CN114874574B

CN114874574B - Blend membrane material of carragheen and polyvinyl alcohol, preparation method and application thereof

Info

Publication number: CN114874574B
Application number: CN202210570568.1A
Authority: CN
Inventors: 郭红革; 张帅; 刘保栋; 马琳·克兰
Original assignee: Qilu University of Technology
Current assignee: Qilu University of Technology
Priority date: 2022-05-24
Filing date: 2022-05-24
Publication date: 2022-11-22
Anticipated expiration: 2042-05-24
Also published as: CN114874574A

Abstract

The invention belongs to the technical field of high polymer materials, and relates to a blend membrane material of carragheen and polyvinyl alcohol, a preparation method and application thereof. The preparation method comprises the following steps: mixing the carrageenan solution and the polyvinyl alcohol solution, adding the plant aldehyde and the plasticizer, and carrying out acetalation reaction on the carrageenan, the polyvinyl alcohol and the plant aldehyde to obtain the composite material. The blending film material prepared by the invention has good mechanical property, higher solvent resistance and degradability, can replace petroleum-based food packaging bags, can also be used as a dip-coating antibacterial fresh-keeping protective film material for fruits and vegetables, and has wide application.

Description

Blend membrane material of carragheen and polyvinyl alcohol and preparation method and application thereof

Technical Field

The invention belongs to the technical field of high polymer materials, and relates to a blend membrane material of carrageenin and polyvinyl alcohol, a preparation method and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Most of traditional plastics are produced by using petrochemical engineering energy as raw materials, have high molecular weight, compact structure and acid and alkali resistance, are difficult to degrade, and release harmful substances in the decomposition process, so that the plastic packaging materials also bring a series of environmental pollution problems, the existing technology is difficult to efficiently recycle the plastic packaging materials, and the landfill also can seriously influence the structure of soil to cause environmental pollution and the like.

Carrageenans (carrageenans) are derived from marine plants, have the advantages of complete biodegradation, short regeneration period, rich processing performance and the like, but the carrageenans which are formed into films independently have the defect of poor water tolerance and thermal stability, so that the application field of the carrageenans is limited. Polyvinyl alcohol (PVA) is a hydrolysis product of Polyvinyl acetate, is a few of high polymer materials with water solubility and biodegradability in petroleum-based synthetic polymers, contains a large number of hydroxyl polymers in the structure, has hydrogen bonds in molecules, has the defects of hydrophilicity and poor water resistance of a Polyvinyl alcohol film, is easy to generate an adhesion phenomenon after moisture absorption, and has the problems of hardening, brittleness and the like of the film under the conditions of low temperature and low humidity. The inventor finds that the mechanical property and the water resistance are poor when the polyvinyl alcohol and the carrageenan are simply blended to prepare the film, so that the polyvinyl alcohol and the carrageenan are difficult to be used as the packaging material.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides a blend film material of carragheen and polyvinyl alcohol, a preparation method and application thereof, which have good mechanical properties and higher solvent resistance and can be used as an environment-friendly degradable novel packaging material.

In order to achieve the purpose, the technical scheme of the invention is as follows:

on one hand, the preparation method of the blend membrane material of the carrageenin and the polyvinyl alcohol comprises the steps of mixing the carrageenin solution and the polyvinyl alcohol solution, adding the plant aldehyde and the plasticizer, and carrying out acetalization reaction on the carrageenin and the polyvinyl alcohol and the plant aldehyde to obtain the blend membrane material.

According to the invention, firstly, the plasticizer is mixed with the carrageenan, the carrageenan has certain rigidity, the polyvinyl alcohol has flexibility, the mixing degree of the carrageenan and the plasticizer is increased, the flexibility of the membrane is improved, meanwhile, the plant aldehyde is added as an end-capping crosslinking agent, the plant aldehyde can generate a cross-linking network structure with the polyvinyl alcohol and the hydroxyl of carrageenan molecular chains through acetalation reaction, the water resistance and the mechanical property of the membrane are improved, and the effects of making up for deficiencies in the mechanical property of blending and co-crosslinking are achieved.

On the other hand, the blend membrane material of the carrageenin and the polyvinyl alcohol is obtained by the preparation method.

In a third aspect, the blended film material of the carrageenan and the polyvinyl alcohol is applied to a packaging material.

In particular to the application of the coating material as a dip-coating antibacterial preservative protective film material for fruits and vegetables, the application as a plastic packaging bag and the like.

