阅读说明：本技术 一种玉米淀粉/羧甲基纤维素钠/脂肪酸复合膜及其制备方法和应用 (Corn starch/sodium carboxymethylcellulose/fatty acid composite membrane and preparation method and application thereof ) 是由 刘鹏飞 崔波 袁超 吴正宗 郭丽 于滨 邹飞雪 方奕珊 卢璐 于 2021-02-05 设计创作，主要内容包括：本发明公开了一种玉米淀粉/羧甲基纤维素钠/脂肪酸复合膜及其制备方法和应用,本发明制备的复合膜中羧甲基纤维素钠与淀粉复配后,可以改善淀粉膜的机械性能,脂肪酸与淀粉复配后改善淀粉膜的疏水性能,采用超声处理工艺增加了亲水性成膜组分和疏水性成膜组分间的相容性,使亲水性的淀粉和羧甲基纤维素钠与疏水性的脂肪酸混溶,从而提高淀粉基膜的机械和疏水性能。本发明工艺绿色环保,制备的产品机械性能、阻水性能优良,制备的玉米淀粉/羧甲基纤维素钠/脂肪酸复合膜具有全降解性,可广泛应用于食品包装领域,可避免传统塑料对环境造成的“白色污染”问题。(The invention discloses a corn starch/sodium carboxymethylcellulose/fatty acid composite membrane and a preparation method and application thereof. The process is green and environment-friendly, the prepared product has excellent mechanical property and water resistance, and the prepared corn starch/sodium carboxymethylcellulose/fatty acid composite film has full degradability, can be widely applied to the field of food packaging, and can avoid the problem of white pollution caused by traditional plastics to the environment.)

1. A preparation method of a corn starch/sodium carboxymethylcellulose/fatty acid composite film is characterized by comprising the following steps:

(1) pasting treatment: adding corn starch into water to prepare a starch milk solution with the mass percentage concentration of 5-10%, then adding sodium carboxymethylcellulose, glycerol and a fatty acid solution, and heating at 90-95 ℃ for 90-120min to obtain a starch pasting solution;

(2) ultrasonic treatment: carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1):

(3) film preparation: and (3) preparing a membrane by taking the starch pasting solution subjected to ultrasonic treatment in the step (2) as a raw material to obtain the corn starch/sodium carboxymethylcellulose/fatty acid composite membrane.

2. The preparation method of claim 1, wherein the membrane preparation method in step (3) is to filter the starch gelatinization liquid warp cloth after ultrasonic treatment, pour the filtered starch gelatinization liquid warp cloth on a glass plate coated with polytetrafluoroethylene, dry and uncover the membrane to obtain the corn starch/sodium carboxymethylcellulose/fatty acid composite membrane.

3. The preparation method according to claim 1, wherein the addition amount of the sodium carboxymethylcellulose in the step (1) is 4-10% of the addition amount of the corn starch; the addition amount of the glycerol is 30-35% of that of the corn starch; the addition amount of the fatty acid is 5-8% of that of the corn starch.

4. The method according to claim 1, wherein the fatty acid in step (1) is one of lauric acid, myristic acid, palmitic acid, stearic acid, and arachidic acid.

5. The method as claimed in claim 1, wherein the ultrasonic power density in the ultrasonic treatment in the step (2) is 240-²The treatment time is 5-30 min.

6. The preparation method according to claim 2, wherein the drying method in the step (2) is hot air circulation oven drying, the drying temperature is 40 ℃, and the drying time is 12 h.

7. A corn starch/sodium carboxymethyl cellulose/fatty acid composite film prepared by the preparation method of any one of claims 1 to 6.

8. The application of the corn starch/sodium carboxymethylcellulose/fatty acid composite film prepared by the preparation method of any one of claims 1-6 in packaging films.

9. The use of claim 8, wherein the packaging film is a vegetable and fruit preservative packaging film or a food packaging film.

Technical Field

The invention belongs to the technical field of degradable composite membranes, and particularly relates to a corn starch/sodium carboxymethylcellulose/fatty acid composite membrane as well as a preparation method and application thereof.

