CN111944207A - Plant fiber starch biomass composite material with open type cellular structure and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the field of green production and preparation, and relates to a plant fiber starch biomass composite material with an open type cellular structure, and a preparation method and application thereof. According to the invention, by adopting the inorganic material calcium carbonate, the natural characteristic that the calcium carbonate can be used as a nucleating agent is utilized to be matched with starch gelatinization and mould pressing foaming, the uniformity of the internal cellular structure of the material is improved by utilizing the physical change characteristic in the hot pressing foaming process of the material, and the like, and the operation is simple and the cost is low.

Description

Plant fiber starch biomass composite material with open type cellular structure and preparation method and application thereof

Technical Field

The invention relates to the introduction of inorganic materials into an open cell structure plant fiber/starch biomass composite to improve the cushioning properties, cushioning strength, and water resistance of the material. Belongs to the field of green production and preparation.

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.

Plastic products are widely used, great convenience is brought to life of people, and meanwhile, great environmental pollution is caused due to the non-degradability of the plastic products, in order to reduce and limit the use of the plastic products, substitutes of the plastic products, such as PLA/PHA/PVA and the like, are searched worldwide, the use of the materials has the problems of long production period, long degradation period, complex process preparation and the like, the new generation of plant fiber/starch-based biomass composite material is also widely proposed, and along with the development of the products, a novel plant fiber/starch composite material with a fully-degradable biomass fully-open type cellular structure, low cost and good waterproofness is researched and prepared.

But the inventor finds that: the biomass material with a fully-open type cellular structure prepared by people at present has the defects of insufficient compressive strength, high moisture absorption rate and low buffer performance caused by insufficient uniformity and fineness of cells.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention utilizes the addition of calcium carbonate into the biomass material, and the addition time and the addition dosage are clearly planned. And the material after will adding through the experiment forms the contrast with preceding material, and the contrast result shows that the bubble of material is more even compact, and shock-absorbing capacity promotes, and the hygroscopicity reduces, and waterproof nature reinforcing.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the invention provides a plant fiber starch biomass composite material with an open type cellular structure, which comprises the following raw materials in parts by weight: 30-50 parts of plant fiber, 50-100 parts of starch, 5-20 parts of inorganic material, 3-5 parts of plant fiber modifier, 4-8 parts of starch modifier, 5-10 parts of foaming agent, 50-100 parts of filler and 300 parts of water 200-containing material;

wherein the inorganic material is calcium carbonate.

The research of the application finds that: 5% -10% of calcium carbonate is added into the water suspension of starch before starch gelatinization and modification, and along with the gelatinization of the starch, the foam uniformity, the compression strength, the buffering performance and the waterproof effect of the full-open type cellular structure of the biomass can be effectively improved by matching with a certain mould pressing foaming temperature.

In a second aspect of the present invention, there is provided a method for preparing a plant fiber/starch biomass composite material with an open cell structure, comprising:

modifying the plant fiber by using hydrogen peroxide to obtain modified plant fiber;

putting starch, calcium carbonate and hydrogen peroxide into water for gelatinization to form slurry;

sequentially adding a foaming agent, a filler and a stripper into the slurry to obtain mixed slurry;

and injecting the mixed slurry into a mold, and carrying out mold pressing and foaming to obtain the polyurethane foam.

The preparation method is simple, and the effect of improving the material performance can be achieved by a simple adding sequence and simple process condition improvement.

In a third aspect of the invention, the application of any one of the plant fiber/starch biomass composite materials with an open cell structure in the fields of buffer packaging, molded products, household appliances, industrial instruments, glass and ceramics is provided.

The plant fiber/starch biomass composite material with the open type cellular structure prepared by the invention has better compactness, buffering property, hygroscopicity and waterproofness, so the plant fiber/starch biomass composite material is expected to be widely applied to the fields of buffering package, molded products, household appliances, industrial instruments, glass and ceramics.