The biodegradable plastic packaging bag can replace a petroleum-based food packaging bag and has degradability.

The invention has the beneficial effects that:

1. according to the invention, the polyvinyl alcohol and the carrageenan are utilized, the plant aldehyde is added as the end-capping cross-linking agent, and the plasticizer is added, so that the membrane material with excellent mechanical property, solvent resistance and antibacterial property can be obtained, and the environment-friendly degradability is realized.

2. The preparation method has the advantages of easily obtained raw materials, simple formula, lower cost, simple production process and convenient operation, and the produced membrane material has better mechanical property, processing property and service property.

3. The raw materials involved in the invention are all green degradable substances, the used solvent is mainly water, and the used auxiliary agents are all nontoxic, do not pollute the environment and accord with a green manufacturing process.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are included to illustrate an exemplary embodiment of the invention and not to limit the invention.

FIG. 1 is an infrared spectrum of blend films prepared in examples 4 and 8 of the present invention;

FIG. 2 is a TGA curve of a pure polyvinyl alcohol film prepared by comparative example 2 and a blend film prepared by example 8 according to the present invention;

FIG. 3 is a graph showing the mechanical properties of the films prepared in comparative examples 1 to 2 and examples 1 to 4 according to the present invention;

FIG. 4 is a graph showing the mechanical properties of blend films prepared in examples 2, 5 to 8 of the present invention.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

In view of the problem that the mechanical property and the water resistance are poor when polyvinyl alcohol and carrageenan are simply blended to prepare a membrane, the invention provides a blend membrane material of carrageenan and polyvinyl alcohol, and a preparation method and application thereof.

The invention provides a preparation method of a blend membrane material of carragheen and polyvinyl alcohol, which comprises the steps of mixing a carragheen solution and a polyvinyl alcohol solution, adding plant aldehyde and a plasticizer, and carrying out acetalation reaction on the carragheen, the polyvinyl alcohol and the plant aldehyde.

In the case of polyvinyl alcohol, the acetalization reaction includes the following scheme:

through the acetalation reaction, the crosslinking degree between the carrageenan and the polyvinyl alcohol is greatly increased, so that the water resistance and the mechanical property of the film are obviously improved.

The flexibility of the film is improved by adding the plasticizer, and researches show that when the plasticizer is mixed with the carrageenan, the flexibility of the blended film material can be further improved.

The Carrageenan is one or a mixture of K-Carrageenan (kappa-Carrageenan), I-Carrageenan (Iota-Carrageenan) and Lambda-Carrageenan (Lambda-Carrageenan).

In some embodiments, the mass ratio of the carrageenan, the polyvinyl alcohol, the vegetable aldehyde and the plasticizer is 1.3-1.4. Further, the mass ratio of the carrageenan, the polyvinyl alcohol, the vegetable aldehyde and the plasticizer is 1.3-1.4.

In some embodiments, the plasticizer is glycerol and/or epoxidized soybean oil. The plasticizer can further increase the environmental friendliness of the film material.

In some embodiments, the plant aldehyde monoaldehyde is cinnamaldehyde or vanillin or the like.

In some embodiments, the temperature of the acetalization reaction is 80 to 80 ℃.

In some embodiments, acid is added during the acetalization reaction to adjust the pH to 2-6. The addition amount of the acid is 5-15% of the mass of the carrageenan. The acetalization reaction process specifically comprises the following steps: heating and reacting for 5-15 min, adding acid to adjust the pH value, and continuing to react for 5-15 min.

In some embodiments, the acid is citric acid, malic acid, gallic acid, tartaric acid, or the like.

In one or more embodiments, the carrageenan is added to water and heated to 85-85 ℃ to obtain a carrageenan solution. Swelling polyvinyl alcohol, and then heating to dissolve the polyvinyl alcohol, wherein the heating temperature is 85-85 ℃ to obtain the polyvinyl alcohol solution. Adding plant aldehyde mixed solution, forming a film on the surface of the fruit by adopting a dip-coating method, and drying for 48 hours at normal temperature to dry and shape the film.

In one or more embodiments, the acetalized material is placed on a flat template, and cast to form a film, and the film is dried to obtain the blended film material. The drying process comprises the following steps: firstly, heating and blowing for drying, and then drying at normal temperature. Specifically, the dried product was dried in a 60 ℃ forced air drying oven for 8 hours. Placing into a silica gel dryer at normal temperature, and adjusting temperature and humidity for 24hr.

The invention also provides a blended film material of carrageenin and polyvinyl alcohol, which is obtained by the preparation method.

