LU500525B1 - Preparation method of banana stem and leaf straw fiber composite material - Google Patents

Abstract

A banana stem and leaf straw fiber composite material, which comprises the following components in parts by mass: 5-40 parts of banana stem and leaf straw fiber, 10-30 parts of adhesive, 5-10 parts of stabilizer and 10-30 parts of filler, wherein the adhesive is potato starch, PVA or peach gum, and the stabilizer is calcium stearate or calcium laurate, and the filler is calcium carbonate or kaolin. The specific preparation steps are as follows: the banana stem and leaf straw is mechanically treated and cut into small straw segments; then the small straw segments are heated and soaked in sodium hydroxide solution for pretreatment; then the surface modification treatment is carried out on the small straw segments by using a coupling agent solution; and the treated banana stem and leaf straw fibers are uniformly mixed with other raw materials, hot-pressed and formed, and naturally cooled to prepare the composite material.

Description

DESCRIPTION LUS00525 Preparation method of banana stem and leaf straw fiber composite material

TECHNICAL FIELD The invention belongs to the field of fiber composite materials, and particularly relates to a banana stem and leaf straw fiber composite material and a preparation method thereof.

BACKGROUND Agriculture is one of the three major industries in the world. Every year, a large number of straw wastes are produced due to agricultural planting in the world, including grain crop straws and cash crop straws. Most of the agricultural waste straws are treated by burning them back to the field in situ, which will not only cause a large amount of waste of renewable resources of crop straws, but also cause serious pollution to the ecological environment due to burning straws. If straw can be turned into valuable, economic benefits can be generated, and an industrial chain can be formed, it will inevitably bring great influence, which is of great significance for alleviating the shortage of resources in China, developing economy and protecting the environment.

At present, the technology of high-value utilization of straw is mainly to extract high value-added substances, and a small amount of straw is used to prepare composite materials,but most of them use crop straws such as wheat and corn to prepare composite boards. The technology of using straw fiber to prepare packaging materials is very rare. Packaging materials refer to materials used to meet product packaging requirements, such as manufacturing packaging containers, packaging decoration, packaging printing, packaging and transportation. In people's daily life, the application range is very wide, and the demand is huge. However, the packaging materials which are widely used at present are mainly non-degradable plastic LU500525 packaging materials, which form serious "white pollution", and their mechanical properties are not very good. If the straw fiber which is easy to obtain is combined with the preparation of packaging material, the straw fiber composite packaging material can be prepared . The straw fiber composite packaging material can not only achieve the reuse of straw materials, but also reduce the environmental pollution caused by straw burning and difficult degradation of plastics, which has great economic and environmental benefits and broad application prospects.

At present, there are some technologies that use straw to prepare composite materials, but there are still many problems in these technologies. For example, it is basically only applied to common crop straws such as wheat straw and corn straw, and the degree of reuse of straw types and straw quantities is relatively small; the processing technology of extracting cellulose is cumbersome, the processing cost is high, and the straw treatment capacity is small, chemical treatment produces secondary pollution; the mechanical properties of composite materials are low, which is difficult to meet the application requirements. These problems limit the large-scale application of this kind of technology. Therefore, it is still of great research significance to adjust the formula and process to prepare a straw fiber composite material with biodegradability, good water resistance, excellent mechanical properties, low cost and little pollution in the production process.

SUMMARY In order to improve the comprehensive utilization of agricultural waste crop straws and solve the problems of difficult degradation and easy pollution of traditional plastic packaging materials, the invention provides a biodegradable straw fiber composite packaging material and a preparation method thereof. Tropical crop straws LU500525 (banana stems and leaves) are used as reinforcing materials, and the composite material is prepared by pretreatment, modification treatment, mixing and hot pressing molding, which can not only improve the water resistance and mechanical properties of the material, but also be biodegradable, and is a low-cost green environmental protection material which can be used in the field of packaging materials to replace traditional plastic packaging materials To achieve the above purpose, the present invention provides the following technical scheme: According to one technical scheme of the invention, the banana stem and leaf straw fiber composite material comprises the following components in parts by mass: 5-40 parts of banana stem and leaf straw fiber, 10-30 parts of adhesive, 5-10 parts of stabilizer and 10-30 parts of filler.

Further, the adhesive is potato starch, PVA or peach gum, and the stabilizer is calcium stearate or calcium laurate, and the filler is calcium carbonate or kaolin.

Further, the banana stem and leaf straw fiber is prepared by mechanical treatment, pretreatment and surface modification of banana stem and leaf straw.

