An ecological rod for water conservation and sand fixation and its preparation method

Abstract

The present invention provides an ecological rod for water retention and sand fixation and a preparation method thereof. The raw materials for preparing the ecological rod for water retention and sand fixation include a columnar outer shell and an internal filler. The raw materials for preparing the columnar outer shell include the following components in parts by weight: 70 to 90 parts of PLA, 10 to 20 parts of PBAT, 5 to 15 parts of modified corn starch, 1 to 3 parts of initiator, and 2 to 6 parts of maleic anhydride. The internal filler includes a water retaining agent and a growth substrate as its raw materials. The ecological rod for water retention and sand fixation prepared by the present invention has good water retention performance, certain sand blocking and sand fixation effects, and also has a certain growth substrate, which can promote plant growth, and is particularly suitable for harsh environments, such as cold, dry, saline-alkali land and other areas where plants grow.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological restoration, and particularly relates to an ecological rod for water retention and sand fixation and a preparation method thereof. Background Art

[0002] With the continuous intensification of global climate change and human activities, soil erosion and desertification have become serious ecological environment problems worldwide. Soil erosion leads to a decline in soil fertility and siltation of rivers and lakes, seriously affecting agricultural production and the functions of the ecosystem; while desertification further exacerbates the waste of land resources and the occurrence of sandstorm disasters, posing a serious threat to the ecological environment and economic development of the surrounding areas.

[0003] At present, in response to the above problems, a variety of ecological restoration technologies have been proposed and applied, such as vegetation restoration, soil improvement, engineering sand fixation, etc. However, these methods often have problems such as high cost, limited effect, and difficulty in long-term maintenance in practical applications. Therefore, it is particularly important to develop an economical, efficient, and sustainable water retention and sand fixation technology.

[0004] The ecological rod for water retention and sand fixation is a new type of ecological restoration material that emerged under this background. By processing nutrient materials such as plant soil, fertilizers, and seeds into a tubular structure through a special process, it not only has a good soil fixation effect but also can effectively retain soil moisture and promote plant growth, thus realizing the effective treatment of soil erosion and desertification.

[0005] Although the existing ecological restoration technologies have alleviated the problems of soil erosion and desertification to a certain extent, there are still the following deficiencies: High cost: Some technologies require high material costs and construction costs and are difficult to be popularized and applied on a large scale. Limited effect: Some technologies can improve the soil condition in the short term, but the long-term effect is not ideal and it is difficult to maintain the stability of the ecosystem. Difficult to degrade: Some sand fixation materials are difficult to degrade and may cause secondary pollution to the soil and groundwater.

[0006] In view of the deficiencies of the existing technology, the present invention aims to provide an economical, efficient, and sustainable ecological rod for water retention and sand fixation and its preparation and application methods. This ecological rod can not only effectively fix sand and retain water, promote plant growth, but also has the advantages of easy degradation and environmental friendliness, providing a new solution for the treatment of soil erosion and desertification problems. Summary of the Invention

[0007] The object of the present invention is to provide an ecological rod for water retention and sand fixation and a preparation method thereof. The ecological rod for water retention and sand fixation can not only effectively fix sand and retain water, but also promote plant growth, is easy to degrade, and is environmentally friendly, providing a new solution for the treatment of soil erosion and desertification problems.

[0008] An ecological rod for water retention and sand fixation provided by the present invention, the preparation raw materials of which include a columnar outer shell and an internal filler.

[0009] The preparation raw materials of the columnar outer shell, by weight, include the following components: 70-90 parts of polylactic acid (PLA), 10-20 parts of polybutylene adipate / terephthalate (PBAT), 5-15 parts of modified corn starch, 1-3 parts of initiator, and 2-6 parts of maleic anhydride.

[0010] Preferably, the melt index of the PLA at 190 °C is 1-5 g / 10 min, the tensile strength is 30-35 MPa, the flexural strength is 53-56 MPa, and the flexural modulus is 2600-2800 MPa.

[0011] In some preferred embodiments, the PLA is purchased from Zibo Tianju Hongchuan New Material Technology, THJS-8801-1.

[0012] Preferably, the elongation at break of the PBAT ≥ 300%, the melt index at 190 °C is 1-5 g / 10 min, and the Vicat softening temperature ≥ 80 °C; further preferably, the elongation at break of the PBAT ≥ 400%, the melt index at 190 °C is 2.5-4.5 g / 10 min, and the Vicat softening temperature ≥ 80 °C.