The invention has the beneficial effects that:

(1) the raw material cost is low, no chemical polymerization reaction exists, and no negative influence is generated on other properties of the material.

(2) By adding one material, various properties of the material can be improved, and the overall use effect of the material is improved.

(3) The effect of improving the material performance can be achieved through a simple adding sequence and simple process condition improvement.

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 incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is an optical microscopic view of the internal cell structure of the material of example 1 of the present invention, wherein (a) calcium carbonate was not added (b) 5 parts calcium carbonate was added (c) 10 parts calcium carbonate was added (d)15 parts calcium carbonate.

FIG. 2 is an SEM photograph of the internal cell structure of the material of example 1 of the present invention wherein (a) calcium carbonate was not added (b) 5 parts calcium carbonate was added (c) 10 parts calcium carbonate was added (d)15 parts calcium carbonate.

Fig. 3 is a graph showing the results of mechanical testing of the material in example 1 of the present invention, wherein (a) is a stress-strain graph and (b) is an energy absorption efficiency-strain graph. TF represents the material without calcium carbonate, TF + a% CaCO₃Represents the material added with a% calcium carbonate, and the total amount is based on the total weight of the plant fiber and the starch.

FIG. 4 is a plot of moisture absorption vs. calcium carbonate content for the material of example 1 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.

The method for improving the overall performance of the material by introducing other basic materials on the existing basis is a low-cost and high-efficiency method. Inorganic non-metallic materials are of great interest among many because of their green color, non-pollution and ready availability. Among them, calcium carbonate materials widely exist in nature and are one of materials that can be used.

The first purpose of the invention is to improve the uniformity of the foam holes of the starch/plant fiber fully-open type foam hole structure and improve the buffer performance; the second purpose is to improve the compression strength, waterproof performance and other performances of the material in use.

In order to achieve the above object, the present invention adopts the following scheme: adding 5-10% calcium carbonate into the water suspension of starch before gelatinization and modification of starch, wherein the calcium carbonate is not used as a simple filler, but is gelatinized together with the starch, and then raising the temperature of mould pressing foaming to 190-210 ℃ for mould pressing foaming in the next mould pressing foaming process. The specific improved material formula is as follows:

30-50 parts of plant fiber, 50-100 parts of starch, 5-20 parts of inorganic material, 3-5 parts of plant fiber modifier, 4-8 parts of starch modifier, 5-10 parts of foaming agent, 50-100 parts of filler and 300 parts of water 200-.

The type of the plant fiber is not particularly limited in the present invention, and in some embodiments, the plant fiber is sisal fiber, rice straw fiber, corn straw, wheat straw, etc. to prepare a biomass material with a fully open cellular structure.

The kind of starch is not particularly limited in the present invention, and in some embodiments, the starch is corn starch, wheat starch, tapioca starch, etc. to form stronger hydrogen bond with plant fiber molecules through plasticization of starch;

in some embodiments, the inorganic material is calcium carbonate; the calcium carbonate is not used as a simple filler, but is gelatinized together with starch, and compared with a mode of adding the calcium carbonate as a common filler before mould pressing, the prepared product has obviously improved bubble uniformity, compression strength, buffering performance and waterproof effect.

In some embodiments, the plant fiber modifier is urea, sodium hydroxide, potassium hydroxide, hydrogen peroxide, etc., to dissolve out part of impurities, lignin and hemicellulose, and obtain more negative charge groups;

in some embodiments, the starch modifier is hydrogen peroxide, sodium hypochlorite, periodic acid, or the like; the starch gelatinization temperature is reduced by oxidizing starch, the hot paste viscosity is reduced, and the starch paste has better film forming property and freeze-thaw resistance.

The type of the foaming agent is not particularly limited in the present invention, and in some embodiments, the foaming agent is azodicarbonamide, a complex protein foaming agent, a nitroso foaming agent to form a cell structure inside the material.