According to the second technical scheme of the invention, the preparation method of the banana stem and leaf straw fiber composite material comprises the following steps: Step 1, mechanically treating banana stem and leaf straws to obtain banana stem and leaf straws; Step 2, pretreating that banana stem and leaf straw segments to obtain pretreated banana stem and leaf straws;

Step 3, carrying out surface modification on that pretreated banana stem and leaf LU500525 straw to obtain banana stem and leaf straw fiber; Step 4, uniformly mixing banana stem and leaf straw fiber, adhesive, stabilizer and filler, hot pressing and forming, and naturally cooling to obtain the banana stem and leaf straw fiber composite material.

Further, the specific operation of step 1 is that banana stem and leaf straws are cut into banana stem and leaf straws segments with a length of 1-5 cm and a width of 1-10 mm.

Further, the specific operation of step 2 is: soaking the banana stem and leaf straw segments in sodium hydroxide solution, heating, neutralizing with acid after heating, washing with water to neutrality, and drying to obtain pretreated banana stem and leaf straw.

Furthermore, the mass concentration of the sodium hydroxide solution is 2-5%, the mass-to-liquid ratio of banana stem and leaf straw segments to the sodium hydroxide solution is 1g:20 ml-50 ml, the heating treatment temperature is 60-80 °C for 30-60min, and the drying temperature is 80-100 °C for 5-8 h.

Further, the neutralization with acid means neutralization with acetic acid solution, and the concentration of acetic acid 1s 2-10%.

Further, the specific operation of step 3 1s as follows: adding the coupling agent solution into the pretreated banana stem and leaf straw in a high-speed stirring state, continuously stirring for 20-30 min after adding, uniformly mixing to obtain a mixture, and drying the mixture at a temperature of 70-110°C for 4-10 h to obtain modified banana stem and leaf straw fibers, wherein the rotating speed of the high-speed stirring is 1000-2000 r/min.

Further, the uniform mixing means that the coupling agent solution fully and LU500525 uniformly soaks the pretreated banana stem and leaf straws to obtain a uniformly mixed mixture.

Furthermore, the solute of the coupling agent solution is silane coupling agent or titanate coupling agent;the solvent is ethanol; the volume ratio of solute to solvent is 1: 5, and the mass ratio of pretreated banana stem and leaf straw to coupling agent is 100: 1-6.

Further, the temperature of the hot pressing in step 4 is 160-180°C, the pressure is 3-6 MPa, and the time is 2-6min.

Straw fiber is the most abundant natural polymer material in nature, which is low in price, low in density, high in elastic modulus and tensile strength, and has biodegradability and reproducibility unmatched by other materials. The natural plant fiber in straw is an ideal reinforcing material for preparing green degradable composite materials. The addition of straw fiber can not only provide certain mechanical strength, but also help to improve the biodegradability of materials.

Compared with the prior art, the invention has the following beneficial effects: (1) The banana stalk fiber is used as the main material. Compared with other common crop straw fibers such as wheat straw fiber, corn straw fiber and rice straw fiber, the banana stalk fiber has a large aspect ratio, which is only 3.7, while the banana stalk fiber has an aspect ratio as high as 58.8, and the large aspect ratio can be as high as 120. Straw fibers with high aspect ratio are easy to interweave and form a network entanglement structure, which is beneficial to improve the connectivity and bonding degree of the intertwined network of composite materials, thus enhancing the mechanical properties of composite materials; according to the invention, a silane coupling agent solution or titanate coupling agent solution is used for carrying out surface modification treatment on banana stem and leaf straws, and the silane LU500525 coupling agent or titanate coupling agent contains a multifunctional structure, which can cross-link with banana stem and leaf straw fibers to generate hydrogen bonds on the one hand, and physically entangle with adhesive macromolecules in a composite material matrix on the other hand, thereby improving the interfacial compatibility, dispersibility and wettability of banana stem and leaf straw fibers.

