CN114369352A

CN114369352A - High-toughness heat-conducting PC composite material and preparation method thereof

Info

Publication number: CN114369352A
Application number: CN202210085067.4A
Authority: CN
Inventors: 郑玉婴; 郑新涛
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2022-01-25
Filing date: 2022-01-25
Publication date: 2022-04-19
Anticipated expiration: 2042-01-25
Also published as: CN114369352B

Abstract

The invention discloses a high-toughness heat-conducting PC composite material and a preparation method thereof, belonging to the field of polymer composite materials. The high-toughness heat-conducting PC composite material is prepared from the following raw materials in parts by weight: 100 parts of PC, 5-20 parts of a toughening agent, 1-8 parts of a heat conduction auxiliary agent and 0.5 part of dioctyl phthalate, wherein the toughening agent is GF-g-PMMA, and the heat conduction agent is BM-TA. The high-toughness heat-conducting PC composite material prepared by the invention has a scientific and reasonable formula and a simple and practical process flow, wherein the toughening agent mainly comprises glass fiber, the surface of the glass fiber is modified by KH560, and PMMA is further grafted on the surface of the glass fiber; according to the invention, the thermal conductive agent utilizes tannic acid to modify boehmite, so that the compatibility of the boehmite with a matrix material can be enhanced.

Description

High-toughness heat-conducting PC composite material and preparation method thereof

Technical Field

The invention belongs to the field of polymer composite materials, and particularly relates to a high-toughness heat-conducting PC composite material and a preparation method thereof.

Background

Polycarbonate (PC) is one of five major engineering plastics in widespread use. The PC has good mechanical properties, particularly excellent impact strength, and can keep the shape unchanged in a wider temperature range. PC is an amorphous transparent material, has good heat resistance, has a heat distortion temperature of 135-145 ℃, and can improve the bending strength, the elastic modulus and the like by heat treatment for a long time above 100 ℃. Since the sixties of the last century entered the market, PCs have been widely used in the fields of electrical appliances, machinery, electronics, automobiles, instruments, aviation, and home life. However, PC has significant disadvantages, such as high melt viscosity, difficulty in processing, high internal stress, susceptibility to stress cracking of the finished product, and resistance to chemical agents, particularly swelling, cracking, and degradation in alkaline and organic solvents. The main chain of the PC structural unit is connected with two benzene rings, so that the PC structural unit has high rigidity and cannot bend. The ester group has larger polarity, strong intermolecular force, difficult movement of polymer molecular chain segments and higher Tg of PC.

The glass fiber is an inorganic non-metallic reinforcing material with excellent performance, has the characteristics of good heat resistance, high mechanical strength and the like, can effectively enhance various performances of the glass fiber by modifying the surface of the glass fiber by using the silane coupling agent, and can enhance the compatibility of PC and the heat-conducting filler added in experiments by grafting the polymethyl methacrylate, thereby enhancing the performances of the glass fiber.

Boehmite (BM) is a fine white crystal, has complete crystallization, fine crystal grains and few crystal structure defects, so the thermal conductivity is higher. However, at present, reliable data of boehmite heat conductivity coefficient do not exist, but the heat conductivity of the room temperature vulcanized silicone rubber filled with boehmite is between that of zinc oxide and silicon nitride, and compared with other heat conducting materials, boehmite has unique advantages, smaller hardness and density, proper price, smaller abrasion to a screw rod in the processing process, smaller product density and competitiveness, and very strong practical value by using boehmite as a heat conducting filler.

According to the invention, the high-toughness heat-conducting PC composite material is prepared by a melt blending method of the toughening agent and the heat conducting agent, the surface of the glass fiber is modified by the toughening agent through KH560, and then PMMA is grafted, so that the compatibility and mechanical property of the matrix material are improved, and agglomeration is prevented. Secondly, the heat conducting agent is based on boehmite, the boehmite has good heat conductivity, the surface of the boehmite is coated with tannic acid, and the tannic acid has a unique molecular structure, good biocompatibility and high chemical activity, and contains a large amount of phenolic hydroxyl on the surface, so that strong van der Waals force and hydrogen bonds can be formed when the tannin is compounded with the boehmite, and the heat conductivity and the mechanical property of the composite material are further improved.

