CN112175366A

CN112175366A - Biodegradable plastic and preparation method thereof

Info

Publication number: CN112175366A
Application number: CN202011071373.XA
Authority: CN
Inventors: 不公告发明人
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-10-09
Filing date: 2020-10-09
Publication date: 2021-01-05

Abstract

The invention discloses a biodegradable plastic and a preparation method thereof. According to the invention, an N-oleoyl polypeptide surfactant is used for modifying PLA fibers, tetramethylammonium glycine ionic liquid is used for modifying bacterial cellulose to obtain ionic liquid-loaded bacterial cellulose, and the crosslinking degree in the substance hybridization process is increased, so that high-strength hybrid fibers are formed; the excellent adsorption effect of tetramethylammonium glycine ionic liquid on carbon dioxide is utilized to cooperate with silicon dioxide to effectively endow the plastic with certain flame retardance; the plastic has affinity effect on seawater organisms by cooperating with celery fiber and silicon dioxide; the light and biological synergistic degradation plastic is produced by utilizing photosensitive substances and 100 percent of biological degradation raw materials. Meanwhile, the plastic has affinity to seawater organisms, can be degraded by 100 percent, and cannot cause burden to the ocean.

Description

Biodegradable plastic and preparation method thereof

Technical Field

The invention relates to the technical field of plastics, in particular to biodegradable plastic and a preparation method thereof.

Background

In recent years, with the rapid development of social economy, the use of high-molecular plastics brings great convenience to people, but the traditional plastics also bring a series of environmental problems in the use process. Therefore, novel environment-friendly plastic monomers such as PLA and the like enter the sight of people, but because of the defects of the environment-friendly plastic monomers such as PLA and the like in performance, some additives are often added in the process of preparation to complement the advantages of the monomers, so that the plastic taking PLA as the main body cannot be degraded by 100 percent and has the residue of so-called micro-plastic, and on the other hand, toxic gas is generated in the degradation process due to the addition of the additives to pollute the environment, such as polyvinyl chloride and plasticizers containing benzene rings. For this reason, researchers are actively solving the problem in this respect, but most of them are working around the research of plastics in soil biodegradation, and less are working around seawater. Because the temperature in the seawater is low, the species of specific organisms are few, most organisms are halophilic and anaerobic, the period for degrading plastics is very slow, and the pollution of the marine plastics is severe. Therefore, there is a need for a plastic that is 100% degradable in seawater and does not pollute the ocean and harm marine life.

Disclosure of Invention

The invention aims to provide biodegradable plastic and a preparation method thereof, so as to solve the problems in the background technology.

In order to solve the technical problems, the invention provides the following technical scheme:

a biodegradable plastic, the biodegradable plastic raw material comprises the following components: 50-70 parts of PLA fiber, 20-30 parts of bacterial cellulose, 2-8 parts of plasticizer, 1-4 parts of celery fiber, 0.5-1 part of white sesame and 0.5-1 part of silicon dioxide.

Further, the plasticizer is diheptyl succinate.

Further, the succinic acid diheptanyl ester is prepared by the esterification reaction of succinic acid and n-heptanol.

Further, the PLA fiber is modified by an anionic surfactant.

Further, the anionic surfactant is an N-oleoyl polypeptide solution, and the concentration of the solution is 1.5-2.5 g/L.

Further, the bacterial cellulose is loaded with ionic liquid.

Further, the ionic liquid is tetramethylammonium glycine ionic liquid or other amino acid ionic liquids.

Further, the mass ratio of the bacterial cellulose to the ionic liquid is (1:0.1) - (1: 0.5).

Further, the preparation method of the biodegradable plastic comprises the following steps:

(1) preparing materials;

(2) modification of PLA fiber;

(3) loading the bacterial cellulose with ionic liquid;

(4) preparing hybrid fiber by electrostatic spinning;

(5) and (3) preparing biodegradable plastic.