It can increase the wettability of banana stem and leaf straw fiber, thus improving the chemical reaction ability between straw fiber and other components of composite material, forming an effective structure of hydrogen bond or physical entanglement, and further improving the mechanical properties of composite material; potato starch, PVA or peach gum have excellent adhesive properties, which can be well combined with banana stem and leaf straw fiber, so that the composite material has better compactness and excellent mechanical properties; a large amount of inorganic filler calcium carbonate or kaolin is used in the invention, and the calcium carbonate or kaolin is inactive in chemical properties, has chemical resistance and electrical insulation, and plays a role in adjusting the stability, rigidity and hardness of the material, thereby improving the mechanical properties and heat resistance of the material and greatly reducing the cost at the same time; according to the invention, based on the characteristics of banana stem and leaf straw fibers and various auxiliary materials as main raw materials, the optimal hot-pressing molding pressure, temperature and time parameters are set, the pressure is too low, the composite material is prone to defects such as pores, and the pressure is too high, so that the raw materials may be extruded; if the temperature is too high or the time is too long, the straw fiber will be pyrolyzed and the surface carbonized; if the temperature is too low or the time is too short, the raw materials will be difficult to solidify, which will make the performance of the composite material worse. However, the hot-pressing molding parameters set by the invention LU500525 can avoid the above phenomena and obtain composite materials with uniform and compact structure and good mechanical properties. According to the invention, banana stem and leaf straw fibers subjected to surface treatment with silane coupling agent solution or titanate coupling agent are selected as main raw materials, and adhesives, stabilizers and fillers are supplemented, and the adjustment of the preparation process is combined to prepare a straw fiber composite material which is biodegradable, good in water resistance, excellent in mechanical properties, low in cost and less in pollution in the production process and can be used as packaging materials in the industrial fields of food, household appliances, and the like.

(2) the preparation method of the invention is simple, reliable and easy to implement; the prepared composite material is renewable and degradable, and is an ideal material for environmental protection and energy saving.

(3) The composite material prepared by the method can be recycled, and an industrial chain of circular economy can be formed.

DESCRIPTION OF THE INVENTION Various exemplary embodiments of the present invention will now be described in detail, which should not be regarded as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics and embodiments of the present invention.

It should be understood that the terms described in the present invention are only for describing specific embodiments, and are not intended to limit the present invention. In addition, as for the numerical range in the present invention, it should be understood that every intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Intermediate values within any stated value or stated range and every smaller range between any other stated value or LU500525 intermediate values within the stated range are also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

Unless otherwise stated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the present invention relates. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe methods and/or materials related to the documents. In case of conflict with any incorporated documents, the contents of this specification shall prevail.

Without departing from the scope or spirit of the invention, it is obvious to those skilled in the art that many modifications and changes can be made to the specific embodiments of the specification of the invention. Other embodiments derived from the description of the present invention will be apparent to the skilled person. The specification and embodiment of that present invention are merely exemplary.

As used herein, "including", "having", "containing", etc. are all open terms, which means including but not limited to.

Example 1 (1) mechanical treatment of straw: cutting the straw into small segments about 2 cm long and 6 mm wide.

(2) pretreatment of straw: soaking the straw segments in 2% of sodium hydroxide solution, the mass ratio of sodium hydroxide solution to straw was 30:1; heating in 80°C water bath for 30 min, taking out, carrying out acid neutralizing with acetic acid solution, washing to pH 7, and drying in an oven at 100°C for 6 h to obtain LU500525 pretreated banana stem and leaf straw.

(3)straw surface modification: KH550 silane coupling agent and ethanol were prepared into a solution according to the volume ratio of 1: 5, the dried pretreated straw was put into a high-speed mixing mixer, stirred at the rotating speed of 2000 r/min, and the coupling agent solution is sprayed while stirring, wherein the mass ratio of KH550 to pretreated straw is 5:100, and after the coupling agent solution was added, stirring is continued for 20-30 min until the pretreated straw is fully and uniformly soaked by the coupling agent solution, and then taken out, drying at 110°C for 8 h to obtain processed banana stem and leaf straw fiber, which was bagged and sealed for later use.

(4) raw material mixing and hot-pressing molding: 38 parts of banana stem and leaf straw fiber, 32 parts of potato starch, 8 parts of calcium stearate and 22 parts of calcium carbonate were fully mixed together under the action of a high-speed mixer, and were hot-pressed and molded by a hot press. The hot pressing temperature was 170°C, the pressure was SMPa, and the hot pressing time was 4 min, and naturally cooling at normal temperature to obtain the molded composite material.

Example 2 (1) mechanical treatment of straw: cutting the straw into small segments about 3 cm long and 5 mm wide.

(2) pretreatment of straw: soaking the straw segments in 2% of sodium hydroxide solution, the mass ratio of sodium hydroxide solution to straw was 35:1, heating in 70°C water bath for 40 min, taking out, carrying put acid neutralizing with acetic acid solution, washing to pH 7, and drying in an oven at 90°C for 6h to obtain pretreated banana stem and leaf straw.