In some embodiments, the filler is talc powder, bentonite, calcium lignosulfonate, or the like to reduce cost and improve the overall performance of the plant fiber/lignin fiber/starch biomass composite material with an open cell structure;

a preparation method of a plant fiber/lignin fiber/starch biomass composite material with an open cell structure comprises the following steps:

(1) mechanically crushing the plant fiber to obtain 2-5mm fiber, soaking the fiber in hydrogen peroxide for 20-30 min, washing with water, and drying in the sun to obtain the modified plant fiber.

(2) Weighing starch and calcium carbonate according to weight, putting the starch, the calcium carbonate and hydrogen peroxide into water for gelatinization at 80-90 ℃ for 20-30 minutes, and uniformly stirring all the time.

(3) And (3) adding a foaming agent into the slurry prepared in the step (2), uniformly stirring for 5 minutes, then adding the modified sisal fibers, and uniformly stirring the filler for 35 minutes to obtain the final slurry.

(4) And (4) placing the mixed slurry in the step (4) into a mold, setting the temperature of the upper mold to be 190-210 ℃, the stability of the lower mold to be 190-210 ℃, keeping the pressure to be 6-8MPa after mold closing, avoiding the phenomenon that the mold is opened and sprayed due to overlarge air pressure in the slurry foaming process, and heating for 3-5 min.

(5) And opening the upper die and the lower die, demolding and taking out the product.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.

In the following examples, the mass concentration of hydrogen peroxide was 10%.

Example 1

(1) The sisal fiber is mechanically crushed to obtain 5mm fiber, then the fiber is soaked in 6 parts of hydrogen peroxide for 25 minutes, washed until the pH value is 7, and dried in the sun to obtain the modified sisal fiber.

(2) Weighing 50 parts of corn starch, 5 parts of calcium carbonate, 10 parts of calcium carbonate and 15 parts of calcium carbonate according to weight parts, putting the starch, the calcium carbonate with different weight parts and 5 parts of hydrogen peroxide into water for gelatinization treatment, wherein the gelatinization temperature is 85 ℃, the gelatinization time is 30 minutes, and the process is accompanied with uniform stirring all the time.

(3) And (3) adding 7 parts of azodicarbonamide into the gelatinized starch prepared in the step (2), uniformly stirring for 5 minutes, then adding 50 parts of modified sisal fiber and 70 parts of talcum powder, and uniformly stirring for 35 minutes to obtain homogeneous mixed slurry.

(4) And (4) placing the mixed slurry in the step (4) into a mold, setting the temperature of an upper mold to be 205 ℃, the stability of a lower mold to be 200 ℃, keeping the pressure to be 7MPa after mold closing, avoiding the phenomenon that the mold is opened and sprayed due to overlarge air pressure in the slurry foaming process, and heating for 3 min.

(5) And opening the upper die and the lower die, demolding and taking out the product.

And (3) performance testing:

the sample is tested by adopting an optical microscope observation method, the measuring range is 400 times, and the result is shown in figure 1; FIG. 2 shows the result of the measurement of a sample by a scanning electron microscope observation method at a measuring range of 40000 times as shown in FIG. 2; FIG. 3 shows the mechanical properties of the materials by means of an instrument and electronic universal tester according to the standard of the static compression test method of the buffer material for packaging in GB/T8168-2008, and the results are shown in FIG. 3; the sample is subjected to a moisture absorption experiment under constant temperature and humidity, the waterproof performance of the material is represented, and the result is shown in fig. 4.

As can be seen from fig. 1 and 2, the cell structure becomes more and more uniform with the addition of calcium carbonate, which indicates that the nucleation of calcium carbonate plays a key role.

Wherein, the optical microscope observation method is mainly used for observing the size of the cell structure in the material, and on the whole, the addition of calcium carbonate can make the cells finer and more uniform, the cells are smaller, the more the cells in unit volume are, the larger the specific surface area is, the more energy can be absorbed by the material, and the better the buffering effect is. A scanning electron microscope observation method is mainly used for observing a certain cell structure in a material, and the size of cells is obviously reduced after calcium carbonate is added.

