Straw cellulose modified composite material, preparation method and application thereof
By constructing covalent bonds between straw cellulose and polylactic acid, and fixing chitosan through amide bonds, the problems of weak interfacial bonding and easy loss of antibacterial agents in straw cellulose-based composite materials are solved, enabling high-performance applications in daily necessities such as toothbrushes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI RIGHTWAY TECH CO LTD
- Filing Date
- 2026-05-11
- Publication Date
- 2026-06-05
AI Technical Summary
Existing straw cellulose-based composite materials have problems with weak interfacial bonding and easy loss of antibacterial agents, making it difficult to meet the needs of daily necessities such as toothbrushes.
By reacting a silane coupling agent with straw cellulose to form covalent bonds, and fixing chitosan through amide bonds, the interfacial binding force is enhanced. At the same time, the antibacterial properties of chitosan are utilized to achieve stable grafting of antibacterial agents.
It improves the interfacial bonding strength and antibacterial durability of composite materials, making them suitable for daily necessities such as toothbrushes and meeting the needs of industrial production.
Smart Images
Figure CN122145893A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmentally friendly composite materials technology, specifically to a straw cellulose modified composite material, its preparation method, and its application. Background Technology
[0003] Straw cellulose-based composite materials face two major technical bottlenecks in practical applications: First, weak interfacial bonding. Straw cellulose has strong hydrophilicity and few active groups on its surface, resulting in poor compatibility with the hydrophobic polylactic acid matrix. This leads to the formation of voids at the interface, causing insufficient mechanical properties of the composite material and easy fiber debonding and powdering. In existing technologies, the interfacial shear strength of unmodified straw cellulose and polylactic acid composite materials is usually only 2-3 MPa, which is insufficient to meet the requirements of daily necessities such as toothbrushes. Second, the antibacterial agent is easily lost. To impart antibacterial function to the composite material, traditional methods often use physical dispersion to add antibacterial agents such as chitosan. However, there is no stable chemical bond between the antibacterial agent and the matrix, so it is easily lost during use due to moisture migration and surface wear, resulting in rapid decay of antibacterial performance. Typically, the antibacterial rate drops below 70% after one month of use, making it impossible to achieve long-term antibacterial effect.
[0004] While existing technologies have achieved nanoscale modification of cellulose, they do not address interfacial bonding enhancement and antibacterial agent fixation techniques, making them unsuitable for the manufacture of daily necessities. For daily necessities such as toothbrushes, materials are required to possess excellent mechanical stability and long-lasting antibacterial properties, which existing straw cellulose composite materials cannot simultaneously meet for widespread application in the daily necessities sector.
[0005] Therefore, there is an urgent need to develop a straw cellulose modified composite material and its preparation method that can simultaneously solve the problems of weak interfacial bonding and easy loss of antibacterial agents, and is suitable for industrial production. Summary of the Invention
[0006] To address the shortcomings of existing technologies, this invention provides a straw cellulose-modified composite material, its preparation method, and its applications. The composite material is composed of modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, a compatibilizer, and an antioxidant. The modified straw cellulose is obtained by reacting straw cellulose with an amino-chitosan via a silane coupling agent. This application constructs covalent bonds between straw cellulose and polylactic acid using a silane coupling agent and achieves strong grafting and fixation of chitosan onto the straw cellulose through amide bonds. This simultaneously solves the problems of weak interfacial bonding between components in the composite material and the easy loss of the loaded antibacterial agent. It is suitable for the manufacture of daily necessities such as toothbrush handles, meets the needs of environmental protection and industrial production, and has broad application prospects.
[0007] To achieve the above objectives, the present invention provides the following technical solution:
[0008] In a first aspect, the present invention provides a straw cellulose modified composite material, the straw cellulose modified composite material comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer and antioxidant;
[0009] The modified straw cellulose is obtained by reacting straw cellulose with a silane coupling agent and amino chitosan.
[0010] Preferably, the mass ratio of the modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, crosslinking agent and antioxidant is (50-55):(30-35):(2-3):(0.7-1):(0.3-0.5):(3-4):(0.1-0.15).