[0013] In some preferred embodiments, the PBAT is purchased from Xinjiang Blue Mountain Tunhe Chemical Industry, TH-801T.

[0014] The preparation method of the modified corn starch includes the following steps: After vacuum drying corn starch at 70-90 °C to constant weight, adding a modifier, stirring evenly and sealing, taking it out after vacuum drying at 70-90 °C for 5-8 h, and melt-blending at 110-130 °C to obtain the modified corn starch.

[0015] Preferably, the addition amount of the modifier is 20-30% of the corn starch.

[0016] Preferably, the modifier is glycerol and sorbitol.

[0017] Preferably, the mass ratio of glycerol to sorbitol is 1:(0.5-2); further preferably, it is 1:1.

[0018] In practical applications, there are relatively high requirements for the columnar outer shell of the ecological rod, which need to have a certain toughness and water resistance. This helps the ecological rod maintain a stable shape under the action of wind, is not easily damaged, improves its wind resistance performance, and at the same time does not absorb too much water, improving its water retention performance. In addition, the outer shell should preferably be made of biodegradable materials. After use, it will not cause long-term pollution to the environment, and the degradation products can also provide nutrients for plant growth as fertilizers. Corn starch is a natural biodegradable material and is inexpensive, but its own structural limitations make it impossible to be processed and formed by the melting method. The inventor found that by using glycerol and sorbitol with a mass ratio of 1:(0.5-2) as modifiers to modify corn starch, it is possible to improve the mechanical properties of the columnar outer shell of the ecological rod while also improving the processing performance. This may be because the two modifiers act synergistically to destroy the original crystalline structure of the starch, making the starch molecules become loose, thereby improving the thermoplasticity of the starch, enabling it to be processed and formed by the melting method, and thus improving the various properties of the columnar outer shell of the formed ecological rod. At the same time, the two substances will also react with the starch to form new bonds, further enhancing the starch strength. The smaller glycerol molecules also have a certain lubricating effect, thereby further improving the processing performance. The inventor found in actual experiments that although glycerol has a better plasticizing effect than sorbitol and can improve the biodegradability of the columnar outer shell, too much addition of it will cause the corn starch to be over-plasticized, and the molecules are more likely to slip between each other, resulting in a decrease in tensile strength and affecting the mechanical properties of the columnar outer shell of the ecological rod. Even after modifying the corn starch, its compatibility with PLA and PBAT is still poor, and the three substances are only physically blended, thus affecting the performance of the finally prepared ecological rod.

[0019] Preferably, the mass ratio of the PLA, PBAT, and modified corn starch is (7-9):(1-2):1; more preferably, it is 16:3:2.

[0020] Preferably, the initiator is benzoyl peroxide.

[0021] The inventors found that by selecting a specific PBAT, with the mass ratio of PLA, PBAT, and modified corn starch being (7-9):(1-2):1, and introducing maleic anhydride simultaneously, it is possible to improve the mechanical properties of the prepared columnar shell while enhancing its water resistance, thereby improving the windproof and water retention properties of the ecological rod. This may be because on the one hand, the segments of PLA will form an interpenetrating network structure with the segments of PBAT, thus enhancing the intermolecular interaction force and also being able to change the crystallization behavior of PBAT, thereby improving the mechanical properties of the columnar shell. On the other hand, the filling effect and interfacial interaction of the modified corn starch can not only reduce the movement of PBAT segments, thereby improving the mechanical properties of the columnar shell, but also be compounded with PLA to hinder the penetration of water molecules to a certain extent, improve the water resistance of the composite material, and improve the barrier properties of the columnar shell. However, too high an addition amount of corn starch will significantly reduce the melt strength, which is not conducive to processing and forming the columnar shell from the material. In addition, the introduction of an appropriate amount of maleic anhydride can not only promote the grafting reaction of glycerol on the molecular chain of corn starch, but also enhance the interfacial bonding force between PLA, PBAT, and the modified corn starch, promote the grafting of corn starch and polymer, improve the interaction force between the two phases, increase the compatibility of corn starch in the system, form a three-dimensional network structure through cross-linking reaction, and reduce the water molecule penetration channels, thereby improving the various properties of the columnar shell. However, if the addition amount of maleic anhydride is too high, intermolecular interaction will occur among itself, which is not conducive to the dispersion of corn starch in the system, thus affecting the forming effect and further affecting the various properties of the finally obtained columnar shell.

