mixed and then post-treated to obtain the surfactant-modified boron nitride.

[0034] In the present invention, the boron nitride is preferably hexagonal boron nitride; and the particle size of the hexagonal boron nitride is preferably 1 to 2 μm.

[0035] In the present invention, the mass concentration of the surfactant solution is preferably 0.04-0.06%, more preferably 0.05%; the solvent of the surfactant solution is preferably deionized water; the mass ratio of the surfactant solution to boron nitride is preferably (90-110): 1. As an embodiment, the mass ratio of the surfactant solution to boron nitride can be (100-105): 1.

[0036] The present invention has no special limitation on the preparation of the surfactant solution, as long as the mass concentration meets the required requirements.

[0037] In the present invention, the mixing of the surfactant solution and boron nitride preferably includes ball milling, stirring and ultrasound in sequence. The present invention uses ball milling, stirring and ultrasound to improve the uniformity of the mixing of the surfactant solution and boron nitride.

[0038] In the present invention, the rotation speed of the ball mill is preferably 350-450 rpm; the ball milling time is preferably 10-14 hours. As an embodiment, the rotation speed of the ball mill can be 380-420 rpm, or 400 rpm; the ball milling time can be 11 hours, 12 hours or 13 hours; the ball-to-material ratio of the ball mill can be 3:1. The present invention limits the process parameters of the ball milling within the above range to make the raw materials mixed more uniformly.

[0039] In the present invention, the stirring time is preferably 1 to 3 hours, more preferably 2 hours. The present invention has no particular limitation on the stirring speed, which can be adjusted according to actual needs.

[0040] In the present invention, the power of the ultrasound is preferably 30 to 50 KHz, more preferably 40 KHz; the time of the ultrasound is preferably 0.5 to 1.5 h, more preferably 1 h.

[0041] In the present invention, the post-treatment preferably includes centrifugation, filtration, washing and drying performed sequentially.

[0042] In the present invention, the centrifugal speed is preferably 2500-3500 rpm, and the centrifugal time is preferably 15-25 min. As an embodiment, the centrifugal speed can be 3000 rpm, and the centrifugal time can be 20 min.

[0043] The present invention has no particular limitation on the filtering, washing and drying operations, and operations well known to those skilled in the art may be used.

[0044] In the present invention, the mass ratio of the surfactant-modified boron nitride to the buffer is preferably (3.5-4.5): 1. As an embodiment, the mass ratio of the surfactant-modified boron nitride to the buffer may be 4:1.

[0045] In the present invention, the mass of the dopamine hydrochloride is preferably 30-60% of the mass of the surfactant-modified boron nitride. As an embodiment, the mass of the dopamine hydrochloride can be 35-55% of the mass of the boron nitride, and can also be 40-50%. The present invention limits the mass of the dopamine hydrochloride to the above range to further improve the modification effect of the boron nitride.

[0046] In the present invention, the mixing of the buffer, dopamine hydrochloride, solvent and surfactant-modified boron nitride preferably comprises: first mixing the buffer, dopamine hydrochloride and solvent, and then adding surfactant-modified boron nitride for second mixing.

[0047] In the present invention, the first mixing is preferably ultrasound; the ultrasound time is preferably 0.5 to 1.5 hours; the ultrasound power is preferably 30 to 50 KHz, more preferably 40 KHz. As an embodiment, the ultrasound time can be 1 hour.

[0048] In the present invention, the second mixing is preferably ultrasound; the ultrasound time is preferably 1.5 to 2.5 hours; the ultrasound power is preferably 30 to 50 KHz, more preferably 40 KHz. As an embodiment, the ultrasound time can be 2 hours.

[0049] In the present invention, the modification temperature is preferably 75-85°C; the modification time is preferably 20-28h. As an embodiment, the modification temperature can be 80°C; the modification time can be 24h. The present invention limits the modification process parameters within the above range to further improve the degree of modification.

[0050] In the present invention, the modification is preferably carried out under stirring conditions. The present invention has no particular limitation on the stirring rate, which can be determined according to the technical common sense of those skilled in the art.

[0051] After the modification is completed, the present invention preferably filters, washes and dries the modified product in sequence to obtain polydopamine-modified boron nitride.

[0052] The present invention has no particular limitation on the filtering, washing and drying operations, and operations well known to those skilled in the art may be used.

[0053] The functional powder provided by the present invention further comprises silicon dioxide loaded on the polydopamine-modified boron nitride. In the present invention, silicon dioxide is loaded on the polydopamine-modified boron nitride, which can improve the mechanical properties of the polyvinyl alcohol composite material.