[0011] Preferably, the straw cellulose has a particle size of 100-300 nm and a carboxyl content of 0.8-1.2 mmol / g; the chitosan has a molecular weight of 50,000-80,000 and a degree of deacetylation ≥85%.
[0012] In this context, the large specific surface area of straw nanofibers can increase the reaction sites with silane coupling agents and amino chitosan; the carboxyl content of 0.8-1.2 mmol / g provides sufficient condensation reaction sites for the silanol groups of silane coupling agents, ensuring the grafting rate; the molecular weight of chitosan can balance water solubility and antibacterial activity, and the degree of deacetylation ensures sufficient amino groups (-NH2) on the molecular chain, providing sites for the activation reaction with maleic anhydride, ensuring covalent grafting efficiency and long-lasting antibacterial effect.
[0013] Preferably, the molecular weight of the polylactic acid is 100,000-150,000; the crosslinking agent includes any one of PLA (polylactic acid) grafted with maleic anhydride and PCL (polycaprolactone) grafted with maleic anhydride; the antioxidant includes any one of antioxidant 1010, antioxidant 1076 and antioxidant 1135; the silane coupling agent includes any one of γ-glycidoxypropyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane.
[0014] In this context, a molecular weight that is too low in polylactic acid (PLA) leads to insufficient mechanical properties, while a molecular weight that is too high results in poor processing flowability. The appropriate molecular weight range strikes a balance between processing flowability and the mechanical properties of the finished product. The hindered phenolic groups in the antioxidant molecule can capture free radicals generated during PLA processing and use, preventing molecular chain breakage. Furthermore, the antioxidant's thermal stability is adapted to the PLA processing temperature, preventing its own decomposition from affecting material properties and extending material lifespan. The alkoxy group of the silane coupling agent is hydrolyzed in an ethanol-water mixture to generate a silanol group (-Si-OH), which forms a stable Si-OC covalent bond with the hydroxyl groups (-OH) on the surface of straw cellulose, anchoring the coupling agent on the cellulose surface. The epoxy group (-COC-) can undergo a ring-opening reaction with the terminal hydroxyl groups (-OH) of the PLA molecular chain to form a COC covalent bond, simultaneously providing active sites for subsequent grafting of aminochitosan, transforming the physical mixing of straw cellulose and PLA into chemical bonding.
[0015] Preferably, the preparation of the aminochitosan includes the following steps:
[0016] Weigh chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide by mass ratio (8-10):(3-4):(1-2). Dissolve chitosan in 1% acetic acid solution by mass ratio 1:(1-20). Add maleic anhydride and N,N'-dicyclohexylcarbodiimide and stir at 50-55℃ for 1-3 hours to obtain an aminochitosan solution.
[0017] Secondly, this application provides a method for preparing straw cellulose modified composite materials, comprising the following steps:
[0018] S1: Add the silane coupling agent to the ethanol-water mixture, stir and hydrolyze, adjust the pH with acetic acid, add straw cellulose, stir, dry and solidify to obtain coupling agent grafted cellulose.
[0019] S2: Mix amino chitosan, cellulose grafted with coupling agent and acetic acid solution, stir, centrifuge, wash 3 times with ethanol and 2 times with deionized water, and vacuum dry to obtain modified straw cellulose.
[0020] S3: Add modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer and antioxidant into a high-speed mixer and stir to obtain a mixture.
[0021] S4: Add the mixture to a twin-screw extruder for melt blending and granulation, vacuum dry the granules, and injection mold them to obtain straw cellulose modified composite material.
[0022] Preferably, in step S1, the pH is adjusted to 4.5-5.5; the stirring conditions are: stirring temperature 60-65℃, stirring time 2-3h; the drying conditions are: drying temperature 80-90℃, drying time 1-2h.
[0023] Preferably, in step S2, the mass ratio of aminochitosan, cellulose grafted with coupling agent, and acetic acid solution is 1:(8-12):(120-150); the volume fraction of the acetic acid solution is 1%; the stirring conditions are: stirring temperature 60-65℃, stirring time 2-3h; the centrifugation conditions are: rotation speed 7000-8000r / min, centrifugation time 10-15min; and the drying conditions are: temperature 80-90℃, drying time 1-2h.