Further, the method comprises the following steps:

(1) preparing materials: preparing PLA fiber, bacterial cellulose, diheptyl succinate, celery fiber, white sesame seed, silicon dioxide, an N-oleoyl polypeptide solution, tetramethylammonium glycine ionic liquid, carbene, absolute ethyl alcohol, DMF (dimethyl formamide) and distilled water for later use;

(2) modification of PLA fiber: fully drying the PLA fiber, controlling the drying temperature to be 80-100 ℃, then immersing the PLA fiber into an N-oleoyl polypeptide solution, ultrasonically dispersing for 10-15min, stirring for 1-2h for activation, and finally drying to obtain modified PLA fiber for later use;

(3) carrying amino acid ionic liquid on bacterial cellulose: firstly, drying the tetramethylammonium glycine ionic liquid in vacuum at 60-80 ℃ for 24-48h for later use; activating the bacterial cellulose at 80-100 ℃ for 2-4h for later use; then adding the dried tetramethylammonium glycine ionic liquid and bacterial cellulose into an anhydrous methanol solution, performing ultrasonic dispersion for 15-30min, and then oscillating for 12-18h, wherein the working temperature is controlled at 20-25 ℃; finally, vacuum drying the bacterial cellulose at 70-80 ℃ for 48h to obtain bacterial cellulose loaded with ionic liquid, and putting the bacterial cellulose in a vacuum drier for later use;

(4) preparing the hybrid fiber by electrostatic spinning: ultrasonically dispersing modified PLA fibers and bacterial cellulose loaded with ionic liquid in DMF (dimethyl formamide), and controlling the ultrasonic time to be 1-2h to serve as an electrostatic spinning solution; then, the roller is taken as a receiver, the rotating speed is controlled to be 5000-;

(5) preparing biodegradable plastic: mixing hybrid fiber, celery fiber and white sesame by using a high-speed mixer, controlling the rotating speed to 10000-; and finally, casting on a polytetrafluoroethylene substrate for cooling to obtain the degradable plastic.

In the technical scheme, the PLA fiber is a 100% degradable substance, can be decomposed into carbon dioxide and water under the action of microorganisms in seawater, and has no harmful substance residue. However, if the plastic is prepared by taking the fiber as a main body, the tensile strength is weak, and the breaking strength is weak, so that the bacterial cellulose and the PLA fiber are introduced to be prepared into hybrid fiber by an immersion evaporation method, and the hybrid fiber is taken as the main body fiber of the plastic to increase the multi-aspect strength of the plastic. Because the bacterial cellulose is a material with an ultra-strong three-dimensional nano structure, has higher porosity and can effectively improve the tensile strength of the fiber with other fibers in the dissolving and reconstructing process.

However, PLA fiber is a natural hydrophobic polymer and has weak dispersibility in a solution, and bacterial cellulose has hydrophilicity, so that the interface action of the two substances is weak, and the biocompatibility is poor; therefore, the PLA fiber is modified by using the N-oleoyl polypeptide anionic surfactant, and the bacterial cellulose loaded by the ionic liquid is obtained by modifying the bacterial cellulose in the tetramethylammonium glycine ionic liquid, so that the dispersion degree of the two substances in the DMF is increased, the interface effect of the two substances is enhanced, the problem of biocompatibility of the two substances caused by different properties is solved, the crosslinking degree of the substances in the hybridization process is increased, and the hybrid fiber is formed.

In addition, the N-oleoyl polypeptide anionic surfactant and the tetramethylammonium glycine ionic liquid are renewable, non-toxic and 100% biodegradable compounds designed according to natural substances, and the bacterial cellulose is prepared according to microbial fermentation and has 100% biodegradable property.

The N-oleoyl polypeptide anionic surfactant not only can modify the property of PLA cellulose, but also serves as a reinforcing agent in the preparation process of the plastic, so that the bonding strength with other substances is effectively enhanced, and the mechanical strength of the plastic is enhanced.