Disclosure of Invention

The invention aims to provide a high-toughness heat-conducting PC composite material and a preparation method thereof. The invention has scientific and reasonable formula and simple and practical process flow, and the produced PC composite material has excellent mechanical property and heat-conducting property by adding the toughening agent and the heat-conducting agent, and can generate huge social and economic benefits.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the high-toughness heat-conducting PC composite material comprises the following raw materials in parts by weight: 100 parts of PC, 5-20 parts of a toughening agent, 1-8 parts of a heat conducting agent and 0.5 part of dioctyl phthalate, wherein the toughening agent is GF-g-PMMA, and the heat conducting agent is BM-TA.

The preparation method of the high-toughness heat-conducting PC composite material comprises the following specific steps:

1) the specific preparation process of the toughening agent GF-g-PMMA comprises the following steps:

preparation of GF-g-PMMA: placing 5g of glass fiber in a muffle furnace, preserving heat for 3h at 500 ℃, adding 65wt% nitric acid, reacting for 5h at 70 ℃, washing the glass fiber to be neutral by using a deionized water-ethanol mixed solution (volume ratio is 1: 1), and placing the glass fiber in a vacuum drying oven at 80 ℃ for drying for 12h to obtain GF. 2g of dried GF is weighed and placed in a three-neck flask, deionized water-ethanol mixed solution (volume ratio is 1: 1) is added, and ultrasonic treatment is carried out for 30 min. Then, 2ml of KH560 was added dropwise, and the mixture was adjusted to pH =4-5 with glacial acetic acid, stirred at room temperature for 30min, mechanically stirred at 80 ℃ for 1h, centrifuged, washed, and dried to obtain modified GF. And then weighing 1g of modified GF, adding the modified GF into a 50ml absolute ethyl alcohol three-neck flask, adding 5 ml of methyl methacrylate, stirring for 10min, adding 0.1g of dibenzoyl peroxide, condensing and refluxing at 50 ℃ for 20min, heating to 85 ℃ after the dibenzoyl peroxide is completely dissolved, reacting at constant temperature for 6h, cooling to room temperature, and centrifugally drying to obtain GF-g-PMMA.

2) The preparation process of the heat conducting agent BM-TA comprises the following steps:

preparation of BM-TA: weighing 0.2g of Tannic Acid (TA) and adding the Tannic Acid (TA) into a beaker filled with 200ml of deionized water, stirring for 30min to fully dissolve the tannic acid, then weighing 0.5g of Boehmite (BM) and adding the boehmite into the tannic acid aqueous solution, stirring for 2h at room temperature, and finally washing, filtering and drying to obtain a product BM-TA.

3) Adding GF-g-PMMA prepared in the step 1) and BM-TA prepared in the step 2) into dioctyl phthalate, uniformly mixing with PC particles in a high-speed mixer at the rotating speed of 300 r/min and the temperature of 60 ℃, and then placing in a 100 ℃ oven for drying for 6 hours.

4) Adding the dried raw materials into a double-screw extruder, wherein the temperature of the first section of the double-screw extruder is 275 ℃, the temperature of the second section of the double-screw extruder is 270 ℃, the temperature of the third section of the double-screw extruder is 270 ℃, the temperature of the fourth section of the double-screw extruder is 260 ℃, and the temperature of the fifth section of the double-screw extruder is 255 ℃; the rotating speed of the screw is 10 r/min; and extruding and granulating to obtain the mixed master batch.

5) Drying the mixed master batch obtained by the double-screw extruder and the granulator in a drying oven at 100 ℃ for 6 hours, and performing injection molding by using an injection molding machine, wherein the temperatures from a feed inlet to a discharge outlet of the injection molding machine are respectively a first section temperature: 300 ℃ and second stage temperature: 290 ℃, third stage temperature: 285 ℃ and fourth stage temperature: 275 ℃ and temperature in the fifth stage: 265 ℃ of water; injection molding pressure: 135 MPa; pressure maintaining: 40MPa, and obtaining the high-toughness heat-conducting PC composite material.