[0024] Preferably, in step S3, the high-speed stirring conditions are: rotation speed 1000-1200 r / min, stirring temperature 120-130℃, and stirring time 10-20 min; in step S4, the parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw rotation speed 300-400 r / min; the drying conditions are: temperature 80-90℃, and drying time 1-2 h; the injection molding conditions are: injection temperature 170-195℃, injection pressure 90-110 MPa, holding time 20-25 s, and cooling time 25-30 s.
[0025] Thirdly, the present invention also provides an application of straw cellulose modified composite material in the preparation of daily necessities.
[0026] Beneficial technical effects:
[0027] This application utilizes the silanol groups (-Si-OH) generated by the hydrolysis of a silane coupling agent to undergo a dehydration condensation reaction with the hydroxyl and carboxyl groups on the surface of straw cellulose, forming stable Si-OC covalent bonds, thus achieving the grafting of the coupling agent onto the cellulose surface. The epoxy group at the other end of the silane coupling agent, under the catalysis of acetic acid solution, undergoes a ring-opening reaction with the terminal hydroxyl groups of the polylactic acid molecular chain to form a COC covalent bond. Simultaneously, maleic anhydride acts as a crosslinking agent, spontaneously undergoing a ring-opening reaction with the amino groups in chitosan at one end to form an amide bond and expose the carboxyl group. At the other end, through this carboxyl group, a ring-opening esterification reaction occurs with the epoxy groups remaining on the fiber surface. Chitosan is covalently grafted onto the fiber surface through amide and ester bonds, achieving interfacial bonding between polylactic acid and cellulose and immobilization of chitosan, simultaneously solving the problems of weak interfacial bonding and easy loss of antibacterial agents. Attached Figure Description
[0028] Figure 1 A flowchart illustrating a method for preparing a straw cellulose-modified composite material provided in this application. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.
[0030] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0031] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. The invention will be further described below with reference to embodiments, but is not limited thereto.
[0032] Example 1
[0033] This embodiment provides a straw cellulose modified composite material, comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer PLA grafted with maleic anhydride, and antioxidant 1010, with a mass ratio of 52:32:2.5:0.8:0.4:3:0.1, wherein the molecular weight of the polylactic acid is 120,000.
[0034] like Figure 1 As shown in the figure, this embodiment provides a method for preparing straw cellulose modified composite material, including the following steps:
[0035] S1: γ-glycidoxypropyltrimethoxysilane was added to an ethanol-water mixture and stirred for hydrolysis. The pH was adjusted to 5.0 with acetic acid, and straw cellulose was added. The mixture was stirred at 60°C for 2 hours and dried at 90°C for 1 hour to solidify, thus obtaining coupling agent grafted cellulose. The straw cellulose had a particle size of 200 nm and a carboxyl content of 1.0 mmol / g.
[0036] S2: Amino chitosan, cellulose grafted with coupling agent and acetic acid solution with a volume fraction of 1% were mixed at a mass ratio of 1:9:140, stirred at 400 r / min and 65℃ for 2 h, centrifuged at 8000 r / min for 10 min, washed 3 times with ethanol and 2 times with deionized water, and vacuum dried at 80℃ for 2 h to obtain modified straw cellulose.
[0037] The preparation of the aminochitosan includes the following steps:
[0038] Chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide were weighed in a mass ratio of 9:3.5:1.5. Chitosan was dissolved in a 1% acetic acid solution in a mass ratio of 1:15. Maleic anhydride and N,N'-dicyclohexylcarbodiimide were added, and the mixture was stirred at 55°C for 3 hours to obtain aminochitosan.
[0039] The chitosan has a molecular weight of 60,000 and a degree of deacetylation of 88%.
[0040] S3: Modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PLA grafted maleic anhydride and antioxidant 1010 are put into a high-speed mixer and stirred at 1200 r / min and 130℃ for 15 min to obtain a mixture.
