Polyvinyl alcohol / starch-based nanocomposite and preparation method and application thereof

Abstract

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

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer composite materials, and particularly relates to a polyvinyl alcohol / starch-based nanocomposite material and a preparation method and application thereof. BACKGROUND

[0002] Environment and food safety have always been the focus of people's attention. Traditional petroleum-based food packaging cannot meet the needs of consumers due to its non-degradability and easy environmental pollution, and environment-friendly packaging has become a substitute for traditional petroleum-based packaging. Polyvinyl alcohol is a non-toxic, degradable and high-mechanical synthetic substance, which belongs to a biodegradable polymer material and can be produced on a large scale by a non-petroleum route. It has outstanding oil and solvent resistance and unique advantages in food and drug packaging. However, polyvinyl alcohol needs to undergo a dissolution and drying process when it is processed in a solution, which has the disadvantages of high cost and slow degradation rate in the natural environment. Starch is a natural biological material with abundant sources and low cost, but it has poor mechanical properties and water resistance. The combination of starch and polyvinyl alcohol can improve the biodegradability of polyvinyl alcohol and reduce the production cost. Therefore, the development of polyvinyl alcohol / starch composite materials is one of the current research hotspots. However, the compatibility between polyvinyl alcohol and starch is limited, and the polyvinyl alcohol / starch composite material lacks ammonia-responsive color change and antibacterial function, which is not conducive to its wide application in the packaging field. The application uses polyvinyl alcohol / starch as the matrix and uses self-made functional complex crystal grains as functional fillers to improve the compatibility, mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, oxygen barrier, water vapor barrier, ammonia-responsive color change, antibacterial properties and other properties of the polyvinyl alcohol / starch composite material, develop polyvinyl alcohol / starch-based nanocomposite materials with excellent performance, and broaden its application in the fields of food packaging, intelligent materials, ammonia detection, environmental monitoring and safety. SUMMARY

[0003] The application aims to overcome the shortcomings of the prior art and provide a polyvinyl alcohol / starch-based nanocomposite material and a preparation method and application thereof. The composite material has excellent compatibility, mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, oxygen barrier, water vapor barrier, ammonia-responsive color change, antibacterial properties and other properties, and can also maintain high visible light transparency. It can be used as an intelligent indicator material and effectively indicates the freshness change of meat food (such as shrimp, pork, fish, etc.) during storage. The preparation process of the composite material is simple, environmentally friendly, low in cost and suitable for large-scale production.

[0004] The technical scheme of the application is as follows:

[0005] The present application provides a polyvinyl alcohol / starch-based nanocomposite, characterized by consisting of the following components in parts by weight: 160 parts of polyvinyl alcohol, 40 parts of starch, and 1-4 parts of functional complex crystal grains.

[0006] The functional complex crystal grains have a particle size of 30-120 nm, and the preparation method comprises the following steps:

[0007] (1) 32 parts of 1H-indazole-6-carboxylic acid and 11 parts of potassium hydroxide are dispersed in 2000 parts of methanol, stirred at room temperature for 3 h to obtain a uniform 1H-indazole-6-carboxylic acid dispersion, which is ready for use;

[0008] (2) 16.5 parts of copper chloride dihydrate is dissolved in 1000 parts of methanol to obtain a uniform copper chloride solution, which is ready for use;

[0009] (3) The copper chloride solution obtained in step (2) is added to the 1H-indazole-6-carboxylic acid solution obtained in step (1), stirred at room temperature for 4 h, and then centrifuged, washed, and dried in sequence to obtain functional complex crystal grains (the color of which is dark green).

[0010] The present application also provides a preparation method of the above-mentioned polyvinyl alcohol / starch-based nanocomposite, characterized by comprising the following steps:

[0011] (1) 40 parts of starch is added to 1000 parts of deionized water, stirred at 95°C for 45 min to obtain a uniform dispersion, which is ready for use;

[0012] (2) 160 parts of polyvinyl alcohol is added to 1500 parts of deionized water, stirred at 95°C for 45 min to obtain a uniform dispersion, which is ready for use;

[0013] (3) The dispersion obtained in step (1) is added to the dispersion obtained in step (2), stirred at 95°C for 30 min to obtain a uniform blending solution, which is ready for use;

[0014] (4) 1-4 parts of functional complex crystal grains is dispersed in 1000 parts of ethanol, stirred at room temperature for 30 min to obtain a uniform dispersion, which is ready for use;

[0015] (5) The dispersion obtained in step (4) is added to the blending solution obtained in step (3), stirred at 95°C for 30 min to obtain a uniform film-forming solution, which is ready for use;

[0016] (6) The film-forming solution obtained in step (5) is poured into a petri dish, dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch-based nanocomposite.

