A preparation method of nanocellulose whisker reinforced nylon composite material

Abstract

A preparation method of cellulose reinforced nylon composite material, first preparing nylon spinning solution and nano cellulose whisker spinning solution, then using nylon spinning solution as the outer layer solution of the spinneret on a coaxial electrostatic spinning machine, using nano cellulose whisker spinning solution as the inner layer solution of the spinneret, obtaining coaxial composite fiber by electrostatic spinning, then shearing the coaxial composite fiber to obtain a reinforcing masterbatch, then mixing the reinforcing masterbatch with nylon resin in a desired proportion, and extruding and granulating the masterbatch into a parallel twin-screw extruder to obtain a cellulose reinforced nylon composite material. The design adds the sheared coaxial composite fiber to the nylon resin as a reinforcing, toughening and wear-resistant material, on the one hand, overcoming the problem of poor adhesion and difficulty in dispersion of nano cellulose whiskers and nylon resin when used alone, and on the other hand, because the coaxial composite fiber has a high-strength core, a small amount of addition can greatly improve the comprehensive performance of the nylon composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite materials, and specifically relates to a method for preparing a nanocellulose whisker reinforced nylon composite material, which is suitable for improving the adhesion between the nanocellulose whisker reinforced material and a nylon substrate, so that the nanocellulose whisker reinforced material is evenly distributed in the nylon substrate, and a small amount of addition can greatly improve the comprehensive performance of nylon. Background Art

[0002] Polyamide is one of the most widely used aliphatic nylon varieties. It is formed by the polycondensation of hexamethylenediamine and adipic acid. There are amide groups (-CO-NH-) in the molecular chain. It is a general engineering plastic with high cost performance and has been widely used. It has excellent mechanical strength, good toughness, stress cracking resistance, good wear resistance and corrosion resistance, and good molding processability. However, in some special places, ordinary nylon materials cannot meet the use requirements for a long time, such as sports equipment, power tools, medical composite materials, automotive parts, electrical accessories, textile equipment, building materials and furniture, logistics packaging and other industries, which require high strength, high toughness, high wear resistance and other comprehensive properties, which cannot be met by ordinary nylon products. Therefore, it must be modified to adapt to the above harsh use environment. At present, the modification methods on the market are mainly fiber reinforcement, including glass fiber reinforcement, mineral reinforcement, etc., but most of them have defects such as poor bonding between the reinforcement material and the substrate and the performance does not meet the use requirements.

[0003] Nanocellulose is the most abundant renewable natural polymer material. It is a nanomaterial extracted from wood. It is renewable and biodegradable. It has the functions of strengthening, toughening and wear resistance for engineering plastics. However, it has poor bonding performance with the substrate. If the amount added is too little, it will not have the effect of strengthening and toughening. If the amount added is too much, the performance will drop sharply. Therefore, there is an urgent need for a preparation method of nanocellulose whisker reinforced nylon composite material that can improve the bonding between nanocellulose whisker reinforced material and nylon substrate, and make the nanocellulose whisker reinforced material evenly distributed in the nylon substrate, so that a small amount of nanocellulose whisker can significantly improve the comprehensive performance of nylon. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide a method for preparing a nanocellulose whisker reinforced nylon composite material which can improve the adhesion between nanocellulose whiskers and a nylon substrate and make the nanocellulose whiskers evenly distributed in the nylon substrate.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A method for preparing a nanocellulose whisker reinforced nylon composite material, the preparation method is carried out in the following steps:

[0007] S1, preparing nylon spinning solution and nanocellulose whisker spinning solution;

[0008] S2, using nylon spinning solution as the outer layer solution of the spinneret on the coaxial electrospinning machine, and nanocellulose whisker spinning solution as the inner layer solution of the spinneret, electrospinning is performed, and the coaxial composite fiber is collected;

[0009] S3. The coaxial composite fibers are sheared to obtain a reinforcing masterbatch, and then the reinforcing masterbatch is uniformly mixed with nylon resin in a desired proportion, and then extruded and granulated to obtain a nanocellulose whisker reinforced nylon composite material.