[0041] S4: The mixture is added to a twin-screw extruder for melt blending and granulation. The parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw speed 300r / min. The granules are vacuum dried at 80℃ for 2 hours and then injection molded at an injection temperature of 185℃ and an injection pressure of 100MPa. The holding time is 20s and the cooling time is 25s to obtain a straw cellulose modified composite material.
[0042] Example 2
[0043] This embodiment provides a straw cellulose modified composite material, comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer PCL grafted with maleic anhydride, and antioxidant 1076, in a mass ratio of 50:35:2.0:0.7:0.3:3.5:0.1, wherein the polylactic acid has a molecular weight of 120,000.
[0044] like Figure 1 As shown in the figure, this embodiment provides a method for preparing straw cellulose modified composite material, including the following steps:
[0045] S1: 3-(2,3-epoxypropoxy)propyltrimethoxysilane was added to an ethanol-water mixture and stirred for hydrolysis. The pH was adjusted to 5.0 with acetic acid, and straw cellulose was added. The mixture was stirred at 60°C for 2 hours and dried at 80°C for 1 hour to solidify, thus obtaining coupling agent grafted cellulose. The straw cellulose had a particle size of 150 nm and a carboxyl content of 0.9 mmol / g.
[0046] S2: Amino chitosan, cellulose grafted with coupling agent and acetic acid solution with a volume fraction of 1% were mixed at a mass ratio of 1:11:120, stirred at 400 r / min and 65℃ for 2 h, centrifuged at 7000 r / min for 15 min, washed 3 times with ethanol and 2 times with deionized water, and vacuum dried at 80℃ for 2 h to obtain modified straw cellulose.
[0047] The preparation of the aminochitosan includes the following steps:
[0048] Chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide were weighed in a mass ratio of 8:3:1. Chitosan was dissolved in a 1% acetic acid solution in a mass ratio of 1:20. Maleic anhydride and N,N'-dicyclohexylcarbodiimide were added, and the mixture was stirred at 55°C for 3 hours to obtain aminochitosan.
[0049] The chitosan has a molecular weight of 50,000 and a degree of deacetylation of 85%.
[0050] S3: Modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PCL-grafted maleic anhydride, and antioxidant 1076 are added to a high-speed mixer and stirred at 1100 r / min and 125℃ for 15 min to obtain a mixture.
[0051] S4: The mixture is added to a twin-screw extruder for melt blending and granulation. The parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, screw speed 350r / min. The granules are vacuum dried at 80℃ for 2h, and then injection molded at an injection temperature of 180℃ and an injection pressure of 100MPa. The holding time is 20s and the cooling time is 25s to obtain a straw cellulose modified composite material.
[0052] Example 3
[0053] This embodiment provides a straw cellulose modified composite material, comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer PLA grafted with maleic anhydride, and antioxidant 1135 in a mass ratio of 55:30:3:1.0:0.5:4:0.15, wherein the polylactic acid has a molecular weight of 120,000.
[0054] like Figure 1 As shown in the figure, this embodiment provides a method for preparing straw cellulose modified composite material, including the following steps:
[0055] S1: 3-(2,3-epoxypropoxy)propyltrimethoxysilane was added to an ethanol-water mixture and stirred for hydrolysis. The pH was adjusted to 4.5 with acetic acid, and straw cellulose was added. The mixture was stirred at 60°C for 2 hours and dried at 80°C for 1 hour to solidify, thus obtaining coupling agent grafted cellulose. The straw cellulose had a particle size of 250 nm and a carboxyl content of 1.1 mmol / g.
[0056] S2: Mix amino chitosan, cellulose grafted with coupling agent and acetic acid solution with a volume fraction of 1% at a mass ratio of 1:9:120, stir at 400 r / min and 65℃ for 2 h, centrifuge at 8000 r / min for 10 min, wash with ethanol 3 times and deionized water 2 times, and vacuum dry at 80℃ for 2 h to obtain modified straw cellulose.
[0057] The preparation of the aminochitosan includes the following steps:
[0058] Chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide were weighed in a mass ratio of 10:4:2. Chitosan was dissolved in a 1% acetic acid solution in a mass ratio of 1:15. Maleic anhydride and N,N'-dicyclohexylcarbodiimide were added, and the mixture was stirred at 55°C for 3 hours to obtain aminochitosan.
