Degradable polyhydroxyalkanoate composite material and preparation method thereof

Abstract

The invention relates to the technical field of biodegradable materials, and discloses a degradable polyhydroxyalkanoate composite material and a preparation method thereof, the degradable polyhydroxyalkanoate composite material comprises the following raw materials by mass: 80-100 parts of polyhydroxyalkanoate, 20-30 parts of composite plant fiber, 10-15 parts of a reinforcing filler, 1.5-2.5 parts of a coupling agent, 0.5-1.5 parts of an antioxidant, and 1-2 parts of a processing aid. Aluminum oxide aerogel with a porous structure is synthesized on the surface of the hydroxyapatite nanowire to serve as reinforcing filler and can be inserted into the polyhydroxyalkanoate composite material, stress generated by absorbing and weakening external force is formed, and the mechanical performance of the polyhydroxyalkanoate composite material is improved; according to the carboxymethyl cellulose composite film, the hexachlorocyclotriphosphazene derivative and the nano calcium carbonate are tightly attached to the surfaces of the plant fibers, so that the mechanical strength of the polyhydroxyalkanoate composite material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biodegradable materials, in particular to a degradable polyhydroxyalkanoate composite material and a preparation method thereof. Background Art

[0002] Degradable polymer materials are polymers that degrade under the action of microorganisms under aerobic and anaerobic conditions to form carbon dioxide, water, methane and other small molecular weight compounds; polyhydroxyalkanoates are a type of bio-based degradable polymer material with good mechanical properties, biocompatibility and biodegradability. They have physical and chemical properties and biodegradability similar to chemical plastics and have been used as environmentally degradable plastics. They can completely replace traditional modified polypropylene and other general plastics to alleviate the increasingly serious problem of white pollution.

[0003] The biodegradable composite materials prepared from polyhydroxyalkanoates have the disadvantages of poor mechanical properties and poor heat resistance, which affect the application scope of polyhydroxyalkanoate composite materials. Adding inorganic materials to polyhydroxyalkanoate composite materials can effectively improve the mechanical properties of the composite materials, but inorganic materials are easy to agglomerate and have poor compatibility with polyhydroxyalkanoates, which affects the performance of the composite materials. Summary of the Invention

[0004] The present invention provides a degradable polyhydroxyalkanoate composite material and a preparation method thereof, which solves the problems of poor mechanical properties and poor heat resistance of the degradable composite material prepared from polyhydroxyalkanoate.

[0005] The technical solution of the present invention:

[0006] A degradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 80-100 parts of polyhydroxyalkanoate, 20-30 parts of composite plant fiber, 10-15 parts of reinforcing filler, 1.5-2.5 parts of coupling agent, 0.5-1.5 parts of antioxidant, and 1-2 parts of processing aid;

[0007] The reinforcing filler is obtained by modifying the surface of hydroxyapatite nanowires with dopamine, mixing the nanowires with alumina sol, aging them, and supercritical drying them.

[0008] The composite plant fiber is obtained by mixing p-hydroxybenzaldehyde, hexachlorocyclotriphosphazene, nano calcium carbonate and sodium carboxymethyl cellulose solution, and then coating the mixture on the surface of the plant fiber.

[0009] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0010] The polyhydroxyalkanoate, composite plant fiber, reinforcing filler, coupling agent, antioxidant and processing aid are mixed and stirred to obtain a mixture, and the mixture is melt-blended and extruded, water-cooled and pelletized, and dried to obtain a degradable polyhydroxyalkanoate composite material.

[0011] Furthermore, the melt blending extrusion is carried out in a twin-screw extruder, with a melt temperature of 180-190° C. and a screw speed of 350-450 r / min.

[0012] Furthermore, the stirring rate is 80-120 r / min, and the stirring time is 30-40 min.

[0013] Furthermore, the plant fiber is selected from any one of bamboo charcoal fiber, flax fiber, ramie fiber and sisal fiber.

[0014] Furthermore, the antioxidant is selected from any one of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0015] Furthermore, the processing aid is selected from any one of stearic acid, stearate, polyethylene wax, oxidized polyethylene wax, and polyfatty acid ester.

[0016] Furthermore, the reinforcing filler is specifically prepared by the following steps:

[0017] A1. Add hydroxyapatite nanowires to Tris-HCl buffer, stir evenly, add dopamine, stir, filter, wash, and dry to obtain polydopamine-modified hydroxyapatite nanowires;

[0018] A2. Aluminum chloride hexahydrate, ethanol, and deionized water were mixed and stirred at 20-30°C for 30-40 min. Propylene oxide was added and stirred until a gel formed. The gel was washed and concentrated to obtain an alumina sol.