[0010] In step S1, the preparation steps of the nylon spinning solution are: first, formic acid and hexafluoroisopropanol are evenly mixed in a required proportion, and then nylon resin is added to the mixture of formic acid and hexafluoroisopropanol in a required proportion, and stirred until the solution is clear and transparent to obtain a nylon spinning solution, wherein the mass ratio of formic acid, hexafluoroisopropanol and nylon resin is 64-74:16-18:8-20.

[0011] In step S1, the preparation step of the nanocellulose whisker spinning solution is: mixing the nanocellulose whisker dispersion and N,N-dimethylformamide in a desired ratio to obtain the nanocellulose whisker spinning solution, wherein the mass ratio of the nanocellulose whisker dispersion to N,N-dimethylformamide is 10-20:10-40.

[0012] In step S1, the mass percentage content of the nanocellulose whiskers in the nanocellulose whisker dispersion is 4%wt, and the solvent of the nanocellulose whisker dispersion is water.

[0013] In step S2, the voltage of the electrospinning is 18-20 kV, the temperature is 25° C., the relative humidity is 60%, and the distance between the spinneret and the receiving device is 20-30 cm.

[0014] In step S2, the diameter of the coaxial composite fiber is 20-50 nm.

[0015] In step S3, the shearing is specifically to firstly grind the coaxial composite fibers at -70°C to -120°C using a liquid nitrogen grinder, and then grind them at low temperature using a high shear grinder to prepare a reinforcement masterbatch.

[0016] In step S3, the coaxial composite fiber is pre-treated before shearing. The pre-treatment is to soak the coaxial composite fiber in deionized water at room temperature for 12 hours and then dry it in a vacuum oven.

[0017] In step S3, the operating temperature of the parallel twin-screw extruder is: 240±5°C in zone 1, 250±5°C in zone 2, 260±5°C in zone 3, 285±5°C in zone 4, and 270±5°C in zone 5.

[0018] In step S3, the reinforcing masterbatch, nylon resin, antioxidant 1076 and antioxidant 168 are first added to a high-speed mixer in a required proportion and mixed evenly, and then discharged into a parallel twin-screw extruder for extrusion granulation to obtain a nanocellulose whisker reinforced nylon composite material, wherein the weight ratio of the reinforcing masterbatch, nylon 66 resin, antioxidant 1076 and antioxidant 168 is 10-30:80-100:0.3-0.5:0.3-0.5.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In a preparation method of a nanocellulose whisker reinforced nylon composite material of the present invention, nylon spinning solution and nanocellulose whisker spinning solution are first prepared, and then the nylon spinning solution is used as the outer layer solution of a spinneret on a coaxial electrostatic spinning machine, and the nanocellulose whisker spinning solution is used as the inner layer solution of the spinneret to perform electrostatic spinning to obtain coaxial composite fibers, and then the coaxial composite fibers are sheared to obtain a reinforced masterbatch, and then the reinforced masterbatch is evenly mixed with a nylon resin in a required proportion, and the mixture is discharged into a parallel twin-screw extruder for extrusion and granulation to obtain a nanocellulose whisker reinforced nylon composite material. The coaxial composite fiber in the design The fiber is a composite fiber with nano cellulose whiskers as the inner core and nylon as the outer shell, and the nano cellulose whiskers are arranged along the axial direction of the nylon outer shell, and the sheared coaxial composite fiber is added to the nylon resin as a reinforcing, toughening and wear-resistant material. On the one hand, since the nylon outer shell of the coaxial composite fiber and the nylon resin substrate belong to the same material, the interface compatibility is good, and the problem of poor adhesion and difficulty in dispersion of the nano cellulose whiskers and nylon resin used alone is overcome. On the other hand, since the coaxial composite fiber has a high-strength core, a small amount of addition can greatly improve the toughness, rigidity and wear resistance of the nylon composite material. Therefore, the present invention can improve the adhesion of the nano cellulose whisker reinforced material and the nylon substrate, make the nano cellulose whisker reinforced material evenly distributed in the nylon substrate, and a small amount of addition can greatly improve the comprehensive performance of nylon. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a working schematic diagram of coaxial electrospinning in the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0023] See also Figure 1, a method for preparing a nanocellulose whisker reinforced nylon composite material, the preparation method is carried out in the following steps:

