Environmentally degradable plastic as well as preparation method and application thereof

Abstract

The invention discloses environmentally degradable plastic as well as a preparation method and application thereof, and belongs to the technical field of degradable plastic. The degradable modified plastic is prepared from the following raw materials: polylactic acid, poly (butylene terephthalate)-adipate, modified thermoplastic starch, modified cellulose, poly (butylene succinate), epoxidized soybean oil, polyvinyl alcohol, glycerol monolaurate and ethylenediaminetetraacetic acid. Wherein the modified thermoplastic starch is obtained by thermoplastic modification of starch through a plasticizer and modification of castor oil and toluene diisocynate; the modified cellulose is obtained by modifying cellulose acetate with chitosan. By regulating and controlling the types and proportions of the raw materials for preparing the plastic, the plastic with excellent degradation performance and mechanical performance can be obtained, the shopping bag is prepared from the plastic, the loading capacity can be remarkably improved, the plastic is easily degraded by microorganisms in the environment after being discarded, and environmental pollution is avoided.

Description

Technical Field

[0001] This invention belongs to the field of degradable plastics technology, specifically relating to an environmentally degradable plastic, its preparation method, and its application. Background Technology

[0002] As is well known, plastic products have advantages such as low price, light weight, durability, and good plasticity, making them widely used in industries such as construction, transportation, packaging, and agricultural production. Shopping bags provide great convenience in daily life and are essential items for shopping trips. Plastic shopping bags are probably the most widespread in China, causing serious environmental pollution. The development and application of biodegradable plastics is one of the most effective ways to solve this problem. Although biodegradable films are already used in current technology, the strength of existing biodegradable shopping bags needs improvement, thus limiting their load-bearing capacity. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides an environmentally degradable plastic, its preparation method and application, to solve the technical problems of existing plastic shopping bags being difficult to degrade in the environment and having limited load-bearing capacity.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is to provide an environmentally degradable plastic, the raw materials of which include the following components in parts by weight:

[0005] 55-65 parts polylactic acid, 20-30 parts polybutylene terephthalate-adipate, 1-3 parts modified thermoplastic starch, 0.5-2 parts modified cellulose, 5-10 parts polybutylene succinate, 3-8 parts epoxidized soybean oil, 3-6 parts polyvinyl alcohol, 1-3 parts glyceryl monolaurate and 3-6 parts ethylenediaminetetraacetic acid;

[0006] Modified thermoplastic starch is obtained through the following steps:

[0007] S1: Dry the starch until the moisture content is less than 1%, then add the dried starch and plasticizer into a mixing device at a mass ratio of 10:2~3 and mix at a mixing speed of 800~1000 rpm for 30~60 minutes to obtain a mixture; the plasticizer is glycerol, sorbitol or ethylenedicarboxamide;

[0008] S2: The mixture is extruded through a single screw extruder. The extrusion temperature from the feed inlet to the outlet is set to 140℃→160℃→150℃→140℃. After extrusion, the mixture is granulated and dried to constant weight to obtain thermoplastic starch granules.

[0009] S3: Castor oil is added dropwise to an acetone solution containing a catalyst and toluene diisocyanate in a water bath at 55~65℃, and stirred for 30~60 min to obtain a coating prepolymer; the catalyst is stannous octoate.

[0010] S4: dipping the thermoplastic starch particles in the coating prepolymer for 30-60s, draining after fishing out, and aging at 75-85℃ for 10-16h to obtain the modified thermoplastic starch;

[0011] The modified cellulose is prepared through the following steps:

[0012] (1) adding chitosan and cellulose acetate in a mass ratio of 5-10:90-95 into an acetic acid aqueous solution with a volume fraction of 4%, swelling at room temperature for 2h, and then stirring at 40-50℃ at a stirring speed of 800-1000rpm until completely dissolved to obtain a blending solution;

[0013] (2) adding an aqueous ferric salt solution into the blending solution under stirring to obtain a mixed solution;

[0014] (3) performing vacuum defoaming treatment on the mixed solution to obtain a spinning solution;

[0015] (4) preparing the spinning solution into a fiber yarn through a wet spinning process to obtain the modified cellulose.