[0059] The chitosan has a molecular weight of 80,000 and a degree of deacetylation of 88%.
[0060] S3: Modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PLA grafted maleic anhydride and antioxidant 1135 are put into a high-speed mixer and stirred at 1000 r / min and 130℃ for 15 min to obtain a mixture.
[0061] S4: The mixture is added to a twin-screw extruder for melt blending and granulation. The parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw speed 400r / min. The granules are vacuum dried at 90℃ for 2 hours and then injection molded at an injection temperature of 195℃ and an injection pressure of 110MPa. The holding time is 20s and the cooling time is 25s to obtain a straw cellulose modified composite material.
[0062] Example 4
[0063] This embodiment provides a straw cellulose modified composite material, comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PCL grafted maleic anhydride, and antioxidant 1010 in a mass ratio of 53:33:2.2:0.9:0.4:3.2:0.1, wherein the polylactic acid has a molecular weight of 120,000.
[0064] like Figure 1 As shown in the figure, this embodiment provides a method for preparing straw cellulose modified composite material, including the following steps:
[0065] S1: 3-(2,3-epoxypropoxy)propyltrimethoxysilane was added to an ethanol-water mixture and stirred for hydrolysis. The pH was adjusted to 5.0 with acetic acid, and straw cellulose was added. The mixture was stirred at 60°C for 2 hours and dried at 80-90°C for 1 hour to solidify, thereby obtaining coupling agent grafted cellulose. The straw cellulose had a particle size of 200 nm and a carboxyl content of 1.0 mmol / g.
[0066] S2: Amino chitosan, cellulose grafted with coupling agent and acetic acid solution with a volume fraction of 1% were mixed at a mass ratio of 1:12:150, stirred at 400 r / min and 65℃ for 2 h, centrifuged at 8000 r / min for 10 min, washed 3 times with ethanol and 2 times with deionized water, and vacuum dried at 80℃ for 2 h to obtain modified straw cellulose.
[0067] The preparation of the aminochitosan includes the following steps:
[0068] Chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide were weighed in a mass ratio of 9:3.5:1.5. Chitosan was dissolved in a 1% acetic acid solution in a mass ratio of 1:20. Maleic anhydride and N,N'-dicyclohexylcarbodiimide were added, and the mixture was stirred at 55°C for 3 hours to obtain aminochitosan.
[0069] The chitosan has a molecular weight of 60,000 and a degree of deacetylation of 88%.
[0070] S3: Modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PCL-grafted maleic anhydride, and antioxidant 1010 are added to a high-speed mixer and stirred at 1200 r / min and 120℃ for 15 min to obtain a mixture.
[0071] S4: The mixture is added to a twin-screw extruder for melt blending and granulation. The parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw speed 300r / min. The granules are vacuum dried at 80℃ for 2h, and then injection molded at an injection temperature of 192℃ and an injection pressure of 90MPa. The holding time is 20s and the cooling time is 25s to obtain a straw cellulose modified composite material.
[0072] Example 5
[0073] This embodiment provides a straw cellulose modified composite material, comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PLA grafted maleic anhydride and antioxidant 1076 in a mass ratio of 51:32:2.5:0.8:0.4:3:0.1, wherein the polylactic acid has a molecular weight of 120,000.
[0074] like Figure 1As shown in the figure, this embodiment provides a method for preparing straw cellulose modified composite material, including the following steps:
[0075] S1: 3-(2,3-epoxypropoxy)propyltrimethoxysilane was added to an ethanol-water mixture and stirred for hydrolysis. The pH was adjusted to 5.0 with acetic acid, and straw cellulose was added. The mixture was stirred at 60°C for 2 hours and dried at 80-90°C for 1 hour to solidify, thereby obtaining coupling agent grafted cellulose. The straw cellulose had a particle size of 200 nm and a carboxyl content of 1.0 mmol / g.
[0076] S2: Amino chitosan, cellulose grafted with coupling agent and acetic acid solution with a volume fraction of 1% were mixed at a mass ratio of 1:10:120, stirred at 400 r / min and 65℃ for 2 h, centrifuged at 8000 r / min for 10 min, washed 3 times with ethanol and 2 times with deionized water, and vacuum dried at 80℃ for 2 h to obtain modified straw cellulose.