[0022] The preparation method of the columnar shell includes the following steps: drying the raw materials and mixing them evenly, extruding the mixture after melt blending to obtain pellets, and then injection molding and pressing the crushed pellets to obtain the columnar shell.

[0023] Preferably, the melt blending temperature is 175-190°C and the rotation speed is 30-50 r / min.

[0024] Preferably, the injection molding pressure is 8-12 MPa and the injection molding temperature is 170-180°C.

[0025] The preparation raw materials of the internal filler include a water retaining agent and a growth substrate.

[0026] The addition amount of the water retaining agent is 2%-5% of the mass of the growth substrate.

[0027] The preparation method of the water retaining agent comprises the following steps: taking poly(succinimide), uniformly dispersing it in water, adding an appropriate amount of crosslinking agent, stirring at 35-40 °C and adding sodium hydroxide solution until the pH is 8-9, cooling to room temperature after the solution becomes clear and transparent, adding modified attapulgite, acrylamide, acrylic acid, and sodium alginate, stirring evenly, heating to 60-70 °C, adding potassium persulfate, continuing to stir for 3-5 h, and then drying and pulverizing to obtain the product.

[0028] Preferably, the average molecular weight of the poly(succinimide) is 8000-10000.

[0029] In some preferred embodiments, the poly(succinimide) is purchased from Shanghai Macklin Biochemical Co., Ltd.

[0030] Preferably, the mass ratio of the poly(succinimide) to water is 1:(20-40).

[0031] Preferably, the crosslinking agent is γ-aminopropyltriethoxysilane (KH550) and γ-methacryloxypropyltrimethoxysilane (KH570).

[0032] Preferably, the mass ratio of KH550 to KH570 is 1:(0.5-2); more preferably, it is 1:1.

[0033] Preferably, the addition amount of the crosslinking agent is 1.5-2 mol% of the poly(succinimide).

[0034] Preferably, the concentration of the sodium hydroxide solution is 1 mol / L.

[0035] The preparation method of the modified attapulgite comprises the following steps: dissolving an attapulgite modifier in an ethanol aqueous solution with a concentration of 80 wt%, adding attapulgite, stirring at 75-85 °C for 2-4 h, filtering, and drying at 100 °C for 12 h to obtain the product.

[0036] Preferably, the attapulgite modifier is sodium dodecylbenzenesulfonate and cetyltrimethylammonium chloride.

[0037] Preferably, the mass ratio of the sodium dodecylbenzenesulfonate to the cetyltrimethylammonium chloride is 1:(1-3); more preferably, it is 1:2.

[0038] Preferably, the mass ratio of the modifier to the ethanol aqueous solution is 1:25-35; more preferably, it is 1:30.

[0039] Preferably, the adsorption rate of the attapulgite is 32%, the compressive strength is 80 MPa, and the particle size is 0.01 μm.

[0040] In some preferred embodiments, the attapulgite clay is purchased from Marlene Mineral Products Processing Factory in Lingshou County.

[0041] Preferably, the mass ratio of the attapulgite clay to the modifier is 1:1 to 2; more preferably, it is 2:3.

[0042] In some preferred embodiments, adding a certain amount of attapulgite clay can not only improve the water-retaining and sand-fixing performance of the water-retaining agent but also enhance its temperature and weather resistance. This is because attapulgite clay has a unique rod-like crystal structure, which can increase the porosity and specific surface area of the soil, thus providing more water storage space. The excellent physical and chemical stability of attapulgite clay helps the soil maintain the stability of its structure and function under extreme climate conditions, improving the temperature and weather resistance of the soil. In addition, attapulgite clay can also adjust the pH value of the soil to keep it within an appropriate range, which is beneficial to the activities of soil microorganisms and the growth of plants, and thus helps the soil maintain its ecological balance and stability under different climate conditions. However, the compatibility between attapulgite clay and the polymer is poor, and it is easy to agglomerate in the system, affecting the effect.

