Shuttle-shaped nanocrystal compatibilized modified carboxymethyl starch / polyvinyl alcohol composite material, and preparation method and application thereof

Abstract

The application belongs to the technical field of polymer composites, and particularly relates to a shuttle-shaped nanocrystal compatibilized modified carboxymethyl starch / polyvinyl alcohol composite material and a preparation method and application thereof. The shuttle-shaped nanocrystal compatibilized modified carboxymethyl starch / polyvinyl alcohol composite material is prepared from the following raw materials: carboxymethyl starch, polyvinyl alcohol and shuttle-shaped nanocrystal. The application further provides a preparation method of the carboxymethyl starch / polyvinyl alcohol composite material. The prepared composite material has excellent compatibility, mechanical strength, toughness, ultraviolet blocking, high-energy blue light blocking, water vapor blocking, antibacterial, ammonia gas response color changing and other performances, and can maintain relatively high visible light transparency. The composite material can be used as an intelligent indicating material and effectively indicates the freshness change of shrimp and other meat food during storage. The composite material preparation process is simple, and has wide application value in the fields of food packaging, intelligent materials, ammonia gas detection, environmental monitoring and safety.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite materials, and particularly relates to a spindle-shaped nano-crystal compatibilized carboxymethyl starch / polyvinyl alcohol composite material and a preparation method and application thereof. Background Art

[0002] Carboxymethyl starch is an anionic polymer that dissolves in cold water to form a transparent solution with high stability and viscosity. Due to its low cost and rapid degradation, carboxymethyl starch holds great promise for the development of environmentally friendly materials and is currently widely used as an emulsifier, thickener, dispersant, stabilizer, sizing agent, water-retaining agent, and film-forming agent. However, carboxymethyl starch suffers from poor mechanical properties, making it difficult to obtain continuous products with high strength and flexibility. As a microbially degradable material, polyvinyl alcohol (PVA) exhibits excellent film-forming properties, biodegradability, biocompatibility, transparency, and mechanical properties, and has been extensively studied for clinical applications, film production, and food packaging. However, pure PVA has drawbacks such as high cost and high stability at room temperature, which makes it difficult to degrade. Adding carboxymethyl starch to PVA can increase the biodegradation rate of the material, leading to the production of more economical and environmentally friendly carboxymethyl starch / PVA-based composites. However, the limited compatibility between carboxymethyl starch and polyvinyl alcohol (PVA) results in poor mechanical, water vapor barrier, and oxygen barrier properties of carboxymethyl starch / PVA blends. Furthermore, the composites lack UV protection, antibacterial properties, and ammonia response, limiting their practical applications. The present invention utilizes carboxymethyl starch / PVA as a matrix and a self-prepared, spindle-shaped nanocrystal as a functional compatibilizer to improve the compatibility, mechanical strength, toughness, UV protection, high-energy blue light protection, water vapor barrier, antibacterial properties, and ammonia response color change properties of the composites. This results in the development of a carboxymethyl starch / PVA composite with excellent overall performance, broadening its application in food packaging, intelligent materials, ammonia detection, environmental monitoring, and safety. Summary of the Invention

[0003] The present invention aims to overcome the shortcomings of the prior art by providing a carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystals for compatibilization and modification, as well as its preparation method and application. This composite material exhibits excellent compatibility, mechanical strength, toughness, UV shielding, high-energy blue light shielding, water vapor barrier, antibacterial properties, and ammonia-responsive color change, while maintaining high visible light transparency. It can be used as an intelligent indicator material to effectively and timely indicate the freshness of meat products (such as shrimp, pork, and fish) during storage. Furthermore, the composite material's preparation process is simple, environmentally friendly, low-cost, and suitable for scale-up production.

[0004] Technical solution of the present invention:

[0005] The present invention provides a spindle-shaped nanocrystal-compatibility-modified carboxymethyl starch / polyvinyl alcohol composite material, which is characterized by being composed of the following components in parts by weight: 40 parts of carboxymethyl starch, 160 parts of polyvinyl alcohol, and 1-4 parts of spindle-shaped nanocrystals;

[0006] The preparation method of the spindle-shaped nanocrystal comprises the following steps:

[0007] (1) Dissolve 10 parts of L-tryptophan in 6000 parts of deionized water and stir at room temperature for 10 minutes to obtain a uniform L-tryptophan solution for later use;

[0008] (2) Take 17 parts of copper chloride dihydrate and dissolve it in 2000 parts of deionized water to obtain a uniform copper chloride solution for later use;

[0009] (3) The copper chloride solution obtained in step (2) was added to the L-tryptophan solution obtained in step (1), and the pH of the solution was adjusted to 9 with 1 mol / L NaOH solution. The solution was stirred at room temperature for 60 min to obtain a uniform spindle-shaped nanocrystal solution. The solution was then centrifuged, washed, and dried to obtain spindle-shaped nanocrystals (green in color).