[0054] The present invention adopts polydopamine to modify boron nitride, so that the compatibility between inorganic filler boron nitride and polyvinyl alcohol is improved, thereby avoiding the agglomeration of boron nitride, and further improving the thermal conductivity and mechanical properties of the polyvinyl alcohol composite material; at the same time, silicon dioxide is loaded on the polydopamine-modified boron nitride, which can improve the mechanical properties of the polyvinyl alcohol composite material; in addition, the functional powder provided by the present invention has a good thermal conductivity coefficient itself, and can be filled inside the matrix as a good thermal conductive filler, which can improve the crystallinity of polyvinyl alcohol, reduce the scattering of phonons, and improve the heat transfer efficiency; and the functional powder has a large specific surface area, which is conducive to the interaction with the surrounding matrix, and can also act as a heterogeneous nucleating agent in the crystallization process of polyvinyl alcohol, thereby improving the mechanical properties of the polyvinyl alcohol composite material.

[0055] The present invention also provides a method for preparing the functional powder described in the above technical solution, comprising:

[0056] The polydopamine-modified boron nitride, a surfactant, an inorganic solvent and a silicon source are mixed, and gelled and dried in sequence to obtain a functional powder.

[0057] In the present invention, the surfactant is preferably sodium dodecylbenzene sulfonate; the mass of the surfactant is preferably 70-90% of the mass of the polydopamine-modified boron nitride. As an embodiment, the mass of the surfactant can be 75-85% of the mass of the polydopamine-modified boron nitride, and can also be 80%. The present invention limits the mass of the surfactant to the above range to further improve the modification effect.

[0058] In the present invention, the inorganic solvent is preferably deionized water; the mass ratio of the inorganic solvent to the polydopamine-modified boron nitride is preferably (225-275): 1. As an embodiment, the mass ratio of the inorganic solvent to the polydopamine-modified boron nitride can be 250:1.

[0059] In the present invention, the silicon source is preferably at least one of potassium silicate (K2O·mSiO2·nH2O) and sodium silicate; the mass of the silicon source is preferably 200-500% of the mass of the polydopamine-modified boron nitride. As an embodiment, the mass of the silicon source can be 250-450% of the mass of the polydopamine-modified boron nitride, and can also be 300-400%. The present invention limits the mass of the silicon source to the above range, which can further increase the loading amount of silicon dioxide, thereby further improving the mechanical properties of the polyvinyl alcohol composite material.

[0060] In the present invention, the mass ratio of the silicon source to the surfactant is preferably (4-6): 1. As an embodiment, the mass ratio of the silicon source to the surfactant may be 5:1.

[0061] In the present invention, the mixing of the polydopamine-modified boron nitride, the surfactant, the inorganic solvent and the silicon source is preferably performed by performing a third mixing of the polydopamine-modified boron nitride, the surfactant and the inorganic solvent, and then adding the silicon source to perform a fourth mixing.

[0062] In the present invention, the third mixing is preferably ultrasound; the ultrasound time is preferably 0.5 to 1.5 h, more preferably 1.0 h; the ultrasound power is preferably 30 to 50 KHz, more preferably 40 KHz.

[0063] In the present invention, the fourth mixing is preferably performed under stirring conditions; the stirring time is preferably 0.5 to 1.5 hours, more preferably 1.0 hour; the temperature of the fourth mixing is preferably 0 to 5° C. The present invention has no particular limitation on the stirring rate, which can be adjusted according to actual needs.

[0064] In the present invention, the gelling preferably comprises sequential addition of acid and standing.

[0065] The present invention has no special limitation on the acid addition operation, as long as the pH value of the solution is guaranteed to be 7. In the present invention, the purpose of adding acid is to provide hydrogen ions to complete K2O·mSiO2·nH2O+2H + →2K + +mSiO2+2mH2O, produces SiO2.

[0066] In the present invention, the standing time is preferably 30 to 42 hours, more preferably 36 hours.

[0067] After the gel is completed, the product obtained from the gel is preferably filtered and washed in sequence. The present invention has no special limitation on the operation of the filtration and washing, and the operation well known to those skilled in the art can be adopted.

[0068] In the present invention, the drying temperature is preferably 50-70° C., more preferably 60° C. The present invention has no particular limitation on the drying time, and the drying time may be until constant weight.

[0069] The functional powder prepared by the present invention using a simple and environmentally friendly method can effectively improve the thermal conductivity of the polyvinyl alcohol composite material.