[0043] The inventors found that using sodium dodecylbenzenesulfonate and cetyltrimethylammonium chloride to modify attapulgite clay can not only improve the compatibility between attapulgite clay and the polymer but also further enhance the water-retaining and sand-fixing effect. This may be because sodium dodecylbenzenesulfonate and cetyltrimethylammonium chloride act synergistically and interact with the surface of attapulgite clay through physical adsorption and chemical bonding, changing its surface properties and forming an organic film on the surface of attapulgite clay, which helps to enhance the compatibility with the polymer. On the one hand, sodium dodecylbenzenesulfonate and cetyltrimethylammonium chloride insert into the interlayer structure of attapulgite clay through intercalation, increasing the interlayer spacing, making the binding between soil particles closer, and also helping to form a closer binding with the polymer. On the other hand, their hydrophilic and hydrophobic ends form a balanced state in the soil, which not only ensures the hydrophilicity of the soil for water storage but also reduces the evaporation of water and the flow of sand grains through the hydrophobic network.

[0044] Preferably, the molar ratio of the polysuccinimide, acrylamide, and acrylic acid is 1:(0.5 to 2):(2 to 4); more preferably, it is 1:1:3.

[0045] The inventors found that when using specific poly(succinimide), acrylamide, and acrylic acid as raw materials to prepare a water-retaining agent, it can not only improve the water-retaining and sand-fixing functions of the ecological rod, but also promote plant growth. This is because the molecular chains of the three polymers are intertwined and crosslinked during the compounding process, forming a stable three-dimensional network structure. This structure not only improves the mechanical strength of the hydrogel, but also enhances its water-retaining property and sand-fixing ability. The carboxyl, hydroxyl and other hydrophilic groups of polyaspartic acid interact with the polar groups of polyacrylamide and polyacrylic acid to form more hydrogen bonds and ionic bonds, thereby improving the water absorption and stability of the hydrogel. In addition, during the degradation process of the water-retaining agent, nutrients such as polyaspartic acid are released, which can be absorbed and utilized by plants to promote the growth and development of plants. At the same time, the degradation products are harmless to the environment and meet the requirements of green chemistry. However, only these three polymers have poor weather resistance and are susceptible to thermal-oxidative aging and photo-oxidative aging, resulting in chain scission and crosslinking reactions, which affect the sand-proof and sand-fixing performance.

[0046] Preferably, the addition amount of the modified attapulgite is 3% to 5% of the total mass of poly(succinimide), acrylamide, and acrylic acid.

[0047] Preferably, the dosage of sodium alginate is 1% to 2% of the total mass of poly(succinimide), acrylamide, and acrylic acid.

[0048] Preferably, the dosage of potassium persulfate is 1% to 2% of the total mass of acrylamide and acrylic acid.

[0049] Preferably, the growth substrate is soil.

[0050] The preparation method of the ecological rod for water retention and sand fixation comprises the step of filling the internal filler into the columnar outer shell.

[0051] In some preferred embodiments, the ecological rod for water retention and sand fixation has a diameter of 10 to 15 cm, and cold-resistant, drought-resistant, salt-tolerant and other shrub plants are cultivated inside it. Under the action of the ecological rod, the plants can grow smoothly, and after the plants grow, they can play a role in sand blocking and sand fixation. It is very suitable for popularization and use, and is of great significance for protecting the environment and controlling soil erosion and desertification problems.

[0052] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0053] 1. The present invention provides an ecological rod for water retention and sand fixation, which can not only effectively fix sand and retain water, but also promote plant growth, is easily degradable, and is environmentally friendly, providing a new solution for the treatment of soil erosion and desertification problems.

[0054] 2. The present invention selects glycerol and sorbitol with a mass ratio of 1:(0.5 - 2) as modifiers to modify corn starch, which can improve the mechanical properties of the ecological rod-shaped shell while also enhancing the processing performance.

[0055] 3. The present invention selects a specific PBAT, and the mass ratio of the PLA, PBAT, and modified corn starch is (7 - 9):(1 - 2):1. Meanwhile, maleic anhydride is introduced, which can improve the mechanical properties of the prepared columnar shell while enhancing its water resistance, thereby improving the wind prevention and water retention of the ecological rod.

[0056] 3. The present invention prepares a water-retaining agent using specific poly(succinimide), acrylamide, and acrylic acid as raw materials, which can not only improve the water retention and sand fixation function of the ecological rod but also promote plant growth.

[0057] 4. The present invention selects attapulgite as one of the raw materials, which can improve the sand fixation and water retention performance of the water-retaining agent while also enhancing its temperature and weather resistance.