[0010] The present invention also provides a method for preparing the above-mentioned spindle-shaped nanocrystal-compatibility-modified carboxymethyl starch / polyvinyl alcohol composite material, which is characterized by comprising the following steps:

[0011] (1) Add 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution for later use;

[0012] (2) Disperse 1-4 parts of spindle-shaped nanocrystals in 1000 parts of deionized water, stir at room temperature for 30 minutes to obtain a uniform dispersion, and set aside;

[0013] (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0014] (4) The film-forming solution obtained in step (3) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystals and enhanced compatibilization.

[0015] The application of the spindle-shaped nanocrystal-compatibility-modified carboxymethyl starch / polyvinyl alcohol composite material is characterized by being used in the fields of food packaging, smart materials, ammonia detection, environmental monitoring and safety.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The carboxymethyl starch / polyvinyl alcohol composite material prepared by the present invention has excellent compatibility, mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, water vapor barrier, antibacterial, ammonia response color change and other properties, while maintaining high visible light transparency. It can be used as an intelligent indicator material to timely and effectively indicate the changes in the freshness of meat foods (such as shrimp, pork, fish, etc.) during storage. In addition, the preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for scale-up production. It has wide application value in food packaging, intelligent materials, ammonia detection, environmental monitoring and safety and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a scanning electron microscope image of the spindle-shaped nanocrystal involved in the present invention;

[0019] Figure 2 This is an infrared spectrum of the spindle-shaped nanocrystals involved in the present invention;

[0020] Figure 3 This is a scanning electron microscope image of the carboxymethyl starch / polyvinyl alcohol composite material prepared in the comparative example of the present invention;

[0021] Figure 4 This is a scanning electron microscope image of the compatibilized and modified carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 1 of the present invention;

[0022] Figure 5 This is a scanning electron microscope image of the compatibilized carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 2 of the present invention;

[0023] Figure 6 This is a scanning electron microscope image of the compatibilized carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is described in detail below by way of examples. It is necessary to point out that the present examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of the present invention. Those skilled in the art may make some non-essential improvements and adjustments based on the above-mentioned contents of the present invention. The parts of the raw materials are by weight unless otherwise specified.

[0025] In the following specific examples and comparative example formulas and preparation methods, the carboxymethyl starch used is a product provided by Roen Reagent Co., Ltd. (CAS No.: 9063-38-1); the polyvinyl alcohol used is a product provided by Shanghai Yingjia Industrial Development Co., Ltd. (model: PVA-2899); L-tryptophan is an analytical grade reagent provided by Shanghai Yien Chemical Technology Co., Ltd.; and copper chloride dihydrate, sodium hydroxide, and ethanol are analytical grade reagents provided by Xilong Scientific Co., Ltd.

[0026] In the following specific embodiments and comparative example formulations and preparation methods, the preparation method of the spindle-shaped nanocrystals includes the following steps:

[0027] (1) Dissolve 10 parts of L-tryptophan in 6000 parts of deionized water and stir at room temperature for 10 minutes to obtain a uniform L-tryptophan solution for later use;

[0028] (2) Take 17 parts of copper chloride dihydrate and dissolve it in 2000 parts of deionized water to obtain a uniform copper chloride solution for later use;

[0029] (3) The copper chloride solution obtained in step (2) was added to the L-tryptophan solution obtained in step (1), and the pH of the solution was adjusted to 9 with 1 mol / L NaOH solution. The solution was stirred at room temperature for 60 min to obtain a uniform spindle-shaped nanocrystal solution. The solution was then centrifuged, washed, and dried to obtain spindle-shaped nanocrystals (green in color).

[0030] Example 1

[0031] A carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystal compatibilization modification is characterized by being composed of the following components in parts by weight: 40 parts of carboxymethyl starch, 160 parts of polyvinyl alcohol, and 1 part of spindle-shaped nanocrystal.