[0019] A3. The polydopamine-modified hydroxyapatite nanowires and alumina sol were mixed, aged in ethanol, placed in a reactor, and supercritically dried at a pressure of 5-10 MPa and a temperature of 260-270°C for 2-4 hours. The mixture was then cooled to room temperature to obtain a reinforcing filler.

[0020] Furthermore, during the above reaction A1, in the Tris-HCl buffer, dopamine can self-polymerize on the surface of the hydroxyapatite nanowires to form polydopamine, thereby forming polydopamine-modified hydroxyapatite nanowires, which is beneficial to the formation of aluminum aerogel on the surface of the hydroxyapatite nanowires.

[0021] Furthermore, in the above-mentioned reaction process A2, aluminum chloride hexahydrate, ethanol, deionized water, and propylene oxide are mixed to form an alumina sol. Propylene oxide serves as a gel promoter, which can promote the hydrolysis and polymerization reaction of aluminum chloride hexahydrate in water and alcohol to form an alumina sol with a three-dimensional network structure.

[0022] Furthermore, during the above-mentioned A3 reaction process, the alumina sol can combine with the phenolic hydroxyl groups on the surface of the polydopamine-modified hydroxyapatite nanowires, so that the alumina sol is deposited on the surface of the hydroxyapatite nanowires. After aging in ethanol and supercritical drying, a porous alumina aerogel is synthesized on the surface of the hydroxyapatite nanowires to obtain a reinforced filler.

[0023] Furthermore, in step A1, the ratio of the hydroxyapatite nanowires, Tris-HCl buffer and dopamine is (1-2) g: (90-110) mL: (0.6-0.8) g.

[0024] Furthermore, in step A2, the ratio of the amount of aluminum chloride hexahydrate, ethanol, deionized water and propylene oxide is (14-16) g: (45-55) mL: (15-25) mL: (7-8) g.

[0025] Furthermore, in step A3, the ratio of the polydopamine-modified hydroxyapatite nanowires, alumina sol and ethanol is (3-4) g: (1-2) g: (25-35) mL.

[0026] Furthermore, the hydroxyapatite nanowires have a length of 100-200 μm and a diameter of 50-80 nm.

[0027] Furthermore, the composite plant fiber is specifically prepared by the following steps:

[0028] B1. Hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde, and potassium carbonate were added to tetrahydrofuran under argon protection and stirred. After the reaction, the tetrahydrofuran was evaporated under reduced pressure and placed in deionized water, stirred until a precipitate was formed. The precipitate was washed and dried to obtain a hexachlorocyclotriphosphazene derivative;

[0029] B2. Sodium carboxymethyl cellulose and deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. Nano-calcium carbonate and hexachlorocyclotriphosphazene derivatives were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0030] B3. Add the plant fiber to the composite, stir evenly, let it stand, filter, wash, and dry to obtain composite plant fiber.

[0031] Furthermore, during the above-mentioned reaction B1, the chlorine atoms in the hexachlorocyclotriphosphazene can undergo a substitution reaction with the hydroxyl groups in p-hydroxybenzaldehyde, so that p-hydroxybenzaldehyde is grafted onto the hexachlorocyclotriphosphazene molecule, providing a large number of reactive functional groups, hydroxyl groups, and rigid benzene ring structures, thereby obtaining a hexachlorocyclotriphosphazene derivative.

[0032] Furthermore, during the above reaction B2, the hydroxyl groups contained in the hexachlorocyclotriphosphazene derivative can be chemically bonded with the carboxyl groups in the sodium carboxymethyl cellulose, so that the hexachlorocyclotriphosphazene derivative is dispersed in the sodium carboxymethyl cellulose solution, and the nano-calcium carbonate can also be dispersed in the sodium carboxymethyl cellulose solution to form a complex.

[0033] Furthermore, during the above-mentioned B3 reaction process, the composite is coated on the surface of the plant fiber. The carboxymethyl groups contained in the sodium carboxymethyl cellulose in the composite exhibit excellent bonding properties and can adhere to the surface of the plant fiber, thereby forming a carboxymethyl cellulose composite film on the surface of the plant fiber to obtain modified plant fiber.

[0034] Furthermore, in step B1, the ratio of the hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde, potassium carbonate, tetrahydrofuran and deionized water is (1-2) g: (2-3) g: (4-5) g: (30-40) mL: (70-90) mL.

[0035] Furthermore, in step B2, the ratio of the amount of sodium carboxymethyl cellulose, deionized water, nano-calcium carbonate and hexachlorocyclotriphosphazene derivative is (1.1-1.5) g: (45-55) mL: (1-2) g: (1.5-1.9) g.