[0077] The preparation of the aminochitosan includes the following steps:
[0078] Chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide were weighed in a mass ratio of 9:3.5:1.5. Chitosan was dissolved in a 1% acetic acid solution in a mass ratio of 1:10. Maleic anhydride and N,N'-dicyclohexylcarbodiimide were added, and the mixture was stirred at 55°C for 3 hours to obtain aminochitosan.
[0079] The chitosan has a molecular weight of 60,000 and a degree of deacetylation of 88%.
[0080] S3: Modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer PLA grafted maleic anhydride and antioxidant 1076 are put into a high-speed mixer and stirred at 1200 r / min and 120℃ for 15 min to obtain a mixture.
[0081] S4: The mixture is added to a twin-screw extruder for melt blending and granulation. The parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw speed 320r / min. The granules are vacuum dried at 80℃ for 2h, and then injection molded at an injection temperature of 178℃ and an injection pressure of 100MPa. The holding time is 20s and the cooling time is 25s to obtain a straw cellulose modified composite material.
[0082] Example 6
[0083] This embodiment provides a straw cellulose modified composite material, comprising modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, PCL grafted maleic anhydride, and antioxidant 1135 in a mass ratio of 4:31:2.6:0.9:0.5:3.8:0.1, wherein the polylactic acid has a molecular weight of 120,000.
[0084] like Figure 1 As shown in the figure, this embodiment provides a method for preparing straw cellulose modified composite material, including the following steps:
[0085] S1: γ-glycidoxypropyltrimethoxysilane was added to an ethanol-water mixture and stirred for hydrolysis. The pH was adjusted to 5.0 with acetic acid, and straw cellulose was added. The mixture was stirred at 60°C for 2 hours and dried at 80-90°C for 1 hour to solidify, thus obtaining coupling agent grafted cellulose. The straw cellulose had a particle size of 220 nm and a carboxyl content of 1.0 mmol / g.
[0086] S2: Mix amino chitosan, cellulose grafted with coupling agent and acetic acid solution with a volume fraction of 1% at a mass ratio of 1:8:120, stir at 400 r / min and 65℃ for 2 h, centrifuge at 8000 r / min for 10 min, wash with ethanol 3 times and deionized water 2 times, and vacuum dry at 80℃ for 2 h to obtain modified straw cellulose.
[0087] The preparation of the aminochitosan includes the following steps:
[0088] Chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide were weighed in a mass ratio of 9:3.6:1.6. Chitosan was dissolved in a 1% (v / v) acetic acid solution in a mass ratio of 1:10. Maleic anhydride and N,N'-dicyclohexylcarbodiimide were added, and the mixture was stirred at 55°C for 3 hours to obtain aminochitosan.
[0089] The chitosan has a molecular weight of 80,000 and a degree of deacetylation of 88%.
[0090] S3: Modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer PCL grafted maleic anhydride and antioxidant 1135 are put into a high-speed mixer and stirred at 1200 r / min and 120℃ for 15 min to obtain a mixture.
[0091] S4: The mixture is added to a twin-screw extruder for melt blending and granulation. The parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw speed 300r / min. The granules are vacuum dried at 80℃ for 2 hours and then injection molded at an injection temperature of 185℃ and an injection pressure of 100MPa. The holding time is 20s and the cooling time is 25s to obtain a straw cellulose modified composite material.
[0092] Comparative Example 1
[0093] This comparative example provides a straw cellulose modified composite material and its preparation method. The difference between this example and Example 1 is that unmodified straw cellulose is used, while other process parameters and operating steps are the same as in Example 1.
[0094] Comparative Example 2
[0095] This comparative example provides a straw cellulose modified composite material and its preparation method. The difference from Example 1 is that chitosan solution is used instead of aminochitosan solution to mix with cellulose grafted with coupling agent. Other process parameters and operation steps are the same as in Example 1.