[0032] The preparation method comprises the following steps:

[0033] (1) Add 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution for later use;

[0034] (2) Disperse 1 part of spindle-shaped nanocrystals in 1000 parts of deionized water and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use;

[0035] (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0036] (4) The film-forming solution obtained in step (3) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystals and enhanced compatibilization.

[0037] Example 2

[0038] A carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystal compatibilization modification is characterized by being composed of the following components in parts by weight: 40 parts of carboxymethyl starch, 160 parts of polyvinyl alcohol, and 2 parts of spindle-shaped nanocrystals.

[0039] The preparation method comprises the following steps:

[0040] (1) Add 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution for later use;

[0041] (2) Disperse 2 parts of spindle-shaped nanocrystals in 1000 parts of deionized water and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use;

[0042] (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0043] (4) The film-forming solution obtained in step (3) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystals and enhanced compatibilization.

[0044] Example 3

[0045] A carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystal compatibilization modification is characterized in that it consists of the following components in parts by weight: 40 parts of carboxymethyl starch, 160 parts of polyvinyl alcohol, and 4 parts of spindle-shaped nanocrystals.

[0046] The preparation method comprises the following steps:

[0047] (1) Add 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution for later use;

[0048] (2) Disperse 4 parts of spindle-shaped nanocrystals in 1000 parts of deionized water and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use;

[0049] (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0050] (4) The film-forming solution obtained in step (3) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystals and enhanced compatibilization.

[0051] Comparative Example

[0052] As a comparison standard for the above embodiments, the present invention provides a carboxymethyl starch / polyvinyl alcohol composite material prepared without containing spindle-shaped nanocrystals, comprising the following steps:

[0053] (1) Add 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution for later use;

[0054] (2) Add 1000 parts of deionized water to the blend solution obtained in step (1), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0055] (3) The film-forming solution obtained in step (2) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a carboxymethyl starch / polyvinyl alcohol composite material.

[0056] Structure and performance test:

[0057] The carboxymethyl starch / polyvinyl alcohol composite material prepared in the above comparative example and the compatibilized carboxymethyl starch / polyvinyl alcohol composite material prepared in the example were subjected to structural and performance tests. The UV-visible properties were tested using a UV-visible spectrometer (Lamdba365, PerkinElmer Instruments), and the average UV transmittance was calculated with reference to GB / T 18830-2009; the tensile properties were tested in accordance with GB / T 1040-2006; the water vapor permeability was tested in accordance with ASTM E 96; the antibacterial properties of the material were tested in accordance with QBT2591-2003; and the ammonia response test method was as follows: the sample material was exposed to an ammonia environment and the color change of the sample material was observed.

[0058] Shrimp freshness monitoring experiment: Fresh shrimp (mass: 30 g) were purchased from the market and placed in a Petri dish. The dish was sealed with a Petri dish lid. The carboxymethyl starch / polyvinyl alcohol composite material prepared in the comparative example and the compatibilized carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 3 (pre-cut into sample materials with a diameter of 1 cm) were attached to the bottom of the lid. The shrimp samples were then stored in a 25°C oven. Changes in the freshness of the shrimp and changes in the color of the sample materials were observed and recorded.

[0059] The above performance test data are shown in Table 1 and Table 2.

[0060] Table 1 Sample performance test data

[0061]

[0062] Table 2 Results of shrimp freshness monitoring experiment (where t is the storage time of fresh shrimp)

[0063]

[0064] The brittle cross section of the carboxymethyl starch / polyvinyl alcohol composite material prepared in the comparative example and the brittle cross section of the carboxymethyl starch / polyvinyl alcohol composite material prepared in the example were observed and analyzed using a scanning electron microscope. Figure 3-6 .Depend on Figure 3-6 It can be seen that the carboxymethyl starch / polyvinyl alcohol composite film material prepared in the comparative example exhibits a rough, uneven morphology and contains a large number of dispersed phase particles (carboxymethyl starch particles) with larger particle sizes. This indicates poor compatibility between polyvinyl alcohol and carboxymethyl starch, and weak interfacial bonding between the carboxymethyl starch / polyvinyl alcohol phases. The carboxymethyl starch / polyvinyl alcohol composite material prepared in the example exhibits a relatively uniform, smooth, and dense morphology with no obvious dispersed phase particles (carboxymethyl starch particles). This indicates that the phase morphology of the system is significantly improved, and the interfacial bonding between the carboxymethyl starch / polyvinyl alcohol phases is significantly improved, thereby contributing to improved mechanical properties. Specifically, the addition of spindle-shaped nanocrystals to the carboxymethyl starch / polyvinyl alcohol blend effectively improves the compatibility of the carboxymethyl starch / polyvinyl alcohol blend and improves the interfacial bonding between the carboxymethyl starch / polyvinyl alcohol phases.