The invention has the beneficial effects that:

the high-toughness heat-conducting PC composite material prepared by the invention is scientific and reasonable in formula and simple and practical in process flow, the high-toughness heat-conducting PC composite material is prepared by a melt blending method of the toughening agent and the heat conducting agent, the surface of the glass fiber is modified by the toughening agent through KH560, and PMMA is grafted, so that the compatibility and mechanical property of a matrix material are improved, and agglomeration is prevented. Secondly, the heat conducting agent is based on boehmite, the boehmite has good heat conductivity, the surface of the boehmite is coated with tannic acid, and the tannic acid has a unique molecular structure, good biocompatibility and high chemical activity, and contains a large amount of phenolic hydroxyl on the surface, so that strong van der Waals force and hydrogen bonds can be formed when the tannin is compounded with the boehmite, and the heat conductivity and the mechanical property of the composite material are further improved.

Drawings

FIG. 1 is an infrared image of GF-g-PMMA prepared in example 1. 2952 cm in the figure^-1And 2859 cm^-1Is the stretching vibration peak of methyl and methylene, 1650cm^-1Is the stretching vibration peak of the carbon-carbon double bond, and shows that KH560 has been successfully introduced to the surface of the glass fiber, 1728 cm^-1Is an antisymmetric stretching vibration peak of a carbon-oxygen double bond, and shows that PMMA is successfully grafted on the surface of GF-KH 560.

FIG. 2 is an SEM image of BM-TA prepared in example 1, which shows that the surface of BM is coated with tannic acid and agglomeration is less pronounced.

Detailed Description

The present invention will be further understood from the following examples, which are not intended to limit the scope of the invention.

Example 1

preparation of GF-g-PMMA: placing 5g of glass fiber in a muffle furnace, preserving heat for 3h at 500 ℃, adding 65wt% nitric acid, reacting for 5h at 70 ℃, washing the glass fiber to be neutral by using a deionized water-ethanol mixed solution (volume ratio is 1: 1), and placing the glass fiber in a vacuum drying oven at 80 ℃ for drying for 12h to obtain GF. 2g of dried GF is weighed and placed in a three-neck flask, deionized water-ethanol mixed solution (volume ratio is 1: 1) is added, and ultrasonic treatment is carried out for 30 min. Then, 2ml of KH560 was added dropwise, and the mixture was adjusted to pH =5 with glacial acetic acid, stirred at room temperature for 30min, and then mechanically stirred at 80 ℃ for 1h, centrifuged, washed, and dried to obtain modified GF. And then weighing 1g of modified GF, adding the modified GF into a 50ml absolute ethyl alcohol three-neck flask, adding 5 ml of methyl methacrylate, stirring for 10min, adding 0.1g of dibenzoyl peroxide, condensing and refluxing at 50 ℃ for 20min, heating to 85 ℃ after the dibenzoyl peroxide is completely dissolved, reacting at constant temperature for 6h, cooling to room temperature, and centrifugally drying to obtain GF-g-PMMA.

preparation of BM-TA: weighing 0.2g of Tannic Acid (TA) and adding the Tannic Acid (TA) into a beaker filled with 200ml of deionized water, stirring for 30min to fully dissolve the tannic acid, then weighing 0.5g of BM and adding the BM into the tannic acid aqueous solution, stirring for 2h at room temperature, and finally washing, filtering and drying to obtain the product BM-TA.

3) Adding 5 parts by weight of toughening agent GF-g-PMMA and 6 parts by weight of heat conducting agent BM-TA into 0.5 part by weight of dioctyl phthalate, uniformly mixing the mixture with 100 parts by weight of PC particles in a high-speed mixer at the rotating speed of 300 r/min and the temperature of 60 ℃, and then placing the mixture in a 100 ℃ oven for drying for 6 hours.

Example 2

3) Adding 10 parts by weight of toughening agent GF-g-PMMA and 6 parts by weight of heat conducting agent BM-TA into 0.5 part by weight of dioctyl phthalate, uniformly mixing, then uniformly mixing with 100 parts by weight of PC particles in a high-speed mixer at the rotating speed of 300 r/min and the temperature of 60 ℃, and then placing in a 100 ℃ oven for drying for 6 hours.