Wherein, tetramethyl ammonium glycine ionic liquid not only can decorate bacterial cellulose, makes up for the not enough, and it has other two effects: firstly, a specific hydrogen bond network in the ionic liquid has thermal stability, so that the ionic liquid has higher glass transition temperature and can effectively enhance the mechanical strength of plastics; secondly, basic groups in the ionic liquid structure can be physically adsorbed with carbon dioxide, so that the ionic liquid has certain oxygen blocking capacity, flame retardance and affinity to anaerobic organisms in seawater.

However, because the bacterial cellulose loaded by the tetramethylammonium glycine ionic liquid has a strong ultraviolet blocking effect, the process of degrading the long chain of the polymer by photocatalysis is seriously hindered, and the rate of degrading the plastic by biology is reduced. Therefore, the celery fiber and the white sesame seed with photosensitivity are introduced to be cooperated for complementary advantages, the two substances are light-absorbing and can absorb ultraviolet rays, and the degradation rate of marine organisms to plastics is assisted by utilizing the damage of the ultraviolet rays to long chains.

Wherein, the white sesame also contains 55 percent of oil, has the function of a lubricant in the preparation process of the plastic, can stabilize the internal structure of the plastic and increase the mechanical property; contains a trace amount of oxalic acid, so that the plastic has certain anti-aging performance.

The celery fiber serves as an ultraviolet absorbent in the plastic, contains abundant mineral substances such as sodium, calcium, iron and phosphorus, is a nutrient component of seawater organisms, and is cooperated with the adsorption performance of tetramethylammonium glycine ionic liquid on carbon dioxide, so that the plastic has an affinity effect on halophilic and anaerobic microorganisms in seawater, and the speed of biodegradation of the plastic is increased in an auxiliary manner.

In addition, diheptan succinate is used as a plasticizer in the raw material components, so that the flowability of a raw material system is increased, the cross-linking effect among the raw materials is increased, and the diheptan succinate is cooperated with an N-oleoyl polypeptide anionic surfactant, tetramethylammonium glycine ionic liquid and white sesame to improve the strength of the plastic.

In addition, the silicon dioxide in the raw material components and the tetramethylammonium glycine ionic liquid are cooperated to effectively endow the plastic with certain flame retardance; secondly, positive charge-wearing substances are generated by dissolving the hybrid fibers in an aqueous solution and are just repelled with the positive charges of the hybrid fibers in water, so that the shrinkage degree of the plastic during curing is reduced, the cohesive force between molecules is reduced, the surface of the plastic is smooth, and meanwhile, the gaps in the plastic are filled by the bonding of the carbene between the two substances, so that the toughness of the plastic is enhanced; thirdly, the silicon dioxide has the function of promoting the growth of seawater organisms after being decomposed in seawater, and can accelerate the metabolism of the seawater organisms, thereby shortening the degradation time of the biodegradable plastic; and fourthly, the composite material also serves as a filling material in the plastic, so that the elastic strength and the wear resistance of the plastic can be effectively improved.

Degradation mechanism: the photodegradation and the biodegradation are synergistic mechanisms. When the plastic is discarded, the photosensitive substance absorbs ultraviolet rays to initiate generation of free radicals, destroy long chains of polymers in the plastic and reduce molecular weight of the plastic, and meanwhile, pores are generated in the plastic due to the destruction of the free radicals, so that bacteria with affinity to halophilic and anaerobic microorganisms in seawater can be attached to the pores of the plastic to slowly phagocytize digestive metabolism and promote the degradation of the plastic.

Compared with the prior art, the invention has the following beneficial effects: according to the invention, an N-oleoyl polypeptide surfactant is used for modifying PLA fibers, tetramethylammonium glycine ionic liquid is used for modifying bacterial cellulose to obtain ionic liquid-loaded bacterial cellulose, and the crosslinking degree in the substance hybridization process is increased, so that high-strength hybrid fibers are formed; the excellent adsorption effect of tetramethylammonium glycine ionic liquid on carbon dioxide is utilized to cooperate with silicon dioxide to effectively endow the plastic with certain flame retardance; the plastic has affinity effect on seawater organisms by cooperating with celery fiber and silicon dioxide; the light and biological synergistic degradation plastic is produced by utilizing photosensitive substances and 100 percent of biological degradation raw materials.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