[0036] Furthermore, in step B3, the ratio of the plant fiber to the composite is (5-6) g: (45-55) mL.

[0037] Furthermore, the particle size of the nano calcium carbonate is 20-30 nm.

[0038] The present invention has the following beneficial effects:

[0039] (1) In the technical solution of the present invention, dopamine can self-polymerize on the surface of hydroxyapatite nanowires to form polydopamine, forming polydopamine-modified hydroxyapatite nanowires, which is beneficial to the formation of alumina aerogel on the surface of hydroxyapatite nanowires; alumina aerogel with a porous structure is synthesized on the surface of polydopamine-modified hydroxyapatite nanowires, thereby increasing the surface roughness of the hydroxyapatite nanowires and the contact area between the hydroxyapatite nanowires and the polyhydroxyalkanoate. Moreover, the hydroxyapatite nanowires have a high aspect ratio and can be inserted into the polyhydroxyalkanoate composite material to form a structure that can absorb and weaken the stress generated by external forces, thereby improving the mechanical properties of the polyhydroxyalkanoate composite material. In addition, the porous structure of the synthesized alumina aerogel has excellent heat stability, thereby improving the heat resistance of the polyhydroxyalkanoate.

[0040] (2) In the technical solution of the present invention, p-hydroxybenzaldehyde is grafted onto the hexachlorocyclotriphosphazene molecule, providing a large number of reactive functional groups, hydroxyl groups, and rigid benzene ring structures, which are conducive to dispersion in sodium carboxymethyl cellulose solution and coating on the surface of plant fibers. In addition, during the combustion process of polyhydroxyalkanoate, the phosphorus and nitrogen elements contained in the hexachlorocyclotriphosphazene derivatives can form a phosphorus-nitrogen synergistic system. This system can produce an inorganic solid phase layer, prevent the combustion of the composite material, and have flame retardant properties.

[0041] (3) In the technical solution of the present invention, a hexachlorocyclotriphosphazene derivative, nano-calcium carbonate and sodium carboxymethyl cellulose solution are mixed to form a composite material which is then coated on the surface of the plant fiber. On the one hand, a carboxymethyl cellulose composite film is formed on the surface of the plant fiber. The carboxymethyl groups contained in the composite film exhibit excellent bonding properties, thereby improving the compatibility between the plant fiber and the polyhydroxyalkanoate. In addition, the nano-calcium carbonate in the composite film can fill the pore structure of the plant fiber, thereby preventing the plant fiber from easily absorbing moisture and causing the performance of the composite material to deteriorate. On the other hand, the formed carboxymethyl cellulose composite film tightly adheres the hexachlorocyclotriphosphazene derivative and nano-calcium carbonate to the surface of the plant fiber, thereby preventing the hexachlorocyclotriphosphazene derivative and nano-calcium carbonate from migrating and precipitating under the action of external force, thereby affecting the performance of the polyhydroxyalkanoate composite material. In addition, the plant fiber is filled into the polyhydroxyalkanoate composite material, thereby improving the mechanical strength of the polyhydroxyalkanoate composite material. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] The raw materials used in the examples of the present invention are as follows, and all reagents used are of analytical grade.

[0044] The plant fiber is selected from bamboo charcoal fiber, with a diameter of 100 nm and a length of 100 μm.

[0045] The coupling agent was titanate coupling agent CT114, purchased from Changzhou New District Lijin Chemical Co., Ltd.

[0046] The graphene oxide has a thickness of 20 nm, an interlayer spacing of 0.6 nm, and a particle size of 10 μm.

[0047] The antioxidant is antioxidant 168 and the processing aid is stearic acid.

[0048] The hydroxyapatite nanowires were 100 μm in length and 60 nm in diameter and were purchased from Suzhou Kaifa New Materials Technology Co., Ltd. The nano-calcium carbonate particles had a diameter of 25 nm.

[0049] Polyhydroxyalkanoate (polyhydroxyalkanoate) was type F5400 and was purchased from Shenzhen Ecoman Biotechnology Co., Ltd.

[0050] Example 1

[0051] A degradable polyhydroxyalkanoate composite material, comprising the following raw materials in parts by weight: 80 parts of polyhydroxyalkanoate, 20 parts of composite bamboo charcoal fiber, 10 parts of reinforcing filler, 1141.5 parts of titanate coupling agent CT1, 1680.5 parts of antioxidant, and 1 part of stearic acid;

[0052] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0053] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 80 r / min for 30 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0054] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 180° C. and a screw speed of 350 r / min.