Example 3

3) 15 parts by weight of a toughening agent GF-g-PMMA and 6 parts by weight of a heat conducting agent BM-TA are added into 0.5 part by weight of dioctyl phthalate and are uniformly mixed, and then the mixture is uniformly mixed with 100 parts by weight of PC particles in a high-speed mixer, wherein the rotating speed of the high-speed mixer is 300 r/min, the temperature is 60 ℃, and then the mixture is placed in a 100 ℃ oven to be dried for 6 hours.

Example 4

3) 20 parts by weight of a toughening agent GF-g-PMMA and 6 parts by weight of a heat conducting agent BM-TA are added into 0.5 part by weight of dioctyl phthalate and are uniformly mixed, and then the mixture is uniformly mixed with 100 parts by weight of PC particles in a high-speed mixer, wherein the rotating speed of the high-speed mixer is 300 r/min, the temperature is 60 ℃, and then the mixture is placed in a 100 ℃ oven to be dried for 6 hours.

Performance testing

TABLE 1

Table 1 shows the results of the performance tests of each of examples 1 to 4. From the above performance test results, it is obvious that, on the basis of adding 6 parts by weight of the thermal conductive agent, as the addition amount of the toughening agent GF-g-PMMA is increased from 5 parts to 15 parts, the tensile strength, the notch impact strength and the bending strength of the PC composite material are increased, and the thermal conductivity is reduced. When the addition amount of the toughening agent is 20 parts by weight, the four performance improving effects are not obvious and even slightly reduced, and the toughening agent is likely to agglomerate in the matrix material to influence the performance. From the comprehensive performance, the effect is best when the addition amount of the toughening agent GF-g-PMMA is 15 parts by weight.

Example 5

3) 15 parts by weight of a toughening agent GF-g-PMMA and 2 parts by weight of a heat conducting agent BM-TA are added into 0.5 part by weight of dioctyl phthalate and are uniformly mixed, and then the mixture is uniformly mixed with 100 parts by weight of PC particles in a high-speed mixer, wherein the rotating speed of the high-speed mixer is 300 r/min, the temperature is 60 ℃, and then the mixture is placed in a 100 ℃ oven to be dried for 6 hours.

Example 6

3) 15 parts by weight of a toughening agent GF-g-PMMA and 4 parts by weight of a heat conducting agent BM-TA are added into 0.5 part by weight of dioctyl phthalate and are uniformly mixed, and then the mixture is uniformly mixed with 100 parts by weight of PC particles in a high-speed mixer, wherein the rotating speed of the high-speed mixer is 300 r/min, the temperature is 60 ℃, and then the mixture is placed in a 100 ℃ oven to be dried for 6 hours.

Example 7

3) 15 parts by weight of a toughening agent GF-g-PMMA and 8 parts by weight of a heat conducting agent BM-TA are added into 0.5 part by weight of dioctyl phthalate and are uniformly mixed, and then the mixture is uniformly mixed with 100 parts by weight of PC particles in a high-speed mixer, wherein the rotating speed of the high-speed mixer is 300 r/min, the temperature is 60 ℃, and then the mixture is placed in a 100 ℃ oven to be dried for 6 hours.

Comparative example 1

A high-toughness PC composite material comprises the following specific steps:

2) Adding 15 parts by weight of a toughening agent GF-g-PMMA to 0.5 part by weight of dioctyl phthalate, uniformly mixing with 100 parts by weight of PC particles in a high-speed mixer at the rotating speed of 300 r/min and the temperature of 60 ℃, and then placing in a 100 ℃ oven for drying for 6 hours.

3) Adding the dried raw materials into a double-screw extruder, wherein the temperature of the first section of the double-screw extruder is 275 ℃, the temperature of the second section of the double-screw extruder is 270 ℃, the temperature of the third section of the double-screw extruder is 270 ℃, the temperature of the fourth section of the double-screw extruder is 260 ℃, and the temperature of the fifth section of the double-screw extruder is 255 ℃; the rotating speed of the screw is 10 r/min; and extruding and granulating to obtain the mixed master batch.