step 1: preparing PLA fiber, bacterial cellulose, diheptyl succinate, celery fiber, white sesame seed, silicon dioxide, an N-oleoyl polypeptide solution, tetramethylammonium glycine ionic liquid, carbene, absolute ethyl alcohol, DMF (dimethyl formamide) and distilled water for later use;

step 2: modification of PLA fiber: fully drying the PLA fiber, controlling the drying temperature to be 80 ℃, then immersing the PLA fiber into an N-oleoyl polypeptide solution, ultrasonically dispersing for 10min, stirring for 1h for activation, and finally drying to obtain modified PLA fiber for later use;

and step 3: carrying amino acid ionic liquid on bacterial cellulose: firstly, carrying out vacuum drying on tetramethylammonium glycine ionic liquid at 60 ℃ for 24 hours for later use; activating the bacterial cellulose at 80 ℃ for 2h for later use; then adding the dried tetramethylammonium glycine ionic liquid and the bacterial cellulose into an anhydrous methanol solution, performing ultrasonic dispersion for 15min, oscillating for 12h, and controlling the working temperature to be 20 ℃; finally, vacuum drying the bacterial cellulose at 70 ℃ for 48h to obtain bacterial cellulose loaded with ionic liquid, and putting the bacterial cellulose in a vacuum drier for later use;

and 4, step 4: preparing the hybrid fiber by electrostatic spinning: ultrasonically dispersing modified PLA fibers and bacterial cellulose loaded with ionic liquid in DMF (dimethyl formamide), and controlling the ultrasonic time to be 1h to serve as an electrostatic spinning solution; then, a roller is used as a receiver, the rotating speed is controlled to be 5000r/min, the working temperature is 80 ℃, the voltage is controlled to be 15kv, the flow rate is 0.6mL/h, the receiving distance is 10cm, and the hybrid fiber with the diameter of 400nm is prepared;

and 5: preparing biodegradable plastic: mixing hybrid fiber, celery fiber and white sesame by using a high-speed mixer, controlling the rotating speed to be 10000r/min, extruding the mixture for 3 times back and forth through a double screw to form uniformly mixed particles, then ultrasonically dispersing the particles in distilled water, adding diheptyl succinate, silicon dioxide and carbene, heating the mixture to 180 ℃, and stirring the mixture for 2 hours to form mixed slurry; and finally, casting on a polytetrafluoroethylene substrate for cooling to obtain the degradable plastic.

In this embodiment: the biodegradable plastic raw material comprises the following components: 50 parts of PLA fiber, 20 parts of bacterial cellulose, 2 parts of plasticizer, 1 part of celery fiber, 0.5 part of white sesame and 0.5 part of silicon dioxide.

The mass ratio of the bacterial cellulose to the ionic liquid is (1: 0.1).

Example 2:

step 2: modification of PLA fiber: fully drying the PLA fiber, controlling the drying temperature to be 100 ℃, then immersing the PLA fiber into an N-oleoyl polypeptide solution, ultrasonically dispersing for 15min, stirring for 2h for activation, and finally drying to obtain modified PLA fiber for later use;

and step 3: carrying amino acid ionic liquid on bacterial cellulose: firstly, carrying out vacuum drying on tetramethylammonium glycine ionic liquid at 80 ℃ for 48 hours for later use; activating the bacterial cellulose at 100 ℃ for 4h for later use; then adding the dried tetramethylammonium glycine ionic liquid and the bacterial cellulose into an anhydrous methanol solution, performing ultrasonic dispersion for 30min, oscillating for 18h, and controlling the working temperature to be 25 ℃; finally, vacuum drying the bacterial cellulose at 80 ℃ for 48h to obtain bacterial cellulose loaded with ionic liquid, and putting the bacterial cellulose in a vacuum drier for later use;