[0017] The application of the polyvinyl alcohol / starch-based nanocomposite material is characterized by being used in the fields of food packaging, smart materials, ammonia detection, environmental monitoring and safety.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The polyvinyl alcohol / starch-based nanocomposite material prepared by the present invention has excellent compatibility, mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, oxygen barrier, water vapor barrier, ammonia response color change, antibacterial and other properties, while maintaining high visible light transparency. It can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of meat foods (such as shrimp, pork, fish, etc.) during storage. The preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for large-scale 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

[0020] Figure 1 is a scanning electron microscope image of the functional complex crystal particles involved in the present invention;

[0021] Figure 2 These are scanning electron microscope images of the polyvinyl alcohol / starch composite material prepared in the comparative example of the present invention and the polyvinyl alcohol / starch-based nanocomposite material prepared in Example 3. DETAILED DESCRIPTION

[0022] 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.

[0023] In the following specific embodiments and comparative example formulas and preparation methods, the polyvinyl alcohol used is a product provided by Shanghai Yingjia Industrial Development Co., Ltd. (model: PVA-2899); the starch used is a soluble starch provided by Xilong Science Co., Ltd. (CAS No.: 9005-84-9); 1H-indazole-6-carboxylic acid is an analytical grade reagent provided by Shanghai Bid Pharmaceutical Technology Co., Ltd.; copper chloride dihydrate, potassium hydroxide, methanol, and ethanol are analytical grade reagents provided by Xilong Science Co., Ltd.

[0024] In the following specific examples and comparative examples, the formulations and preparation methods, the functional complex particles have a particle size of 30-120 nm, and the preparation method thereof comprises the following steps:

[0025] (1) Disperse 32 parts of 1H-indazole-6-carboxylic acid and 11 parts of potassium hydroxide in 2000 parts of methanol, and stir at room temperature for 3 h to obtain a uniform 1H-indazole-6-carboxylic acid dispersion for later use;

[0026] (2) Take 16.5 parts of copper chloride dihydrate and dissolve it in 1000 parts of methanol to obtain a uniform copper chloride solution for later use;

[0027] (3) The copper chloride solution obtained in step (2) is added to the 1H-indazole-6-carboxylic acid solution obtained in step (1), and the mixture is stirred at room temperature for 4 h. The mixture is then centrifuged, washed, and dried to obtain functional complex crystals (which are dark green in color).

[0028] Example 1

[0029] A polyvinyl alcohol / starch-based nanocomposite material is characterized by being composed of the following components in parts by weight: 160 parts of polyvinyl alcohol, 40 parts of starch, and 1 part of functional complex crystals.

[0030] The preparation method comprises the following steps:

[0031] (1) Add 40 parts of starch to 1000 parts of deionized water and stir at 95°C for 45 minutes to obtain a uniform dispersion for later use;

[0032] (2) Add 160 parts of polyvinyl alcohol to 1500 parts of deionized water and stir at 95°C for 45 minutes to obtain a uniform dispersion for later use;

[0033] (3) Add the dispersion obtained in step (1) to the dispersion obtained in step (2), and stir at 95°C for 30 minutes to obtain a uniform blend solution for later use;

[0034] (4) Disperse 1 part of the functional complex crystals in 1000 parts of ethanol and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use;

[0035] (5) Add the dispersion obtained in step (4) to the blended solution obtained in step (3), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0036] (6) The film-forming solution obtained in step (5) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch-based nanocomposite material.

[0037] Example 2

[0038] A polyvinyl alcohol / starch-based nanocomposite material is characterized by the following components in parts by weight: 160 parts of polyvinyl alcohol, 40 parts of starch, and 2 parts of functional complex crystal grains.

[0039] A preparation method comprises the following steps:

[0040] (1) 40 parts of starch are added to 1000 parts of deionized water, stirred at 95°C for 45 min to obtain a uniform dispersion solution, which is prepared for use;

[0041] (2) 160 parts of polyvinyl alcohol are added to 1500 parts of deionized water, stirred at 95°C for 45 min to obtain a uniform dispersion solution, which is prepared for use;

[0042] (3) The dispersion solution obtained in step (1) is added to the dispersion solution obtained in step (2), stirred at 95°C for 30 min to obtain a uniform blending solution, which is prepared for use;

[0043] (4) 2 parts of functional complex crystal grains are dispersed in 1000 parts of ethanol, stirred at room temperature for 30 min to obtain a uniform dispersion solution, which is prepared for use;

[0044] (5) The dispersion solution obtained in step (4) is added to the blending solution obtained in step (3), stirred at 95°C for 30 min to obtain a uniform film-forming solution, which is prepared for use;

[0045] (6) The film-forming solution obtained in step (5) is poured into a petri dish, dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch-based nanocomposite material.