(3) Straw surface modification: preparing KHS50 silane coupling agent and LU500525 ethanol into solution according to the volume ratio of 1: 5, putting the dried pretreated straw into a high-speed mixer, stirring at the speed of 1500 r/min, spraying coupling agent solution while stirring; the mass ratio of KH550 to pretreated straw was 4:100, continue stirring for 20-30min after the coupling agent solution was added until the pretreated straw was fully and uniformly soaked by the coupling agent solution, and then take it out; drying at 110°C for 7 h to obtain processed banana stem and leaf straw fiber powder, which was bagged and sealed for later use.

(4) raw material mixing and hot-pressing molding: 35 parts of banana stem and leaf straw fiber, 28 parts of peach gum, 9 parts of calcium stearate and 28 parts of kaolin were fully mixed together under the action of a high-speed mixer, and hot- pressing molding was carried out by a hot press. The hot pressing temperature was 160°C, and the pressure was 4 MPa, and the hot pressing time was 5 min, and naturally cooling at normal temperature to obtain the molded composite material.

Example 3 (1) mechanical treatment of straw: cutting the straw into small segments about 4 cm long and 4 mm wide.

(2) pretreatment of straw: soaking the straw segments in 2% of sodium hydroxide solution, the mass ratio of sodium hydroxide solution to straw was 25:1, heating it in 75°C water bath for 50 min, taking it out, neutralizing it with acetic acid solution, washing it with water to pH 7, and drying it in an oven at 95°C for 6h to obtain pretreated banana stem and leaf straw.

(3) straw surface modification: titanate coupling agent and ethanol were prepared into a solution according to the volume ratio of 1: 5, and the dried pretreated straw was put into a high-speed mixing mixer, stirred at the rotating speed of 2000 r/min,

and the coupling agent solution was sprayed while stirring, wherein the mass ratio of LU500525 titanate coupling agent to pretreated straw is 5:100; after adding the coupling agent solution, continue to stir for 20-30 min until the pretreated straw was fully and uniformly soaked by the coupling agent solution, and then take it out, drying it at 100°C for 9 h to obtain the processed banana stem and leaf straw fiber powder, which is bagged and sealed for later use.

(4) raw material mixing and hot-pressing molding: 32 parts of banana stem and leaf straw fiber, 25 parts of PVA, 18 parts of calcium silicate and 25 parts of kaolin were fully mixed together under the action of a high-speed mixer, and hot-pressing molding was carried out by a hot press. The hot pressing temperature was 180°C, and the pressure was SMPa, and the hot pressing time was 3 min, and naturally cooling at normal temperature to obtain the molded composite material.

Example 4 (1) mechanical treatment of straw: cutting the straw into small segments about 4 cm long and 8 mm wide.

(2) pretreatment of straw: soaking the straw segments in 2% of sodium hydroxide solution, the mass ratio of sodium hydroxide solution to straw was 45:1, heating in 65°C ,watering bath for 60 min, taking out, carrying out acid neutralizing with acetic acid solution, washing with water to pH 7, and drying in an oven at 95°C for 8 h to obtain pretreated banana stem and leaf straw.

(3) straw surface modification: titanate coupling agent and ethanol were prepared into a solution according to the volume ratio of 1: 5, and the dried pretreated straw was put into a high-speed mixer, stirred at the rotating speed of 1000 r/min, and the coupling agent solution was sprayed while stirring, wherein the mass ratio of titanate coupling agent to pretreated straw was 3:100, and after the coupling agent solution was added, stirring was continued for 20-30 min until the pretreated straw was fully LU500525 and uniformly soaked by the coupling agent solution, and then take it out ; drying at 95°C for 8 h to obtain processed banana stem and leaf straw fiber powder, which was bagged and sealed for later use.

(4) raw material mixing and hot-pressing forming: 30 parts of banana stem and leaf straw fiber, 24 parts of peach gum, 18 parts of calcium stearate and 28 parts of calcium carbonate were fully mixed together under the action of a high-speed mixer, and were hot-pressed and formed by a hot press. The hot pressing temperature was 170°C, and the pressure was 5 MPa, and the hot pressing time was 6 min; and naturally cooling at normal temperature to obtain the molded composite material.

Comparative example 1 Same as Example 1, the difference is that wheat straw was used instead of banana stem and leaf straw.

Comparative example 2 Same as Example 1, the difference is that the operation of straw surface modification in Step (3) was omitted, and the straw pretreated in Step (2) was directly mixed with other raw materials for hot pressing molding.