[0070] The present invention also provides a polyvinyl alcohol composite material, the components of which include the functional powder described in the above technical solution or the functional powder prepared by the preparation method described in the above technical solution and polyvinyl alcohol.

[0071] The present invention has no particular limitation on the particle size of the functional powder, which can be adjusted according to actual needs.

[0072] In the present invention, the molecular weight of the polyvinyl alcohol is preferably 20,000 to 150,000. As an embodiment, the polyvinyl alcohol may be PVA17-99; the degree of polymerization of the polyvinyl alcohol may be 1.7k; the alcoholysis degree of the polyvinyl alcohol may be 99%; the density of the polyvinyl alcohol may be 1.080 g / cm 3 .

[0073] In the present invention, the mass of the functional powder is preferably 0.1-2.0% of the mass of the polyvinyl alcohol. As an embodiment, the mass of the functional powder can be 0.3%, 0.5% or 1.0% of the mass of the polyvinyl alcohol.

[0074] The polyvinyl alcohol composite material provided by the invention has excellent thermal conductivity and mechanical properties.

[0075] The present invention also provides a method for preparing the polyvinyl alcohol composite material described in the above technical solution, comprising:

[0076] Functional powder, polyvinyl alcohol and an inorganic solvent are mixed and molded to obtain a polyvinyl alcohol composite material.

[0077] In the present invention, the inorganic solvent is preferably deionized water; the mass ratio of the inorganic solvent to polyvinyl alcohol is preferably (13-17): 1. As an embodiment, the mass ratio of the inorganic solvent to polyvinyl alcohol can be (14-15): 1.

[0078] In the present invention, the mixing of the functional powder, polyvinyl alcohol and inorganic solvent is preferably carried out under stirring conditions; the stirring temperature is preferably 90 to 100°C, more preferably 95°C; the stirring time is preferably 3 to 6 hours. As an embodiment, the stirring time can be 4 to 5 hours. The present invention limits the mixing process parameters within the above range to make the raw materials mixed more uniformly.

[0079] In the present invention, the forming is preferably film forming; and the film forming is preferably film casting. The present invention has no special limitation on the operation of the film casting, and the operation well known to those skilled in the art can be adopted.

[0080] After the molding is completed, the present invention preferably dries the molded product to obtain a polyvinyl alcohol composite material.

[0081] In the present invention, the drying temperature is preferably room temperature; the drying time is preferably 30 to 42 hours, more preferably 36 hours. The present invention uses drying to remove the solvent in the molded product.

[0082] In the present invention, the thickness of the polyvinyl alcohol composite material is preferably 100 to 120 μm.

[0083] The invention uses a relatively simple process to prepare the polyvinyl alcohol composite material, which has excellent thermal conductivity and good mechanical properties.

[0084] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] Example 1

[0086] The functional powder consists of polydopamine-modified boron nitride and silicon dioxide loaded on the polydopamine-modified boron nitride;

[0087] The preparation method of the functional powder is:

[0088] (1) preparing 80 g of a 0.05 wt% aqueous solution of sodium cholate, weighing 0.8 g of hexagonal boron nitride with a particle size of 1 to 2 μm, adding the mixture to a polytetrafluoroethylene ball mill, setting the planetary ball mill speed to 400 rpm, and the ball-to-material ratio to 3:1 for ball milling for 12 h, stirring for 2 h, then ultrasonicating at 40 KHz for 1 h, and then centrifuging at 3000 rpm for 20 min, retaining the supernatant, filtering, washing and drying the supernatant in turn, and obtaining surfactant-modified boron nitride;

[0089] (2) Weigh 0.1 g of Tris-HCl powder and 0.2 g of dopamine hydrochloride, dissolve in 150 mL of deionized water, and ultrasonicate at 40 KHz for 30 min. Then add 0.4 g of the surfactant-modified boron nitride obtained in step (1) and ultrasonicate at 40 KHz for 2 h. Then, stir in an oil bath at 80° C. for modification for 24 h to obtain a black suspension. Then, filter, wash and dry in sequence to obtain polydopamine-modified boron nitride, denoted as PDA / h-BN.

[0090] (3) Weigh 0.2 g of the polydopamine-modified boron nitride obtained in step (1) and 0.16 g of sodium dodecylbenzene sulfonate, add them to 50 mL of deionized water, and then ultrasonicate at 40 kHz for 30 min, then add 0.8 g of potassium silicate (produced by Gulf Group), stir in an ice-water bath at 0°C for 30 min, and then slowly titrate with 1 mol / L HCl solution to a solution pH of 7, then let stand for 36 h to form a gel, then filter and wash in sequence, and then dry at 60°C to obtain a functional powder, recorded as PDA / h-BN@SiO2.