[0016] On the basis of the above technical solutions, the application can be further improved as follows.

[0017] Further, the raw materials for preparation include the following components in mass parts:

[0018] 60 parts of polylactic acid, 25 parts of polybutylene adipate terephthalate, 2 parts of modified thermoplastic starch, 1 part of modified cellulose, 6 parts of polybutylene succinate, 5 parts of epoxy soybean oil, 4 parts of polyvinyl alcohol, 2 parts of lauric acid monoglyceride, and 5 parts of ethylenediaminetetraacetic acid.

[0019] Further, the starch in S1 is corn powder, cassava powder or wheat powder.

[0020] Further, the amount of castor oil and toluene diisocyanate in S3 is n(-NCO) / n(-OH)=2-4:1.

[0021] Further, the solute of the aqueous ferric salt solution in step (2) is ferric chloride, ferric nitrate or ferric sulfate.

[0022] Further, the mass ratio of the added ferric salt to chitosan is 2-5:10.

[0023] The beneficial effects of the technical scheme of the present application are: the degradable plastic in the present application takes polylactic acid, polybutylene adipate terephthalate, polybutylene succinate, epoxy soybean oil and polyvinyl alcohol as main raw materials, which all have good biodegradability and can be rapidly degraded by microorganisms in the environment, and the finally obtained plastic can be effectively degraded in the environment, which can effectively avoid the environmental pollution problem caused by the use of plastic.

[0024] In addition to the above components, the raw materials for preparing the plastic in the present application also include modified thermoplastic starch and modified cellulose. The modified thermoplastic starch is obtained by continuing to modify the starch after thermoplastic modification by a plasticizer, and then modifying by castor oil and toluene diisocyanate. The modified thermoplastic starch retains the biodegradable core structure of the starch itself and can also improve the performance of the starch, so that it can be uniformly distributed in the plastic system as a dispersed phase. When the plastic is invaded by microorganisms, the modified thermoplastic starch uniformly dispersed in the plastic is first decomposed, thereby forming a microporous structure in the plastic, increasing the surface area of the plastic, and accelerating the breakage of the polymer molecular chain in the plastic, thereby promoting the degradation process of the entire plastic. At the same time, the oligosaccharides or monosaccharides produced by the decomposition of the modified thermoplastic starch can serve as a nutrient source for microorganisms, thereby promoting the growth and reproduction of microorganisms and further accelerating the degradation of the plastic. In addition, the modified starch can improve the compatibility between the starch and the degradable plastic matrix, and when added to the plastic system, it helps to reduce interfacial defects and improve stress transfer efficiency, thereby enhancing the tensile strength and elongation at break of the material. Moreover, the introduction of the modified thermoplastic starch not only increases the hydrogen bond interaction in the material, thereby improving the toughness of the material and making the plastic more difficult to deform under stress, but also uniformly distributes in the plastic matrix, which helps to form a "sea-island" structure that can inhibit the initiation and propagation of cracks, thereby improving the toughness of the plastic. The modified cellulose is obtained by modifying cellulose acetate with chitosan. Although cellulose acetate itself has a certain biodegradability, its degradation rate is greatly affected by the degree of substitution. However, after modification with chitosan, a material with a double degradation mechanism is formed, i.e. hydrolytic degradation of the cellulose acetate backbone and enzymatic degradation of chitosan, thereby accelerating the degradation process of the entire material. Moreover, iron ions are introduced into the cellulose system during the modification process, and the finally obtained modified cellulose can release iron ions. Iron ions not only act as catalysts for redox reactions to promote the degradation of plastic, but also promote the activity of bacterial enzymes, thereby accelerating the decomposition of plastic by microorganisms. The introduction of modified cellulose into the plastic system can improve the mechanical properties of the plastic in cooperation with the modified thermoplastic starch, and impart high strength to the obtained plastic.