Background

The severity and harmfulness of the "white pollution" caused by the existing packaging materials, especially high molecular plastics, are gradually recognized, and the large amount of waste after the use thereof causes non-negligible negative effects on the environment on which human beings live. Most of them are derived from food plastic packaging waste, and therefore, people are required to develop food packaging towards convenience and pollution-free. Researchers are gradually focusing on natural environment-friendly polymers having biodegradability. Research and application of degradable packaging films taking renewable resources such as natural polymers and the like as raw materials gradually become the research focus of scientific research work. Starch has the advantages of environmental friendliness, degradability and the like, and is considered as one of the most potential natural biodegradable materials.

But the existing starch-based degradation material has the problem that the mechanical property and the hydrophobic property are poor, so that the starch-based degradation material is not suitable to be used as an outer packaging material of food. How to improve the mechanical properties and hydrophobic properties of starch-based degradable materials is the focus of current research. The carboxymethyl cellulose sodium can improve the mechanical property of the starch film due to the chemical structure similar to that of starch after being compounded with the starch. The fatty acid has hydrophobic carbon chains, so that the hydrophobic property of the starch film can be improved by compounding the fatty acid with the starch to prepare the film. However, hydrophilic starch and sodium carboxymethyl cellulose are thermodynamically immiscible with hydrophobic fatty acids. Therefore, there is an urgent need to further improve the processing techniques to increase the compatibility between hydrophilic and hydrophobic film-forming components, thereby improving the mechanical and hydrophobic properties of the starch film.

Disclosure of Invention

Aiming at the problem that the starch-based membrane in the prior art is poor in mechanical property and hydrophobicity, the invention provides the corn starch/sodium carboxymethylcellulose/fatty acid composite membrane and the preparation method and application thereof, and the prepared starch-based membrane is degradable and has good mechanical and hydrophobic properties.

The invention is realized by the following technical scheme:

a preparation method of a corn starch/sodium carboxymethylcellulose/fatty acid composite film comprises the following steps:

(1) pasting treatment: adding corn starch into water to prepare a starch milk solution with the mass percentage concentration of 5-10%, then adding sodium carboxymethylcellulose, glycerol and a fatty acid solution, and heating at 90-95 ℃ for 90-120min to obtain a starch pasting solution;

(2) ultrasonic treatment: carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1):

(3) film preparation: and (3) preparing a membrane by taking the starch pasting solution subjected to ultrasonic treatment in the step (2) as a raw material to obtain the corn starch/sodium carboxymethylcellulose/fatty acid composite membrane.

And (3) filtering the starch pasting liquid warp cloth after ultrasonic treatment, pouring the filtered starch pasting liquid warp cloth on a glass plate coated with polytetrafluoroethylene, drying and uncovering the film to obtain the corn starch/sodium carboxymethylcellulose/fatty acid composite film.

Further, the adding amount of the sodium carboxymethyl cellulose in the step (1) is 4-10% of the adding amount of the corn starch; the addition amount of the glycerol is 30-35% of that of the corn starch; the addition amount of the fatty acid is 5-8% of that of the corn starch.

Further, the fatty acid in the step (1) is one of lauric acid, myristic acid, palmitic acid, stearic acid and arachidic acid.

Further, the ultrasonic power density in the ultrasonic treatment in the step (2) is 240-560W/cm²The treatment time is 5-30 min.

Further, the drying method in the step (2) is drying in a hot air circulation oven, the drying temperature is 40 ℃, and the drying time is 12 hours.

In the invention, the corn starch/sodium carboxymethylcellulose/fatty acid composite membrane prepared by the preparation method is provided.

In the invention, the corn starch/sodium carboxymethylcellulose/fatty acid composite film prepared by the preparation method is applied to a packaging film.

Furthermore, the packaging film is a vegetable and fruit fresh-keeping packaging film and a food packaging film.

According to the invention, the mechanical property of the starch film can be improved after the sodium carboxymethyl cellulose is compounded with starch due to the chemical structure similar to that of the starch, the hydrophobic property of the starch film can be improved by compounding the starch film with the fatty acid due to the hydrophobic carbon chain, and the compatibility between the hydrophilic film forming component and the hydrophobic film forming component is increased by adopting an ultrasonic treatment process, so that the hydrophilic starch and the sodium carboxymethyl cellulose are mixed with the hydrophobic fatty acid, and the mechanical and hydrophobic properties of the starch-based film are improved.