It can be seen from fig. 3(a) that the stress is increased after adding calcium carbonate under the same strain, and the energy absorption efficiency of the material added with 5% calcium carbonate in fig. 3(b) is obviously higher than that of the material without the calcium carbonate.

The yield strength can represent the compressive strength of the material, and the specific data TF is 1.25 MPa; TF + 5% CaCO₃ 3.21MPa；TF+10％CaCO₃ 3.09MPa；TF+15％CaCO₃ 3.10MPa；

Energy absorption efficiency, which can represent the buffering performance of the material, and the specific data TF 21.9%; TF + 5% CaCO₃ 22.8％；TF+10％CaCO₃ 19.1％；TF+15％CaCO₃ 18.2％；

Fig. 4 shows that the moisture absorption rate of the material is reduced along with the increase of the calcium carbonate content under different humidities, which shows that the calcium carbonate has a good effect on the improvement of the waterproof performance of the material.

The moisture absorption rates of the materials with different amounts are added under different humidities to reflect the waterproof performance of the material, and RH refers to relative humidity, according to the graph of FIG. 4, it is obvious that under the same humidity, along with the increase of the content of calcium carbonate, the moisture absorption rate of the material can be reduced, which indicates that the waterproof performance of the material is improved.

Example 2

(1) The straw fibers were mechanically pulverized to obtain 2mm fibers, which were then soaked in 3 parts of urea for 30 minutes, washed with water to PH 7, and dried in the sun to obtain modified straw fibers.

(2) Weighing 75 parts of wheat starch and 12 parts of calcium carbonate by weight, putting the starch, the calcium carbonate and 6 parts of sodium hypochlorite into water for gelatinization at the gelatinization temperature of 80 ℃ for 30 minutes, and uniformly stirring all the time.

(3) And (3) adding 5 parts of azodicarbonamide into the gelatinized starch prepared in the step (2), uniformly stirring for 8 minutes, then adding 30 parts of modified straw fiber and 50 parts of bentonite, and uniformly stirring for 40 minutes to obtain homogeneous mixed slurry.

(4) And (4) placing the mixed slurry in the step (4) into a mold, setting the temperature of an upper mold to be 210 ℃, the stability of a lower mold to be 205 ℃, keeping the pressure of the mold after closing the mold to be 6MPa, avoiding the phenomenon that the mold is opened and sprayed due to overlarge air pressure in the slurry foaming process, and heating for 5 min.

(5) And opening the upper die and the lower die, demolding and taking out the product.

Example 3

(1) The corn stalks are mechanically crushed to obtain fibers with the diameter of 4mm, then the fibers are soaked in 5 parts of potassium hydroxide for 35 minutes, washed until the pH value is 7, and dried in the sun to obtain the modified corn stalks.

(2) Weighing 100 parts of corn starch and 20 parts of calcium carbonate by weight, and putting the starch, the calcium carbonate and 8 parts of periodic acid into water for gelatinization at 90 ℃ for 20 minutes, wherein the process is accompanied with uniform stirring all the time.

(3) And (3) adding 10 parts of azodicarbonamide into the gelatinized starch prepared in the step (2), uniformly stirring for 10 minutes, then adding 50 parts of modified corn straw and 100 parts of calcium lignosulfonate, and uniformly stirring for 50 minutes to obtain a homogeneous mixed slurry.

(4) And (4) placing the mixed slurry in the step (4) into a mold, setting the temperature of an upper mold to be 195 ℃, the stability of a lower mold to be 190 ℃, keeping the pressure to be 8MPa after mold closing, avoiding the phenomenon that the mold is opened and sprayed due to overlarge air pressure in the slurry foaming process, and heating for 4 min.

(5) And opening the upper die and the lower die, demolding and taking out the product.

Comparative example 1

The difference from example 1 is that calcium carbonate was not added.