[0055] The reinforcing filler is specifically prepared by the following steps:

[0056] A1. 1 g of hydroxyapatite nanowires was added to 90 mL of Tris-HCl buffer (pH 8.5). The mixture was stirred at 25°C and 2000 rpm for 20 min. 0.6 g of dopamine was added and the mixture was stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0057] A2. 14 g of aluminum chloride hexahydrate, 45 mL of ethanol, and 15 mL of deionized water were mixed and stirred at 20 ° C for 30 min. 7 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0058] A3. 3 g of polydopamine-modified hydroxyapatite nanowires and 1 g of alumina sol were mixed, placed in 25 mL of ethanol, aged for 30 min, placed in a reactor, supercritically dried at 260°C at a pressure of 5 MPa for 2 h, and cooled to room temperature to obtain a reinforced filler.

[0059] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0060] B1. 1 g of hexachlorocyclotriphosphazene, 2 g of p-hydroxybenzaldehyde, and 4 g of potassium carbonate were added to 30 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 70 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0061] B2. 1.1 g of sodium carboxymethyl cellulose and 45 mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 1 g of nano-calcium carbonate and 1.5 g of a hexachlorocyclotriphosphazene derivative were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0062] B3. Add 5 g of plant fiber to 45 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0063] Example 2

[0064] A biodegradable polyhydroxyalkanoate composite material, comprising the following raw materials in parts by weight: 90 parts of polyhydroxyalkanoate, 25 parts of composite bamboo charcoal fiber, 13 parts of reinforcing filler, 1142 parts of titanate coupling agent CT1, 1681 parts of antioxidant, and 1.5 parts of stearic acid;

[0065] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0066] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 100 r / min for 35 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0067] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 185° C. and a screw speed of 400 r / min.

[0068] The reinforcing filler is specifically prepared by the following steps:

[0069] A1. 1.5 g of hydroxyapatite nanowires were added to 100 mL of Tris-HCl buffer (pH 8.5) and stirred at 25°C and 2000 rpm for 20 min. 0.7 g of dopamine was added and stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0070] A2. 15 g of aluminum chloride hexahydrate, 50 mL of ethanol, and 20 mL of deionized water were mixed and stirred at 25 ° C for 35 min. 7.5 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0071] A3. 3.5 g of polydopamine-modified hydroxyapatite nanowires and 1.5 g of alumina sol were mixed, placed in 30 mL of ethanol and aged for 30 min, placed in a reactor, supercritically dried at 265°C at a pressure of 7 MPa for 3 h, and cooled to room temperature to obtain a reinforced filler.

[0072] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0073] B1. 1.5 g of hexachlorocyclotriphosphazene, 2.5 g of p-hydroxybenzaldehyde, and 4.5 g of potassium carbonate were added to 35 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 80 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0074] B2. 1.3 g of sodium carboxymethyl cellulose and 50 mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 1.5 g of nano-calcium carbonate and 1.7 g of a hexachlorocyclotriphosphazene derivative were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0075] B3. Add 5.5 g of plant fiber to 50 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70 ° C for 10 min to obtain composite bamboo charcoal fiber.

[0076] Example 3

[0077] A biodegradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 100 parts of polyhydroxyalkanoate, 30 parts of composite bamboo charcoal fiber, 15 parts of reinforcing filler, 1142.5 parts of titanate coupling agent CT1, 1681.5 parts of antioxidant, and 2 parts of stearic acid;

[0078] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0079] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 120 r / min for 40 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0080] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 190° C. and a screw speed of 450 r / min.

[0081] The reinforcing filler is specifically prepared by the following steps:

[0082] A1. 2 g of hydroxyapatite nanowires were added to 110 mL of Tris-HCl buffer (pH 8.5) and stirred at 25°C and 2000 rpm for 20 min. 0.8 g of dopamine was added and stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0083] A2. 16 g of aluminum chloride hexahydrate, 55 mL of ethanol, and 25 mL of deionized water were mixed and stirred at 30 ° C for 40 min. 8 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0084] A3. 4 g of polydopamine-modified hydroxyapatite nanowires and 2 g of alumina sol were mixed, placed in 35 mL of ethanol, aged for 30 min, placed in a reactor, supercritically dried at 270°C at a pressure of 10 MPa for 4 h, and cooled to room temperature to obtain a reinforced filler.