[0046] Example 3

[0047] A polyvinyl alcohol / starch-based nanocomposite material is characterized by the following components in parts by weight: 160 parts of polyvinyl alcohol, 40 parts of starch, and 4 parts of functional complex crystal grains.

[0048] A preparation method comprises the following steps:

[0049] (1) 40 parts of starch are added to 1000 parts of deionized water, stirred at 95°C for 45 min to obtain a uniform dispersion solution, which is prepared for use;

[0050] (2) 160 parts of polyvinyl alcohol are added to 1500 parts of deionized water, stirred at 95°C for 45 min to obtain a uniform dispersion solution, which is prepared for use;

[0051] (3) The dispersion solution obtained in step (1) is added to the dispersion solution obtained in step (2), stirred at 95°C for 30 min to obtain a uniform blending solution, which is prepared for use;

[0052] (4) Disperse 4 parts of functional complex crystals in 1000 parts of ethanol and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use;

[0053] (5) Add the dispersion obtained in step (4) to the blended solution obtained in step (3), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use;

[0054] (6) The film-forming solution obtained in step (5) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch-based nanocomposite material.

[0055] Comparative Example

[0056] As a comparison standard for the above embodiments, the present invention provides a polyvinyl alcohol / starch composite material prepared without containing functional complex particles, comprising the following steps:

[0057] (1) Add 40 parts of starch to 1000 parts of deionized water and stir at 95°C for 45 minutes to obtain a uniform dispersion for later use;

[0058] (2) Add 160 parts of polyvinyl alcohol to 1500 parts of deionized water and stir at 95°C for 45 minutes to obtain a uniform dispersion for later use;

[0059] (3) Add the dispersion obtained in step (1) to the dispersion obtained in step (2), and stir at 95°C for 30 minutes to obtain a uniform blend solution for later use;

[0060] (4) Add 1000 parts of ethanol to the blend solution obtained in step (3), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for later use;

[0061] (5) The film-forming solution obtained in step (4) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch composite material.

[0062] Structure and performance test:

[0063] The polyvinyl alcohol / starch composite material prepared in the above comparative example and the polyvinyl alcohol / starch-based nanocomposite 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.

[0064] The oxygen permeability coefficient test method is as follows:

[0065] The film sample (diameter: 1.8 cm) was sealed in a glass vial containing 3 g of deoxidizer (including 1.0 g of activated carbon, 1.5 g of sodium chloride, and 0.5 g of reduced iron powder), and the vial was weighed (denoted as W1). It was then placed in a sealed container at a relative humidity of 90% and a temperature of 25°C. After 48 h, the vial was reweighed (denoted as W2). The oxygen permeability coefficient OP = (W2–W1) / (S×t), where S and t represent the area of ​​the film sample and the placement time.

[0066] 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 polyvinyl alcohol / starch composite material prepared in the comparative example and the polyvinyl alcohol / starch-based nanocomposite 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.

[0067] The above performance test data are shown in Table 1 and Table 2.

[0068] Table 1 Sample performance test data

[0069]

[0070] Table 2 Results of shrimp freshness monitoring experiment (where t is the storage time of fresh shrimp)

[0071]

[0072] The brittle fracture surfaces of the polyvinyl alcohol / starch composite material prepared in the comparative example and the brittle fracture surfaces of the polyvinyl alcohol / starch-based nanocomposite material prepared in Example 3 were observed and analyzed using a scanning electron microscope. Figure 2 .Depend on Figure 2It can be seen that for the polyvinyl alcohol / starch composite material prepared in the comparative example, its brittle cross section exhibits a rough and uneven morphology, with a large number of dispersed phase particles (starch particles) with larger particle sizes. This indicates that the compatibility between polyvinyl alcohol and starch is poor, and the two-phase interface bonding of polyvinyl alcohol / starch is weak. For the polyvinyl alcohol / starch-based nanocomposite prepared in Example 3, it can be observed that its brittle cross section exhibits a relatively uniform, smooth, and dense morphology, and the dispersed phase particle size is significantly reduced, that is, the phase morphology structure of the system is significantly improved, and the two-phase interface bonding of polyvinyl alcohol / starch is also significantly improved, which is conducive to the improvement of mechanical properties. It can be seen that after the functional complex crystals are added to the polyvinyl alcohol / starch blend system, the compatibility of the polyvinyl alcohol / starch blend system can be effectively improved, the dispersed phase particle size can be significantly reduced, and the two-phase interface bonding of polyvinyl alcohol / starch can be improved.