Advantageous effects

(1) The compatibility between the hydrophilic film forming component and the hydrophobic film forming component is increased by adopting an ultrasonic treatment process, the sodium carboxymethyl cellulose and the fatty acid can be uniformly dispersed in the starch, and the reinforcing effect of the sodium carboxymethyl cellulose and the effect of improving the hydrophobic property of the starch film by the fatty acid are fully exerted;

(2) the raw materials and auxiliary materials used in the invention can be completely degraded, and the raw materials have wide sources, low price and lower production cost;

(3) the preparation method disclosed by the invention is simple in process operation, safe, efficient, green and environment-friendly, and the prepared composite film is high in stretchability and flexibility, good in transparency and excellent in water resistance, and can be widely applied to the fields of vegetable and fruit fresh-keeping packaging, food packaging and the like.

Detailed Description

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention in conjunction with the following examples, but it will be understood that the description is intended to illustrate the features and advantages of the invention further, and not to limit the invention.

The amylose and amylopectin contents of the corn starch in the invention are respectively 25.3% and 74.7%.

Example 1

(1) Pasting treatment: adding corn starch into an aqueous solution to prepare a starch milk solution with the mass percentage concentration of 10%, adding sodium carboxymethylcellulose accounting for 5% of the addition amount of the corn starch dry powder, glycerol accounting for 30% of the addition amount of the corn starch dry powder and lauric acid accounting for 5% of the addition amount of the corn starch dissolved by absolute ethyl alcohol, and heating at 90 ℃ for 120min to obtain a starch pasting solution;

(2) ultrasonic treatment: at 560W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 15min under the ultrasonic power density;

(3) film preparation: and (3) filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the warp cloth in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose/lauric acid composite membrane.

Example 2

(1) Pasting treatment: adding corn starch into an aqueous solution to prepare a starch milk solution with the mass percentage concentration of 8%, adding sodium carboxymethylcellulose accounting for 6% of the addition amount of the corn starch dry powder, glycerol accounting for 32% of the addition amount of the corn starch dry powder and myristic acid which is dissolved by absolute ethyl alcohol and accounts for 7% of the addition amount of the corn starch dry powder, and heating for 90min at 95 ℃ to obtain a starch pasting solution;

(2) ultrasonic treatment: at 240W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 30min under the ultrasonic power density;

(3) film preparation: and (3) filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered starch pasting liquid warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the glass plate in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose/myristic acid composite membrane.

Example 3

(1) Pasting treatment: adding corn starch into an aqueous solution to prepare a starch milk solution with the mass percentage concentration of 6%, adding sodium carboxymethylcellulose accounting for 7% of the addition amount of the corn starch dry powder, glycerol accounting for 35% of the addition amount of the corn starch dry powder and palmitic acid accounting for 8% of the addition amount of the corn starch dry powder after being dissolved by absolute ethyl alcohol, and heating at 95 ℃ for 100min to obtain a starch pasting solution;

(2) ultrasonic treatment: at 560W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 30min under the ultrasonic power density;

(3) film preparation: and (3) filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered starch pasting liquid warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the glass plate in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose/palmitic acid composite membrane.

Example 4

(1) Pasting treatment: adding corn starch into an aqueous solution to prepare a starch milk solution with the mass percentage concentration of 7%, adding sodium carboxymethylcellulose accounting for 6% of the addition amount of the corn starch dry powder, glycerol accounting for 33% of the addition amount of the corn starch dry powder and stearic acid accounting for 8% of the addition amount of the corn starch dry powder after being dissolved by absolute ethyl alcohol, and heating at 90 ℃ for 110min to obtain a starch pasting solution;

(2) ultrasonic treatment: at 240W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 15min under the ultrasonic power density;

(3) film preparation: and (3) filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the warp cloth in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose/stearic acid composite membrane.

Example 5

(1) Pasting treatment: adding corn starch into an aqueous solution to prepare a starch milk solution with the mass percentage concentration of 10%, adding sodium carboxymethylcellulose accounting for 9% of the addition amount of the corn starch dry powder, glycerol accounting for 30% of the addition amount of the corn starch dry powder and arachidic acid which is dissolved by absolute ethyl alcohol and accounts for 6% of the addition amount of the corn starch dry powder, and heating at 95 ℃ for 95min to obtain a starch pasting solution;

(2) ultrasonic treatment: at 560W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 5min under the ultrasonic power density;

(3) film preparation: and (3) filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered starch pasting liquid warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the glass plate in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose/arachidic acid composite membrane.