[0085] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0086] B1. 2 g of hexachlorocyclotriphosphazene, 3 g of p-hydroxybenzaldehyde, and 5 g of potassium carbonate were added to 40 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 90 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0087] B2. 1.5 g of sodium carboxymethyl cellulose and 55 mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 2 g of nano-calcium carbonate and 1.9 g of a hexachlorocyclotriphosphazene derivative were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0088] B3. Add 6 g of plant fiber to 55 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0089] Comparative Example 1

[0090] A biodegradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 100 parts of polyhydroxyalkanoate, 30 parts of composite bamboo charcoal fiber, 15 parts of reinforcing filler, 1142.5 parts of titanate coupling agent CT1, 1681.5 parts of antioxidant, and 2 parts of stearic acid;

[0091] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0092] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 120 r / min for 40 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0093] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 190° C. and a screw speed of 450 r / min.

[0094] The reinforcing filler is specifically prepared by the following steps:

[0095] A1. 16 g of aluminum chloride hexahydrate, 55 mL of ethanol, and 25 mL of deionized water were mixed and stirred at 30°C for 40 min. 8 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60°C to obtain an alumina sol.

[0096] A2. 4 g of hydroxyapatite nanowires and 2 g of alumina sol were mixed, placed in 35 mL of ethanol, aged for 30 min, placed in a reactor, supercritically dried at 270 ° C for 4 h at a pressure of 10 MPa, and cooled to room temperature to obtain a reinforcing filler.

[0097] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0098] B1. 2 g of hexachlorocyclotriphosphazene, 3 g of p-hydroxybenzaldehyde, and 5 g of potassium carbonate were added to 40 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 90 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0099] B2. 1.5 g of sodium carboxymethyl cellulose and 55 mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 2 g of nano-calcium carbonate and 1.9 g of a hexachlorocyclotriphosphazene derivative were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0100] B3. Add 6 g of plant fiber to 55 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0101] Comparative Example 2

[0102] A biodegradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 100 parts of polyhydroxyalkanoate, 30 parts of composite bamboo charcoal fiber, 15 parts of reinforcing filler, 1142.5 parts of titanate coupling agent CT1, 1681.5 parts of antioxidant, and 2 parts of stearic acid;

[0103] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0104] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 120 r / min for 40 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0105] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 190° C. and a screw speed of 450 r / min.

[0106] The reinforcing filler is specifically prepared by the following steps:

[0107] A1. 2 g of hydroxyapatite nanowires were added to 110 mL of Tris-HCl buffer (pH 8.5) and stirred at 25°C and 2000 rpm for 20 min. 0.8 g of dopamine was added and stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0108] A2. 16 g of aluminum chloride hexahydrate, 55 mL of ethanol, and 25 mL of deionized water were mixed and stirred at 30 ° C for 40 min. 8 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0109] A3. 4 g of polydopamine-modified hydroxyapatite nanowires and 2 g of alumina sol were mixed to obtain a reinforcing filler.

[0110] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0111] B1. 2 g of hexachlorocyclotriphosphazene, 3 g of p-hydroxybenzaldehyde, and 5 g of potassium carbonate were added to 40 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 90 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0112] B2. 1.5 g of sodium carboxymethyl cellulose and 55 mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 2 g of nano-calcium carbonate and 1.9 g of a hexachlorocyclotriphosphazene derivative were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0113] B3. Add 6 g of plant fiber to 55 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0114] Comparative Example 3

[0115] A biodegradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 100 parts of polyhydroxyalkanoate, 30 parts of composite bamboo charcoal fiber, 15 parts of reinforcing filler, 1142.5 parts of titanate coupling agent CT1, 1681.5 parts of antioxidant, and 2 parts of stearic acid;

[0116] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0117] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 120 r / min for 40 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0118] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 190° C. and a screw speed of 450 r / min.

[0119] The reinforcing filler is specifically prepared by the following steps:

[0120] A1. 2 g of hydroxyapatite nanowires were added to 110 mL of Tris-HCl buffer (pH 8.5) and stirred at 25°C and 2000 rpm for 20 min. 0.8 g of dopamine was added and stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0121] A2. 16 g of aluminum chloride hexahydrate, 55 mL of ethanol, and 25 mL of deionized water were mixed and stirred at 30 ° C for 40 min. 8 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0122] A3. 4 g of polydopamine-modified hydroxyapatite nanowires and 2 g of alumina sol were mixed, placed in 35 mL of ethanol, aged for 30 min, placed in a reactor, supercritically dried at 270°C at a pressure of 10 MPa for 4 h, and cooled to room temperature to obtain a reinforced filler.

[0123] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0124] B1. 1.5g of sodium carboxymethyl cellulose and 55mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 2g of nano-calcium carbonate and 1.9g of hexachlorocyclotriphosphazene were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0125] B3. Add 6 g of plant fiber to 55 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0126] Comparative Example 4

[0127] A biodegradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 100 parts of polyhydroxyalkanoate, 30 parts of composite bamboo charcoal fiber, 15 parts of reinforcing filler, 1142.5 parts of titanate coupling agent CT1, 1681.5 parts of antioxidant, and 2 parts of stearic acid;

[0128] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0129] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 120 r / min for 40 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0130] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 190° C. and a screw speed of 450 r / min.