[0058] 5. The present invention uses sodium dodecylbenzenesulfonate and cetyltrimethylammonium chloride to modify attapulgite, which can not only improve the compatibility between attapulgite and the polymer but also further enhance the water retention and sand fixation effect. Detailed implementation manners

[0059] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0060] All raw materials used in the present invention are commercially available. Specifically:

[0061] PLA, with a melt index of 1 - 5 g / 10 min at 190°C, a tensile strength of 30 - 35 MPa, a flexural strength of 53 - 56 MPa, and a flexural modulus of 2600 - 2800 MPa, is purchased from Zibo Tianju Hongchuan New Material Technology Co., Ltd., THJS - 8801 - 1.

[0062] PBAT, with an elongation at break ≥ 400%, a melt index of 2.5 - 4.5 g / 10 min at 190°C, and a Vicat softening temperature ≥ 80°C, is purchased from Xinjiang Blueshirt Tunhe Chemical Co., Ltd., TH - 801T.

[0063] Poly(succinimide), with an average molecular weight of 8000 - 10000, is purchased from Shanghai Macklin Biochemical Co., Ltd.

[0064] Attapulgite clay, with an adsorption rate of 32%, a compressive strength of 80 MPa, and a particle size of 0.01 μm, was purchased from Marlene Mineral Products Processing Factory in Lingshou County.

[0065] Example 1

[0066] This example provides an ecological rod for water retention and sand fixation, and its preparation raw materials are a columnar outer shell and internal filler.

[0067] The preparation raw materials of the columnar outer shell, by weight, include the following components: 80 parts of PLA, 15 parts of PBAT, 10 parts of modified corn starch, 2 parts of initiator, and 4 parts of maleic anhydride.

[0068] The preparation method of the modified corn starch includes the following steps: After vacuum drying corn starch at 8°C until constant weight, add a modifier, stir evenly and seal, take it out after vacuum drying at 80°C for 7 h, and blend at 120°C to obtain the modified corn starch.

[0069] The added mass of the modifier is 25% of the corn starch.

[0070] The modifier is glycerol and sorbitol.

[0071] The mass ratio of glycerol to sorbitol is 1:1.

[0072] The initiator is benzoyl peroxide.

[0073] The preparation method of the columnar outer shell is as follows: Dry the raw materials and mix them evenly, extrude the melt blend to obtain pellets, and then crush and injection mold the pellets to obtain it.

[0074] The melt blending temperature is 180°C and the rotation speed is 40 r / min.

[0075] The injection pressure is 10 MPa and the injection temperature is 190°C.

[0076] The internal filler, its preparation raw materials, are a water retention agent and a growth substrate.

[0077] The addition amount of the water retention agent is 3% of the mass of the growth substrate.

[0078] The preparation method of the water retention agent includes the following steps: Take poly(succinimide) and disperse it evenly in water, add an appropriate amount of crosslinking agent, stir at 38°C and add sodium hydroxide solution until the pH is 8.5. After the solution is clear and transparent, cool it to room temperature, add modified attapulgite clay, acrylamide, acrylic acid, and sodium alginate, stir evenly and then heat up to 65°C, add potassium persulfate, continue to stir for 4 h, and then dry and crush to obtain it.

[0079] The mass ratio of poly(succinimide) to water is 1:30.

[0080] The crosslinking agent is KH550 and KH570.

[0081] The mass ratio of KH550 to KH570 is 1:1.

[0082] The addition amount of the crosslinking agent is 1.5 mol% of poly(succinimide).

[0083] The concentration of the sodium hydroxide solution is 1 mol / L.

[0084] The preparation method of the modified attapulgite includes the following steps: Dissolve the attapulgite modifier in an ethanol aqueous solution with a concentration of 80 wt%, then add attapulgite, stir at 80 °C for 3 h, filter, and dry at 100 °C for 12 h to obtain.

[0085] The attapulgite modifier is sodium dodecylbenzenesulfonate and cetyltrimethylammonium chloride.

[0086] The mass ratio of sodium dodecylbenzenesulfonate to cetyltrimethylammonium chloride is 1:2.

[0087] The mass ratio of the modifier to the ethanol aqueous solution is 1:30.

[0088] The mass ratio of attapulgite to the modifier is 2:3.

[0089] The molar ratio of poly(succinimide), acrylamide, and acrylic acid is 1:1:3.

[0090] The addition amount of the modified attapulgite is 4% of the total mass of poly(succinimide), acrylamide, and acrylic acid.

