A compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film and its preparation method and application

Abstract

The present invention belongs to the technical field of polymer composite materials, and specifically relates to a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film and its preparation method and application. It is prepared from the following raw materials: carboxymethyl starch, polyvinyl alcohol, and L-tyrosine copper-based nanocrystals. The present invention also provides a preparation method of the above-mentioned carboxymethyl starch / polyvinyl alcohol composite film material. The prepared composite film material has excellent compatibility, mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, antibacterial, water vapor barrier, oxygen barrier, ammonia-responsive color change and other properties, and can maintain high visible light transparency at the same time. It can be used as an intelligent indicator material to timely and effectively indicate the freshness change of meat foods such as shrimp during storage. Moreover, the preparation process of this composite material is simple, and it has broad application value in the fields of food packaging, intelligent materials, ammonia detection, environmental monitoring and safety, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer composite materials, and particularly relates to a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film, a preparation method thereof, and an application thereof. Background Art

[0002] Polyvinyl alcohol and starch are biodegradable materials, which are environmentally friendly organic polymer polymers with good film-forming properties and biocompatibility, and have broad application prospects in the fields of food packaging, biomedicine, intelligent gels, etc. However, pure polyvinyl alcohol materials have disadvantages such as high cost and being very stable and not easily degradable under normal temperature conditions. A method to overcome the disadvantages of pure polyvinyl alcohol materials is to mix them with biodegradable substances. Carboxymethyl starch is rich in sources and low in price, and has advantages such as water solubility and biodegradability. Its aqueous solution has good viscosity, stability, protective colloid property and film-forming property, and is widely used as a film-forming material for films, and has potential application value in various fields such as food packaging, agricultural production, papermaking, and electronic devices. Adding carboxymethyl starch to polyvinyl alcohol materials can obtain a more economical and environmentally friendly carboxymethyl starch / polyvinyl alcohol composite material. However, due to poor compatibility and brittleness of the carboxymethyl starch / polyvinyl alcohol composite material, it is impossible to obtain products with higher strength and flexibility. At the same time, it lacks functions such as ammonia response, ultraviolet barrier, antibacterial, water vapor barrier, and oxygen barrier, which limits its practical application to a certain extent. The present invention uses L-tyrosine copper-based nanocrystals as a functional compatibilizer with carboxymethyl starch / polyvinyl alcohol as the matrix to improve the compatibility of carboxymethyl starch / polyvinyl alcohol, and enhance the mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, antibacterial, water vapor barrier, oxygen barrier, ammonia response color change and other properties of the carboxymethyl starch / polyvinyl alcohol composite film material, develop a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material, and broaden its application in the fields of food packaging, intelligent materials, ammonia detection, environmental monitoring and safety, etc. Summary of the Invention

[0003] The object of the present invention is to overcome the drawbacks of the prior art and provide a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film, its preparation method and application. After adding L-tyrosine copper-based nanocrystals to the carboxymethyl starch / polyvinyl alcohol blend system, the present invention can not only improve the compatibility of the system and enhance the interfacial adhesion between the two phases of carboxymethyl starch / polyvinyl alcohol, but also effectively improve the mechanical strength, toughness, ultraviolet barrier, high-energy blue light barrier, antibacterial, water vapor barrier, oxygen barrier, ammonia-responsive color change and other properties of the carboxymethyl starch / polyvinyl alcohol composite film material. At the same time, it can maintain high visible light transparency and can be used as an intelligent indicator material to timely and effectively indicate the freshness change of meat foods (such as shrimp, pork, fish, etc.) during storage. Moreover, the preparation process of this composite material is simple, environmentally friendly, low-cost and suitable for large-scale production.