[0131] The reinforcing filler is specifically prepared by the following steps:

[0132] A1. 2 g of hydroxyapatite nanowires were added to 110 mL of Tris-HCl buffer (pH 8.5) and stirred at 25°C and 2000 rpm for 20 min. 0.8 g of dopamine was added and stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0133] A2. 16 g of aluminum chloride hexahydrate, 55 mL of ethanol, and 25 mL of deionized water were mixed and stirred at 30 ° C for 40 min. 8 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0134] A3. 4 g of polydopamine-modified hydroxyapatite nanowires and 2 g of alumina sol were mixed, placed in 35 mL of ethanol, aged for 30 min, placed in a reactor, supercritically dried at 270°C at a pressure of 10 MPa for 4 h, and cooled to room temperature to obtain a reinforced filler.

[0135] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0136] B1. 2 g of hexachlorocyclotriphosphazene, 3 g of p-hydroxybenzaldehyde, and 5 g of potassium carbonate were added to 40 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 90 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0137] B2. 1.5 g of sodium carboxymethyl cellulose and 55 mL of deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. 1.9 g of a hexachlorocyclotriphosphazene derivative was added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex.

[0138] B3. Add 6 g of plant fiber to 55 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0139] Comparative Example 5

[0140] A biodegradable polyhydroxyalkanoate composite material comprises the following raw materials in parts by weight: 100 parts of polyhydroxyalkanoate, 30 parts of composite bamboo charcoal fiber, 15 parts of reinforcing filler, 1142.5 parts of titanate coupling agent CT1, 1681.5 parts of antioxidant, and 2 parts of stearic acid;

[0141] A method for preparing a degradable polyhydroxyalkanoate composite material comprises the following steps:

[0142] The polyhydroxyalkanoate, composite bamboo charcoal fiber, reinforcing filler, titanate coupling agent CT114, antioxidant 168 and stearic acid were mixed and stirred at 120 r / min for 40 min to obtain a mixture. The mixture was melt-blended and extruded, water-cooled and pelletized, and dried at 80°C for 10 min to obtain a degradable polyhydroxyalkanoate composite material.

[0143] The melt blending extrusion is carried out in a twin-screw extruder with a melt temperature of 190° C. and a screw speed of 450 r / min.

[0144] The reinforcing filler is specifically prepared by the following steps:

[0145] A1. 2 g of hydroxyapatite nanowires were added to 110 mL of Tris-HCl buffer (pH 8.5) and stirred at 25°C and 2000 rpm for 20 min. 0.8 g of dopamine was added and stirred at 30°C and 2000 rpm for 2 h. The mixture was filtered, washed three times with deionized water, and dried in an oven at 70°C for 10 min to obtain polydopamine-modified hydroxyapatite nanowires.

[0146] A2. 16 g of aluminum chloride hexahydrate, 55 mL of ethanol, and 25 mL of deionized water were mixed and stirred at 30 ° C for 40 min. 8 g of propylene oxide was added and stirred until a gel formed. The gel was washed three times with deionized water and concentrated at 60 ° C to obtain an alumina sol.

[0147] A3. 4 g of polydopamine-modified hydroxyapatite nanowires and 2 g of alumina sol were mixed, placed in 35 mL of ethanol, aged for 30 min, placed in a reactor, supercritically dried at 270°C at a pressure of 10 MPa for 4 h, and cooled to room temperature to obtain a reinforced filler.

[0148] The composite bamboo charcoal fiber is specifically prepared by the following steps:

[0149] B1. 2 g of hexachlorocyclotriphosphazene, 3 g of p-hydroxybenzaldehyde, and 5 g of potassium carbonate were added to 40 mL of tetrahydrofuran under argon protection and stirred for 48 h. The tetrahydrofuran was then evaporated under reduced pressure at 40°C, and the mixture was placed in 90 mL of deionized water and stirred until a precipitate formed. The precipitate was washed three times with deionized water and dried in an oven at 50°C for 10 min to obtain a hexachlorocyclotriphosphazene derivative.

[0150] B2. 2g of nano-calcium carbonate and 1.9g of a hexachlorocyclotriphosphazene derivative were mixed to obtain a complex;

[0151] B3. Add 6 g of plant fiber to 55 mL of the composite, stir evenly, let it stand for 2 h, filter, wash with deionized water three times, and dry in an oven at 70°C for 10 min to obtain composite bamboo charcoal fiber.