[0091] The dosage of sodium alginate is 1.5% of the total mass of poly(succinimide), acrylamide, and acrylic acid.

[0092] The dosage of potassium persulfate is 1.2% of the total mass of acrylamide and acrylic acid.

[0093] The growth substrate is soil.

[0094] The preparation method of the ecological rod for water retention and sand fixation is: Fill the internal filler into the columnar outer shell to obtain.

[0095] Example 2

[0096] The difference between this example and Example 1 is that the raw materials for preparing the columnar outer shell, by weight, include the following components: 70 parts of PLA, 10 parts of PBAT, 10 parts of modified corn starch, 2 parts of initiator, and 4 parts of maleic anhydride.

[0097] Example 3

[0098] The difference between this example and Example 1 is that the molar ratio of the poly(succinimide), acrylamide, and acrylic acid is 1:2:3.

[0099] Comparative Example 1

[0100] The difference between this comparative example and Example 1 is that the raw materials for preparing the columnar outer shell include the following components by weight: 60 parts of PLA, 15 parts of PBAT, 10 parts of modified corn starch, 2 parts of initiator, and 4 parts of maleic anhydride.

[0101] Comparative Example 2

[0102] The difference between this comparative example and Example 1 is that the raw materials for preparing the columnar outer shell include the following components by weight: 80 parts of PLA, 15 parts of PBAT, 10 parts of modified corn starch, 2 parts of initiator, and 10 parts of maleic anhydride.

[0103] Comparative Example 3

[0104] The difference between this comparative example and Example 1 is that the modifier is glycerol.

[0105] Comparative Example 4

[0106] The difference between this comparative example and Example 1 is that the attapulgite modifier is sodium dodecylbenzenesulfonate.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 1 is that the preparation method of the water retaining agent comprises the following steps: taking poly(succinimide) and uniformly dispersing it in water, adding an appropriate amount of crosslinking agent, stirring at 38°C and adding sodium hydroxide solution until the pH is 8.5, cooling to room temperature after the solution becomes clear and transparent, adding attapulgite, acrylamide, acrylic acid, and sodium alginate, stirring evenly and then heating to 65°C, adding potassium persulfate, continuing to stir for 4 h, and then drying and pulverizing to obtain.

[0109] Comparative Example 6

[0110] The difference between this comparative example and Example 1 is that the preparation method of the water retaining agent comprises the following steps: taking poly(succinimide) and uniformly dispersing it in water, adding an appropriate amount of crosslinking agent, stirring at 38°C and adding sodium hydroxide solution until the pH is 8.5, cooling to room temperature after the solution becomes clear and transparent, adding modified attapulgite, acrylic acid, and sodium alginate, stirring evenly and then heating to 65°C, adding potassium persulfate, continuing to stir for 4 h, and then drying and pulverizing to obtain.

[0111] The molar ratio of the poly(succinimide) to the acrylic acid is 1:3.

[0112] The addition amount of the modified attapulgite is 4% of the total mass of the poly(succinimide) and the acrylic acid.

[0113] The dosage of the sodium alginate is 1.5% of the total mass of the poly(succinimide) and acrylic acid.

[0114] The dosage of the potassium persulfate is 1.2% of the mass of the acrylic acid.

[0115] Comparative Example 7

[0116] The difference between this comparative example and Example 1 is that the molar ratio of the poly(succinimide), acrylamide, and acrylic acid is 1:3:5.

[0117] Performance test

[0118] Completely immerse the internal filler and the columnar outer shell in water, take them out after soaking until the mass does not change, and put them into the columnar outer shell, and measure their mass M1 at this time. Put the water-saturated internal filler into the columnar outer shell, and place it in an environment with a temperature of 50 °C, a relative humidity of 0, and a light intensity of 100% for 7 days, and then test its mass M2. The mass loss rate = (M1 - M2) / M1 × 100%. The lower the mass loss rate, the better the water retention performance. Referring to the method of Patent 202110090064.5, place alfalfa seeds in the water-saturated ecological rod for cultivation, and set the external environmental conditions as: temperature of 50 °C, relative humidity of 0, and light intensity of 100%, and record the germination rate of the seeds for 30 days. The results are shown in Table 1.