[0004] The technical solution of the present invention:

[0005] The present invention provides a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material, which is characterized by being composed of the following components in parts by weight: 60 parts of carboxymethyl starch, 140 parts of polyvinyl alcohol, and 1-4 parts of L-tyrosine copper-based nanocrystals;

[0006] The L-tyrosine copper-based nanocrystals have a particle size of 10-40 nm, and its preparation method includes the following steps:

[0007] (1) Dissolve 18 parts of L-tyrosine in 5000 parts of ethanol, and while stirring, dropwise add an ethanol solution of 1 mol / L NaOH to make the pH of the L-tyrosine solution 8. Stir at room temperature for 40 min to obtain a uniform L-tyrosine solution for standby;

[0008] (2) Take 20 parts of copper acetate and dissolve it in 2000 parts of ethanol to obtain a uniform copper acetate solution for standby;

[0009] (3) Add the copper acetate solution obtained in step (2) to the L-tyrosine solution obtained in step (1), and use an ethanol solution of 1 mol / L NaOH to adjust the pH of the solution to 8. Stir and react at room temperature for 15 min to obtain a uniform L-tyrosine copper-based nanocrystal solution. Subsequently, it is successively subjected to centrifugal separation, washing with ethanol, and drying to obtain L-tyrosine copper-based nanocrystals (its color is green and the particle size is about 10-40 nm).

[0010] The present invention also provides a preparation method of the above-mentioned compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material, which is characterized by including the following steps:

[0011] (1) Add 60 parts of carboxymethyl starch and 140 parts of polyvinyl alcohol to 3000 parts of deionized water, and stir at 90 °C for 60 min to obtain a uniform blend solution for standby;

[0012] (2) Disperse 1 - 4 parts of L - tyrosine copper - based nanocrystals in 1000 parts of deionized water, and stir at room temperature for 30 min to obtain a uniform dispersion for standby;

[0013] (3) Add the dispersion obtained in step (2) to the blend solution obtained in step (1), and stir at 90 °C for 15 min to obtain a uniform film - forming solution for standby;

[0014] (4) Pour the film - forming solution obtained in step (3) into an organic glass dish, and dry it in an oven at 60 °C for 12 h to obtain a compatibilized and modified high - performance carboxymethyl starch / polyvinyl alcohol composite film material.

[0015] The application of the compatibilized and modified high - performance carboxymethyl starch / polyvinyl alcohol composite film material is characterized in that it is used in the fields of food packaging, intelligent materials, ammonia detection, environmental monitoring and safety, etc.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] By using L - tyrosine copper - based nanocrystals as functional compatibilizers, the present invention can effectively improve the compatibility of the carboxymethyl starch / polyvinyl alcohol blend system, improve the interfacial adhesion between the two phases of carboxymethyl starch / polyvinyl alcohol. The prepared high - performance carboxymethyl starch / polyvinyl alcohol composite film material has excellent mechanical strength, toughness, ultraviolet barrier, high - energy blue light barrier, antibacterial, water vapor barrier, oxygen barrier, ammonia - responsive color - changing and other properties. At the same time, it can also maintain 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, pork, fish, etc.) during storage. Moreover, the preparation process of this composite material is simple, environmentally friendly, low - cost, and suitable for large - scale production, and has broad application value in the fields of food packaging, intelligent materials, ammonia detection, environmental monitoring and safety, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the scanning electron microscope image of the L - tyrosine copper - based nanocrystals involved in the present invention;

[0019] Figure 2 It is the infrared spectrum of the L - tyrosine copper - based nanocrystals involved in the present invention;

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

[0021] Figure 4 Scanning electron micrograph of the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared in Example 1 of the present invention;

[0022] Figure 5 Scanning electron micrograph of the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared in Example 2 of the present invention;

[0023] Figure 6 Scanning electron micrograph of the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared in Example 3 of the present invention. Detailed implementation manners

[0024] The present invention will be specifically described below through examples. It is necessary to point out here that these examples are only used to further illustrate the present invention and should not be construed as limiting the scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the content of the present invention above. Unless otherwise specified, the parts of raw materials are in weight parts.