Comparative example 2

The difference from example 1 is that calcium carbonate was not added in step (2), and calcium carbonate was added in step (3) together with a filler in an amount of 5 parts.

The test result shows that: by direct addition of CaCO ₃5% CaCO compared to the addition of calcium carbonate as filler (comparative example 2) and gelatinization of the starch (example 1)₃The compressive strength added as a filler was 3.24MPa, slightly stronger than 3.21MPa following gelatinization of the starch. Buffer Performance aspect, corresponding to FIG. 3(b), 5% CaCO₃The energy absorption efficiency added as a filler was 19.5% and that gelatinized with starch was 22.1%, demonstrating better buffering properties of gelatinization with starch. In terms of water-repellent performance, 5% CaCO at 60% RH, corresponding to FIG. 4₃The moisture absorption rate of the filler is 5.8%, and the moisture absorption rate of the filler is only 3.8% when the filler is gelatinized together with starch, so that the gelatinization of the starch proves that the waterproof performance of the filler is better.

It should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and the present invention is not limited thereto, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications and equivalents can be made in the technical solutions described in the foregoing embodiments, or equivalents thereof. 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. Although the present invention has been described with reference to the specific embodiments, it should be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. The plant fiber starch biomass composite material with the open type cell structure is characterized by comprising the following raw materials in parts by weight: 30-50 parts of plant fiber, 50-100 parts of starch, 5-20 parts of inorganic material, 3-5 parts of plant fiber modifier, 4-8 parts of starch modifier, 5-10 parts of foaming agent, 50-100 parts of filler and 300 parts of water 200-containing material;

wherein the inorganic material is calcium carbonate.

2. The plant fiber starch biomass composite material with an open cell structure as claimed in claim 1, which comprises the following raw materials in parts by weight: 30-40 parts of plant fiber, 50-75 parts of starch, 5-12 parts of inorganic material, 3-4 parts of plant fiber modifier, 4-6 parts of starch modifier, 5-7.5 parts of foaming agent, 50-75 parts of filler and 200-250 parts of water;

or comprises the following raw materials in parts by weight: 30-50 parts of plant fiber, 75-100 parts of starch, 12-20 parts of inorganic material, 4-5 parts of plant fiber modifier, 6-8 parts of starch modifier, 7.5-10 parts of foaming agent, 75-100 parts of filler and 300 parts of water.

3. The open cell structured plant fiber starch biomass composite of claim 1, wherein the plant fiber is at least one of sisal fiber, rice straw fiber, corn stover, and wheat straw.

4. The open cell structured plant fiber starch biomass composite of claim 1, wherein said starch is at least one of corn starch, wheat starch and tapioca starch.

5. The open cell structured plant fiber starch biomass composite of claim 1, wherein the plant fiber modifier is urea, hydrogen peroxide, sodium hydroxide or potassium hydroxide.

6. The open cell structured plant fiber starch biomass composite of claim 1, wherein the starch modifier is hydrogen peroxide, sodium hypochlorite or periodic acid.

7. The open cell structured plant fiber starch biomass composite of claim 1, wherein the blowing agent is azodicarbonamide, a complex protein blowing agent, or a nitroso blowing agent.

8. The open cell structured plant fiber starch biomass composite of claim 1, wherein the filler is at least one of talc, bentonite, calcium lignosulfonate.

9. A preparation method of a plant fiber starch biomass composite material with an open type cell structure is characterized by comprising the following steps:

modifying the plant fiber by using hydrogen peroxide to obtain modified plant fiber;

putting starch, calcium carbonate and hydrogen peroxide into water for gelatinization to form slurry;

sequentially adding a foaming agent, a filler and a stripper into the slurry to obtain mixed slurry;

and injecting the mixed slurry into a mold, and carrying out mold pressing foaming.

10. Use of the open cell structured plant fiber starch biomass composite of any of claims 1 to 8 in the field of cushioning packaging, molded articles, household appliances, industrial instrumentation, glass, ceramics.

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