[0119] Table 1 Measurement results

[0120] Mass loss rate / % Germination rate / % Example 1 13.8 95.8 Example 2 14.2 95.4 Example 3 14.3 95.3 Comparative Example 1 18.6 90.5 Comparative Example 2 19.1 89.7 Comparative Example 3 17.5 92.1 Comparative Example 4 20.1 90.3 Comparative Example 5 28.3 78.8 Comparative Example 6 22.9 84.6 Comparative Example 7 19.7 88.5

[0121] According to statistics, the ecological rods for water retention and sand fixation prepared in Examples 1 to 3 of the present invention have a lower mass loss rate in harsh environments and a higher plant germination rate at the same time. In Comparative Example 1, the addition amount of PLA is too small. In Comparative Example 2, the addition amount of maleic anhydride is too large. In Comparative Example 3, the sorbitol modifier is not added. In Comparative Example 4, the hexadecyltrimethylammonium chloride attapulgite modifier is not added. In Comparative Example 5, the attapulgite is not modified. In Comparative Example 6, acrylamide is not added. In Comparative Example 7, the addition amounts of acrylamide and acrylic acid are excessive. The prepared ecological rods have a higher mass loss rate and a low seed germination rate. Therefore, the ecological rods for water retention and sand fixation prepared by using the raw materials and methods described in the present application can not only effectively fix sand and retain water, but also promote plant growth, are easily degradable, and are environmentally friendly, providing a new solution for the treatment of soil erosion and desertification problems.

[0122] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. An ecological stick for retaining water and fixing sand, characterized in that: In parts by weight, raw materials are prepared, including a columnar shell and an internal filler; The raw materials for preparing the columnar shell include, by weight: 70-90 parts of PLA, 10-20 parts of PBAT, 5-15 parts of modified corn starch, 1-3 parts of initiator, and 2-6 parts of maleic anhydride; PLA has a melt index of 1-5 g / 10 min at 190° C., a tensile strength of 30-35 MPa, a flexural strength of 53-56 MPa, and a flexural modulus of 2600-2800 MPa; PBAT has an elongation at break of ≥300%, a melt index of 1-5 g / 10 min at 190° C., and a Vicat softening temperature of ≥80° C. The raw materials for preparing the internal filling material include a water retaining agent and a growth substrate; The preparation method of the water retaining agent comprises: uniformly dispersing polysuccinimide in water, adding a proper amount of a crosslinking agent, stirring at 35-40°C and adding a sodium hydroxide solution until the pH value is 8-9, cooling the solution to room temperature after the solution becomes clear and transparent, adding modified attapulgite, acrylamide, acrylic acid, and sodium alginate, stirring evenly and heating to 60-70°C, adding potassium persulfate, continuing stirring for 3-5 hours, and drying and crushing to obtain the water retaining agent; the molar ratio of polysuccinimide, acrylamide, and acrylic acid is 1: (0.5-2): (2-4); The preparation method of modified corn starch comprises: vacuum drying corn starch at 70-90° C. to constant weight, adding a modifier, stirring evenly and sealing, vacuum drying at 70-90° C. for 5-8 hours and then taking out, and melt blending at 110-130° C. to obtain modified corn starch; the modifier is composed of glycerol and sorbitol in a mass ratio of 1:(0.5-2); The preparation method of modified attapulgite comprises: dissolving an attapulgite modifier in an ethanol aqueous solution having a concentration of 80 wt%, adding attapulgite, stirring at 75 to 85 ° C for 2 to 4 hours, filtering, and drying at 100 ° C for 12 hours to obtain; the attapulgite modifier is composed of sodium dodecylbenzene sulfonate and hexadecyltrimethylammonium chloride in a mass ratio of 1: (1 to 3); The mass ratio of PLA, PBAT and modified corn starch is (7~9):(1~2):

1.

2. The water-retaining and sand-fixing ecological stick according to claim 1, characterized in that: The preparation method of the columnar shell comprises the following steps: drying the raw materials and mixing them evenly, extruding them after melt blending to obtain pellets, and crushing the pellets and then performing injection molding to obtain the pellets.

3. The water-retaining and sand-fixing ecological stick according to claim 1, characterized in that: The average molecular weight of the polysuccinimide is 8000-10000.

4. The method for preparing the water-retaining and sand-fixing ecological stick according to claim 1, characterized in that: The growth substrate is soil.

5. A method for preparing the water-retaining and sand-fixing ecological stick according to any one of claims 1 to 4, characterized in that: The steps are as follows: filling the internal filling material into the columnar outer shell.