[0025] In the following specific examples, comparative examples, formulations and preparation methods, the carboxymethyl starch used is a product provided by Ron Reagent Co., Ltd. (CAS No.: 9063-38-1); the polyvinyl alcohol used is a product provided by Aladdin Reagent Co., Ltd. (degree of alcoholysis: 98-99 mol%, viscosity: 54.0-66 mPa·s); L-tyrosine is an analytical reagent provided by Shanghai Yian Chemical Technology Co., Ltd.; copper acetate, sodium hydroxide, and ethanol are analytical reagents provided by Xilong Scientific Co., Ltd.

[0026] In the following specific examples, comparative examples, formulations and preparation methods, the L-tyrosine copper-based nanocrystals have a particle size of 10-40 nm, and the preparation method includes the following steps:

[0027] (1) Dissolve 18 parts of L-tyrosine in 5000 parts of ethanol, and while stirring, dropwise add an ethanol solution of 1 mol / L NaOH to make the pH of the L-tyrosine solution 8, and stir at room temperature for 40 min to obtain a uniform L-tyrosine solution for standby;

[0028] (2) Take 20 parts of copper acetate and dissolve it in 2000 parts of ethanol to obtain a uniform copper acetate solution for standby;

[0029] (3) Add the copper acetate solution obtained in step (2) to the L-tyrosine solution obtained in step (1), and adjust the pH of the solution to 8 with a 1 mol / L NaOH ethanol solution. Stir and react at room temperature for 15 min to obtain a uniform L-tyrosine copper-based nanocrystal solution. Then, successively perform centrifugal separation, wash with ethanol, and dry to obtain L-tyrosine copper-based nanocrystals (their color is green and the particle size is about 10 - 40 nm).

[0030] Example 1

[0031] A compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite membrane material, characterized in that it is composed of the following components in parts by weight: 60 parts of carboxymethyl starch, 140 parts of polyvinyl alcohol, and 1 part of L-tyrosine copper-based nanocrystals.

[0032] The preparation method includes the following steps:

[0033] (1) Add 60 parts of carboxymethyl starch and 140 parts of polyvinyl alcohol to 3000 parts of deionized water, and stir at 90 °C for 60 min to obtain a uniform blend solution for standby;

[0034] (2) Disperse 1 part of L-tyrosine copper-based nanocrystals in 1000 parts of deionized water, and stir at room temperature for 30 min to obtain a uniform dispersion for standby;

[0035] (3) Add the dispersion obtained in step (2) to the blend solution obtained in step (1), and stir at 90 °C for 15 min to obtain a uniform film-forming solution for standby;

[0036] (4) Pour the film-forming solution obtained in step (3) into an organic glass dish, and dry it in an oven at 60 °C for 12 h to obtain the compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite membrane material.

[0037] Example 2

[0038] A compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite membrane material, characterized in that it is composed of the following components in parts by weight: 60 parts of carboxymethyl starch, 140 parts of polyvinyl alcohol, and 2 parts of L-tyrosine copper-based nanocrystals.

[0039] The preparation method includes the following steps:

[0040] (1) Add 60 parts of carboxymethyl starch and 140 parts of polyvinyl alcohol to 3000 parts of deionized water, and stir at 90 °C for 60 min to obtain a uniform blend solution for standby;

[0041] (2) Disperse 2 parts of L-tyrosine copper-based nanocrystals in 1000 parts of deionized water, and stir at room temperature for 30 min to obtain a uniform dispersion for standby;

[0042] (3) Add the dispersion obtained in step (2) to the blend solution obtained in step (1), stir at 90 °C for 15 min to obtain a uniform film-forming solution, and set aside;

[0043] (4)Pour the film-forming solution obtained in step (3) into an organic glass dish and dry it in an oven at 60 °C for 12 h to obtain a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material.

[0044] Example 3

[0045] A compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material, characterized in that it is composed of the following components in parts by weight: 60 parts of carboxymethyl starch, 140 parts of polyvinyl alcohol, and 4 parts of L-tyrosine copper-based nanocrystals.