[0024] S1. Preparation of nylon spinning solution and nanocellulose whisker spinning solution

[0025] S2, using nylon spinning solution as the outer layer solution of the spinneret on the coaxial electrospinning machine, and nanocellulose whisker spinning solution as the inner layer solution of the spinneret, electrospinning is performed, and the coaxial composite fiber is collected;

[0026] S3. The coaxial composite fibers are sheared to obtain a reinforcing masterbatch, and then the reinforcing masterbatch is uniformly mixed with nylon resin in a desired proportion, and then extruded and granulated to obtain a nanocellulose whisker reinforced nylon composite material.

[0027] In step S1, the preparation steps of the nylon spinning solution are: first, formic acid and hexafluoroisopropanol are evenly mixed in a required proportion, and then nylon resin is added to the mixture of formic acid and hexafluoroisopropanol in a required proportion, and stirred until the solution is clear and transparent to obtain a nylon spinning solution, wherein the mass ratio of formic acid, hexafluoroisopropanol and nylon resin is 64-74:16-18:8-20.

[0028] In step S1, the preparation step of the nanocellulose whisker spinning solution is: mixing the nanocellulose whisker dispersion and N,N-dimethylformamide in a desired ratio to obtain the nanocellulose whisker spinning solution, wherein the mass ratio of the nanocellulose whisker dispersion to N,N-dimethylformamide is 10-20:10-40.

[0029] In step S1, the mass percentage content of the nanocellulose whiskers in the nanocellulose whisker dispersion is 4%wt, and the solvent of the nanocellulose whisker dispersion is water.

[0030] In step S2, the voltage of the electrospinning is 18-20 kV, the temperature is 25° C., the relative humidity is 60%, and the distance between the spinneret and the receiving device is 20-30 cm.

[0031] In step S2, the diameter of the coaxial composite fiber is 20-50 nm.

[0032] In step S3, the shearing is specifically to firstly grind the coaxial composite fibers at -70°C to -120°C using a liquid nitrogen grinder, and then grind them at low temperature using a high shear grinder to prepare a reinforcement masterbatch.

[0033] In step S3, the coaxial composite fiber is pre-treated before shearing. The pre-treatment is to soak the coaxial composite fiber in deionized water at room temperature for 12 hours and then dry it in a vacuum oven.

[0034] In step S3, the operating temperature of the parallel twin-screw extruder is: 240±5°C in zone 1, 250±5°C in zone 2, 260±5°C in zone 3, 285±5°C in zone 4, and 270±5°C in zone 5.

[0035] In step S3, the reinforcing masterbatch, nylon resin, antioxidant 1076 and antioxidant 168 are first added to a high-speed mixer in a required proportion and mixed evenly, and then discharged into a parallel twin-screw extruder for extrusion granulation to obtain a nanocellulose whisker reinforced nylon composite material, wherein the weight ratio of the reinforcing masterbatch, nylon 66 resin, antioxidant 1076 and antioxidant 168 is 10-30:80-100:0.3-0.5:0.3-0.5.

[0036] Embodiment 1:

[0037] See also Figure 1 , a method for preparing a nanocellulose whisker reinforced nylon composite material, which is specifically carried out according to the following steps:

[0038] S1. Preparation of nylon spinning solution and nanocellulose whisker spinning solution

[0039] The preparation steps of the nylon spinning solution are as follows: first, formic acid and hexafluoroisopropanol are added into a magnetic stirrer in a required proportion and mixed evenly, and then nylon resin is slowly added into the mixture of formic acid and hexafluoroisopropanol in a required proportion and stirred for 3-6 hours to make the mixed solution clear and transparent, thereby obtaining the nylon spinning solution, wherein the mass ratio of formic acid, hexafluoroisopropanol and nylon resin is 64:16:8, and formic acid and hexafluoroisopropanol are both spinning solvents;