[0091] Example 2

[0092] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g of PVA, dissolve 0.002g of the functional powder prepared in Example 1 in 30mL of deionized water, stir in a 95°C oil bath for 4h, then pour into a mold for cast film formation, and then dry at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm; wherein the molecular weight of PVA is 20000-150000, is PVA17-99 type, has a degree of polymerization of 1.7k, a degree of alcoholysis of 99%, and a density of 1.080g / cm 3 .

[0093] Example 3

[0094] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g of PVA, dissolve 0.006g of the functional powder prepared in Example 1 in 30mL of deionized water, stir in a 95°C oil bath for 4h, then pour into a mold for cast film formation, and then dry at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm; wherein the molecular weight of PVA is 20000-150000, is PVA17-99 type, has a degree of polymerization of 1.7k, a degree of alcoholysis of 99%, and a density of 1.080g / cm 3 .

[0095] Example 4

[0096] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g of PVA, dissolve 0.01g of the functional powder prepared in Example 1 in 30mL of deionized water, stir in a 95°C oil bath for 4h, then pour into a mold for cast film formation, and then dry at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm; wherein the molecular weight of PVA is 20000-150000, is PVA17-99 type, has a degree of polymerization of 1.7k, a degree of alcoholysis of 99%, and a density of 1.080g / cm 3 .

[0097] Example 5

[0098] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g of PVA, dissolve 0.02g of the functional powder prepared in Example 1 in 30mL of deionized water, stir in a 95°C oil bath for 4h, then pour into a mold for cast film formation, and then dry at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm; wherein the molecular weight of PVA is 20000-150000, is PVA17-99 type, has a degree of polymerization of 1.7k, a degree of alcoholysis of 99%, and a density of 1.080g / cm 3 .

[0099] Example 6

[0100] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g of PVA, dissolve 0.04g of the functional powder prepared in Example 1 in 30mL of deionized water, stir in a 95°C oil bath for 4h, then pour into a mold for cast film formation, and then dry at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm; wherein the molecular weight of PVA is 20000-150000, is PVA17-99 type, has a degree of polymerization of 1.7k, a degree of alcoholysis of 99%, and a density of 1.080g / cm 3 .

[0101] Comparative Example 1

[0102] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g PVA and dissolve it in 30mL deionized water, stir it in a 95°C oil bath for 4h, then pour it into a mold for cast film formation, and then dry it at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm.

[0103] Comparative Example 2

[0104] The preparation method of the polyvinyl alcohol composite film is as follows: weigh 2g PVA and 0.04g hexagonal boron nitride, dissolve them in 30mL deionized water, stir them in a 95°C oil bath for 4h, then pour them into a mold for cast film formation, and then dry them at room temperature for 36h to obtain a polyvinyl alcohol composite film with a thickness of 110μm.

[0105] Comparative Example 3

[0106] The preparation method of the polyvinyl alcohol composite film is as follows: 2 g of PVA and 0.04 g of the polydopamine-modified boron nitride prepared in Example 1 are weighed, dissolved in 30 mL of deionized water, stirred in a 95°C oil bath for 4 h, then poured into a mold for cast film formation, and then dried at room temperature for 36 h to obtain a polyvinyl alcohol composite film with a thickness of 110 μm.

[0107] The mechanical properties of the polyvinyl alcohol composite films prepared in Examples 2 to 6 and Comparative Examples 1 to 3 were tested, and the results are shown in Table 1. The mechanical properties were tested using a HF-6008 computer single-column tensile testing machine in accordance with the national standard GB / T1040.3-2006.

[0108] Table 1 Mechanical properties data of polyvinyl alcohol composite films prepared in Examples 2 to 6 and Comparative Examples 1 to 3

[0109]

[0110]

[0111] As can be seen from Table 1, compared with Comparative Example 1, when Example 1 breaks, the tensile strength increases from 47.2 MPa to 56.5 MPa, an increase of 19.7%; when Example 5 breaks, the tensile strength increases from 47.2 MPa to 68.5 MPa, an increase of 45.1%; this is because the added functional powder has a large specific surface area, which is conducive to interaction with the surrounding matrix, and can also act as a heterogeneous nucleating agent during the crystallization process of PVA, which is the key to improving the mechanical properties of PVA; in addition, the addition of functional powders to the PVA matrix is ​​conducive to energy dissipation, and the addition of functional powders leads to a decrease in the free volume of PVA molecules, increases the interaction between the strongly polar -OH groups in the PVA molecules and the H atoms in the -CH2 groups, increases the intermolecular forces in the entire model, and leads to an increase in tensile strength.