[0152] The performance of the degradable polyhydroxyalkanoate composite materials prepared in Examples 1-3 and Comparative Examples 1-7 was tested.

[0153] The biodegradable polyhydroxyalkanoate composite material prepared above was selected and injection-molded into strips for performance testing, wherein the injection pressure was 90 MPa and the injection temperature was 280°C.

[0154] Mechanical property test: The tensile strength and elongation at break of the biodegradable polyhydroxyalkanoate composite material prepared above were measured using the GB / T1040.3-2006 standard.

[0155] Degradation performance test: The biodegradability of the biodegradable polyhydroxyalkanoate composite material prepared above was determined using the GB / T19277-2011 standard. The final release of carbon dioxide after 60 days of degradation of the biodegradable polyhydroxyalkanoate composite material was tested, and the ratio of the actual carbon dioxide release to its theoretical maximum release was used to express the biodegradation rate (%) of the material.

[0156] Heat resistance test: GB / T1633-2000 standard was used to test the heat resistance of the biodegradable polyhydroxyalkanoate composite material prepared above.

[0157] Flame retardancy test: The flame retardancy of the biodegradable polyhydroxyalkanoate composite material prepared above was tested using the UL94 standard.

[0158] The test results are shown in Table 1 below.

[0159] Table 1 Performance test of degradable polyhydroxyalkanoate composite materials prepared in Examples 1-3 and Comparative Examples 1-5

[0160]

[0161]

[0162] It can be seen from the data in Table 1 that the degradable polyhydroxyalkanoate composite materials prepared in Examples 1-3 have high mechanical properties, heat resistance and flame retardancy, and are degradable.

[0163] In Comparative Example 1, the polydopamine-modified hydroxyapatite nanowires were replaced with reinforcing fillers prepared from hydroxyapatite nanowires and added to the degradable polyhydroxyalkanoate composite material. Its mechanical properties and heat resistance decreased, proving that the self-polymerization of polydopamine on the surface of hydroxyapatite nanowires is beneficial to the formation of alumina aerogel on the surface of hydroxyapatite nanowires, thereby improving the heat resistance and mechanical properties of polyhydroxyalkanoate.

[0164] In comparative example 2, the reinforcing filler prepared without supercritical drying in step A3 was added to the degradable polyhydroxyalkanoate composite material, and its mechanical properties and heat resistance decreased, proving that alumina was coated on the surface of polydopamine-modified hydroxyapatite nanowires. After supercritical drying, a porous alumina aerogel was synthesized on the surface of the hydroxyapatite nanowires. The porous structure had excellent heat stability, increased the surface roughness of the hydroxyapatite nanowires, and increased the contact area between the hydroxyapatite nanowires and the polyhydroxyalkanoate.

[0165] In Comparative Example 3, the composite bamboo charcoal fiber prepared by replacing the hexachlorocyclotriphosphazene derivative with hexachlorocyclotriphosphazene was added to the degradable polyhydroxyalkanoate composite material, and its flame retardant properties decreased. This proves that the grafting of p-hydroxybenzaldehyde onto the hexachlorocyclotriphosphazene molecule provides a large number of reactive functional groups, hydroxyl groups, and rigid benzene ring structures, which are conducive to dispersion in the sodium carboxymethyl cellulose solution, and then coating on the surface of the plant fiber and adding it to the degradable polyhydroxyalkanoate composite material to improve its flame retardant properties.

[0166] In Comparative Example 4, the composite bamboo charcoal fiber prepared without adding nano-calcium carbonate was added to the degradable polyhydroxyalkanoate composite material, and its mechanical properties decreased, proving that nano-calcium carbonate can fill the pore structure of plant fibers and prevent the plant fibers from absorbing moisture easily, which leads to a decrease in the performance of the composite material.

[0167] In Comparative Example 5, the composite bamboo charcoal fiber prepared without adding sodium carboxymethyl cellulose solution was added to the degradable polyhydroxyalkanoate composite material, and its mechanical properties decreased, proving that a carboxymethyl cellulose composite film was formed on the surface of the plant fiber. The carboxymethyl groups contained in the composite film exhibited excellent bonding properties, thereby improving the compatibility of the plant fiber and the polyhydroxyalkanoate. In addition, the formed carboxymethyl cellulose composite film tightly adhered the hexachlorocyclotriphosphazene derivative and the nano-calcium carbonate to the surface of the plant fiber, thereby preventing the hexachlorocyclotriphosphazene derivative and the nano-calcium carbonate from migrating and precipitating under the action of external force, thereby affecting the performance of the polyhydroxyalkanoate composite material.