[0065] The results of the ammonia response test experiment show that the carboxymethyl starch / polyvinyl alcohol composite material prepared in the comparative example is colorless and transparent. After exposure to an ammonia environment, its color does not change, and it still exhibits colorless and transparent optical properties; the volume-modified carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 1 is light green, and after exposure to an ammonia environment, its color changes to light blue; the volume-modified carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 2 is light green, and after exposure to an ammonia environment, its color changes to light blue; the volume-modified carboxymethyl starch / polyvinyl alcohol composite material prepared in Example 3 is green, and after exposure to an ammonia environment, its color changes to blue.

[0066] In summary, the prepared compatibilized carboxymethyl starch / polyvinyl alcohol composite material has excellent compatibility, mechanical strength, toughness, UV barrier, high-energy blue light barrier, water vapor barrier, antibacterial, and ammonia-responsive color change properties. It also maintains high visible light transparency and can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of meat products such as shrimp during storage (see Table 2). In addition, the preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for scale-up production. It has wide application value in food packaging, intelligent materials, ammonia-responsive materials, ammonia detection, environmental monitoring and safety, and other fields.

[0067] The content of the present invention is not limited to the embodiments listed. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the description of the present invention is covered by the claims of the present invention.

Claims

1. A spindle-shaped nanocrystal-compatibility-modified carboxymethyl starch / polyvinyl alcohol composite material, characterized in that: The invention is composed of the following components in parts by weight: 40 parts of carboxymethyl starch, 160 parts of polyvinyl alcohol, and 1-4 parts of spindle-shaped nanocrystals; The spindle-shaped nanocrystals are prepared by the following method: (1) dissolving 10 parts of L-tryptophan in 6000 parts of deionized water, stirring at room temperature for 10 minutes to obtain a uniform L-tryptophan solution for later use; (2) taking 17 parts of copper chloride dihydrate, dissolving it in 2000 parts of deionized water, obtaining a uniform copper chloride solution for later use; (3) adding the copper chloride solution obtained in step (2) to the L-tryptophan solution obtained in step (1), adjusting the pH value of the solution to 9 with a 1 mol / L NaOH solution, stirring at room temperature for 60 minutes to obtain a uniform spindle-shaped nanocrystal solution, and then centrifuging, washing, and drying in sequence to obtain spindle-shaped nanocrystals; The preparation method of the spindle-shaped nanocrystal-enlarged carboxymethyl starch / polyvinyl alcohol composite material comprises the following steps: (1) adding 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stirring at 95°C for 60 minutes, obtaining a uniform blend solution for standby use; (2) dispersing 1-4 parts of spindle-shaped nanocrystals in 1000 parts of deionized water, stirring at room temperature for 30 minutes, obtaining a uniform dispersion solution for standby use; (3) adding the dispersion solution obtained in step (2) to the blend solution obtained in step (1), stirring at 95°C for 30 minutes, obtaining a uniform film-forming solution for standby use; (4) pouring the film-forming solution obtained in step (3) into an organic glass dish, and drying in an oven at 60°C for 12 hours to obtain the spindle-shaped nanocrystal-enlarged carboxymethyl starch / polyvinyl alcohol composite material.

2. The method for preparing the spindle-shaped nanocrystalline compatibilized carboxymethyl starch / polyvinyl alcohol composite material according to claim 1, characterized in that The steps include: (1) Add 40 parts of carboxymethyl starch and 160 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 95°C for 60 minutes to obtain a uniform blend solution for later use; (2) Disperse 1-4 parts of spindle-shaped nanocrystals in 1000 parts of deionized water, stir at room temperature for 30 minutes to obtain a uniform dispersion, and set aside; (3) Add the dispersion obtained in step (2) to the blended solution obtained in step (1), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use; (4) The film-forming solution obtained in step (3) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a carboxymethyl starch / polyvinyl alcohol composite material with spindle-shaped nanocrystals and enhanced compatibilization.

3. The use of the spindle-shaped nanocrystal-compatibility-modified carboxymethyl starch / polyvinyl alcohol composite material according to claim 1, characterized in that: Used in food packaging, smart materials, ammonia detection, environmental monitoring and safety fields.

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