[0046] The preparation method includes the following steps:

[0047] (1)Add 60 parts of carboxymethyl starch and 140 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 90 °C for 60 min to obtain a uniform blend solution, and set aside;

[0048] (2)Disperse 4 parts of L-tyrosine copper-based nanocrystals in 1000 parts of deionized water, stir at room temperature for 30 min to obtain a uniform dispersion, and set aside;

[0049] (3)Add the dispersion obtained in step (2) to the blend solution obtained in step (1), stir at 90 °C for 15 min to obtain a uniform film-forming solution, and set aside;

[0050] (4)Pour the film-forming solution obtained in step (3) into an organic glass dish and dry it in an oven at 60 °C for 12 h to obtain a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material.

[0051] Comparative Example

[0052] As a comparison standard for the above examples, the present invention provides a carboxymethyl starch / polyvinyl alcohol composite film material prepared without L-tyrosine copper-based nanocrystals, including the following steps:

[0053] (1)Add 60 parts of carboxymethyl starch and 140 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 90 °C for 60 min to obtain a uniform blend solution, and set aside;

[0054] (2)Add 1000 parts of deionized water to the blend solution obtained in step (1), stir at 90 °C for 15 min to obtain a uniform film-forming solution, and set aside;

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

[0056] Structure and property tests:

[0057] Perform structure and property tests on the carboxymethyl starch / polyvinyl alcohol composite film material prepared in the above comparative example and the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared in the example. Among them, the ultraviolet-visible performance is tested using an ultraviolet-visible spectrometer (Lamdba365, PerkinElmer Instruments), and the average ultraviolet transmittance is calculated with reference to GB / T 18830-2009; the tensile property is tested according to GB / T 1040-2006; the water vapor transmission coefficient is tested according to ASTM E 96; the antibacterial property of the material is tested according to QBT2591-2003; the ammonia response test method is as follows: expose the sample material to an ammonia environment and observe the color change of the sample material.

[0058] The experimental method for the oxygen transmission coefficient is as follows:

[0059] Seal 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) with the film sample (diameter: 1.8 cm), and weigh the vial (recorded as W1); then place it in a sealed container with a relative humidity of 90% and a temperature of 25 °C. After 48 h, reweigh the vial (recorded as W2); the oxygen transmission coefficient OP = (W2 - W1) / (S × t), where S and t represent the area and placement time of the film sample.

[0060] Freshness monitoring experiment of shrimp: Purchase fresh shrimp from the market, place the shrimp (mass: 30 g) in a Petri dish and seal it with a Petri dish cover. Under the cover, attach the carboxymethyl starch / polyvinyl alcohol composite film material prepared in the comparative example and the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared in Example 3 (pre-cut into sample film materials with a diameter of 1 cm). Then place the above shrimp samples in an oven at 25 °C for storage, and observe and record the change in the freshness of the shrimp and the color change of the sample material.

[0061] The above performance test data are shown in Table 1 and Table 2.

[0062] Table 1 Sample performance test data

[0063]

[0064] Table 2 Results of the freshness monitoring experiment of shrimp (where t is the storage time of fresh shrimp)

[0065]

[0066] The brittle cross section of the carboxymethyl starch / polyvinyl alcohol composite film material prepared in the comparative example and the brittle cross section of the high-performance carboxymethyl starch / polyvinyl alcohol composite film 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 for the carboxymethyl starch / polyvinyl alcohol composite film material prepared in the comparative example, it can be observed that its brittle section presents a rough and uneven morphology, and there are more dispersed phase particles (carboxymethyl starch particles) with larger particle sizes, which indicates that the compatibility between polyvinyl alcohol and carboxymethyl starch is poor, and the two-phase interface bonding effect of carboxymethyl starch / polyvinyl alcohol is weak. For the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared in the embodiment, it can be observed that its brittle section shows a relatively uniform, smooth, and dense morphology, and no obvious dispersed phase particles (carboxymethyl starch particles) are presented, that is, the phase morphology structure of the system is significantly improved, and the two-phase interface bonding effect of carboxymethyl starch / polyvinyl alcohol is significantly improved, which is conducive to the improvement of mechanical properties. That is, after L-tyrosine copper-based nanocrystals are added to the carboxymethyl starch / polyvinyl alcohol blending system, the compatibility of the carboxymethyl starch / polyvinyl alcohol blending system can be effectively improved, and the two-phase interface bonding effect of carboxymethyl starch / polyvinyl alcohol can be improved.