4) Drying the mixed master batch obtained by the double-screw extruder and the granulator in a drying oven at 100 ℃ for 6 hours, and performing injection molding by using an injection molding machine, wherein the temperatures from a feed inlet to a discharge outlet of the injection molding machine are respectively a first section temperature: 300 ℃ and second stage temperature: 290 ℃, third stage temperature: 285 ℃ and fourth stage temperature: 275 ℃ and temperature in the fifth stage: 265 ℃ of water; injection molding pressure: 135 MPa; pressure maintaining: 40MPa, and obtaining the high-toughness PC composite material.

Comparative example 2

A heat-conducting PC composite material comprises the following specific steps:

1) the preparation process of the heat conducting agent BM-TA comprises the following steps:

2) Adding 6 parts by weight of heat conducting agent BM-TA into 0.5 part by weight of dioctyl phthalate, uniformly mixing with 100 parts by weight of PC particles in a high-speed mixer at the rotating speed of 300 r/min and the temperature of 60 ℃, and drying in an oven at the temperature of 100 ℃ for 6 hours.

4) Drying the mixed master batch obtained by the double-screw extruder and the granulator in a drying oven at 100 ℃ for 6 hours, and performing injection molding by using an injection molding machine, wherein the temperatures from a feed inlet to a discharge outlet of the injection molding machine are respectively a first section temperature: 300 ℃ and second stage temperature: 290 ℃, third stage temperature: 285 ℃ and fourth stage temperature: 275 ℃ and temperature in the fifth stage: 265 ℃ of water; injection molding pressure: 135 MPa; pressure maintaining: and (4) obtaining the heat-conducting PC composite material under 40 MPa.

Comparative example 3

A high-toughness heat-conducting PC composite material comprises the following specific steps:

2) 15 parts by weight of a toughening agent GF-g-PMMA and 6 parts by weight of BM are added into 0.5 part by weight of dioctyl phthalate and uniformly mixed, and then the mixture is uniformly mixed with 100 parts by weight of PC particles in a high-speed mixer, wherein the rotating speed of the high-speed mixer is 300 r/min, the temperature is 60 ℃, and then the mixture is placed in a 100 ℃ oven to be dried for 6 hours.

4) Drying the mixed master batch obtained by the double-screw extruder and the granulator in a drying oven at 100 ℃ for 6 hours, and performing injection molding by using an injection molding machine, wherein the temperatures from a feed inlet to a discharge outlet of the injection molding machine are respectively a first section temperature: 300 ℃ and second stage temperature: 290 ℃, third stage temperature: 285 ℃ and fourth stage temperature: 275 ℃ and temperature in the fifth stage: 265 ℃ of water; injection molding pressure: 135 MPa; pressure maintaining: 40MPa, and obtaining the high-toughness heat-conducting PC composite material.

Performance testing

TABLE 2

Table 2 shows the results of the performance tests of examples 5, 6, 3, and 7 and comparative examples 1, 2, and 3. From the above performance test results, it is apparent that in examples 5, 6, 3, and 7, the tensile strength, the notched impact strength, and the bending property of the PC composite material gradually increased with the increase of the addition amount of the heat conductive agent, but the increase tendency was small, and the heat conductive property was continuously improved. Comparing the comparative example 2 with the example 3, it can be seen that the addition of the toughening agent GF-g-PMMA can effectively improve the mechanical property of the PC composite material and simultaneously reduce the thermal conductivity, and as the glass fiber is a heat insulating material and has low thermal conductivity, the thermal conductivity of the composite material is continuously reduced along with the further increase of the addition amount. As can be seen by comparing example 3 with comparative example 3, whether or not TA is grafted on boehmite has an effect on both the mechanical properties and the thermal conductivity of the PC composite. The tannic acid TA has good biocompatibility and high chemical activity, and the surface of the tannic acid TA contains a large amount of phenolic hydroxyl groups, so that strong van der Waals force and hydrogen bonds can be formed when the tannic acid TA is compounded with boehmite, the compatibility of the boehmite and a PC material can be improved, the agglomeration condition of the boehmite is improved, and the mechanical property and the thermal conductivity of the composite material are improved. In view of comprehensive performance, the PC composite material with excellent mechanical property and thermal conductivity can be prepared under the condition that 15 parts by weight of the toughening agent GF-g-PMMA and 8 parts by weight of the thermal conductive agent BM-TA are added.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the claims of the present invention should be covered by the present invention.