[0073] The results of the ammonia response test experiment show that the polyvinyl alcohol / starch 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 polyvinyl alcohol / starch-based nanocomposite material prepared in Example 1 is light green, and after exposure to an ammonia environment, its color changes to light blue; the polyvinyl alcohol / starch-based nanocomposite material prepared in Example 2 is light green, and after exposure to an ammonia environment, its color changes to light blue; the polyvinyl alcohol / starch-based nanocomposite material prepared in Example 3 is dark green, and after exposure to an ammonia environment, its color changes to blue.

[0074] In summary, the sample structure and performance test data (see Table 1 and Figure 2 ) It can be seen that the polyvinyl alcohol / starch-based nanocomposite material prepared by the present invention has excellent compatibility, mechanical strength, toughness, UV barrier, high-energy blue light barrier, oxygen barrier, water vapor barrier, ammonia response color change, antibacterial and other properties, while maintaining high visible light transparency, and can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of meat foods 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 large-scale production. It has wide application value in food packaging, intelligent materials, ammonia detection, environmental monitoring and safety and other fields.

[0075] 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 polyvinyl alcohol / starch-based nanocomposite material, characterized in that: The invention is composed of the following components in parts by weight: 160 parts of polyvinyl alcohol, 40 parts of starch, and 1-4 parts of functional complex crystals; The functional complex crystal particles have a particle size of 30-120 nm, and the preparation method thereof comprises the following steps: (1) dispersing 32 parts of 1H-indazole-6-carboxylic acid and 11 parts of potassium hydroxide in 2000 parts of methanol, stirring at room temperature for 3 hours to obtain a uniform 1H-indazole-6-carboxylic acid solution for standby use; (2) taking 16.5 parts of copper chloride dihydrate, dissolving it in 1000 parts of methanol, obtaining a uniform copper chloride solution for standby use; (3) adding the copper chloride solution obtained in step (2) to the 1H-indazole-6-carboxylic acid solution obtained in step (1), stirring at room temperature for 4 hours, and then centrifuging, washing, and drying in sequence to obtain functional complex crystal particles; The preparation method of the polyvinyl alcohol / starch-based nanocomposite material comprises the following steps: (1) adding 40 parts of starch to 1000 parts of deionized water, stirring at 95°C for 45 minutes to obtain a uniform dispersion, which is set aside; (2) adding 160 parts of polyvinyl alcohol to 1500 parts of deionized water, stirring at 95°C for 45 minutes to obtain a uniform dispersion, which is set aside; (3) adding the dispersion obtained in step (1) to the dispersion obtained in step (2), stirring at 95°C for 45 minutes, and then adding the dispersion obtained in step (1) to the dispersion obtained in step (2). Stir for 30 minutes to obtain a uniform blend solution for later use; (4) disperse 1-4 parts of functional complex crystals in 1000 parts of ethanol and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use; (5) add the dispersion obtained in step (4) to the blend solution obtained in step (3), stir at 95°C for 30 minutes to obtain a uniform film-forming solution for later use; (6) pour the film-forming solution obtained in step (5) into an organic glass dish and dry it in an oven at 60°C for 12 hours to obtain a polyvinyl alcohol / starch-based nanocomposite material.

2. The method for preparing the polyvinyl alcohol / starch-based nanocomposite material according to claim 1, characterized in that The steps include: (1) Add 40 parts of starch to 1000 parts of deionized water and stir at 95°C for 45 minutes to obtain a uniform dispersion for later use; (2) Add 160 parts of polyvinyl alcohol to 1500 parts of deionized water and stir at 95°C for 45 minutes to obtain a uniform dispersion for later use; (3) Add the dispersion obtained in step (1) to the dispersion obtained in step (2), and stir at 95°C for 30 minutes to obtain a uniform blend solution for later use; (4) Disperse 1-4 parts of functional complex crystals in 1000 parts of ethanol and stir at room temperature for 30 minutes to obtain a uniform dispersion for later use; (5) Add the dispersion obtained in step (4) to the blended solution obtained in step (3), and stir at 95°C for 30 minutes to obtain a uniform film-forming solution for standby use; (6) The film-forming solution obtained in step (5) was poured into a plexiglass dish and dried in an oven at 60°C for 12 h to obtain a polyvinyl alcohol / starch-based nanocomposite material.

3. The use of the polyvinyl alcohol / starch-based nanocomposite 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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