[0067] 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 being exposed to an ammonia environment, its color does not change, and it still presents colorless and transparent optical properties; the carboxymethyl starch / polyvinyl alcohol-based nanocomposite material prepared in Example 1 is light green, and after being exposed to an ammonia environment, its color changes to light brown; the carboxymethyl starch / polyvinyl alcohol-based nanocomposite material prepared in Example 2 is light green, and after being exposed to an ammonia environment, its color changes to light brown; the carboxymethyl starch / polyvinyl alcohol-based nanocomposite material prepared in Example 3 is green, and after being exposed to an ammonia environment, its color changes to brown.

[0068] In summary, it can be seen from the sample performance test data (see Tables 1 and 2) that the high-performance carboxymethyl starch / polyvinyl alcohol composite film material prepared by the present invention has excellent compatibility, mechanical strength, toughness, UV blocking, high-energy blue light blocking, antibacterial, water vapor blocking, oxygen blocking, ammonia response color change and other properties, while maintaining a high visible light transparency, and can be used as an intelligent indicator material to timely and effectively indicate the freshness changes of shrimp and other meat foods during storage (see Table 2). The preparation process of the composite material is simple, environmentally friendly, low-cost, and suitable for large-scale production. It has a wide range of application value in food packaging, intelligent materials, ammonia detection, environmental monitoring and safety and other fields.

[0069] The content of the present invention is not limited to the examples listed. Any equivalent transformation of the technical solution of the present invention made by those of ordinary skill in the art by reading the specification of the present invention is covered by the claims of the present invention.

Claims

1. A compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite membrane material, characterized in that, It consists of the following components in parts by weight: 60 parts of carboxymethyl starch, 140 parts of polyvinyl alcohol, and 1 - 4 parts of L - tyrosine copper - based nanocrystals; The L - tyrosine copper - based nanocrystals have a particle size of 10 - 40 nm, and its preparation method includes the following steps: (1) Dissolve 18 parts of L - tyrosine in 5000 parts of ethanol, dropwise add an ethanol solution of 1 mol / L NaOH while stirring to make the pH of the L - tyrosine solution 8, and stir at room temperature for 40 min to obtain a uniform L - tyrosine solution for standby; (2) Take 20 parts of copper acetate, dissolve it in 2000 parts of ethanol to obtain a uniform copper acetate solution for standby; (3) Add the copper acetate solution obtained in step (2) to the L - tyrosine solution obtained in step (1), and adjust the pH of the solution to 8 with an ethanol solution of 1 mol / L NaOH, stir and react at room temperature for 15 min to obtain a uniform L - tyrosine copper - based nanocrystal solution, and then successively carry out centrifugal separation, washing with ethanol, and drying to obtain L - tyrosine copper - based nanocrystals.

2. The preparation method of a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite membrane material according to claim 1, characterized in that It includes the following steps: (1) Add 60 parts of carboxymethyl starch and 140 parts of polyvinyl alcohol to 3000 parts of deionized water, stir at 90 °C for 60 min to obtain a uniform blend solution for standby; (2) Disperse 1 - 4 parts of L - tyrosine copper - based nanocrystals in 1000 parts of deionized water, stir at room temperature for 30 min to obtain a uniform dispersion for standby; (3) Add the dispersion obtained in step (2) to the blend solution obtained in step (1), stir at 90 °C for 15 min to obtain a uniform film - forming solution for standby; (4) Pour the film - forming solution obtained in step (3) into an organic glass dish, and dry it in an oven at 60 °C for 12 h to obtain a compatibilized and modified high - performance carboxymethyl starch / polyvinyl alcohol composite film material.

3. Application of a compatibilized and modified high-performance carboxymethyl starch / polyvinyl alcohol composite film material according to claim 1, characterized in that, It is used in the fields of food packaging, intelligent materials, ammonia detection, environmental monitoring, and safety.

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