Comparative example 1

(1) Pasting treatment: adding corn starch into the aqueous solution to prepare a starch milk solution with the mass percentage concentration of 10%, adding sodium carboxymethylcellulose accounting for 5% of the addition amount of the corn starch dry powder and glycerol accounting for 30% of the addition amount of the corn starch dry powder, and heating at 90 ℃ for 120min to obtain a starch pasting solution;

(2) ultrasonic treatment: at 560W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 15min under the ultrasonic power density;

(3) film preparation: and (3) filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the warp cloth in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose composite membrane.

Comparative example 2

(1) Pasting treatment: adding corn starch into the aqueous solution to prepare a starch milk solution with the mass percentage concentration of 10%, adding glycerol accounting for 30% of the addition amount of the corn starch dry powder and lauric acid accounting for 5% of the addition amount of the corn starch dissolved by absolute ethyl alcohol, and heating at 90 ℃ for 120min to obtain starch pasting liquid;

(2) ultrasonic treatment: at 560W/cm²Carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 15min under the ultrasonic power density;

(3) film preparation: filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered starch pasting liquid warp cloth onto a glass plate coated with polytetrafluoroethylene, placing the glass plate in a hot air circulation oven for drying at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/lauric acid composite membrane.

Comparative example 3

(1) Pasting treatment: adding corn starch into the aqueous solution to prepare a starch milk solution with the mass percentage concentration of 10%, adding glycerol accounting for 30% of the addition amount of the corn starch dry powder, and heating at 90 ℃ for 120min to obtain starch pasting liquid;

(2) ultrasonic treatment: at 560W/cm²And (2) carrying out ultrasonic treatment on the starch pasting liquid obtained in the step (1) for 15min under the ultrasonic power density.

(3) Film preparation: filtering the starch pasting liquid warp cloth subjected to ultrasonic treatment obtained in the step (2), pouring the filtered warp cloth on a glass plate coated with polytetrafluoroethylene, placing the glass plate in a hot air circulation oven for drying at the drying temperature of 40 ℃ for 12 hours, and removing the membrane after drying to obtain the corn starch membrane.

Comparative example 4

(1) Pasting treatment: adding corn starch into an aqueous solution to prepare a starch milk solution with the mass percentage concentration of 10%, adding sodium carboxymethylcellulose accounting for 5% of the addition amount of the corn starch dry powder, glycerol accounting for 30% of the addition amount of the corn starch dry powder and lauric acid accounting for 5% of the addition amount of the corn starch dissolved by absolute ethyl alcohol, and heating at 90 ℃ for 120min to obtain a starch pasting solution;

(2) film preparation: and (2) filtering the starch pasting liquid warp cloth obtained in the step (1), pouring the filtered starch pasting liquid warp cloth onto a glass plate coated with polytetrafluoroethylene, drying the glass plate in a hot air circulation oven at the drying temperature of 40 ℃ for 12 hours, and uncovering the membrane after drying to obtain the corn starch/sodium carboxymethylcellulose/lauric acid composite membrane.

And (3) performance testing:

(1) mechanical properties: measurement of tensile Strength (MPa):

an intelligent tensile testing machine is adopted to test the mechanical property of the starch film, a sample is placed in a constant temperature and humidity box (23 +/-2) degrees C, RH = 53%) for 48 hours before testing, and the test specification of the sample is 15 mm multiplied by 100 mm. The initial nip distance was set to 80 mm.

The calculation formula is as follows:

TS = F/S × 10^-6 MPa

f is the force at break of the film (N), S is the cross-sectional area of the sample (m)²）。

(2) Testing the water vapor transmission rate:

water vapor Transmission Rate of starch film PERME was used^TMW3/030 was measured by an automatic water vapour transmission tester. The sample was placed in a constant temperature and humidity chamber ((23 ± 2) ℃ with RH = 53%) for 48 h before testing. A80 mm diameter disc was taken from the film sample with a sampler and tested. The preheating time is 4 h, the test temperature is 38 ℃, and the test area is 33.00 cm²The test relative humidity was 90% and the weighing interval was 120 min.

(3) The film materials prepared in examples 1 to 5 and comparative examples 1 to 4 were subjected to tests for mechanical properties (tensile strength) and water vapor transmission rate, and the results are shown in table 1 below:

TABLE 1 characterization of the Performance of the composite membranes prepared in examples 1-5 and comparative examples 1-4

。