[0040] The preparation step of the nanocellulose whisker spinning solution is as follows: adding a nanocellulose whisker dispersion and N,N-dimethylformamide in a required ratio into a magnetic stirrer and mixing them evenly to obtain a nanocellulose whisker spinning solution, wherein the mass ratio of the nanocellulose whisker dispersion to the N,N-dimethylformamide is 10:10, the mass percentage content of the nanocellulose whisker dispersion is 4%wt, the solvent of the nanocellulose whisker dispersion is water, and the N-dimethylformamide is a spinning solvent;

[0041] S2, coaxial electrospinning

[0042] Using nylon spinning solution as the outer solution of the spinneret on the coaxial electrospinning machine, and nanocellulose whisker spinning solution as the inner solution of the spinneret, the positive electrode of the high-voltage DC power supply is connected to the spinneret, the negative electrode is connected to the aluminum foil on the receiving device and grounded, and electrospinning is started to collect coaxial composite fibers with a diameter of 20-50nm, wherein the electrospinning voltage is 18kV, the temperature is 25°C, the relative humidity is 60%, and the distance between the spinneret and the receiving device is 20cm;

[0043] S3. Preparation of Nanocellulose Whisker Reinforced Nylon Composites

[0044] The coaxial composite fiber is pre-treated and sheared in sequence to obtain a reinforcing masterbatch, and then the reinforcing masterbatch, nylon resin, antioxidant 1076 and antioxidant 168 are added into a high-speed mixer in a required proportion and mixed evenly, and then discharged into a parallel twin-screw extruder for extrusion and granulation to obtain a cellulose reinforced nylon composite material, wherein the pre-treatment is to first soak the coaxial composite fiber in deionized water at room temperature for 12 hours, and then place it in a vacuum oven for drying, and the shearing is to first use a liquid nitrogen crusher to crush the coaxial composite fiber at -70°C to -120°C. At low temperature, the long fiber is easy to be brittle and crushed. The long fibers are converted into short fibers of about 20 μm, and then ground by a high shear grinder at low temperature to further convert them into short fibers of about 5 μm to obtain a reinforced masterbatch. The weight ratio of the reinforced masterbatch, nylon 66 resin, antioxidant 1076, and antioxidant 168 is 10:80:0.3:0.3. The antioxidant 1010 and antioxidant 168 are respectively an anti-heat aging agent and an auxiliary antioxidant. The operating temperature of the parallel twin-screw extruder is: 240±5°C for zone one, 250±5°C for zone two, 260±5°C for zone three, 285±5°C for zone four, and 270±5°C for zone five.

[0045] Embodiment 2:

[0046] The difference from Example 1 is that:

[0047] In step S1, the mass ratio of formic acid, hexafluoroisopropanol and nylon resin is 74:18:20, and the mass ratio of nanocellulose whisker dispersion to N,N-dimethylformamide is 20:40;

[0048] In step S2, the voltage of the electrospinning is 20 kV, the temperature is 25° C., the relative humidity is 60%, and the distance between the spinneret and the receiving device is 30 cm;

[0049] In step S3, the weight ratio of the reinforcing masterbatch, nylon 66 resin, antioxidant 1076, and antioxidant 168 is 30:100:0.5:0.5.

[0050] Embodiment 3:

[0051] The difference from Example 1 is that:

[0052] In step S1, the mass ratio of formic acid, hexafluoroisopropanol and nylon resin is 69:17:14, and the mass ratio of nanocellulose whisker dispersion to N,N-dimethylformamide is 15:25;

[0053] In step S2, the voltage of the electrospinning is 19 kV, the temperature is 25° C., the relative humidity is 60%, and the distance between the spinneret and the receiving device is 25 cm;

[0054] In step S3, the weight ratio of the reinforcing masterbatch, nylon 66 resin, antioxidant 1076, and antioxidant 168 is 20:90:0.4:0.4.

[0055] Performance Verification

[0056] In order to verify the reinforcing effect of the coaxial composite fiber in the cellulose reinforced nylon composite material prepared by the present invention, the product prepared in Example 1 was used as an experimental example, commercially available PA66 was used as comparative example 1, and the product prepared by blending nanocellulose whiskers as reinforcing fibers with nylon resin at a mass ratio of 4:96 was used as comparative example 2 (the extrusion granulation process was the same as that in Example 1). Performance tests were carried out, and the test results are shown in Table 1:

[0057] Table 1 Performance test results

[0058] .