The third embodiment of the invention provides an application of the blend film material of carrageenan and polyvinyl alcohol as a packaging material.

In particular to the application of the coating material as a dip-coating antibacterial fresh-keeping protective film material for fruits and vegetables, the application as a plastic packaging bag and the like. The plastic packaging bag can replace petroleum-based food packaging bags, such as food packaging bags, shopping bags, garbage bags, mail express bags, agricultural films and the like, and has degradability.

In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the technical solution of the present invention will be described in detail below with reference to specific examples and comparative examples.

The formulations of the following examples and comparative examples are shown in table 1:

TABLE 1 formulation of each example and comparative example

COMPARATIVE EXAMPLE 1 (formulation 1)

1. Weighing 4g of carrageenan powder, adding 200mL of deionized water at normal temperature, stably heating to about 80 ℃, and then heating and stirring for 45min to prepare 2% (w/v) carrageenan solution.

2. The carrageenan solution was quickly poured onto a flat template, mechanically to avoid the formation of bubbles, and dried in a 60 ℃ forced air drying cabinet for 8 hours. Placing into a normal temperature silica gel dryer, adjusting temperature and humidity for 24hr, and peeling to obtain pure carrageenan membrane material.

COMPARATIVE EXAMPLE 2 (formulation 2)

1. Preparing a polyvinyl alcohol solution: weighing 4g of polyvinyl alcohol powder, adding 100mL of deionized water at normal temperature for swelling for 24 hours, and then heating and stirring at about 80 ℃ to obtain 4% (w/v) of polyvinyl alcohol solution.

2. The polyvinyl alcohol solution was quickly poured onto a flat template, mechanically protected from the formation of bubbles, and dried in a 60 ℃ forced air drying cabinet for 8 hours. Placing into a normal temperature silica gel dryer for temperature and humidity adjustment treatment for 24hr, and peeling to obtain pure polyvinyl alcohol membrane material.

Example 1 (formulation 3)

A blend membrane material of carragheen and polyvinyl alcohol is prepared by the following steps:

1. weighing 4g of polyvinyl alcohol powder, adding 100mL of deionized water at normal temperature, swelling for 24 hours, and continuously stirring and dissolving for 3 hours at 80 ℃ to obtain 4% (w/v) of polyvinyl alcohol solution.

2. Weighing 4g of carrageenan powder, adding 200mL of deionized water at normal temperature, stably heating to about 80 ℃, and then heating and stirring for 45min to prepare 2% (w/v) carrageenan solution.

3. The mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 2.5wt% of cinnamaldehyde, and heating and stirring at 80 ℃ for less than 10min to obtain a film-forming solution.

4. Immersing the fruit in the filming solution to coat the film on the surface of the fruit, and drying at normal temperature for 48 hr to dry and shape the film.

Example 2 (formulation 4)

1. weighing 4g of polyvinyl alcohol powder, adding 100mL of deionized water at normal temperature, swelling for 24 hours, and continuously stirring and dissolving for 3 hours at the temperature of 80 ℃ to obtain a 4% (w/v) polyvinyl alcohol solution.

3. The mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 5wt% of cinnamaldehyde, and heating and stirring at 80 ℃ for less than 10min to obtain a film forming solution.

4. Immersing the fruits into the film forming solution to coat the surfaces of the fruits with the film forming solution, and drying for 48 hours at normal temperature to dry and shape the film.

Example 3 (formulation 5)

3. The mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 7.5wt% of cinnamaldehyde, and heating and stirring at 80 ℃ for less than 10min to obtain a film forming solution.

Example 4 (formulation 6)

3. The mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 10wt% of cinnamaldehyde, and heating and stirring at 80 ℃ for less than 10min to obtain a film forming solution.

Example 5 (formulation 7)

1. weighing 4g of polyvinyl alcohol powder, adding 100mL of deionized water at normal temperature for swelling for 24 hours, and then heating and stirring at about 80 ℃ to obtain 4% (w/v) of polyvinyl alcohol solution.

2. Weighing 4g of carrageenan powder in sequence, adding 200mL of deionized water at normal temperature, stably heating to about 80 ℃, and then heating and stirring for 45min to prepare 2% (w/v) carrageenan solution.

3. According to the mixture ratio, the mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 2.5wt% of cinnamaldehyde, heating and stirring at 80 ℃ for 10min, adding 10% of citric acid to adjust the pH value to acidity, playing roles of catalysis, end capping, crosslinking and co-crosslinking, and stirring at 80 ℃ for 10min to obtain a film forming solution.