[0025] The preparation raw material of the plastic in the application further includes lauric acid monoglyceride and ethylenediaminetetraacetic acid; wherein, the lauric acid monoglyceride has good emulsifying performance, can effectively improve the dispersibility and compatibility between components in the plastic, thereby endowing the plastic with excellent mechanical properties; and adding a specific amount of lauric acid monoglyceride can improve the surface properties of the plastic, so that microorganisms can more easily attach to and erode the plastic, thereby promoting the degradation of the plastic in the environment; in addition, the lauric acid monoglyceride has excellent low-temperature performance and toughness, and after being added to the plastic, it can act together with the filler to improve the toughness of the plastic, so that the plastic can better resist deformation and rupture when subjected to external force.

[0026] The application further discloses a preparation method of the environment-degradable plastic.

[0027] (1) mixing formula amount of raw material components, then putting the mixture into a banbury mixer for banburying to obtain a base material;

[0028] (2) putting the base material into a screw extruder, extruding and shaping through the screw extruder, and thus obtaining the environment-degradable plastic.

[0029] Further, the banburying temperature in step (1) is 180-190 DEG C, and the banburying time is 45-60 min.

[0030] Further, in step (2), the screw extruder is sequentially provided with a first melting section with a temperature of 140-150 DEG C, a second melting section with a temperature of 160-170 DEG C and a third melting section with a temperature of 130-140 DEG C from the feeding end to the discharging end, the screw rotating speed is 110 rpm, and the extrusion outlet temperature is 135 DEG C.

[0031] The application further discloses an application of the environment-degradable plastic, and specifically, the environment-degradable plastic is used for preparing a plastic shopping bag.

[0032] The application has the beneficial effects that: by regulating the types and proportions of the preparation raw materials of the plastic, a plastic with excellent degradation performance and mechanical properties can be obtained, the plastic is made into a shopping bag, the load-carrying capacity of the shopping bag can be significantly improved, and the shopping bag can be easily degraded by microorganisms in the environment after being discarded, so that environmental pollution is avoided. DETAILED DESCRIPTION

[0033] Unless otherwise specified, all the materials used in the embodiments of the application are commercially available products.

[0034] The specific embodiments of the application are described in detail below with reference to the examples.

[0035] Example 1

[0036] An environment-degradable plastic, preparation raw materials include the following components by mass:

[0037] Polylactic acid 60 parts, polybutylene adipate terephthalate 25 parts, modified thermoplastic starch 2 parts, modified cellulose 1 part, polybutylene succinate 6 parts, epoxy soybean oil 5 parts, polyvinyl alcohol 4 parts, lauric acid monoglyceride 2 parts and ethylenediaminetetraacetic acid 5 parts; wherein the modified thermoplastic starch is prepared by the following steps:

[0038] S1: dry the corn starch to a moisture content of less than 1%, then put the dried corn starch and glycerol into a mixing device at a mass ratio of 10:2, mix at a mixing speed of 1000 rpm for 30 min to obtain a mixture;

[0039] S2: extrude the mixture through a single-screw extruder, set the extrusion temperature from the feeding port to the outlet to 140℃→160℃→150℃→140℃, granulate after extrusion and dry to constant weight to obtain thermoplastic starch particles;

[0040] S3: in a 60℃ water bath, drop castor oil into an acetone solution containing stannous octoate and toluene diisocyanate, and incubate and stir for 45 min to obtain a coating prepolymer; the amount of castor oil and toluene diisocyanate is based on n(-NCO) / n(-OH)=3:1; the concentrations of stannous octoate and toluene diisocyanate in the acetone solution are 0.01 g / mL and 2 g / mL, respectively;

[0041] S4: immerse the thermoplastic starch particles in the coating prepolymer for 45 s, drain after lifting out, and then incubate at 80℃ for 12 h to obtain modified thermoplastic starch;

[0042] The modified cellulose is prepared by the following steps:

[0043] (1) add chitosan and cellulose acetate to an aqueous acetic acid solution with a volume fraction of 4% at a mass ratio of 8:92, swell at room temperature for 2 h, then stir at 45℃ at a stirring speed of 900 rpm until completely dissolved to obtain a blended solution;

[0044] (2) add an aqueous ferric chloride solution dropwise to the blended solution under stirring to obtain a mixed solution; the mass ratio of ferric chloride to chitosan added is 3:10;

[0045] (3) vacuum degassing treatment is performed on the mixed solution to obtain a spinning solution;

[0046] (4) the spinning solution is prepared into a fiber yarn by using a conventional wet spinning process to obtain the modified cellulose.