[0096] Comparative Example 3
[0097] This comparative example provides a straw cellulose modified composite material and its preparation method. The difference between this example and Example 1 is that no compatibilizer is used, while other process parameters and operating steps are the same as in Example 1.
[0098] The interfacial shear strength, flexural strength, water absorption, 90-day degradation rate and antibacterial rate of the straw cellulose modified composite materials prepared in Examples 1-6 and Comparative Examples 1-3 of this application were tested and compared. The results are shown in Table 1.
[0099] Test method:
[0100] Interfacial shear strength: Prepare a 10mm×10mm×20mm specimen and shear it at a rate of 1mm / min using a universal testing machine at room temperature. Record the maximum breaking force and divide it by the area of the specimen subjected to force to obtain the result.
[0101] Bending strength: Dumbbell-shaped specimens were prepared and stretched at a rate of 5 mm / min at room temperature. The maximum load was recorded, and the strength was calculated by the load and specimen dimensions. Elongation at break was calculated by the rate of change of gauge length before and after stretching.
[0102] Water absorption rate: Take a 20mm×20mm×4mm sample, dry it to constant weight and weigh it, immerse it in distilled water at 25℃ for 72h, absorb the surface moisture and weigh it again, and calculate the proportion of the mass increase to the original mass.
[0103] 90-day degradation rate: After crushing the sample, it was mixed with compost at a ratio of 1:10 and cultured for 90 days at 25℃ and 60-70% humidity. The total amount of carbon dioxide released was measured and compared with the theoretical maximum release to obtain the degradation rate.
[0104] Antibacterial rate: The Escherichia coli bacterial solution (10...) 6 CFU / mL was added to the sample surface and incubated at 37℃ and high humidity for 24 hours. The colony count was then performed on plates. Using sterile glass slides as a control, the proportion of the difference in colony count between the two groups to the control group was calculated.
[0105] Table 1 Performance test results of straw cellulose modified composite materials prepared in the examples and comparative examples
[0106]
[0107] The straw cellulose modified composite materials prepared in Examples 1-6 of this invention utilize silanol groups (-Si-OH) generated by the hydrolysis of silane coupling agents. These silanol groups react with the hydroxyl and carboxyl groups on the surface of straw cellulose through a dehydration condensation reaction, forming stable Si-OC covalent bonds, thus achieving the grafting of the coupling agent onto the cellulose surface. Simultaneously, the epoxy group at the other end reacts with the terminal hydroxyl group of the polylactic acid molecular chain to form a COC covalent bond through a ring-opening reaction. Under the catalysis of N,N'-dicyclohexylcarbodiimide, maleic anhydride (MAH) acts as a crosslinking agent, forming an active intermediate with the amino group of chitosan at one end and reacting with the residual epoxy groups on the fiber surface at the other end. This covalently grafts chitosan onto the fiber surface via amide bonds, achieving interfacial bonding between polylactic acid and cellulose and fixing chitosan, thus simultaneously solving the problems of weak interfacial bonding and easy loss of antibacterial agents.
[0108] Comparative Example 1 used unmodified straw cellulose, whose fiber surface lacked active sites that matched polylactic acid. The large difference in polarity between the two resulted in extremely poor interfacial bonding, making it prone to interfacial debonding and fiber agglomeration under external force. In addition, there were no covalently grafted antibacterial components, leading to a significant decrease in the material's mechanical properties and antibacterial effect. Comparative Example 2 used chitosan solution instead of aminochitosan solution to mix with cellulose grafted with a coupling agent. Chitosan was only physically adsorbed on the fiber surface and could not form stable amide bonds. It was easily dissolved and lost during use, failing to achieve long-term antibacterial effect, and the interfacial bonding was not strengthened. Comparative Example 3 did not add a compatibilizer and relied solely on the point-like covalent connection of the silane coupling agent. This could not completely eliminate the interfacial voids between the fiber and the polylactic acid matrix or alleviate the polarity mismatch problem. Stress transmission was poor, resulting in a significant decrease in the material's mechanical properties. The overall performance of the material failed to meet the requirements for use.
[0109] It should be understood that the above are only some embodiments of the present invention. It should be pointed out that for those skilled in the art, other modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.