4. The film-forming solution was quickly poured onto a flat template, mechanically protected from air bubbles, and dried in a 60 ℃ forced air drying cabinet for 8 hours. Placing into a normal temperature silica gel dryer, adjusting temperature and humidity for 24hr, and peeling to obtain the blend membrane material of carrageenan and polyvinyl alcohol.

Example 6 (formulation 8)

3. According to the mixture ratio, the mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 5wt% of cinnamaldehyde, heating and stirring at 80 ℃ for less than 10min, adding 10% of citric acid to adjust the pH value to be acidic, playing roles of catalysis, end capping, crosslinking and co-crosslinking, and stirring at 80 ℃ for less than 10min to obtain a film forming solution.

4. The film forming solution was quickly poured onto a flat template, mechanically to avoid the formation of bubbles, and dried in a 60 ℃ forced air drying oven for 8 hours. Placing into a normal temperature silica gel dryer, adjusting temperature and humidity for 24hr, and peeling to obtain the blend membrane material of carrageenan and polyvinyl alcohol.

Example 7 (formulation 8)

3. According to the mixture ratio, the mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 7.5wt% of cinnamaldehyde, heating and stirring at 80 ℃ for less than 10min, adding 10% of citric acid to adjust the pH value to be acidic, playing roles of catalysis, end capping, crosslinking and co-crosslinking, and stirring at 80 ℃ for less than 10min to obtain a film forming solution.

Example 8 (formulation 10)

3. According to the mixture ratio, the mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 10wt% of cinnamaldehyde, heating and stirring at 80 ℃ for 10min, adding 10% of citric acid to adjust the pH value to acidity, playing roles of catalysis, end capping, crosslinking and co-crosslinking, and stirring at 80 ℃ for 10min to obtain the film forming solution.

Example 8 (formulation 11)

1. weighing 4g of polyvinyl alcohol resin, adding 100mL of deionized water at normal temperature, swelling for 24 hours, and continuously stirring and dissolving for 3 hours at 80 ℃ to obtain 4% (w/v) polyvinyl alcohol solution.

2. Weighing 4g parts of carrageenan resin powder, adding 200mL of deionized water at normal temperature, and stirring for 45min at 80 ℃ to obtain a 2% (w/v) carrageenan solution.

3. The mass of the carrageenan is taken as a reference substance, and the mass portion is 100wt%. Adding 33.3wt% of PVA, uniformly blending the solution, adding 40wt% of glycerol and 10wt% of vanillin, heating and stirring at 80 ℃ for less than 10min, adjusting the pH (2-6) of the mixture solution containing the PVA, the glycerol and the vanillin by using citric acid, and stirring at 80 ℃ for less than 10min to obtain a film forming solution.

4. And (3) injecting the mixed solution into a mold, drying for 24 hours in an environment with 50% relative humidity, transferring the film into a drying oven after the surface of the film is basically dried, drying at 40 ℃ to constant weight, and stripping to obtain the blend film material of the carrageenan and the polyvinyl alcohol.

And (4) performance testing:

1. and (3) microscopic property detection:

total reflection infrared spectroscopy: and detecting the infrared spectrums of the blend films and the pure films with different formulas, and judging the degree of the crosslinking reaction according to the deviation of the spectrum peak. The results of the tests for

formulations

6 and 10 are shown in FIG. 1.

As can be seen from FIG. 1, for PVA, the O-H groups of the intermolecular and intramolecular hydrogen bonds result in 3000 to 3600cm ^-1 Large strips in between. Has a obvious change, and the formula 6 is 2888.5cm ^-1 A wide absorption peak appears; this is caused by the C-H group of CIN aldehyde. The formulation 10 is 870cm ^-1 The formation of a new absorption peak corresponds to the tensile vibration of the C-O-C bond of the cyclic ether. Formula 10 is 2888.5cm of CIN aldehyde ^-1 The disappearance of the C-H peak confirms that acetalization occurred between the hydroxyl group of PVA and the aldehyde group of CIN during film formation. In addition, the relative strength of the O-H bands in the crosslinked film was reduced, confirming the crosslinking.

TGA curve: and (3) representing the heat resistance degree of the material according to the thermal weight loss curves of different blend films, and indirectly representing the structural forms among the blends. The results of the tests for

formulations

2 and 10 are shown in fig. 2.