[0047] The environmentally degradable plastic in this embodiment is prepared by the following steps:

[0048] (1) The raw material components in the formula amount are mixed, and then the mixture is put into an internal mixer to be mixed for 50 min at a temperature of 185℃ to obtain a base material;

[0049] (2) The mixed base material is immediately transferred to a screw extruder, the screw extruder is provided with a first melting section with a temperature of 145℃, a second melting section with a temperature of 165℃ and a third melting section with a temperature of 135℃ from the feeding end to the discharging end in sequence, the screw rotation speed is 110 rpm, the extrusion outlet temperature is 135℃, and the base material is extruded and shaped through the screw extruder.

[0050] Example 2

[0051] An environmentally degradable plastic, the raw materials for preparation include the following components by mass fraction:

[0052] 55 parts of polylactic acid, 30 parts of polybutylene adipate terephthalate, 1 part of modified thermoplastic starch, 2 parts of modified cellulose, 5 parts of polybutylene succinate, 8 parts of epoxy soybean oil, 3 parts of polyvinyl alcohol, 3 parts of monoglyceride of lauric acid and 3 parts of ethylenediaminetetraacetic acid; wherein the modified thermoplastic starch is prepared by the following steps:

[0053] S1: Dry cassava starch to a water content of less than 1%, then put the dried cassava starch and sorbitol into a mixing device at a mass ratio of 10:3, mix at a mixing speed of 800 rpm for 60 min to obtain a mixture;

[0054] S2: Extrude the mixture through a single screw extruder, set the extrusion temperature from the feeding port to the outlet to be 140℃→160℃→150℃→140℃, granulate and dry to constant weight after extrusion to obtain thermoplastic starch particles;

[0055] S3: In a 55℃ water bath, drop castor oil into an acetone solution containing stannous octoate and toluene diisocyanate, and incubate and stir for 45 min to obtain a coating prepolymer; the amount of castor oil and toluene diisocyanate is based on n(-NCO) / n(-OH)=2:1; the concentrations of stannous octoate and toluene diisocyanate in the acetone solution are 0.01 g / mL and 2 g / mL respectively;

[0056] S4: Dip the thermoplastic starch particles in the coating prepolymer for 30 s, drain after lifting out, and then incubate at 75℃ for 16 h to obtain modified thermoplastic starch;

[0057] The modified cellulose is prepared by the following steps:

[0058] (1) Cystose and cellulose acetate are added to an aqueous acetic acid solution with a volume fraction of 4% at a mass ratio of 5:95, swelled at room temperature for 2 h, and then completely dissolved by stirring at 1000 rpm at 40℃ to obtain a blended solution;

[0059] (2) drop the aqueous solution of ferric nitrate into the blending solution under stirring to obtain a mixed solution; the mass ratio of the ferric nitrate added to the chitosan is 3:10;

[0060] (3) perform vacuum defoaming treatment on the mixed solution to obtain a spinning solution;

[0061] (4) prepare the spinning solution into a fiber yarn by using a conventional wet spinning process, to obtain the modified cellulose.

[0062] The environment-degradable plastic in the embodiment is prepared by the following steps:

[0063] (1) mix the raw material components in a formula amount, and then put the mixture into a banbury mixer to be mixed at a temperature of 180℃ for 60 min, to obtain a base material;

[0064] (2) immediately transfer the mixed base material to a screw extruder, and the screw extruder is sequentially provided with a first melting section with a temperature of 140℃, a second melting section with a temperature of 160℃ and a third melting section with a temperature of 130℃ from the feeding end to the discharging end, the screw rotation speed is 110 rpm, and the extrusion temperature is 135℃, to be extruded and shaped by the screw extruder, to obtain the environment-degradable plastic.

[0065] Example 3

[0066] An environment-degradable plastic, the preparation raw materials include the following components in mass parts:

[0067] 65 parts of polylactic acid, 20 parts of polybutylene adipate terephthalate, 3 parts of modified thermoplastic starch, 0.5 parts of modified cellulose, 10 parts of polybutylene succinate, 3 parts of epoxy soybean oil, 6 parts of polyvinyl alcohol, 1 part of lauric acid monoglyceride and 6 parts of ethylenediaminetetraacetic acid; wherein the modified thermoplastic starch is prepared by the following steps:

[0068] S1: dry the wheat flour to a water content of less than 1%, and then put the dried wheat flour and ethylenediamine in a mass ratio of 10:2 into a mixing device to mix at a mixing rotation speed of 900 rpm for 45 min, to obtain a mixed material;

[0069] S2: extrude the mixed material through a single-screw extruder, and set the extrusion temperature from the feeding port to the outlet to be 140℃→160℃→150℃→140℃, to be granulated and dried to a constant weight after extrusion, to obtain thermoplastic starch particles;

[0070] S3: In a 65℃ water bath, castor oil was added dropwise into an acetone solution containing stannous octoate and toluene diisocyanate, and stirred for 30 min to obtain a coating prepolymer; the amount of castor oil and toluene diisocyanate was determined according to n(-NCO) / n(-OH)=4:1; the concentrations of stannous octoate and toluene diisocyanate in the acetone solution were 0.01 g / mL and 2 g / mL, respectively;

[0071] S4: The thermoplastic starch particles were immersed in the coating prepolymer for 60 s, then drained after being fished out, and then cured at 85℃ for 10 h to obtain the modified thermoplastic starch;

[0072] The modified cellulose was prepared by the following steps:

[0073] (1) Chitosan and cellulose acetate were added into a 4% acetic acid aqueous solution at a mass ratio of 10:90, and then swelled at room temperature for 2 h, and then completely dissolved by stirring at 800 rpm at 50℃ to obtain a blending solution;

[0074] (2) The aqueous solution of ferric sulfate was added dropwise into the blending solution under stirring to obtain a mixed solution; the mass ratio of ferric sulfate to chitosan added was 3:10;

[0075] (3) The mixed solution was subjected to vacuum degassing treatment to obtain a spinning solution;

[0076] (4) The spinning solution was prepared into a fiber yarn by using a conventional wet spinning process to obtain the modified cellulose.

[0077] The environment-degradable plastic in the embodiment was prepared by the following steps:

[0078] (1) The raw material components in the formula amount were mixed, and then the mixture was placed in an internal mixer for internal mixing at a temperature of 190℃ for 45 min to obtain a base material;

[0079] (2) The internal mixed base material was immediately transferred to a screw extruder, and the screw extruder was sequentially provided with a first melting section with a temperature of 150℃, a second melting section with a temperature of 170℃, and a third melting section with a temperature of 140℃ from the feeding end to the discharging end, and the screw rotation speed was 110 rpm, and the extrusion outlet temperature was 135℃, and the material was extruded and shaped by the screw extruder to obtain the environment-degradable plastic.

[0080] Comparative Example 1

[0081] An environment-degradable plastic, compared with Example 1, the modified thermoplastic starch in the preparation raw material was replaced by an equal amount of thermoplastic starch prepared by Example 1 S2, and the other components remained unchanged; the plastic preparation method was the same as that of Example 1.

[0082] Comparative Example 2

[0083] An environment-degradable plastic, compared with Example 1, modified cellulose in the preparation raw material is replaced by cellulose acetate in equal amount, and the rest of the components remain unchanged; the plastic preparation method is the same as Example 1.

[0084] Comparative Example 3

[0085] An environment-degradable plastic, compared with Example 1, modified thermoplastic starch in the preparation raw material is replaced by polylactic acid in equal amount, and the rest of the components remain unchanged; the plastic preparation method is the same as Example 1.

[0086] Comparative Example 4

[0087] An environment-degradable plastic, compared with Example 1, modified cellulose in the preparation raw material is replaced by polylactic acid in equal amount, and the rest of the components remain unchanged; the plastic preparation method is the same as Example 1.

[0088] Experimental Example

[0089] The environment-degradable plastics in the above examples and comparative examples are used as raw materials to make plastic shopping bags by using conventional shopping bag preparation process; then the biodegradation rate of the shopping bags is detected, and the specific detection method is as follows:

[0090] The biodegradation performance of the plastic bags prepared by using the plastics in Examples 1-3 and Comparative Examples 1-4 is detected according to the detection method recorded in GB / T20197-2006 after landfilling for 30d, 60d and 120d. The detection results are shown in Table 1.

[0091] Table 1

[0092]

[0093] As can be seen from Table 1, the plastic prepared by using the technical scheme in the present application (Examples 1-3) has excellent biodegradation performance and can be quickly degraded in the landfill site, without causing pollution to the environment.

[0094] Comparative Example 1, compared with Example 1, modified thermoplastic starch in the preparation raw material is replaced by thermoplastic starch, and the degradation performance does not change greatly, and the modified thermoplastic starch mainly affects the mechanical properties of the plastic.

[0095] Comparative Example 2, compared with Example 1, modified cellulose in the preparation raw material is replaced by conventional cellulose acetate, and the natural degradation performance of cellulose acetate is poor, and the plastic system lacks iron ions, which cannot promote the activity of microorganisms, thereby causing the plastic degradation to be poor.

[0096] Comparative Example 3, compared with Example 1, the preparation raw material lacks modified thermoplastic starch, and the plastic cannot form a "breakthrough point" during the degradation process, nor can it provide a nutrient source for microorganisms, thereby causing the plastic degradation to be poor.

[0097] Comparative Example 4 lacks modified cellulose in the raw material for preparation, does not introduce iron ions into the plastic system, and does not have the dual degradation mechanism in Example 1, thereby causing the plastic degradation to be poor.

[0098] The puncture performance of the plastic shopping bag was tested by using the test process in ASTM D5748-95 (2001). The results are shown in Table 2.

[0099] Table 2

[0100]

[0101] As can be seen from Table 2, the plastic prepared by using the technical solution in the application (Examples 1-3) has excellent puncture resistance, which can effectively improve the load capacity of the plastic bag.

[0102] Comparative Example 1 replaces the modified thermoplastic starch in the raw material for preparation with thermoplastic starch, and the puncture energy decreases significantly, because the thermoplastic starch cannot effectively improve the compatibility between the matrix and increase the plastic toughness, thereby causing the puncture resistance of the plastic to be poor.

[0103] Comparative Example 2 replaces the modified cellulose in the raw material for preparation with conventional cellulose acetate, and the puncture energy does not decrease significantly, indicating that the cellulose acetate can also have a certain synergistic effect with the modified thermoplastic starch, thereby improving the puncture resistance of the plastic.

[0104] Comparative Example 3 lacks modified thermoplastic starch in the raw material for preparation, the hydrogen bond effect brought by the modified starch particles is enhanced, and the effect of forming an "island-sea" structure in the plastic disappears, thereby causing the puncture resistance of the plastic to decrease significantly.

[0105] Comparative Example 4 lacks modified cellulose in the raw material for preparation, and the synergistic enhancement effect of cellulose and modified thermoplastic starch disappears, thereby causing the puncture resistance of the plastic to decrease.

[0106] Although the specific embodiments of the application are described in detail in combination with the examples, it should not be understood as limiting the protection scope of the patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the protection scope of the patent.

Claims

1. An environmentally degradable plastic, characterized in that, The raw materials for preparation include the following components by mass fraction: 55~65 parts of polylactic acid, 20~30 parts of polybutylene adipate terephthalate, 1~3 parts of modified thermoplastic starch, 0.5~2 parts of modified cellulose, 5~10 parts of polybutylene succinate, 3~8 parts of epoxy soybean oil, 3~6 parts of polyvinyl alcohol, 1~3 parts of lauric acid monoglyceride, and 3~6 parts of ethylenediaminetetraacetic acid; The modified thermoplastic starch is prepared by the following steps: S1: dry the starch to a water content of less than 1%, then put the dried starch and a plasticizer into a mixing device at a mass ratio of 10:2~3, mix at a mixing speed of 800~1000 rpm for 30~60 min to obtain a mixture; the plasticizer is glycerol, sorbitol or ethylenediamine; S2: extrude the mixture through a single-screw extruder, set the extrusion temperature from the feeding port to the outlet to be 140℃→160℃→150℃→140℃, granulate and dry to constant weight after extrusion to obtain thermoplastic starch granules; S3: in a 55~65℃ water bath, drop castor oil into an acetone solution containing a catalyst and toluene diisocyanate, and incubate and stir for 30~60 min to obtain a coating prepolymer; the catalyst is stannous octoate; S4: immerse the thermoplastic starch granules in the coating prepolymer for 30~60 s, drain after fishing out, and then incubate at 75~85℃ for 10~16 h to obtain the modified thermoplastic starch; The modified cellulose is prepared by the following steps: (1) add chitosan and cellulose acetate to an aqueous acetic acid solution with a volume fraction of 4% at a mass ratio of 5~10:90~95, swell at room temperature for 2 h, then stir at a stirring speed of 800~1000 rpm until completely dissolved at 40~50℃ to obtain a blended solution; (2) drop an aqueous iron salt solution into the blended solution under stirring to obtain a mixed solution; (3) perform vacuum degassing treatment on the mixed solution to obtain a spinning solution; (4) prepare the spinning solution into a fiber by a wet spinning process to obtain the modified cellulose.

2. The environmentally degradable plastic according to claim 1, characterized in that, The raw materials for preparation include the following components by mass fraction: 60 parts of polylactic acid, 25 parts of polybutylene adipate terephthalate, 2 parts of modified thermoplastic starch, 1 part of modified cellulose, 6 parts of polybutylene succinate, 5 parts of epoxy soybean oil, 4 parts of polyvinyl alcohol, 2 parts of lauric acid monoglyceride, and 5 parts of ethylenediaminetetraacetic acid.

3. The environmentally degradable plastic according to claim 1, characterized in that: The starch in S1 is corn flour, cassava flour or wheat flour.

4. The environmentally degradable plastic of claim 1, wherein: The amount of castor oil and toluene diisocyanate in S3 is n(-NCO) / n(-OH)=2~4:

1.

5. The environmentally degradable plastic of claim 1, wherein: The solute of the aqueous iron salt solution in step (2) is ferric chloride, ferric nitrate or ferric sulfate.

6. The environmentally degradable plastic according to claim 5, characterized in that: The mass ratio of the added iron salt to chitosan is 2~5:

10.

7. Process for the production of an environmentally degradable plastic according to any one of claims 1 to 6, characterized in that The following steps are included: (1) mix the raw material components in the formula amount, then put the mixture into an internal mixer to be internally mixed to obtain a base material; (2) put the base material into a screw extruder, extrude through the screw extruder and shape to obtain the product.

8. The method of claim 7, wherein: The internal mixing temperature in step (1) is 180~190℃, and the internal mixing time is 45~60 min.

9. The method of claim 7, wherein: In step (2), the screw extruder is provided with a first melting section with a temperature of 140-150 DEG C, a second melting section with a temperature of 160-170 DEG C and a third melting section with a temperature of 130-140 DEG C from the feeding end to the discharging end in sequence, the screw rotating speed is 110 rpm, and the extrusion outlet temperature is 135 DEG C.

10. Use of the environmentally degradable plastic according to any one of claims 1 to 6, characterized in that: The environment degradable plastic is used for preparing plastic shopping bags.

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