Claims
1. A straw cellulose-modified composite material, characterized in that, Including modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer, and antioxidant; The modified straw cellulose is obtained by reacting straw cellulose with a silane coupling agent and amino chitosan.
2. The straw cellulose modified composite material according to claim 1, characterized in that, The mass ratio of the modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer and antioxidant is (50-55):(30-35):(2-3):(0.7-1):(0.3-0.5):(3-4):(0.1-0.15).
3. The straw cellulose modified composite material according to claim 1, characterized in that, The straw cellulose has a particle size of 100-300 nm and a carboxyl content of 0.8-1.2 mmol / g; the aminochitosan has a molecular weight of 50,000-80,000 and a degree of deacetylation ≥85%.
4. The straw cellulose modified composite material according to claim 1, characterized in that, The molecular weight of the polylactic acid is 100,000-150,000; the compatibilizer includes any one of PLA grafted with maleic anhydride and PCL grafted with maleic anhydride; the antioxidant includes any one of antioxidant 1010, antioxidant 1076 and antioxidant 1135; the silane coupling agent includes any one of γ-glycidoxypropyltrimethoxysilane and 3-(2,3-epoxypropoxy)propyltrimethoxysilane.
5. The straw cellulose modified composite material according to claim 1, characterized in that, The preparation of the aminochitosan includes the following steps: Weigh chitosan, maleic anhydride, and N,N'-dicyclohexylcarbodiimide by mass ratio (8-10):(3-4):(1-2). Dissolve chitosan in 1% acetic acid solution by mass ratio 1:(1-20). Add maleic anhydride and N,N'-dicyclohexylcarbodiimide. Stir at 50-55℃ for 1-3 hours. Filter and dry to obtain aminochitosan.
6. A method for preparing a straw cellulose-modified composite material as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Add the silane coupling agent to the ethanol-water mixture, stir and hydrolyze, adjust the pH with acetic acid, add straw cellulose, stir, dry and solidify to obtain coupling agent grafted cellulose; S2: Mix amino chitosan, cellulose grafted with coupling agent and acetic acid solution, stir, centrifuge, wash with ethanol and then with deionized water, and vacuum dry to obtain modified straw cellulose. S3: Add modified straw cellulose, polylactic acid, tributyl citrate, calcium stearate, titanium nitride, compatibilizer and antioxidant into a high-speed mixer and stir to obtain a mixture. S4: Add the mixture to a twin-screw extruder for melt blending and granulation, vacuum dry the granules, and injection mold them to obtain straw cellulose modified composite material.
7. The method for preparing a straw cellulose-modified composite material according to claim 6, characterized in that, In step S1, the pH is adjusted to 4.5-5.5; the stirring conditions are: stirring temperature 60-65℃, stirring time 2-3h; the drying conditions are: drying temperature 80-90℃, drying time 1-2h.
8. The method for preparing a straw cellulose-modified composite material according to claim 6, characterized in that, In step S2, the mass ratio of aminochitosan, cellulose grafted with coupling agent, and acetic acid solution is 1:(8-12):(120-150); the volume fraction of the acetic acid solution is 1%; the stirring conditions are: stirring temperature 60-65℃, stirring time 2-3h; the centrifugation conditions are: rotation speed 7000-8000r / min, centrifugation time 10-15min; the drying conditions are: temperature 80-90℃, drying time 1-2h.
9. The method for preparing a straw cellulose-modified composite material according to claim 6, characterized in that, In step S3, the high-speed stirring conditions are: rotation speed 1000-1200 r / min, stirring temperature 120-130℃, and stirring time 10-20 min; in step S4, the parameters of the twin-screw extruder are: feeding zone 155℃, compression melting zone 170℃, homogenization mixing zone 180℃, die head 175℃, and screw rotation speed 300-400 r / min; the drying conditions are: temperature 80-90℃, and drying time 1-2 h; the injection molding conditions are: injection temperature 170-195℃, injection pressure 90-110 MPa, holding time 20-25 s, and cooling time 25-30 s.
10. The application of a straw cellulose modified composite material as described in any one of claims 1-5 in the preparation of daily necessities.