Claims

1. A high-toughness heat-conducting PC composite material is characterized in that: the raw materials comprise the following components in parts by weight: 100 parts of PC, 5-20 parts of a toughening agent, 1-8 parts of a heat conducting agent and 0.5 part of dioctyl phthalate, wherein the toughening agent is GF-g-PMMA, and the heat conducting agent is BM-TA.

2. A high toughness, thermally conductive PC composite material according to claim 1, characterized in that: the preparation method of the toughening agent GF-g-PMMA comprises the following steps:

placing 5g of glass fiber in a muffle furnace, preserving heat for 3h at 500 ℃, adding 65% nitric acid by mass, reacting for 5h at 70 ℃, washing the glass fiber to be neutral by using a deionized water-ethanol mixed solution, and placing the glass fiber in a vacuum drying oven for drying to obtain GF; weighing 2g of GF, placing the GF in a three-neck flask, adding deionized water-ethanol mixed solution, performing ultrasonic treatment for 30min, then dropwise adding 2ml of KH560, adjusting the pH to be =4-5 by using glacial acetic acid, stirring the mixture for 30min at room temperature, mechanically stirring the mixture for 1h at 80 ℃, performing centrifugal washing, and drying to obtain modified GF; and then weighing 1g of modified GF, adding the modified GF into a 50ml absolute ethyl alcohol three-neck flask, adding methyl methacrylate, stirring for 10min, adding a small amount of dibenzoyl peroxide, condensing and refluxing at 50 ℃ for 20min, heating to 85 ℃ after the dibenzoyl peroxide is completely dissolved, reacting at constant temperature for 6h, cooling to room temperature, and centrifugally drying to obtain GF-g-PMMA.

3. A high toughness, thermally conductive PC composite material according to claim 2, characterized in that: the volume ratio of the deionized water to the ethanol mixed solution is 1: 1; vacuum drying at 80 deg.C for 12 hr; the mass ratio of methyl methacrylate to dibenzoyl peroxide was 50: 1.

4. A high toughness, thermally conductive PC composite material according to claim 1, characterized in that: the preparation method of the heat conducting agent BM-TA comprises the following steps:

adding 0.2g of tannic acid into 200ml of deionized water, stirring for 30min to fully dissolve the tannic acid, then adding 0.5g of boehmite into the tannic acid aqueous solution, stirring for 2h at room temperature, and finally washing, filtering and drying to obtain the product BM-TA.

5. A high toughness, thermally conductive PC composite material according to claim 4 wherein: the mass ratio of boehmite to tannin was 5: 2.

6. A process for preparing a high toughness, thermally conductive PC composite as claimed in any one of claims 1 to 5, characterized in that: the method comprises the following steps:

1) adding a toughening agent and a heat conducting agent into dioctyl phthalate, uniformly mixing, adding into a high-speed stirrer, uniformly mixing with PC, and drying at 100 ℃ for 6 hours;

2) adding the dried material into a double-screw extruder, and performing extrusion granulation to obtain master batches;

3) and drying the obtained master batch in a vacuum drying oven, and then performing injection molding to obtain the high-toughness heat-conducting PC composite material.

7. The method of claim 6, wherein: the rotating speed of the high-speed stirrer in the step 1) is 300 r/min, and the temperature is 60 ℃.

8. The method of claim 6, wherein: the extrusion temperature of the twin-screw extruder used in the step 2) is as follows: the first section is 275 ℃, the second section is 270 ℃, the third section is 270 ℃, the fourth section is 260 ℃ and the fifth section is 255 ℃; the screw rotation speed is 10 r/min.

9. The method of claim 6, wherein: the drying temperature in the step 3) is 100 ℃, and the drying time is 6 hours; during injection molding, the injection molding temperature from the feed inlet to the discharge outlet is the first section temperature respectively: 300 ℃ and second stage temperature: 290 ℃, third stage temperature: 285 ℃ and fourth stage temperature: 275 ℃ and temperature in the fifth stage: the injection pressure is 135MPa and the pressure maintaining pressure is 40MPa at 265 ℃.