Comparative example 3 Same as example 1, the difference is that KH550 silane coupling agent in step (3) was replaced by chitosan.

Effect verification Take the composite materials prepared in Examples 1-4 and Comparative Examples 1-3 for mechanical performance testing, and the standards adopted for each item are as follows: The tensile properties refer to GB/T 1040.5-2008 test;

The bending performance refers to GB/T 9341-2008 test; LU500525 The compression performance refers to GB/T 1041-2008 test, and the compression ratio 1s 20%; The impact performance refers to GB/T 1451-2005 test.

The test result of mechanical performance testing 1s shown in Table 1: Table 1 Test result of mechanical performance Impac Tensil Compre | t strength e Strength Bending | ssive /kJ*m /MPa strength/MPa | strength/MPa | -2 Exampl el 35.2 78.4 56.2 8.5 Exampl e2 29.6 83.7 47.5 Exampl e3 32.4 74.2 52.8 9.2 Exampl e4 33.5 76.8 49.6 8.7 Compa rative example 1 15.3 40.2 24.2 4.9 Compa rative example 2 17.8 36.4 25.1 3.7 Compa rative example 3 12.8 34.5 21.2 4.5 The foregoing descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention.

Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

CLAIMS: LU500525

1. A banana stem and leaf straw fiber composite material, which is characterized by comprising the following components in parts by mass: 5-40 parts of banana stem and leaf straw fiber, 10-30 parts of adhesive, 5-10 parts of stabilizer and 10-30 parts of filler.

2. The banana stem and leaf straw fiber composite material according to claim 1 is characterized in that the adhesive is potato starch, PVA or peach gum, and the stabilizer is calcium stearate or calcium laurate, and the filler is calcium carbonate or kaolin.

3. The banana stem and leaf straw fiber composite material according to claim 1 is characterized in that the banana stem and leaf straw fiber is prepared by mechanical treatment, pretreatment and surface modification of banana stem and leaf straw.

4. The preparation method of the banana stem and leaf straw fiber composite material according to any of claims 1-3 comprises the following steps: step 1, mechanically treating banana stem and leaf straws to obtain banana stem and leaf straws; step 2, pretreating that banana stem and leaf straw segments to obtain pretreated banana stem and leaf straws; step 3, carrying out surface modification on that pretreated banana stem and leaf straw to obtain banana stem and leaf straw fiber; step 4, uniformly mixing banana stem and leaf straw fiber, adhesive, stabilizer and filler, hot pressing and forming, and naturally cooling to obtain the banana stem and leaf straw fiber composite material.

5. The preparation method of banana stem and leaf straw fiber composite material according to claim 4 is characterized in that, in the step 1, the banana stem and leaf straw are cut into small pieces with a length of 1-5 cm and a width of 1-10 LUS00525 mm.

6. The preparation method of banana stem and leaf straw fiber composite material according to claim 4 is characterized in that the specific operation of step 2 is: soaking the banana stem and leaf straw segments in sodium hydroxide solution, heating, neutralizing with acid, washing to neutrality, and drying to obtain pretreated banana stem and leaf straw.

7. The preparation method of banana stem and leaf straw fiber composite material according to claim 6 is characterized in that the mass concentration of sodium hydroxide solution is 2-5%, and the mass-liquid ratio of banana stem and leaf straw to sodium hydroxide solution is 1 g:20 ml-50 ml, and the heating temperature is 60-80°C for 30-60 min, and the drying temperature is 80-100°C for 5-8h .

8. The preparation method of banana stem and leaf straw fiber composite material according to claim 4 is characterized in that the specific operation of step 3 is: adding coupling agent solution to pretreated banana stem and leaf straw under high-speed stirring, then continuously stirring for 20-30 min after adding, uniformly mixing to obtain a mixture, and drying the mixture at 70-110°C for 4-10 h to obtain banana stem and leaf straw fiber, wherein the rotating speed of high-speed stirring is 1000-2000r/min.

9. The preparation method of banana stem and leaf straw fiber composite material according to claim 8 is characterized in that the solute of the coupling agent solution 1s silane coupling agent or titanate coupling agent, and the solvent is ethanol, the volume ratio of solute to solvent is 1: 5, and the mass ratio of pretreated banana stem and leaf straw to coupling agent 1s 100: 1-6.

10. The preparation method of banana stem and leaf straw fiber composite LU500525 material according to claim 4 is characterized in that the temperature of hot pressing in step 4 is 160-180°C, and the pressure is 3-6 MPa, and the time is 2-6 min.