[0112] Figure 1 The in-plane thermal conductivity and thermal conductivity growth rate curves of the polyvinyl alcohol composite films prepared in Examples 2 to 6 and Comparative Example 1 are shown; wherein the in-plane thermal conductivity is measured using a Hot Disk TPS2500S thermal conductivity meter in accordance with international standard ISO 22007-2.

[0113] from Figure 1 It can be seen that the in-plane thermal conductivity of pure polyvinyl alcohol (Comparative Example 1) at 25°C is 0.329 Wm -1 ·K -1 After adding the functional powder, the in-plane thermal conductivity of the polyvinyl alcohol composite film is significantly improved. When the addition amount of the functional powder is only 0.1wt%, the growth rate reaches an astonishing 463.53%. This improvement is mainly due to the filling of hexagonal boron nitride as a good thermal conductive filler in the matrix, which improves the heat transfer efficiency. With the increase of the content of functional powder, the content of thermal conductive filler in the matrix gradually increases. When the addition content is 2%, the in-plane thermal conductivity of Example 6 reaches 2.320Wm -1 ·K -1 , which is 605.17% higher than that of comparison example 1.

[0114] In order to vividly and intuitively demonstrate the thermal conductivity of polyvinyl alcohol composite film, Figure 2 The surface temperature changes of the polyvinyl alcohol composite films prepared in Examples 2 to 6 and Comparative Example 1 when heated by the same heat source for the same duration; Figure 3 It is a function curve of the surface temperature of the polyvinyl alcohol composite film prepared in Examples 2 to 6 and Comparative Example 1 changing with time when the same heat source is used for the same heating time.

[0115] from Figure 2 and 3 It can be seen that the temperature of comparative example 1 increased by 2°C in the first second after heating, and the temperature increased by 15.1°C after 10 seconds; while the temperature of example 6 increased by 19.5°C in the first second, and the temperature increased by 71.5°C after 10 seconds. Compared with comparative example 1, the heating temperature of example 6 in the first second was 17.5°C higher than that of comparative example 1, with a growth rate of 875%, and the heating temperature was 69.5°C higher after 10 seconds, with a growth rate of 3475%. The general trend was observed: (1) for the same heating time, the faster the heating rate of the polyvinyl alcohol composite film of the present invention, the higher the heating temperature, and the better the heating effect; (2) for the same temperature increase, the shorter the required heating time; this helps to explain that with the increase of the amount of functional powder added, the thermal conductivity of the polyvinyl alcohol composite film increases.

[0116] It can be seen from the above embodiments that the functional powder provided by the present invention can be uniformly dispersed in the polyvinyl alcohol matrix, thereby improving the thermal conductivity and mechanical properties of the polyvinyl alcohol composite material.

[0117] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A functional powder comprising polydopamine-modified boron nitride and silicon dioxide supported on the polydopamine-modified boron nitride.

2. The functional powder according to claim 1, characterized in that: The preparation method of the polydopamine-modified boron nitride comprises: The buffer, dopamine hydrochloride, solvent and surfactant-modified boron nitride are mixed and modified to obtain polydopamine-modified boron nitride.

3. The functional powder according to claim 2, characterized in that: The mass of the dopamine hydrochloride is 30-60% of the mass of the boron nitride.

4. The functional powder according to claim 2, characterized in that: The modification temperature is 75-85° C., and the modification time is 20-28 hours.

5. The method for preparing the functional powder according to any one of claims 1 to 4, comprising: The polydopamine-modified boron nitride, a surfactant, an inorganic solvent and a silicon source are mixed, and gelled and dried in sequence to obtain a functional powder.

6. The preparation method according to claim 5, characterized in that: The mass of the silicon source is 200-500% of the mass of the polydopamine-modified boron nitride.

7. The preparation method according to claim 5, characterized in that: The mass ratio of the silicon source to the surfactant is (4-6):

1.

8. A polyvinyl alcohol composite material, comprising the functional powder according to any one of claims 1 to 4 or the functional powder prepared by the preparation method according to any one of claims 5 to 7 and polyvinyl alcohol.

9. The polyvinyl alcohol composite material according to claim 8, characterized in that: The mass of the functional powder is 0.1-2.0% of the mass of polyvinyl alcohol.

10. The method for preparing the polyvinyl alcohol composite material according to claim 8 or 9, comprising: Functional powder, polyvinyl alcohol and an inorganic solvent are mixed and molded to obtain a polyvinyl alcohol composite material.

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