Figure 2 shows that there are 3 major stages of mass loss for PVA membranes. The decomposition temperature in the first stage is 50-200 ℃, which is caused by the evaporation of water, glycerol, and low molecular compounds. The mass loss in the second stage is caused by thermal decomposition of the PVA. Pure PVA films undergo a sharp thermal decomposition at 200 ℃. For the crosslinked film, the initial temperature of the second stage of thermal decomposition was shifted to 220 ℃, indicating that the thermal stability of the crosslinked film was improved. Analysis showed that structural changes in PVA are mainly caused by molecular interactions between PVA and CIN, increasing decomposition temperature and thermal stability.

2. Solvent resistance test: cutting the film into a certain size according to the standard, soaking the film in a required standard solvent, and characterizing the solvent resistance of the blended film by a weight increasing method or a swelling volume change method. The results for formulation 1/6/10 are shown in Table 2.

TABLE 2 swelling ratio

As can be seen from Table 2, when a certain proportion of cinnamaldehyde is added, the swelling ratio of the film in deionized water is reduced; the swelling ratio further decreases when crosslinking occurs. In the ethanol environment, the formulation 10 swelling ratio decreased, which is the reason for the cross-linking reaction.

3. Mechanical property experiment: the dry film is cut into a tensile test strip and a pants-type tearing test strip according to the national standard, and the tensile strength, the elongation at break and the tearing strength of the film are tested by a universal tensile machine, so that the mechanical property requirement of replacing a petroleum-based plastic packaging film can be met. The results are shown in FIGS. 3 to 4.

As shown in figure 3, the polyvinyl alcohol/carrageenan film with a certain proportion of cinnamaldehyde is not changed greatly in mechanical property, and can be used for fruit film soaking.

It can be seen from fig. 4 that, after the acid is added, cinnamaldehyde is crosslinked with polyvinyl alcohol and carrageenan, so that the mechanical property of the film can be further improved, and the addition amount of the plant aldehyde can be selected according to actual needs. Can be used for plastic packaging bags.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a blend membrane material of carragheen and polyvinyl alcohol is characterized in that after a carragheen solution and a polyvinyl alcohol solution are mixed, plant aldehyde and a plasticizer are added, acetalation reaction is carried out on the carragheen, the polyvinyl alcohol and the plant aldehyde, a membrane forming solution is obtained through co-crosslinking, the membrane forming solution is placed on a flat template, casting and film forming are carried out, and the blend membrane material is obtained after drying;

the plant aldehyde is cinnamaldehyde or vanillin;

adding acid in the acetalation reaction process;

the acid is citric acid, malic acid, gallic acid or tartaric acid;

the mass ratio of the carrageenan, the polyvinyl alcohol, the vegetable aldehyde and the plasticizer is 1.

2. The method for preparing the blending film material of carrageenan and polyvinyl alcohol according to claim 1, wherein the plasticizer is glycerol and/or epoxidized soybean oil.

3. The preparation method of the blended film material of carrageenan and polyvinyl alcohol according to claim 1, wherein the acetalization temperature is 80 to 90 ℃;

adding acid, and adjusting the pH value to 2-6.

4. The preparation method of the blended film material of carrageenan and polyvinyl alcohol according to claim 1, wherein the addition amount of acid is 5 to 15% of the mass of carrageenan.

5. The preparation method of the blended film material of carrageenan and polyvinyl alcohol according to claim 1, which is characterized in that the acetalization reaction process comprises the following steps: heating for reaction for 5-15min, adding acid to adjust the pH value, and continuing the reaction for 5-15min.

6. The preparation method of the blended film material of carrageenan and polyvinyl alcohol according to claim 1, which is characterized in that the carrageenan is added with water and heated to 85 to 95 ℃ to obtain a carrageenan solution;

swelling polyvinyl alcohol, heating to dissolve the polyvinyl alcohol, wherein the heating temperature is 85 to 95 ℃, and adding the plant aldehyde mixed solution.

7. The preparation method of the blended film material of carrageenan and polyvinyl alcohol according to claim 1, which is characterized in that the drying process comprises the following steps: firstly, heating and blowing for drying, and then drying at normal temperature.

8. A blend film material of carragheen and polyvinyl alcohol, which is characterized in that the blend film material is obtained by the preparation method of any one of claims 1 to 7.

9. The use of the blended film material of carrageenan and polyvinyl alcohol according to claim 8 as a packaging material.

10. The use according to claim 9, characterized by the use of a dip-coated antimicrobial preservative film material for fruits and vegetables or plastic packaging bags.