[0059] According to the above table, when nanocellulose whiskers are added to nylon resin as reinforcing materials alone, the interface bonding between nanocellulose whiskers and nylon resin is poor, and the dispersion of nanocellulose whiskers in nylon resin is not good, the performance of the obtained product will be uneven, and the overall comprehensive performance will deteriorate, but the heat resistance will be enhanced, and the glass transition temperature will be increased. However, the nanocellulose reinforced nylon composite material prepared by the present invention is added to nylon resin with coaxial composite fibers as reinforcing, toughening and wear-resistant materials, and the interface bonding is good, the coaxial composite fibers are evenly dispersed in the nylon resin, and the comprehensive performance of the product is significantly improved.

Claims

1. A method for preparing a nanocellulose whisker reinforced nylon composite material, Features: The preparation method is carried out in the following steps: S1, preparing nylon spinning solution and nanocellulose whisker spinning solution; S2, using nylon spinning solution as the outer layer solution of the spinneret on the coaxial electrospinning machine, and nanocellulose whisker spinning solution as the inner layer solution of the spinneret, electrospinning is performed, and the coaxial composite fiber is collected; S3, shearing the coaxial composite fibers to obtain a reinforcing masterbatch, then uniformly mixing the reinforcing masterbatch with nylon resin in a desired proportion, extruding and granulating, and obtaining a nanocellulose whisker reinforced nylon composite material; In step S1, the preparation step of the nylon spinning solution is: firstly, formic acid and hexafluoroisopropanol are uniformly mixed in a required proportion, and then nylon resin is added to the mixture of formic acid and hexafluoroisopropanol in a required proportion, and stirred until the solution is clear and transparent to obtain the nylon spinning solution, wherein the mass ratio of formic acid, hexafluoroisopropanol and nylon resin is 64-74:16-18:8-20; In step S1, the preparation step of the nanocellulose whisker spinning solution is: mixing the nanocellulose whisker dispersion and N,N-dimethylformamide in a desired proportion to obtain the nanocellulose whisker spinning solution, wherein the mass ratio of the nanocellulose whisker dispersion to N,N-dimethylformamide is 10-20:10-40.

2. A method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S1, the mass percentage content of the nanocellulose whiskers in the nanocellulose whisker dispersion is 4%wt, and the solvent of the nanocellulose whisker dispersion is water.

3. A method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S2, the voltage of the electrospinning is 18-20 kV, the temperature is 25° C., the relative humidity is 60%, and the distance between the spinneret and the receiving device is 20-30 cm.

4. The method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S2, the diameter of the coaxial composite fiber is 20-50 nm.

5. The method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S3, the shearing is specifically to firstly grind the coaxial composite fibers at -70°C to -120°C using a liquid nitrogen grinder, and then grind them at low temperature using a high shear grinder to prepare a reinforcement masterbatch.

6. A method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S3, the coaxial composite fiber is pre-treated before shearing. The pre-treatment is to soak the coaxial composite fiber in deionized water at room temperature for 12 hours and then dry it in a vacuum oven.

7. The method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S3, the extrusion granulation is carried out in a parallel twin-screw extruder, and the operating temperature of the parallel twin-screw extruder is: 240±5°C in zone 1, 250±5°C in zone 2, 260±5°C in zone 3, 285±5°C in zone 4, and 270±5°C in zone 5.

8. The method for preparing a nanocellulose whisker reinforced nylon composite material according to claim 1, Features: In step S3, the reinforcing masterbatch, nylon resin, antioxidant 1076 and antioxidant 168 are first added to a high-speed mixer in a required proportion and mixed evenly, and then discharged into a parallel twin-screw extruder for extrusion and granulation to obtain a nanocellulose whisker reinforced nylon composite material, wherein the weight ratio of the reinforcing masterbatch, nylon 66 resin, antioxidant 1076 and antioxidant 168 is 10-30:80-100:0.3-0.5:0.3-0.5.

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