[0168] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0169] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the scope defined by the invention, they should all fall within the scope of protection of the present invention.

Claims

1. A degradable polyhydroxyalkanoate composite material, characterized in that: The invention comprises the following raw materials in parts by weight: 80-100 parts of polyhydroxyalkanoate, 20-30 parts of composite plant fiber, 10-15 parts of reinforcing filler, 1.5-2.5 parts of coupling agent, 0.5-1.5 parts of antioxidant, and 1-2 parts of processing aid; The reinforcing filler is obtained by modifying the surface of hydroxyapatite nanowires with dopamine, mixing the nanowires with alumina sol, aging them, and supercritical drying them. The composite plant fiber is obtained by mixing p-hydroxybenzaldehyde, hexachlorocyclotriphosphazene, nano calcium carbonate and sodium carboxymethyl cellulose solution, and then coating the mixture on the surface of the plant fiber.

2. A degradable polyhydroxyalkanoate composite material according to claim 1, characterized in that: The reinforcing filler is specifically prepared by the following steps: A1. Add hydroxyapatite nanowires to Tris-HCl buffer, stir evenly, add dopamine, stir, filter, wash, and dry to obtain polydopamine-modified hydroxyapatite nanowires; A2. Aluminum chloride hexahydrate, ethanol, and deionized water were mixed and stirred at 20-30°C for 30-40 min. Propylene oxide was added and stirred until a gel formed. The gel was washed and concentrated to obtain an alumina sol. A3. The polydopamine-modified hydroxyapatite nanowires and alumina sol were mixed, aged in ethanol, placed in a reactor, and supercritically dried at a pressure of 5-10 MPa and a temperature of 260-270°C for 2-4 hours. The mixture was then cooled to room temperature to obtain a reinforcing filler.

3. A degradable polyhydroxyalkanoate composite material according to claim 2, characterized in that: In step A1, the ratio of the hydroxyapatite nanowires, Tris-HCl buffer and dopamine is (1-2) g: (90-110) mL: (0.6-0.8) g.

4. The degradable polyhydroxyalkanoate composite material according to claim 2, characterized in that: In step A2, the ratio of aluminum chloride hexahydrate, ethanol, deionized water and propylene oxide is (14-16) g: (45-55) mL: (15-25) mL: (7-8) g.

5. The degradable polyhydroxyalkanoate composite material according to claim 2, characterized in that: In step A3, the ratio of the polydopamine-modified hydroxyapatite nanowires, alumina sol and ethanol is (3-4) g: (1-2) g: (25-35) mL.

6. The degradable polyhydroxyalkanoate composite material according to claim 1, characterized in that: The composite plant fiber is specifically prepared by the following steps: B1. Hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde, and potassium carbonate were added to tetrahydrofuran under argon protection and stirred. After the reaction, the tetrahydrofuran was evaporated under reduced pressure and placed in deionized water, stirred until a precipitate was formed. The precipitate was washed and dried to obtain a hexachlorocyclotriphosphazene derivative; B2. Sodium carboxymethyl cellulose and deionized water were mixed and stirred until completely dissolved to obtain a sodium carboxymethyl cellulose solution. Nano-calcium carbonate and hexachlorocyclotriphosphazene derivatives were added to the sodium carboxymethyl cellulose solution and stirred to obtain a complex. B3. Add the plant fiber to the composite, stir evenly, let it stand, filter, wash, and dry to obtain composite plant fiber.

7. The degradable polyhydroxyalkanoate composite material according to claim 6, characterized in that: In step B1, the ratio of hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde, potassium carbonate, tetrahydrofuran and deionized water is (1-2) g: (2-3) g: (4-5) g: (25-35) mL: (70-90) mL.

8. The degradable polyhydroxyalkanoate composite material according to claim 6, characterized in that: In step B2, the ratio of sodium carboxymethyl cellulose, deionized water, nano-calcium carbonate and hexachlorocyclotriphosphazene derivative is (1.1-1.5) g: (45-55) mL: (1-2) g: (1.5-1.9) g.

9. The degradable polyhydroxyalkanoate composite material according to claim 6, characterized in that: In step B3, the ratio of the plant fiber to the composite is (5-6) g: (45-55) mL.

10. A method for preparing the degradable polyhydroxyalkanoate composite material according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: The polyhydroxyalkanoate, composite plant fiber, reinforcing filler, coupling agent, antioxidant and processing aid are mixed and stirred to obtain a mixture, and the mixture is melt-blended and extruded, water-cooled and pelletized, and dried to obtain a degradable polyhydroxyalkanoate composite material.

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