and 4, step 4: preparing the hybrid fiber by electrostatic spinning: ultrasonically dispersing modified PLA fibers and bacterial cellulose loaded with ionic liquid in DMF (dimethyl formamide), and controlling the ultrasonic time to be 2h to serve as an electrostatic spinning solution; then, the roller is used as a receiver, the rotating speed is controlled to be 8000r/min, the working temperature is 100 ℃, the voltage is controlled to be 19kv, the flow rate is 0.8mL/h, the receiving distance is 20cm, and the hybrid fiber with the diameter of 800nm is prepared;

and 5: preparing biodegradable plastic: mixing hybrid fiber, celery fiber and white sesame by using a high-speed mixer, controlling the rotating speed to be 20000r/min, extruding the mixture for 3 times back and forth through a double screw to form uniformly mixed particles, then ultrasonically dispersing the particles in distilled water, adding diheptyl succinate, silicon dioxide and carbene, heating the mixture to 200 ℃, and stirring the mixture for 4 hours to form mixed slurry; and finally, casting on a polytetrafluoroethylene substrate for cooling to obtain the degradable plastic.

In this embodiment: the biodegradable plastic raw material comprises the following components: 70 parts of PLA fiber, 30 parts of bacterial cellulose, 8 parts of plasticizer, 4 parts of celery fiber, 1 part of white sesame and 1 part of silicon dioxide.

The mass ratio of the bacterial cellulose to the ionic liquid is (1: 0.5).

Example 3:

step 2: modification of PLA fiber: fully drying the PLA fiber, controlling the drying temperature to be 90 ℃, then immersing the PLA fiber into an N-oleoyl polypeptide solution, ultrasonically dispersing for 12min, stirring for 1.5h for activation, and finally drying to obtain modified PLA fiber for later use;

and step 3: carrying amino acid ionic liquid on bacterial cellulose: firstly, carrying out vacuum drying on tetramethylammonium glycine ionic liquid at 70 ℃ for 36 hours for later use; activating the bacterial cellulose at 90 ℃ for 3h for later use; then adding the dried tetramethylammonium glycine ionic liquid and the bacterial cellulose into an anhydrous methanol solution, performing ultrasonic dispersion for 26min, oscillating for 15h, and controlling the working temperature to be 22 ℃; finally, vacuum drying the bacterial cellulose at 75 ℃ for 48h to obtain bacterial cellulose loaded with ionic liquid, and putting the bacterial cellulose in a vacuum drier for later use;

and 4, step 4: preparing the hybrid fiber by electrostatic spinning: ultrasonically dispersing modified PLA fibers and bacterial cellulose loaded with ionic liquid in DMF (dimethyl formamide), and controlling the ultrasonic time to be 1.5h to serve as an electrostatic spinning solution; then, a roller is used as a receiver, the rotating speed is controlled to be 6500r/min, the working temperature is 90 ℃, the voltage is controlled to be 17kv, the flow rate is 0.7mL/h, the receiving distance is 15cm, and the hybrid fiber with the diameter of 600nm is prepared;

and 5: preparing biodegradable plastic: mixing hybrid fiber, celery fiber and white sesame by using a high-speed mixer, controlling the rotating speed at 15000r/min, extruding the mixture for 3 times back and forth through a double screw to form uniformly mixed particles, then ultrasonically dispersing the particles in distilled water, adding diheptyl succinate, silicon dioxide and carbene, heating to 190 ℃, and stirring for 3 hours to form mixed slurry; and finally, casting on a polytetrafluoroethylene substrate for cooling to obtain the degradable plastic.

In this embodiment: the biodegradable plastic raw material comprises the following components: 60 parts of PLA fiber, 25 parts of bacterial cellulose, 5 parts of plasticizer, 2.5 parts of celery fiber, 0.7 part of white sesame and 0.7 part of silicon dioxide.

The mass ratio of the bacterial cellulose to the ionic liquid is (1: 0.3).

Example 4: as in example 2, no bacterial cellulose was added.

Example 5: as in example 2, neither N-oleoyl polypeptide solution surfactant nor tetramethylammonium glycine ionic liquid was added.

Example 6: as in example 2, only the N-oleoyl polypeptide solution surfactant was not added.

Example 7: as in example 2, only tetramethylammonium glycine ionic liquid was not added.

Example 8: as in example 2, the celery fiber and white sesame were not added.

Example 9: the same as example 2, no celery fiber and no tetramethylammonium glycine ionic liquid were added.

Example 10: the same as example 2, silica and tetramethylammonium glycine ionic liquid were not added.

Experiment:

examples 1-10 were tested for tensile strength with reference to GB/1040.2-2006, respectively; the degradation rate is calculated by soaking in seawater for 30 days according to GB/T19276.1-2003 and DB 35/343-. The sample was tested for the oxygen index of the sample (LOI) according to the standard test method of GB/T2406-1993, and the results are shown in Table 1:

TABLE 1

Comparing examples 1-3, it can be found that the tensile strength of the plastic is more than 40MPa, and the degradation rate in 30 days is more than 56%. The data difference between the degradation rate and the polar oxygen index shows that the more the tetramethylammonium glycine ionic liquid is loaded, the higher the degradation rate and the higher the flame retardance are. The reason is that the tetramethylammonium glycine ionic liquid has excellent carbon dioxide adsorption performance, on one hand, oxygen is blocked, the flame retardance of the plastic is increased, and on the other hand, the tetramethylammonium glycine ionic liquid has certain affinity to anaerobic seawater organisms, and the degradation rate of the plastic is increased.

Example 4 compares with example 2, indicating that bacterial cellulose is the main factor for enhancing the strength of plastics, and further compares with examples 5, 6 and 7, indicating that the N-oleoyl polypeptide surfactant and the tetramethylammonium glycine ionic liquid indeed enhance the interfacial action between PLA fibers and bacterial cellulose.

Example 8 in comparison with example 2 shows that the photosensitive substance celery fiber and sesame are indeed synergistic to accelerate the degradation speed of the plastic.

Example 9 compares with example 2, shows that celery fiber and tetramethylammonium glycine ionic liquid synergistically increase the affinity of plastics to seawater organisms and accelerate degradation speed.

Example 10 compares to example 2, showing that silica and tetramethylammonium glycine ionic liquid synergistically increase the flame retardancy of the plastic.

Finally, it should be noted that: 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 changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. 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.

Claims

1. A biodegradable plastic characterized in that: the biodegradable plastic raw material comprises the following components: 50-70 parts of PLA fiber, 20-30 parts of bacterial cellulose, 2-8 parts of plasticizer, 1-4 parts of celery fiber, 0.5-1 part of white sesame and 0.5-1 part of silicon dioxide.

2. A biodegradable plastic according to claim 1, characterized in that: the plasticizer is succinic acid diheptanoate.

3. A biodegradable plastic according to claim 2, characterized in that: the succinic acid diheptanyl ester is prepared by the esterification reaction of succinic acid and n-heptanol.

4. A biodegradable plastic according to claim 1, characterized in that: the PLA fiber is modified by an anionic surfactant.

5. A biodegradable plastic according to claim 4, characterized in that: the anionic surfactant is an N-oleoyl polypeptide solution, and the concentration of the solution is 1.5-2.5 g/L.

6. A biodegradable plastic according to claim 1, characterized in that: the bacterial cellulose is loaded with ionic liquid.

7. A biodegradable plastic according to claim 6, characterized in that: the ionic liquid is tetramethylammonium glycine ionic liquid or other amino acid ionic liquids.

8. A biodegradable plastic according to claim 6, characterized in that: the mass ratio of the bacterial cellulose to the ionic liquid is (1:0.1) - (1: 0.5).

9. A method for preparing biodegradable plastic is characterized in that: the method comprises the following steps:

(1) preparing materials;

(2) modification of PLA fiber;

(3) loading the bacterial cellulose with ionic liquid;

(4) preparing hybrid fiber by electrostatic spinning;

(5) and (3) preparing biodegradable plastic.

10. The method for preparing biodegradable plastic according to claim 9, wherein: the method comprises the following steps: