CN117844267A

CN117844267A - Multi-element combined synergistic refined biodegradable straw and preparation method thereof

Info

Publication number: CN117844267A
Application number: CN202410150530.8A
Authority: CN
Inventors: 谭卓华; 黄炜岚
Original assignee: Guangzhou Lvhui New Material Research Institute Co ltd
Current assignee: Guangzhou Lvhui New Material Research Institute Co ltd
Priority date: 2024-02-02
Filing date: 2024-02-02
Publication date: 2024-04-09

Abstract

The invention relates to a multi-element combined synergistic refined biodegradable straw and a preparation method thereof, wherein the biodegradable straw is prepared from poly (p-dioxanone) (PPDO), polylactic acid-glycolic acid copolymer (PLGA), compatibilizer, rice flour, high amylose starch, compound plasticizer, plant fiber, modifier, natural antioxidant, antibacterial agent and eggshell calcium carbonate; melting and extruding at 55-140 ℃ through a double-stage serial screw extruder set, drawing, cooling, cutting, packaging and obtaining the multi-element combined synergistic refined biodegradable straw; changing a forming die and a cutting knife in a production line to produce various tubular objects in a large scale; can degrade soil and marine organisms; the adopted raw materials have rich sources, simple process and low comprehensive cost of production and raw materials.

Description

Multi-element combined synergistic refined biodegradable straw and preparation method thereof

Technical Field

The invention belongs to the technical field of preparation of biodegradable materials, and particularly relates to a multi-element combined synergistic refined biodegradable straw and a preparation method thereof.

Background

Stabilized polymers such as polyethylene, polypropylene, polystyrene, poly (meth) acrylate, aromatic polyesters and polyamides having a strong C-C or C-heteroatom backbone are considered to be a major source of microplastic contamination; while conventional biodegradable polymers (aliphatic and aliphatic-aromatic polyesters), such as polylactic acid (PLA), polycaprolactone (PCL), lactide-glycolide copolymers, etc., have not attracted much attention, although they produce microplastic together;

The reason may be that the use of these polymers is also relatively limited and that it is generally misunderstood: they are believed to degrade under any environmental conditions. However, the fact that biodegradable polymers degrade only under specific conditions (temperature, humidity, light, oxygen availability and microorganisms) does not exclude the potential risk of environmental contamination because they are called "biodegradable polymers".

The environment is an important factor affecting the degradation performance of the biodegradable material, and the seawater environment is completely different from the soil or composting environment. Low temperature, strong fluidity, high salt and high pressure are the main characteristics of marine environment; in the marine environment, most of the microorganisms are distributed in offshore areas, where the microorganism content is low or even absent.

According to the global challenge, 14 days 7, 2017, volume 1, phase 4. The paper published by the university of belvedere, germany Amir Reza Bagheri, christian Laforsch et al, the so-called fate of biodegradable polymers in seawater, shows that:

polylactic acid (PLA) and polylactic acid-glycolic acid copolymer (PLGA), polybutylene terephthalate adipate (PBAT), polyhydroxybutyrate (PHB), polycaprolactone (PCL) and polyethylene terephthalate (PET) are immersed into sea water and fresh water which are naturally illuminated at 25 ℃ for one year, and experimental observation is carried out; as a result, it was found that 100% of the bulk degradation was achieved by comparing the degradation of different polymers under the same conditions in fresh water and sea water, with PLGA only at about 270 days, PHB degraded by about 8% within 365 days, and there was a difference between the degradation mechanisms of the two. PLGA and PHB were observed by Scanning Electron Microscopy (SEM) and GPC, and PHB was found to exhibit degradation only by surface erosion, and only morphological changes on the surface, although with a mass loss of 8.5%, the molecular weight in GPC did not change;

In addition, PBAT, PCL, PLA and PET samples were not substantially degraded with a hydrolysis rate of <2%. So-called biodegradable polymers do not exhibit any significant degradability under the test conditions. The degradation rate of the polymer in the seawater and the fresh water is relatively consistent; while the amorphous nature of the polymer may be responsible for the faster hydrolysis and complete degradation of PLGA, this property allows for easy diffusion of water throughout the volume.

Tsuji et al have performed comparative degradation of PCL, PLA (amorphous and crystalline) and poly (3-hydroxybutyrate) (PHB) in Pacific sea water at 25℃for a predetermined period of time. The result was 25% degradation of PCL within 10 weeks, while PHB was only 9% degraded.

In 2017, the national institute of science and chemical institute of China and the national engineering research center for engineering plastics organize nearly 10 doctor researches on seawater degradable plastics, and the research results of the research on the degradation performance of typical biodegradable polyesters in seawater are published on the report on functional polymer in 10 months in 2020, and the research shows that: PLA is substantially non-degradable in 6 different bodies of water; PLA is hardly degraded in natural seawater within 364 days, and the molecular weight, the weight loss, the mechanical properties and the like are not obviously changed. The weight loss of PBAT and PBS is not more than 3% within 364 days, the degradation rate is slow, and the molecular weight and the mechanical property are obviously reduced, but the weight loss is not obvious; PCL is degraded fastest, a surface corrosion mechanism is shown in seawater, the weight loss rate is 32% after 364 days, and as degradation proceeds, the size of the material is gradually reduced but the molecular weight and mechanical properties remain unchanged.

The actual soil of Mediterranean for Greek university of agriculture in 2010 is used as a degradation test of PLA biodegradable plastic, and the degradation test is carried out for 11 months, and only partial physical disintegration and partial fragmentation are carried out.

In 2014, the university of south forestry science and technology simulates natural soil, and a plastic bag made of PLA is buried in the simulated natural soil, so that the quality of the plastic bag is only lost by 0.23% after 12 months, and the plastic bag is hardly degraded.

The above studies show that the degradation rate of the biodegradable material PLA, PBAT, PHA, PCL in seawater is less than 10%, wherein the degradation rate of the main material PLA in the market in seawater is less than 1%. This means that even if biodegradable plastics are used in the marine field instead of conventional plastics, the intended effect is not obtained-i.e. degradation is achieved and plastic pollution in the sea is reduced, most polymers do not degrade in natural environments; biodegradation of biodegradable plastics generally requires relatively high moisture and temperature conditions and microbial abundance, e.g., composting degradation requires 70% humidity and 55 ℃, a limitation that is not always available in the natural environment. Only developed countries such as Europe and America generally have large industrial composting factories, and biodegradable plastics have high requirements on garbage classification systems. Therefore, if garbage classification and an industrial composting factory are not guaranteed, a large amount of biodegradable plastics can enter the nature or the ocean, and the biodegradable plastics are difficult to degrade to realize cyclic regeneration and difficult to biodegrade. These plastics are discarded and if not properly disposed of, are gradually released into the environment and eventually flow through the river to the ocean and accumulate in large quantities, causing serious damage to their health if accidentally consumed by marine organisms and birds. Therefore, whether biodegradable plastics can be a promising approach to solve the problem of plastic accumulation in the long term remains a problem;

In view of the above, under natural environmental conditions, investigation and evaluation of the degradation process of biodegradable plastics and the formation of potential secondary pollutants are largely required. So far, the study of biological effects of biodegradable plastics is still in the cradle stage. Lack of standards and testing methods to evaluate the biodegradability of plastic materials in unmanaged freshwater ecosystems (including lakes, streams and rivers) and most marine environments; furthermore, secondary plastic particles may be released during degradation of the biodegradable plastic, thereby bringing a potential ecological risk. However, limited research has been conducted primarily in aquatic environments, while relatively little research has been conducted with respect to biodegradable plastic microplastics, formed in other environmental media (e.g., air and soil environments). Furthermore, there is a lack of data on the concentration of microplastic particles formed during degradation of biodegradable plastics, which would be of greater value for microplastic toxicity studies. The biodegradation monitoring of the biodegradable plastic in the natural environment is crucial, the knowledge gap of the environmental behavior of the biodegradable plastic is not well solved, and the large-scale application of the biodegradable plastic is promoted to be at risk.

Only a few studies have focused on the degradability of biodegradable polymers in water samples and the disputed conclusions shown, whereas most of them, samples are usually placed in perforated baskets in seawater, whereby the weight change of the residue is recorded without distinguishing between the weight loss due to biodegradation or just the loss due to the decomposition of the sample into microplastic material as secondary microplastic material. It is therefore necessary to study under controlled conditions using canonical characterization methods to understand the degradation behavior of polymers and to provide evaluation criteria.

According to the report of the NHK television station in Japan, aiming at the problem of marine pollution, chemical enterprises in China such as Japan, germany and Italy are developing "marine environment-friendly plastics" which can be dissolved in the ocean, and the economic industry in Japan is proposing a station policy to support the Japan enterprises which are developing related technologies;

about 1000 ten thousand tons of plastic are produced annually in japan according to the japan economic industry province exposure, but the proportion of plastic that can be decomposed in seawater is very small. In order to popularize environmental protection plastics that can be dissolved in seawater, japanese government regulations have encouraged the development of plastic materials that have minimal impact on the marine environment. For example, such a substance may be capable of dissolving in seawater.

Disclosure of Invention

At present, relatively few degradation researches on degradation materials in a seawater environment are carried out, and a multi-element combination cross comparison and integrated compounding research is carried out to obtain a multi-element combination synergistic refined biodegradable straw and a preparation method thereof; there are also certain limitations in industrial use; under the condition that the degradation environment is not changed, the marine pollution problem is more effectively solved, and research and development of the natural degradable and marine biodegradable material with excellent water degradation performance are particularly important.

The method aims at overcoming the defects of the prior art, adopts a degradation material with better hydrolysis performance to modify the material, and has the advantages of avoiding the defects; the preparation method can not only obtain soil degradation and marine biodegradation meeting the performance requirements, but also reduce the cost and has simple process; the method has no report on the aspect, and the application effectively fills the blank of the aspect and has great significance.

In order to achieve the above purpose, the technical scheme adopted by the invention comprises the following process steps:

a multi-element combined synergistic refined biodegradable straw is prepared from the following raw materials in parts by weight: 5 to 50 Parts of Polydioxanone (PPDO), 5 to 50 parts of polylactic acid-glycolic acid copolymer (PLGA), 0.8 to 4.4 parts of compatibilizer, 20 to 60 parts of rice flour, 3 to 8 parts of high amylose starch, 1.8 to 6.8 parts of compound plasticizer, 3 to 8 parts of plant fiber, 0.3 to 1.2 parts of modifier, 0.02 to 0.05 part of natural antioxidant, 0.06 to 0.1 part of antibacterial agent and 3 to 8 parts of eggshell calcium carbonate;

The polylactic acid-glycolic acid copolymer (PLGA) is any one of PLGA90/10, PLGA80/20, PLGA75/25, PLGA50/50 and PLGA10/90, the molecular weight is 10000-30000, the median diameter D50 is less than or equal to 0.113 mu m, and the detection method is that a laser particle size analyzer is used for wet particle size detection;

the molecular weight of the polydioxanone (PPDO) is 10000-30000, the median diameter D50 is less than or equal to 0.125 mu m, and the detection method is that a laser particle size analyzer is adopted for wet particle size detection;

the modifier is an epoxy functionalized ADR4468 chain extender of Basoff company;

the antibacterial agent is Velsan SPA multifunctional antibacterial agent of Clariant company.

The rice flour is one or two of early long-shaped rice flour, chen Mifen and crushed rice flour, and the median of the particle size D50 is less than or equal to 0.442 mu m; the detection method is that a laser particle size analyzer is adopted for wet particle size detection.

The high amylose starch is one or a mixture of two of high amylose corn starch and high amylose epidermoid pleated pea starch, the amylose content of the high amylose starch is 85-95%, and the median particle size D50 is less than or equal to 0.320

μm; the detection method is that a laser particle size analyzer is adopted for wet particle size detection.

The plant fiber is sugarcane fiber with the median diameter D50 less than or equal to 0.261 mu m and the median diameter D50 less than or equal to 0.316

One or two of bamboo fiber with the diameter of 50-0.230 mu m; the detection method is that a laser particle size analyzer is adopted for wet particle size detection.

The compatibilizer is any one of PLGA-b-PPDO block copolymer and PGA-b-PPDO block copolymer; the PLGA-b-PPDOS block copolymer has the proportion of PLGA to PPDOS of 2:1, a step of;

the PGA-b-PPDOS block copolymer has a PGA and PPDOS ratio of 2:1.

the compound plasticizer is a mixture of two or more of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer, 1-ethyl-3-methylimidazole acetate, isosorbide, acetyl tributyl citrate, polyethylene glycol stearate, acetyl monoglyceride, propylene glycol, glycerol and poloxamer.

The natural antioxidant is one or two of vitamin E, tea polyphenols and soybean polyphenols.

The preparation method comprises the following steps:

(1) weighing according to the weight portion: adding 20-60 parts of rice flour, 3-8 parts of high amylose starch and 1.8-6.8 parts of compound plasticizer into a mixer together, stirring for 5-12 minutes at a rotating speed of 1500-2000 rpm, sealing and placing the obtained material at room temperature for 24 hours, drying until the water content is less than or equal to 1%, and sealing for later use;

(2) Weighing according to the weight portion: 3 to 8 parts of plant fiber, 0.3 to 1.2 parts of modifier, 3 to 8 parts of eggshell calcium carbonate, 0.02 to 0.05 part of natural antioxidant and 0.06 to 0.1 part of antibacterial agent are added into a mixer, stirred for 5 minutes at the rotating speed of 800 to 1000rpm, and then dried until the water content is less than or equal to 1 percent, and sealed for standby;

(3) weighing according to the weight portion: 5 to 50 Parts of Polydioxanone (PPDO), 5 to 50 parts of polylactic acid-glycolic acid copolymer (PLGA) and 0.8 to 4.4 parts of compatibilizer are added into a mixer, and the mixture is stirred for 10 minutes at the rotating speed of 300 to 500rpm and then sealed for standby;

(4) adopting a double-stage serial screw extruder unit, wherein the length-diameter ratio of a screw extruder in the first stage is 32:1, and the length-diameter ratio of a single screw extruder in the second stage is 16:1; the temperature of the barrel temperature zone of the screw extruder in the first stage is set as follows in sequence: 75-80 ℃, 85-90 ℃, 90-95 ℃, 95-100 ℃, 110-120 ℃, 120-125 ℃, 125-130 ℃, and setting the barrel temperature zone temperature of the second-stage single screw extruder as follows: 130-140 ℃, 130-135 ℃, 125-130 ℃, 105-110 ℃, 75-80 ℃ and 55-60 ℃ in thirteen temperature areas, adding the raw material in the step (1) into a first feeding port arranged in a first temperature area of a double-stage serial screw extruder unit through a vacuum feeder conveying device, adding the raw material in the step (2) through fully mixing, conveying to a second feeding port arranged in a third temperature area, and adding the raw material in the step (3) through fully mixing, conveying to a third feeding port arranged in a fifth temperature area; the screw speed is 150-200 r/min, and the multi-element combined synergistic refined biodegradable straw is obtained through the steps of melting extrusion, traction, cooling, cutting and packaging at 55-140 ℃.

According to the preparation method, the forming die and the cutting knife are changed in a production line, and various tubular objects are produced in a large scale.

Advantageous effects

The environment-friendly composite material has two meanings, namely, the production and the use do not release harmful substances; secondly, the used waste can be biodegraded, and the environment is not burdened, namely, the waste has the performance of 'life ending'; in research and preparation of the water degradation material, adjustment and modification are carried out according to the mechanism of biodegradation, and the nature of biodegradation is that bonds of the internal structure of the material are hydrolyzed or hydrolyzed.

The poly (p-dioxanone) (PPDO) and the poly (lactic-co-glycolic acid) (PLGA) are two degradable high polymer materials with excellent performances, and have excellent physical and mechanical properties, good biocompatibility, no toxicity and capability of being discharged through metabolism degradation of human bodies. Poly (p-dioxanone) (PPDO) and poly (lactic-co-glycolic acid) (PLGA) are polymeric materials that are approved by the United states Food and Drug Administration (FDA) and European Medical Administration (EMA) for use in humans.

According to the international green plastics (6 common degradable plastics, which have the highest degradation speed in nature) in the text, under the conditions of table 1;

The study conclusion shows that: PPDO, after 6 months of degradation, show the highest weightlessness potential in air (54.7±9.1%) and soil (56.8±4.8%) due to its special ether linkage and abundant microorganisms on the biofilm; the microbiota on PPDO is unique, rich in phylum green and thick-walled bacteria (Firmicutes), which are responsible for carbon recycling and organic degradation. The weight loss of polylactic acid is only 1.1-8.0%, the weight loss of PBAT is 0.8-6.8%, and other plastics are basically undegradable.

In addition, the biodegradability of polydioxanone (PPDO) in natural ecological environment has also been confirmed by related studies. More importantly, for the recovered waste polydioxanone (PPDO) product, the polymerization monomer can be recovered under simple conditions, the recovery rate is as high as 93-99%, and the recovered monomer can be used for polymerization of the polydioxanone (PPDO) so as to realize repeated recycling; for applications where recovery is not desirable, the polydioxanone (PPDO) is completely biodegradable. Therefore, the poly-p-dioxanone (PPDO) is a polymer variety which is less in polymer family, has complete biodegradability and is easy to recycle as a monomer, and is a real green polymer material. It can be seen that polydioxanone (PPDO) is a truly low carbon and environment-friendly product;

The poly-p-dioxanone (PPDOS) has unique ether bond in the main chain structure, so that the flexibility of the polymer chain segment is increased, and further, the poly-p-dioxanone (PPDOS) has good flexibility and mechanical stability, meanwhile, the chain segment has good flexibility, is easy to arrange and fold to form a crystalline phase, has high tensile strength and knotting strength, and has high strength retention rate in the degradation process; thus, strength retention during degradation is large. The poly-p-dioxanone (PPDO) has low crystallization speed and low melt strength, and is difficult to mold and process, so that the application range of the poly-p-dioxanone is limited; even a single high molecular weight poly-p-dioxanone (PPDON) polymer has lower tensile strength (about 30 MPa), and has poorer thermal stability, and is easy to degrade at high temperature, so that the mechanical property of the material is further reduced; therefore, in order to expand the application of the polydioxanone (PPDO) polymer in other fields, the polydioxanone (PPDO) polymer can be used as a general polymer material, and the mechanical property and the thermal stability of the polydioxanone (PPDO) polymer are required to be improved, especially the thermal stability of the polydioxanone (PPDO) polymer is particularly important for processing and use.

Several researchers at the university of belvedere, germany, have passed the 400-day test to place various biodegradable plastics in seawater and fresh water, and finally PLA has only about 0.5% mass loss, which is almost indistinguishable from the degradation rate of common plastic bottles (such as PET mineral water bottles); PLGA is completely degraded at about 270 days, PHB is degraded by about 8% within 365 days, and PCL, PLA and PET are hardly degraded. The study results were published in ADVANCED SCIENCE NEWS at 2017, 6, 23;

polylactic acid-glycolic acid copolymer (PLGA) is a non-crystalline aliphatic ester polymer, so that the polylactic acid-glycolic acid copolymer has excellent biocompatibility, marine biodegradation and film forming performance, controllable degradation speed and no toxicity, is a completely biodegradable high polymer material, and has good application and industrialization prospects. But has the disadvantages of too fast degradation speed, large brittleness, low heat distortion temperature, poor impact resistance and insufficient mechanical strength; therefore, the application field of polylactic acid-glycolic acid copolymer (PLGA) is greatly limited.

The PLGA and PPDOs of the biodegradable materials with excellent comprehensive properties are not widely applied to the field of general materials like other biodegradable materials; the main reason for this is that the cost of PLGA and PPDO is far higher than that of PLA, PBAT, PHA, PCL material, and the PLGA and PPDO do not have the cost advantage of being used in the field of general materials with high added value, such as biomedical materials, and the like, and are unacceptable in the market; or when used singly, PLGA and PPDOs have insufficient performances per se and are difficult to use on a large scale; therefore, research on seawater degradation materials is also being vigorously conducted in all countries of the world to improve this situation.

Therefore, the research of the application is started from the following aspects based on the degradation mechanism of the polymer material in the water environment.

The transmitter adopts submicron poly-p-dioxanone (PPDO) and polylactic-co-glycolic acid (PLGA) blend materials as framework materials.

The two submicron materials are blended in a certain proportion, so that the advantages and disadvantages of the two materials are complemented, and a new raw material is obtained. Experimental studies in this application found and verified:

the thermal degradation data of submicron PLGA, submicron PPDO and submicron PLGA/PPDO blend materials are shown in table 2;

as can be seen from Table 2, the maximum thermal weight loss rate temperatures of PLGA, PPDO and PLGA/PPDO of the present application are similar, indicating that the thermal degradation processes of PLGA, PPDO and PLGA/PPDO of the present application are similar. The carbon residue rates of the pure PLGA and the PPDO are respectively reduced from 11% and 12% to 2%, and the reduction is obvious, which shows that the submicron PLGA and the submicron PPDO are blended, and the degradation process of the material is facilitated.

Thermal performance data of submicron PLGA, submicron PPDO and submicron PLGA and submicron PPDO blend materials in the application are shown in Table 3

As can be seen from Table 3, in the DSC curve of PLGA/PPDOs of the present application, two glass transition temperatures-13℃and 35℃respectively correspond to the glass transition temperatures of PLGA and PPDOs, but both temperatures do not tend to approach each other, indicating that the compatibility of the two polymer materials is poor. In addition, since PLGA is a non-crystalline polymer, PLGA does not show a cold crystallization peak and a melting peak in the DSC profile. The cold crystallization temperature of the PPDO after mixing is increased from 47 ℃ to 56 ℃, and the melting temperature is reduced from 106 ℃ to 105 ℃, which means that the addition of PLGA increases the winding degree among high molecular chain segments in the melt blending process, and the interference is generated on the regular arrangement of the PPDO in the crystallization process, so that the temperature requirement of the PPDO in the cold crystallization process is higher, the PPDO crystallization degree is reduced, the melting point is reduced, and TGA results show that the blending material of the PPDO/PLGA after blending the PPDO and the PLGA has reduced thermal degradation performance compared with the pure PPDO and the pure PLGA due to the influence of the PLGA on the crystallization performance of the PPDO in the blending process, so that the material is easier to be degraded, and the purpose of the application is met.

In order to make the mechanical properties of the blend materials of submicron PPDO and submicron PLGA of the present application better and more stable, it is necessary to prepare compatibilizers to increase the compatibility of the two polymers, so that the phase interfaces of the two phases are more tightly combined to ensure more stable properties of the blend materials; because the submicron PLGA and the PGA are compatible similarly, the PGA-b-PPDO segmented copolymer is adopted as one of the compatibilizers of the submicron PPDO and the submicron PLGA; meanwhile, PLGA-b-PPDOs synthesized by solvent-free bulk polymerization are particularly used as the compatibilizer with the best compatibilizing effect.

Third, the thermal performance data of the submicron PPDOs, submicron PLGA and blending materials added with different compatilizer proportions are shown in table 4;

note that: the addition amount of the A proportion compatilizer is 4% of the total weight of PPDO/PLGA, the B proportion compatilizer is 8%, and the C proportion compatilizer is 12%;

from Table 4, it can be seen that the difference between Tg1 and Tg2 from 0% to 12% of the addition amount of the compatibilizer, which is the ratio of PLGA/PPDO to PLGA/PPDO/C, is reduced from 48 ℃ to 38 ℃, thus indicating that the compatibilizer has a compatibilizing effect, but at the same time, the strength of the compatibilizer is weakened when the addition amount of the compatibilizer is increased to 12%, so that the compatibilizing effect is optimal when the addition amount of the compatibilizer is 8%, and the expected effect can be obtained; meanwhile, the addition of PLGA also accelerates the degradation rate of PPDO.

2. The application adopts submicron-level rice flour with the median value of the grain diameter of D50 being less than or equal to 0.442 mu m, high amylose starch with the median value of the grain diameter of D50 being less than or equal to 0.320 mu m and a compound plasticizer to carry out thermoplastic compound modification, and the submicron-level plant fiber and the modifier are compounded with the thermoplastic compound modification to prepare the composite material, so that the corresponding structure and physicochemical properties of the composite material are changed, and the application range is greatly enlarged.

The rice, the starch and the plant fiber are all natural polymer substances synthesized by plants through photosynthesis, harmful substances are not generated in the synthesis process, air can be purified and oxygen can be produced, and the rice, the starch and the plant fiber can be completely degraded under the actions of environment and microorganisms after being abandoned, so that the rice, the starch and the plant fiber are ideal green renewable resources.

The method comprises the following steps of adopting the structure of submicron rice flour and high amylose starch and influencing physicochemical properties:

with the improvement of the living standard of people, the demands of people on high-quality rice are increasing, however, partial low-quality rice, such as early long-shaped rice, broken rice in the process of stock aging of rice and rice processing, is rarely eaten directly in recent years due to loose grain structure, high amylose content, small rice viscosity and poor taste; at present, the rice resources in China are relatively rich, the development and utilization of the rice resources are the current important research subject, the research of deep processing technology of the rice is emphasized, and the method is a necessary way for improving the added value of the rice.

Amylose has similar fiber performance, good transparency, flexibility and tensile strength, is nontoxic and pollution-free, and has mechanical properties of various brands of starch plastics published at home and abroad, and can be generally compared with traditional plastics applied in the same class; however, the service performance of the plastic is often unsatisfactory, one of the main disadvantages is that the starch-containing degradable plastic is easy to age, has poor water resistance and poor wet strength, the mechanical property of the plastic is seriously reduced when meeting water, and the water resistance is just the advantage of the traditional plastic in the use process, thus greatly limiting the wide application of the plastic.

Compared with traditional rice flour and starch currently on the market, the lowest particle size technology is d50=150 respectively

The grain size is smaller than or equal to 0.442 mu m, the grain size is smaller than or equal to 0.320 mu m, the high amylose starch with the grain size smaller than or equal to 0.442 mu m is adopted in the application, the submicron superfine structure is achieved, the total volume of the material is unchanged, but the change of the property is caused due to the change of the structure of the material, so that the specific surface area of the material is also increased drastically, the microstructure and the property of the raw material powder are changed, and experimental researches in the application find and verify that:

(1) in terms of structure, the crystal structure of the particles is damaged layer by layer from outside to inside, and the lattice structure is damaged, so that the crystallinity of the material is reduced.

(2) The chemical reaction is easier to carry out because of the higher internal energy of aggregation of the particles and the formation of a large number of new surfaces, which makes the particles in a more active state. The product formed by the product and other degradable substances has good mechanical property, lower water absorption and the like under the condition of high content of submicron rice flour and high amylose, and effectively changes the paste property of the submicron rice flour and high amylose, low apparent viscosity, thixotropic property and shear thinning and nearly Newtonian fluid.

(3) Form a network structure, and the molecular weight and the crystallinity are reduced. The submicron rice flour and high amylose starch molecules adopted by the application are easier to combine with water molecules, the solubility is increased, gelatinization can be realized at a lower temperature, the expansion degree is reduced, therefore, the peak viscosity is small, the viscosity curve is flat, the drop value is reduced, the better viscosity thermal stability and cold stability are shown, the transparency and the gel consistency are increased, and gel and aging are not easy to form.

(4) The particle size is reduced, the specific surface area is increased, the contact area with the modifier is larger, the liquid absorption capacity is enhanced, the liquid absorption capacity is more sufficient and complete, the mass transfer is good, the accessibility is good, the subsequent reaction and utilization are facilitated, the size of a reaction substrate is further verified to be reduced, and the improvement of the reactivity of the substrate is facilitated.

(5) Greatly increases the specific surface area, and the surface area, dispersibility, adsorption capacity, surface activity and the like of the comparative raw powder are comprehensively changed; the specific surface area is greatly increased, so that the solubility and dissolution rate of the raw powder are obviously increased, the raw powder is easy to disperse, the contact area with other materials of the raw powder is enlarged, the adhesive force is enhanced, and the defect that the traditional raw powder is easy to iron when the end product is used is avoided. Meanwhile, the addition amount of submicron rice flour and high amylose adopted by the straw can be greatly improved, the addition amount of other biomass compositions with relatively high price and cost of raw materials is reduced, the cost of the straw is greatly saved on the premise that the application function of the straw is not affected, and the straw has high competitive power even if compared with the price of other products of the same country; the comprehensive cost is lower than that of the traditional compost degradation plastic in the current market.

(6) When 5 parts of the submicron starch of the present application is added to the system of the present application, it increases the crystallization temperature and enthalpy of crystallization of the system of the present application and exhibits nucleation. As the starch content continues to increase, the onset and peak crystallization temperatures of the blends of the systems of the present application cannot be increased further. Thus, when the starch content in the blend is 5wt%, the nucleation effect is saturated.

The application adopts the compound plasticizer that contains the plasticizer complex that high relative molecular mass of hydroxyl and low relative molecular mass formed, plasticizes this application system matrix:

at present, the common plasticizers are mainly alcohol and amide plasticizers, the plasticizing principle is polar groups of the plasticizers, and through the interaction with hydroxyl groups in and among molecules of materials, the intramolecular acting force is reduced, so that the processing temperature is reduced. Therefore, the plasticizer with high efficiency is synthesized, and the plasticizer with multiple functional groups is prepared by an organic synthesis method, so that the advantages of the plasticizer are one of the possible development directions.

The experimental study of the application finds and verifies that the advantages of some plasticizers can be optimized by compounding and combining different plasticizers, and the defects existing when a certain plasticizer is singly used can be eliminated, so that the purposes of reducing cost and improving plasticizing effect are achieved. Under the condition of keeping two or more plasticizers and mixing and plasticizing the matrix of the system, the mechanical property of the straw is improved.

(1) Compounding 1-ethyl-3 methylimidazole acetate and poloxamer:

the 1-ethyl-3-methylimidazole acetate changes the entanglement mode of amylose, and the starch-based film is more uniform, has no gel, lower molecular level, better plasticizing effect and obviously improved flexibility. Poloxamers are very low in toxicity and can be used for shaping and emulsifying, wetting, lubricating, dispersing, dusting, viscosity regulating. The two are compounded, and the heat treatment and flexibility are excellent, so that the performance of the matrix of the system can be improved, the matrix is more flexible, and the flow characteristic is changed.

(2) Polyethylene glycol stearate and acetyl tributyl citrate are compounded:

the polyethylene glycol stearate has one end of hydrophilic medium-high molecular weight polyethylene glycol and one end of lipophilic stearic acid, and thus can be adsorbed onto the mutually exclusive surfaces of oil and water to form a thin molecular layer, so that the interfacial tension of the two phases is reduced, the original mutually insoluble substances are uniformly mixed to form a uniform dispersion system, and the physical state of the raw materials is changed. The polyethylene glycol stearate with medium and high molecular weight can reduce acting force among matrix molecules of the system, improve processing performance and avoid high-temperature decomposition and carbonization of submicron rice flour, high-amylose starch and plant fibers adopted in the system. The function of the surfactant is as follows: stearic acid forms an insoluble complex with the submicron rice flour and high amylose starch employed herein to produce an anti-aging effect. Therefore, the modified polyurethane can not only play the role of a plasticizer, but also play the role of a surfactant. The acetyl tributyl citrate is used as a water-blocking plasticizer, has better plasticity to the poly (p-dioxanone) (PPDO) and the polylactic acid-glycolic acid copolymer (PLGA) of the application, so the addition of the acetyl tributyl citrate better ensures the common plasticization of the whole system, and the breaking elongation of the acetyl tributyl citrate is better than that of polyethylene glycol according to the breaking elongation, and has better mildew resistance;

The addition of polyethylene glycol stearate and citrate (ATBC) improves the tensile strength of the whole system, and illustrates that the addition of the two plasticizers all interact with a composite system to form a stronger hydrogen bond, thereby promoting the compatibility of the matrix of the system and the formation of an intercalation structure.

(3) Compounding glycerol and xylitol:

the glycerol with small molecular weight is easier to move than xylitol molecules with slightly larger molecular weight, can more effectively permeate between starch molecular chains, has larger destructive power on the action force between submicron rice flour and high amylose starch molecules adopted in the application, has more hydroxyl numbers in each molecule of xylitol with more carbon atoms, has strong action force between the xylitol and matrix molecules of the application system, and has far lower permeation effect than glycerol with smaller molecular weight. The molecular chain flexibility size was discerned by calculating the viscous flow activation energy AEq of the different blends, and it was found that aen=225.1 kg/mol for xylitol blends, and aen=122.5 kg/mol for glycerol blends, with large activation energy indicating enhanced rigidity of the molecular chain. Can effectively reduce the melt viscosity of the system and reduce the moisture absorption phenomenon of the submicron rice flour and the high amylose starch adopted by the thermoplastic polymer.

(4) The larger the molecular mass of the compound plasticizer is, the weaker the water absorption capacity is, the better the water-blocking steam property of the film is, and on the contrary, the worse the water-blocking steam property is.

(5) The thermoplastic submicron rice flour and high amylose starch materials adopted by the application show regular change in mechanical properties by adding different contents of the compound plasticizer, and generally have reduced tensile strength and increased elongation along with the increase of the content of the compound plasticizer.

(6) The crystallization rate of submicron rice flour, high amylose that this application adopted, along with moisture content's increase improves, and because this application compound plasticizer and submicron rice flour, high amylose that this application adopted between stronger hydrogen bond effect, can make the activity of starch chain and the stability of combining water reduce, this application compound plasticizer content increases, can make crystallization rate decline. However, if the compound plasticizer has higher hygroscopicity, the moisture content in the material is correspondingly increased, and the crystallization rate of submicron rice flour and high amylose adopted in the application is increased instead.

(7) The stronger the hydrogen bond forming capability between the compound plasticizer and the submicron rice flour and the high amylose adopted by the application, the better the retrogradation resistance of the submicron rice flour and the high amylose adopted by the application.

(8) In the starch, the proportion of the amylose is different, the effect of the plasticizer after plasticizing and the performance and microscopic state of the composite film prepared by blending the plasticizer are greatly different, and the higher the content of the amylose in the starch, the more favorable the plasticizing and the mixing with the poly (p-dioxanone) (PPDO) and the poly (lactic-co-glycolic acid) (PLGA) are.

Third, the application adopts submicron plant fiber, and the action in the application system:

the most commonly used plant fiber powder in the plant composite material is used as the mesh number of the filled plant fibers, has important influence on the mechanical property, the flow property and the microstructure of the composite material, the particle size of the plant fibers has remarkable influence on the plant molding composite effect, and the particle size of the plant fibers determines the dispersion degree of the plant fibers in a matrix and finally influences the material performance. According to the fiber reinforcement principle, the larger the mesh number of the plant fiber is, the smaller the particle size is, the more uniform the dispersion of the plant fiber in the polymer matrix is, and the better the mechanical property of the composite material is, which is related to the different interface combination of the plant fiber and the matrix plastic, the different fiber morphology, the different surface roughness and the different internal gap conditions; the number of plant fibers is thus an important parameter to consider in the preparation of plant molding composite materials.

However, in the process of preparing plant fiber materials in the market at present, the used equipment is mainly general plastic processing equipment, so that the problems of small grain size of plant fibers, high production energy consumption, unstable process, low production efficiency of equipment, difficulty in obtaining stable processing conditions, insufficient use performance and the like cannot be fundamentally solved, and plant fiber products with higher mesh numbers cannot be produced; according to reports, the highest mesh of traditional plant fibers currently on the market is d50=19 μm for german technology and d50=10 μm for chinese technology (laboratory scale). Therefore, the plant fiber products with low mesh number in the market at present can only be used in the fields of outdoor decorative materials, building materials, wood plastic materials and the like with low added value.

The application adopts the sugarcane fiber with the median of the submicron particle diameter of which the plant fiber is D50 less than or equal to 0.261 mu m, the bamboo fiber with the D50 less than or equal to 0.316 mu m and the lotus leaf fiber with the D50 less than or equal to 0.230 mu m, and the plant fiber plays a role in preventing the polymer molecule chain segment from moving under the action of tensile load; the smaller the particle size of the plant fiber, the higher the interweaving and dispersing degree of the polymer molecular chain and the plant fiber, and the stronger the blocking effect on the movement of the polymer molecular chain, so that the strength of the material is gradually improved; the composite material has the excellent characteristics of small particle size, high crystallinity, high specific surface area, high activity surface, high mechanical strength, excellent elastic modulus, low thermal expansion, good melt flow rate, biodegradability, recycling, low density, thermal stability, low cost and the like, and is used as a reinforcing phase to be added into the base material of the application, so that various physical and chemical properties and application performances of the composite material are improved.

The preparation method adopts submicron rice flour, high amylose starch and compound plasticizer to carry out thermoplastic compound modification, and prepares the composite material by compounding submicron plant fiber and modifier with the submicron rice flour, thereby changing the corresponding structure and physicochemical properties of the composite material and greatly expanding the application range.

Experimental studies in this application found and verified:

(1) the effect of the submicron-sized plant fiber on the performance of the present application.

Firstly, can restrict the mobility of this application to the chain of polydioxanone (PPDO) and polylactic acid-glycolic acid copolymer (PLGA), form network structure simultaneously, thermal stability and mechanical properties are improved, and in the within a small range, this application submicron level plant fiber content's increase, mechanical properties are also steadily increasing.

Second, the submicron plant fiber with different addition amounts can improve the breaking elongation of the straw, and the toughness is greatly improved; the yield strength and the breaking strength generally tend to increase and then decrease when the usage amount of the submicron plant fiber is 8%, and the breaking elongation yield strength of the straw is the highest.

Thirdly, as the dosage of the submicron plant fiber increases, the flaky structure of the section of the material gradually disappears, and the uniform orientation disappearance of the blending material is presented, so that the mechanical property of the straw is improved to a great extent.

Fourthly, the hydrophobicity of the material can be improved by adding lotus leaf powder; 3 to 8 parts of lotus leaf powder is added into the material, the surface energy of the material can be reduced to 13 to 40 percent, and the physical and mechanical properties of the material are not affected; while also providing a synergistic effect on the surface hydrophobicity of the pipette of the present application.

Fifth, the submicron-level plant fiber of the application is finer in particles, smaller in particle size and larger in specific surface area, coating and complete compatibility of other components are facilitated, a compact structure is formed between the submicron-level plant fiber and other materials, and therefore the water absorption capacity of the straw of the application is reduced.

(2) The application relates to the influence of submicron plant fiber filling quantity on a composite material.

First, the impact strength of the composite material increases with the increase of the filling amount of the plant fiber, which indicates that the plant fiber can be well combined with rice flour and high amylose starch, thereby absorbing the energy during impact. However, when the filling amount of the plant fiber is more than 8 parts by weight, the impact strength is reduced to a certain extent, and when the filling amount is 12 parts by weight, the impact strength is reduced to 9kJ/m < 2 >, which is caused by the increase of the probability of occurrence of defects in the composite material, and the continuity of the composite material matrix is affected.

The hardness of the second, composite material increases with increasing loading of the plant fibers of the present application, particularly with greater loading of plant fibers of greater than 3 parts by weight. It can be inferred from this that when the plant fiber filling amount was 3 parts by weight, the plant fiber showed its own rigidity in the composite material remarkably, so that the overall hardness of the composite material was remarkably improved, and when the plant fiber filling amount was 8 parts by weight, the hardness reached 40, which was nearly doubled compared with that when it was 3 parts by weight.

Thirdly, when the filling amount of the plant fiber is more than 12 parts by weight, the melting time is increased, the melting torque of the composite material is increased, the fluidity of the material is obviously reduced, and the melting becomes difficult; in order to ensure higher plant fiber filling quantity and certain plasticizing processability in the composite material, the plant fiber filling quantity of 8 parts by weight basically can obtain better mechanical strength and proper fluidity.

(3) The effect of the proportion of the compound plasticizer on the composite material is achieved.

First, the tensile strength of the composite material shows an increasing trend along with the increase of the proportion of the compound plasticizer, so that it is inferred that the compound plasticizer is added into the composite material, and the tensile resistance of the material can be improved within a certain range. However, when the amount of the plasticizer is more than 8 parts by weight, the tensile strength is remarkably decreased.

Second, the adoption adds this application and compounds the content of plasticizer 4 ~ 8 parts, and combined material impact strength wholly descends to 6kJ/m2, is the decline trend, and when adopting single plasticizer to add, impact strength is 15kJ/m2, is unfavorable for absorption and consumption to impact energy, leads to combined material to receive the fragile fracture of easily taking place when the impact effect.

Thirdly, the adoption adds the content of this application compound plasticizer 4 ~ 8 parts, along with the increase of compound plasticizer, combined material hardness constantly improves. It can be inferred that the compound plasticizer can limit the movement of rice flour and high amylose starch molecules in the composite material, so that the strength of the composite material is improved.

(4) Impact of the modifier on composite properties.

Compared with the composite material prepared without the modifier, the modifier can improve the tensile strength and the impact strength of the composite material, and is specifically expressed as follows: the tensile strength is increased from 15MPa to 17MPa, the impact strength is increased from 11KJ/m < 2 > to 13KJ/m < 2 >, and the hardness is slightly reduced. The mechanical properties of the composite material are reduced by directly adding the plant fiber, and the composite material is mainly characterized in that the compatibility of the directly added plant fiber and the matrix composite material is poor and cannot be well dispersed, and the plant fiber can improve the matrix compatibility by adopting the modifier, so that the stretching resistance and the impact resistance of the composite material are improved.

3. The application adopts eggshell calcium carbonate to enhance the degradation speed and physical strength of the system.

Experimental studies in this application found and verified:

the eggshell calcium carbonate is used in the straw, and can remarkably improve the tensile strength, the elongation at break, the bending strength, the bending modulus, the hardness, the heat resistance and other performance indexes of the straw. Not only can obviously improve the strength and toughness of the suction pipe and increase the rigidity of the suction pipe, but also has the characteristics of good dispersibility, high temperature resistance and the like.

The eggshell calcium carbonate is neutral and alkaline after being reacted with water, and can promote the chemical degradation of the poly-p-dioxanone (PPDO) and the polylactic acid-glycolic acid copolymer (PLGA) in the straw material in alkaline environment to reduce the molecular weight, thereby being beneficial to improving the microbial or marine degradation rate of the poly-p-dioxanone (PPDO) and the polylactic acid-glycolic acid copolymer (PLGA), and in addition, after the straw containing the eggshell calcium carbonate is buried underground, the eggshell calcium carbonate reacts with carbon dioxide and water to generate Ca (HCO 3) which can be dissolved in water ₂ Leaving this application straw, leaving fine hole on the straw, increase straw and surrounding air and microorganism contact's area to promote the straw degradation, realize the complete quick degradation of this application straw material, can also greatly reduce cost.

Aiming at the defects and shortcomings in the prior art, the application provides a multi-element combined synergistic refined biodegradable straw and a multi-element compounding preparation method thereof, and compared with other known methods, the biodegradable straw has the following advantages.

1. New materials of submicron PLGA/PPDO/PGA-b-PPDO and PLGA/PPDO/PLGA-b-PPDO are prepared.

PPDO and PLGA each have some drawbacks due to their own structural factors, such as slow crystallization rate, low melt strength, poor hydrolytic stability, etc., which form a big obstacle for their use as general materials; the PPDO has unique ether bond in the main chain structure, so that the flexibility of the polymer chain segment is increased, and the PPDO has good flexibility and mechanical stability; but simultaneously, because the chain segment has better flexibility, the chain segment is easy to arrange and fold to form crystalline phase, and the degradation time of the material is long. PLGA is an amorphous aliphatic ester polymer, and thus has excellent degradation properties, but has disadvantages of large brittleness and insufficient mechanical strength; these limit the wide range of applications of PPDO and PLGA.

Therefore, according to the defects of the PPDO and the PLGA, the compatibilizer is used for preparing the PLGA/PPDO ∈ by mixing and combining two submicron materials in a certain proportion

New raw materials of PGA-b-PPDO or PLGA/PPDO/PLGA-b-PPDO; the advantages and disadvantages of the two materials are complemented, the respective advantages are exerted, the disadvantages are discarded, and the biodegradable material with more excellent comprehensive performance is prepared:

the method comprises the steps that according to the similar compatibility principle, a PLGA chain segment is replaced by PGA, and a PGA-b-PPDO block copolymer is adopted as one of the compatibilizers blended by the PPDO and the PLGA; meanwhile, PLGA-b-PPDOs synthesized by solvent-free bulk polymerization are used as the compatibilizer for the application, so that the compatibilizer has the best compatibilizing effect;

(2) Compared with the traditional compatibilization method, the method has the advantages that as the reaction is carried out in the organic solvent, the toxic residues of the solvent are difficult to remove, and the compatilizer is safer and more environment-friendly;

compared with the traditional degradable high polymer material, the high polymer material with biodegradability can be degraded gradually through hydrolysis and enzymolysis without residue while playing the role;

the material is blended by melt blending under the condition that the melting point and the decomposition temperature of PLGA and PPDOs are matched, so that organic solvent residues brought to the blend by using solution blending in the traditional method are avoided.

2. The performance of double-modified thermoplastic treatment is obviously superior to that of single-modified thermoplastic treatment in the traditional sense by adopting the technology of submicron rice flour and high-amylose composite compound plasticizer.

In the traditional thermoplastic treatment, the thermal movement of molecules can be increased by increasing the reaction time within a certain time, so that more plasticizer molecules penetrate into starch molecules, the substitution reaction rate is improved, the substitution degree is increased, but the general chemical reaction is carried out within a shorter time, the reaction time is too long, and the generated products are cracked, denatured and the like, so that the resource waste is caused; the reaction temperature can directly influence the action of the modifier and the starch, and experiments with slightly higher or lower temperature can not be carried out smoothly.

Compared with traditional rice flour and starch in the market at present, the technology of the lowest particle size is D50=150 mu m and 74 mu m respectively, and the adopted D50 is less than or equal to 0.442 mu m rice flour and D50 is less than or equal to 0.320 mu m high amylose starch in the application reach a submicron ultra-fine structure, the total volume of the material is unchanged, the surface area is greatly increased, so that the specific surface area of the material is also greatly increased, the microstructure and the property of the raw material powder are further changed, the crystal structure of particles is damaged from outside to inside in the aspect of structure, the crystal lattice structure is damaged, and the crystallinity of the material is reduced until the material becomes amorphous; the chemical bond of the substance is broken to generate electrons, ions or unsaturated groups, so that the molecular weight of the substance is reduced, and the space structure is changed; the particles are in a more active state due to the higher internal energy of aggregation of the particles and the formation of a large number of new surfaces, under the condition of certain other influencing factors, the smaller the particles of the material are, the more the groups in the material are exposed, the probability of the plasticizer contacting the groups is increased, and the modifying condition can accelerate the action of the plasticizer and promote the substitution reaction, so that the modifying effect is obvious, and under the condition of the same other conditions, the substitution degree of the submicron rice powder and the high amylose starch is higher than that of the original high amylose starch, and the chemical reaction is easier to carry out; as one of the components of the composite material, the addition of the composite material not only improves the mechanical property of the composite material, but also improves the biodegradability of the composite material, has excellent environmental protection performance and has some special physical or chemical properties.

Experimental studies in this application found and verified:

the method has the advantages that the smaller the particles are, the more groups in the materials are exposed, the probability of contact between the modifier and the groups is increased, the modifying condition can accelerate the action of the modifier and promote the substitution reaction, so that the modifying effect is obvious, and the substitution degree of the superfine crushed materials is higher than that of the original powder under the condition that other conditions are the same. The detection according to the Kjeldahl nitrogen method GB12091-89 shows that the substitution degree of the traditional single modified starch which is not subjected to superfine grinding is 0.1, and the substitution degree of the traditional single modified starch is 0.3; under the same conditions, the substitution degree of the modified starch is higher than that of the traditional single modified starch, and the particle size influences the modification effect of the plasticizer on the modified starch, so that the submicron particle size plays a non-negligible role.

(2) The experimental test shows that the traditional single modified high amylose starch product which is not subjected to superfine grinding has only 34% of weight loss after 50d of soil burying and poorer degradation performance. After the outdoor soil is buried for 50 days, the weight loss rate is 72.2%, the soil can be completely degraded for about 4 months, the degradation performance is obviously superior to that of the traditional single modified high-amylose starch, and the environment-friendly material meets the concept of modern environment-friendly materials; under the same conditions, the weight loss rate of the modified starch is higher than that of the traditional single modified high-amylose starch, which indicates that the size of the particles influences the modification effect of the plasticizer on the particles, and the submicron particle size plays a non-negligible role.

(3) According to the detection of the X-diffraction pattern, the crystallinity of the traditional single modified high amylose starch is higher than that of the traditional single modified high amylose starch, the traditional single modified high amylose starch is easier to process and form, DSC results show that the heat stability of the traditional single modified high amylose starch is higher than that of the traditional single modified starch, the transmittance of the traditional single modified starch is higher than that of the traditional single modified starch, the viscosity of the traditional single modified starch is lower than that of the traditional single modified starch, and the traditional single modified starch is beneficial to the processing and the product effect after the processing.

Experiments on mechanical properties, water resistance, thermal stability and the like show that the compatibility, mechanical properties, water resistance and thermal stability of the modified starch composite material are obviously improved compared with those of the original starch composite material and the traditional single modified high-amylose starch composite material, and the film forming property of the modified starch composite material is stronger than those of the original starch and the traditional single modified thermoplastic high-amylose starch.

The application adopts submicron rice flour and high amylose starch, and has huge specific surface area, compared with other known methods:

(1) the application exposes more free hydroxyl groups, the larger the contact area with the modifier is, the liquid absorption capacity is enhanced, the more sufficient and complete is realized, the mass transfer is good, the accessibility is good, the subsequent reaction and utilization are facilitated, the size of a reaction substrate is further verified to be reduced, and the improvement of the reaction performance of the substrate is facilitated. The activity of the submicron rice flour and the high amylose starch is increased, the adsorption capacity is also enhanced, and even if the addition amount of the submicron rice flour and the high amylose starch is very high in the product of the application, the submicron rice flour and the high amylose starch have good mechanical property and lower water absorption compared with products formed by other degradable substances;

(2) The specific surface area of the composite powder is greatly increased, and the surface area, dispersibility, adsorption capacity, surface activity and the like of the composite powder are comprehensively changed; the specific surface area is greatly increased, so that the solubility and dissolution rate of the raw powder are remarkably increased, the raw powder is easy to disperse, the contact area with other materials of the raw powder is enlarged, the adhesive force is enhanced, and the defect that the traditional raw powder is easy to iron when the end product is used is avoided;

(3) compared with other known methods, the filler has the advantages that the filler has the addition amount of not more than 30 parts by weight, the specific surface area is larger, the contact area with the outside is increased, the surface area, the dispersibility, the adsorption capacity and the like of the filler are comprehensively changed compared with those of the raw powder, and the coating of other components is facilitated; the addition amount of submicron rice flour and high amylose starch adopted by the method is greatly improved, the addition amount of other biomass compositions with relatively high price and cost of raw materials is reduced, and the comprehensive cost of the end product is greatly and remarkably reduced on the premise of not affecting the application performance of the straw; even compared with the prices of other products of the same country, the composite cost is lower than the traditional compost degradation plastic in the current market.

3. Compared with the traditional compost degradation straw, the submicron plant fiber with larger specific surface area is added, so that more remarkable mechanical performance and high natural degradability are provided.

According to the fiber reinforcement principle, the larger the mesh number of the plant fiber is, the smaller the particle size is, the more uniform the dispersion of the plant fiber in the polymer matrix is, and the better the mechanical property of the composite material is, which is related to the different interface combination of the plant fiber and the matrix plastic, the different fiber morphology, the different surface roughness and the different internal gap conditions; thus, the number of plant fibers is an important parameter to consider in the preparation of plant molded composites.

According to reports, the highest mesh of traditional plant fibers currently on the market is d50=19 μm for german technology and d50=10 μm for chinese technology (laboratory scale). Therefore, the plant fiber products with low mesh number in the market at present can only be used in the fields of outdoor decorative materials, building materials, wood plastic materials and the like with low added value.

The application adopts the sugarcane fiber with the median of the submicron particle diameter of which the plant fiber is D50 less than or equal to 0.261 mu m, the bamboo fiber with the D50 less than or equal to 0.316 mu m and the lotus leaf fiber with the D50 less than or equal to 0.230 mu m, and the plant fiber plays a role in preventing the polymer molecule chain segment from moving under the action of tensile load; the smaller the particle size of the plant fiber, the higher the interweaving and dispersing degree of the polymer molecular chain and the plant fiber, and the stronger the blocking effect on the movement of the polymer molecular chain, so that the strength of the material is gradually improved; the composite material has the excellent characteristics of small particle size, high crystallinity, high specific surface area, high activity surface, high mechanical strength, excellent elastic modulus, low thermal expansion, good melt flow rate, biodegradability, recycling, low density, thermal stability, low cost and the like, and is used as a reinforcing phase to be added into the base material to improve various physical and chemical properties and application properties of the composite material.

Experimental studies in this application found and verified:

compared with the traditional composting degradation straw, the submicron plant fiber with larger specific surface area is added, so that a mixture is endowed with a denser structure, and gaps among materials are filled greatly; the denser texture also provides the straw of the present application with better water resistance and can be stabilized in water for 4 hours without color-change.

The mechanical properties of this application straw have been strengthened. Compared with the traditional compost degradation straw, the bending strength of the straw is improved by about 5 times, the tensile strength is improved by about 60 times, and the straw has enough waterproof property (the wet mechanical strength is about 12 times that of the current commercial paper straw).

The structural stability of the suction tube in extrusion is maintained, and the diameter of the suction tube in a set range and the surface smoothness of a product are ensured; the submicron plant fiber increases the toughness and the processability of the straw, and simultaneously, the prepared straw has good rebound resilience. Not only greatly improves the melt strength of the material and improves the processing performance of the material, but also obviously plays a role in reinforcing plant fibers, and makes an excellent contribution to obtaining the high-strength straw. Meanwhile, the excellent mechanical property of the material also provides strong competitive power for industrial production.

The submicron plant fiber with larger specific surface area is adopted in the application and has good interface compatibility with the PPD0 matrix, so that the researches provide a new research thought for the research of natural organic plant fiber materials/biodegradable polymer composite materials.

Fifthly, submicron rice flour, high amylose starch and plant fiber are finer, smaller in particle size and larger in specific surface area, so that the coating and complete compatibility of other components are facilitated, a compact structure is formed between the submicron rice flour, high amylose starch and plant fiber and other materials, and the water absorption capacity of the suction pipe is reduced; compared with other known methods, the modified polypropylene composite material has the advantages of high mechanical strength, excellent elastic modulus, low thermal expansion, better melt flow rate, biodegradability, recycling, low density, thermal stability, low cost and the like.

4. In order to reduce the cost and ensure the degradation performance of the product, starch-based biodegradable plastics are hot spot products which are concerned worldwide. The application research of the starch-based natural polymer materials at present mainly comprises the following two classes: the first type is starch filled degradable material, plasticizer and resin are added into starch base for mixing, if common non-degradable resin is added into the material, the material has the defects of low biodegradation rate and long degradation period, and the material still brings great burden to the environment in terms of environmental protection; if the fully biodegradable polyester is added, the addition amount of starch is greatly limited, so that the cost is too high; the second category is high content starch degrading materials: the starch content is high, but the finished product has the defects of brittleness, high density, easy fragmentation and limited application range caused by poor mechanical property; in addition, the existing starch modification method is often modified through catalysis, and the cost is high. At present, the U.S. KTM starch company adopts high amylose starch, and the performance of the high amylose starch, polyvinyl alcohol, foaming agent and the like, which are produced on a double screw machine, is basically satisfied with the use requirement, but the problems of low foaming rate, uneven cell diameter, uneven foam surface and the like still exist, and the application range of the high amylose starch foaming material is greatly limited.

The following requirements must be met in order to enter the market:

(1) the practicability is similar to that of the compostable degradable plastic; the mechanical property and the mutual matching property of elastic modulus are excellent enough; easy molding, preservation and low cost;

(2) degradability, has adjustable degradation rate, can be degraded in soil and marine environment quickly after the use function is completed, and finally returns to nature;

(3) safety, no harm or potential hazard to soil and marine environment in the degradation process;

(4) economical, the price is close to or equal to that of the compostable degradable plastic. However, the price of the existing degradable plastic is over 50% higher than that of the similar existing plastic products, wherein the price of the existing degradable plastic is 4-8 times higher than that of the existing plastic products, and the existing degradable plastic becomes the biggest obstacle for popularization and application.

For the series of requirements, the submicron polydioxanone (PPDO) and the polylactic acid-glycolic acid copolymer (PLGA) are taken as the suction pipe of the application as a framework, submicron rice powder and high amylose starch are taken as a matrix, submicron plant fibers and eggshell calcium carbonate are taken as reinforcements, and the reinforcement is combined with related auxiliary agents, and the blending and copolymerization measures are adopted, and the melt extrusion is carried out at 55-140 ℃ through a double-stage serial screw granulator unit to form a novel intermolecular assembly structure, so that the excellent mechanical properties of the polydioxanone (PPDO) and the polylactic acid-glycolic acid copolymer (PLGA) are achieved, and the suction pipe of the application obtains good effects by means of the water resistance and the mechanical strength of the submicron plant fibers and the eggshell calcium carbonate.

The rice flour, the high amylose starch, the plant fiber and the eggshell calcium carbonate are rich in sources and low in cost.

The submicron poly-p-dioxanone (PPDON) is extremely easy to hydrolyze, can be rapidly degraded even in the air, is very rarely used as a biodegradable polymer capable of realizing complete closed loop recycling, is most suitable for being applied to the field of disposable products, can realize repeated recycling and complete biodegradation after being abandoned, and has important significance in simultaneously solving the problems of resources and environment.

The degradation of the high molecular polymer is generally closely related to the molecular weight, the size and shape, the temperature and the degradation environment. Through experimental study, the water absorption and mass loss, pH characteristic viscosity number, sample morphology and crystal structure in the degradation process of the submicron polydioxanone (PPDO) are observed regularly, the change of thermodynamic property and mechanical property is realized, and the analysis on the aspects of the submicron polydioxanone (PPDO) such as the weight loss, the water absorption, the tensile property, the morphology and the like is found and verified:

(1) the poly (p-dioxanone) (PPDO) with high molecular weight is found to be capable of presenting a relatively stable degradation process in a neutral and weakly alkaline environment;

(2) It was found that the relatively high molecular weight polydioxanone (PPDO) degraded relatively smoothly in the early degradation period (weeks 1-3), at a relatively slow rate, and significantly increased in the degradation period (weeks 4-6), with a concomitant decrease in the weight loss rate and decrease in tensile strength, however, the electron microscopy scan suggested that the polydioxanone (PPDO) was only a surface structure failure without involvement of the central portion, and that the tensile strength of the polydioxanone (PPDO) was further decreased after week 7. This degradation process is similar to previous research reports. In relatively low molecular weight polydioxanone (PPDO) degradation experiments, this procedure, while similar, has significantly reduced degradation time of polydioxanone (PPDO) with an increase in weight loss and a significant decrease in tensile strength;

(3) the relatively high molecular weight polydioxanone (PPDO) is found that the mass loss and the water absorption rate are not greatly changed in the degradation process, but the molecular weight is obviously reduced, and meanwhile, the surface defects of the sample are gradually increased; the crystallinity and the glass transition temperature are changed along with the change, but the crystal structure of the poly-p-dioxanone is basically unchanged, which is a direct result brought by the improvement of the molecular weight, and proves that the poly-p-dioxanone (PPDO) with high molecular weight has slower degradation speed and shows good stability;

(4) In the past, experimental data about in vitro degradation of polydioxanone (PPDO) are mostly derived from the degradation experimental result of the polydioxanone (PPDO) of a surgical suture, and the surgical suture has great limitation on the degradation experimental result due to the small surface area and high orientation degree and the limitation of the shape;

however, after the poly (p-dioxanone) (PPDO) is prepared into a tubular sample, the degradation behavior of the sample is correspondingly changed due to the change of the shape of the sample, and the molecular weight becomes one of the most important factors influencing the degradation. The chemical structural formula of the polydioxanone (PPDO) is as follows: - { O- (CH 2) 2-O-CH2-CO } n-is a polymer synthesized by ring-opening polymerization of p-dioxanone, and the degradation takes place by hydrolysis. The relative molecular weight of polydioxanone (PPDO) is one factor that determines the degradation time, and in the same external environment, the low molecular weight polydioxanone (PPDO) degrades for a shorter period of time, while the high molecular weight polydioxanone (PPDO) degrades for a longer period of time, thus providing longer mechanical support properties;

(5) analysis by capillary rheometry shows that the submicron grade polydioxanone (ppdi) of the present application has a lower melt viscosity than the commercially available ppdi-cyclohexanone (ppdi) of the same molecular weight, and that the melt viscosity is lower as the mesh number of the ppdi of the present application is reduced. In addition, the influence of the molecular weight on the flow property of the melt is very remarkable, and the apparent viscosity of the melt increases along with the increase of the molecular weight; the melt flow behavior of the submicron polydioxanone (PPDO) is very sensitive to the temperature, and the apparent viscosity of the submicron polydioxanone (PPDO) is quickly reduced along with the rise of the temperature;

(6) The degradation experiment shows that the submicron polydioxanone (PPDO) has a weight loss rate faster than that of the commercial polydioxanone (PPDO) with the same molecular weight due to the special structure, the weight retention rate of the commercial polydioxanone (PPDO) is 70.94 percent after 13 weeks of degradation, and the weight retention rate of the submicron polydioxanone (PPDO) is 60.59 percent, which is 10 percent different; this is probably because the submicron polydioxanone (PPDO) of the present application has a larger specific surface area, is easier to contact with water and hydrolyzes faster than a linear polymer of the same molecular weight; another reason is that the end ester bond of the polymer molecule is easier to hydrolyze than the intra-molecular ester bond, and the sub-micron poly-p-dioxanone (PPDO) of the application accelerates the degradation speed due to the increase of the end ester bond due to the branched structure;

(7) the submicron poly-p-dioxanone (PPDO) of the present application degrades faster in phosphate buffer solution than linear PPDO of the same molecular weight, and the degradation rate is faster with decreasing molecular weight. The pH value of the degradation environment has great influence on the degradation rate, the submicron poly-p-dioxanone (PPDO) is most sensitive to the alkaline environment, the polymer is most rapidly degraded in the alkaline environment, the weight loss rate is faster in a neutral solution than in an acidic solution, but the molecular weight is slowly reduced;

(8) By H-NMR analysis of the degraded sample, it was shown that the hydrolysis of the submicron poly-p-dioxanone (PPDO) herein occurs primarily on the ester linkages of the segment, but not on the ester linkages attached to the polyol; DSC analysis showed that after 11 weeks, the crystallinity of the submicron polydioxanone (PPDO) of the present application began to drop and the crystalline region had also begun to be destroyed.

As the research on the degradation of the polydioxanone (PPDO) with high molecular weight in the field of general materials except for high added value such as biomedical materials is also reported recently at home and abroad, the application achieves controllable degradation speed by adjusting and adding the polydioxanone (PPDO) with different molecular weights, and expands the application field of the polydioxanone (PPDO) biodegradable material with different purposes, so that the polydioxanone (PPDO) has wider application prospect.

Aliphatic polyesters are often used for biomedical materials and environmentally friendly materials, and thus biodegradability is an important index for evaluating the performance thereof. The biodegradability of a polymer is greatly affected by the structure, molecular weight, hydrophilicity, crystallinity, and degradation environment of the polymer. The submicron polylactic acid-glycolic acid copolymer (PLGA) has a plurality of special properties compared with the commercial polylactic acid-glycolic acid copolymer (PLGA) with the same molecular weight due to the unique structure. Through experimental study, the application finds and verifies that:

(1) Commercially available polylactic acid-glycolic acid copolymers (PLGA) have higher glass transition temperature, melting point, crystallization temperature and crystallinity, but WAXD shows that they have a similar crystalline structure. Experimental results also show that the commercial polylactic acid-glycolic acid copolymer (PLGA) has higher intrinsic viscosity in a dilute solution, and the dynamic viscosity and loss modulus of the commercial polylactic acid-glycolic acid copolymer (PLGA) are lower than those of the commercial polylactic acid-glycolic acid copolymer (PLGA) in a concentrated solution;

(2) the degradation performance in phosphate buffer solution shows that the submicron polylactic acid-glycolic acid copolymer (PLGA) has higher weight loss rate than the commercial polylactic acid-glycolic acid copolymer (PLGA) with the same molecular weight, but the molecular weight change is not obvious as that of the commercial polylactic acid-glycolic acid copolymer (PLGA);

(3) the application achieves controllable degradation characteristics by adjusting the copolymerization ratio of two monomers added with different submicron polylactic acid-glycolic acid copolymers (PLGA), and the application finds and verifies that in a 24h alkaline environment, the degradation rate of PLGA70/30 modified materials is 35%, the degradation rate of PLGA80/20 modified materials is 28%, and the degradation rate of PLGA90/10 modified materials is 20; therefore, the application has important significance for the research and evaluation of the degradation performance of the polylactic acid-glycolic acid copolymer (PLGA), and provides a solid experimental foundation for further exploring the degradation mechanism of the polylactic acid-glycolic acid copolymer (PLGA) and improving the performance of the polylactic acid-glycolic acid copolymer (PLGA); the submicron polylactic acid-glycolic acid copolymer (PLGA) has excellent hydrolytic degradation characteristics, and provides an effective solution for the pollution problem of microplastic which is widely focused at present.

The structure of ⒌ polymer, including chemical structure, physical structure, surface structure, etc., as well as the hydrophilicity of the polymer, the stability of degradable bonds, crystallinity, aggregation state structure, etc., have great influence on the degradation performance of the polymer; the submicron polylactic acid-glycolic acid copolymer (PLGA), submicron polydioxanone (PPDO) and the commercially available polylactic acid-glycolic acid copolymer (PLGA), polydioxanone (PPDO) show different degradation performance and a plurality of different physical properties due to different molecular structures;

the submicron poly-p-dioxanone (PPDO) and the nanometer polylactic acid-glycolic acid copolymer (PLGA) have more terminal hydroxyl groups and special structures, so that the affinity with submicron rice flour, high amylose starch and plant fibers and the curing speed are increased, and higher coating efficiency is obtained;

compared with the commercial polylactic acid-glycolic acid copolymer (PLGA) and the poly (p-dioxanone) (PPDO) with the same molecular weight, the submicron poly (p-dioxanone) (PPDO) and the submicron polylactic acid-glycolic acid copolymer (PLGA) have lower hydrodynamic volume, so that the melt viscosity and the solution viscosity are lower; the submicron polydioxanone (PPDO) and submicron polylactic acid-glycolic acid copolymer (PLGA) can be widely applied to industries such as agriculture, medicine, cosmetics, environment-friendly materials and the like;

The application adopts submicron poly-p-dioxanone (PPDO) and submicron polylactic acid-glycolic acid copolymer (PLGA) to design and synthesize the polymer with novel structure, so that the polymer has wider application prospect in the aspects of drug release systems and tissue engineering materials.

In summary, the multi-element combined synergistic refined biodegradable straw well meets the series of requirements, has lower cost of the adopted raw materials, and can better balance the comprehensive performance and biodegradability of the product, so that the product has good mechanical property and proper service life; the physical, chemical or biological properties of the material are regulated and controlled by changing the composition, chemical structure and molecular weight of the material; through certain technology, the degradation rate and degradation period of the material are regulated and controlled, the straw is ensured to keep better effective use performance in a certain use period, and after the straw is used, the straw can be degraded in soil and marine environment according to requirements and returns to ecological cycle, and meanwhile, the straw can have good biodegradation performance in soil and marine environment, which is an incomparable advantage of other materials with the application.

6. The blend melt extrusion employed in the present application.

The traditional research is mainly focused on physical blending of the thermoplastic material and the biodegradable polymer and modification of the composite layer, the two-phase interface of the composite material obtained by the two methods is poor in compatibility, the addition amount of the thermoplastic material is small, and the obtained composite material is poor in water resistance and mechanical property.

The blending melt extrusion adopted in the application is characterized in that the mixture materials are subjected to transesterification or cross-linking or grafting under high temperature and high pressure in the extrusion process, so that the polymer with amphipathy is obtained, the compatibility of the mixture materials and the processability of the blend are improved, and experimental research in the application finds and verifies that the method can increase the addition amount of the thermoplastic materials, is excellent in performance, and has excellent mechanical properties, low cost, low density and high degradability.

Based on the advantages, the straw has great potential to replace the traditional compost degradation straw, which provides a solid theoretical basis for industrially preparing the high-performance straw, and the research can be widely applied to the research work of soil-degradable and marine biodegradable materials with larger scale and deeper.

Detailed Description

The present application is further illustrated by the following examples, which are provided only to illustrate the present application and not to limit the scope of the present application.

Examples

A multi-element combined synergistic refined biodegradable straw and a preparation method thereof comprise the following steps:

(1) weighing according to the weight portion: chen Mifen 60 parts of high-amylose corn starch 8 parts, 3.5 parts of compound plasticizer polyethylene glycol stearate and 2.5 parts of acetyl tributyl citrate are added into a mixer together, stirred for 5 minutes at a rotating speed of 1500rpm, and then the obtained material is sealed and placed for 24 hours at room temperature, dried until the water content is less than or equal to 1 percent, and sealed for later use;

(2) weighing according to the weight portion: adding 8 parts of plant fiber bamboo fiber, 8 parts of eggshell calcium carbonate, 1.2 parts of epoxy functionalized ADR4468 chain extender of modifier Pasteur company, 0.05 part of natural antioxidant soybean polyphenol and 0.1 part of antimicrobial Velsan SPA multifunctional antimicrobial agent into a mixer, stirring for 5 minutes at 800rpm, drying until the water content is less than or equal to 1%, and sealing for later use;

(3) weighing according to the weight portion: 4.8 Parts of Polydioxanone (PPDO), 7.2 parts of polylactic acid-glycolic acid copolymer (PLGA) and 0.96 part of compatibilizer PLGA-b-PPDO segmented copolymer are added into a mixer, and the mixture is stirred for 10 minutes at the rotating speed of 300rpm and then sealed for standby;

(4) Adopting a double-stage serial screw extruder unit, wherein the length-diameter ratio of a screw extruder in the first stage is 32:1, and the length-diameter ratio of a single screw extruder in the second stage is 16:1; the temperature of the barrel temperature zone of the screw extruder in the first stage is set as follows in sequence: the barrel temperature zone temperature of the single screw extruder at 75 ℃, 85 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃ in sequence is set as follows: adding the raw materials in the step (1) into a first feeding port arranged in a first temperature zone of a double-stage serial screw extruder unit through a vacuum feeder conveying device in thirteen temperature zones of 140 ℃, 130 ℃, 125 ℃, 105 ℃, 75 ℃ and 55 ℃, adding the raw materials in the step (2) through fully mixing, conveying to a second feeding port arranged in a third temperature zone, and adding the raw materials in the step (3) through fully mixing, conveying to a third feeding port arranged in a fifth temperature zone; the rotational speed of the screw is 150r/min, and the biodegradable straw which is cooperatively refined by multiple combinations is obtained through the steps of melt extrusion, traction, cooling, cutting and packaging at 55-140 ℃;

and (5) changing the forming die and the cutting knife in a production line to produce various tubular objects in large scale.

Examples

(1) Weighing according to the weight portion: adding 20 parts of early long-shaped rice powder, 5 parts of high-linear-chain-epidermis pleated pea starch, 1.35 parts of compound plasticizer 1-ethyl-3-methylimidazole acetate and 0.9 part of poloxamer into a mixer together, stirring for 12 minutes at a rotating speed of 2000rpm, sealing and placing the obtained material at room temperature for 24 hours, and drying until the water content is less than or equal to 1%, and sealing for later use;

(2) weighing according to the weight portion: 3 parts of plant fiber lotus leaf fiber, 3 parts of eggshell calcium carbonate, 0.3 part of modifier Pasteur company epoxy functionalized ADR4468 chain extender, 0.02 part of natural antioxidant vitamin E and 0.06 part of antibacterial agent Velsan SPA multifunctional antibacterial agent are added into a mixer, and after stirring for 5 minutes at the speed of 1000rpm, the mixture is dried until the water content is less than or equal to 1 percent, and the mixture is sealed for later use;

(3) weighing according to the weight portion: 5 Parts of Polydioxanone (PPDO), 45 parts of polylactic acid-glycolic acid copolymer (PLGA), 4 parts of compatibilizer PGA-b-PPDO block copolymer are added into a mixer, and the mixture is stirred for 10 minutes at a rotation speed of 500rpm and then sealed for standby;

(4) adopting a double-stage serial screw extruder unit, wherein the length-diameter ratio of a screw extruder in the first stage is 32:1, and the length-diameter ratio of a single screw extruder in the second stage is 16:1; the temperature of the barrel temperature zone of the screw extruder in the first stage is set as follows in sequence: the barrel temperature zone temperature of the single screw extruder at 80 ℃, 90 ℃, 95 ℃, 100 ℃, 120 ℃, 125 ℃, 130 ℃ in sequence is set as follows: adding the raw materials in the step (1) into a first feeding port arranged in a first temperature zone of a double-stage serial screw extruder unit through a vacuum feeder conveying device in thirteen temperature zones of 140 ℃, 135 ℃, 130 ℃, 110 ℃, 80 ℃ and 60 ℃, adding the raw materials in the step (2) through fully mixing, conveying to a second feeding port arranged in a third temperature zone, and adding the raw materials in the step (3) through fully mixing, conveying to a third feeding port arranged in a fifth temperature zone; the rotational speed of the screw is 200r/min, and the biodegradable straw which is cooperatively refined by multiple combinations is obtained through the steps of melting extrusion, traction, cooling, cutting and packaging at the temperature of 60-140 ℃;

Examples

(1) weighing according to the weight portion: adding 30 parts of crushed rice powder, 3 parts of high-linear-chain-skin pleated pea starch, 1.77 parts of compound plasticizer glycerol and 1.2 parts of xylitol into a mixer, stirring for 9 minutes at 1700rpm, sealing and placing the obtained material at room temperature for 24 hours, drying until the water content is less than or equal to 1%, and sealing for later use;

(2) weighing according to the weight portion: 5 parts of plant fiber and sugarcane fiber, 4 parts of eggshell calcium carbonate, 0.8 part of epoxy functionalized ADR4468 chain extender of modifier Pasteur company, 0.04 part of natural antioxidant tea polyphenol and 0.08 part of antibacterial agent Velsan SPA multifunctional antibacterial agent are added into a mixer, and after stirring for 5 minutes at 900rpm, the mixture is dried until the water content is less than or equal to 1 percent, and the mixture is sealed for later use;

(3) weighing according to the weight portion: 45 Parts of Polydioxanone (PPDO), 5 parts of polylactic acid-glycolic acid copolymer (PLGA), 4 parts of compatibilizer PLGA-b-PPDO segmented copolymer are added into a mixer, and the mixture is stirred for 10 minutes at 400rpm and then sealed for standby;

(4) Adopting a double-stage serial screw extruder unit, wherein the length-diameter ratio of a screw extruder in the first stage is 32:1, and the length-diameter ratio of a single screw extruder in the second stage is 16:1; the temperature of the barrel temperature zone of the screw extruder in the first stage is set as follows in sequence: 78 ℃, 88 ℃, 93 ℃, 98 ℃, 115 ℃, 123 ℃, 128 ℃ and setting the barrel temperature zone temperature of the second-stage single screw extruder as follows: adding the raw materials in the step (1) into a first feeding port arranged in a first temperature zone of a double-stage serial screw extruder unit through a vacuum feeder conveying device in thirteen temperature zones of 135 ℃, 130 ℃, 128 ℃, 108 ℃, 78 ℃ and 58 ℃, adding the raw materials in the step (2) through fully mixing, conveying to a second feeding port arranged in a third temperature zone, and adding the raw materials in the step (3) through fully mixing, conveying to a third feeding port arranged in a fifth temperature zone; the rotating speed of the screw rod is 180r/min, and the multi-element combined synergistic refined biodegradable straw is obtained through the steps of melt extrusion, traction, cooling, cutting and packaging at 58-135 ℃;

Currently, more research demonstrates that the original purpose of using biodegradable plastics is or is not achieved. On the one hand, most of them are compost-degradable plastics, which also need to meet certain conditions and be affected by oxygen, humidity, temperature, specific microorganisms, etc. This means that the biodegradable plastic product cannot be discarded at will after use, and degradation is also a requirement. However, in natural environment, it is difficult to reach the degradation condition, conditions are required to be created artificially, and the biodegradable plastic is greatly expanded, and meanwhile, the following of supporting facilities is also required;

On the other hand, with the current process conditions, biodegradable plastics may not be as "environmentally friendly" as one would expect unless the degradation requirements were reduced, or the biodegradable waste could be discarded into kitchen waste bins; biodegradable plastic articles are intended to replace plastics that are not controlled to flow into the natural environment, reducing the impact on the environment. However, research data of the university of Qinghua shows that about 97% of the research data still enter the incineration and landfill links.

According to the bio-degradable straw which is obtained by the multi-element combination synergistic refining and is obtained in the embodiment, experimental research shows that:

the procedure of example 1 of the present application was carried out according to ASTM D5338 (Standard method for measuring aerobic biodegradation of plastics in a simulated urban waste pile environment). In the whole testing process, the aeration rate of the container is kept constant, the ambient environment of the container is measured to be changed, samples are taken every other appointed days, distilled water is used for washing, vacuum drying is carried out at 60 ℃ until the constant weight is reached, and the change of the weight is measured;

note that: the waste mixture comprises crushed leaves, food waste, kitchen waste, wood dust, urine and distilled water, and has humidity of 60-70%;

The straw compost landfill biodegradation rate in example 1 of the present application is shown in table 5;

meets the ASTM D5338 standard for degradation rate and the definition of compost landfill degradation.

2. In example 2 of the application, the degradation rate of the suction pipe for 180 days is more than or equal to 90 percent according to the standard test method of the weight consumption of plastic materials hatched in a marine environment through an open system aquarium according to ASTM D7473-12, and the requirements of the ASTM D7473-12 on the degradation rate and the definition of marine degradation are met.

3. The suction pipe of the embodiment 3 meets the requirement of the ASTM D5988 standard on the degradation rate and the definition of soil degradation according to the ASTM D5988 soil degradation standard test, wherein the 120-day degradation rate of the suction pipe is more than or equal to 90 percent.

All of the foregoing descriptions of specific exemplary embodiments of the present application are presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the present application and its practical application to thereby enable one skilled in the art to make and utilize the present application in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. Or equivalent replacement of part of the technical features; these modifications, substitutions, and other conceivable alternatives are within the scope of the present application, and do not depart from the spirit and scope of the embodiments of the present application.

Claims

1. A multi-element combined synergistic refined biodegradable straw is prepared from the following raw materials in parts by weight: 5 to 50 Parts of Polydioxanone (PPDO), 5 to 50 parts of polylactic acid-glycolic acid copolymer (PLGA), 0.8 to 4.4 parts of compatibilizer, 20 to 60 parts of rice flour, 3 to 8 parts of high amylose starch, 1.8 to 6.8 parts of compound plasticizer, 3 to 8 parts of plant fiber, 0.3 to 1.2 parts of modifier, 0.02 to 0.05 part of natural antioxidant, 0.06 to 0.1 part of antibacterial agent and 3 to 8 parts of eggshell calcium carbonate;

the polylactic acid-glycolic acid copolymer (PLGA) is any one of PLGA90/10, PLGA80/20, PLGA75/25, PLGA50/50 and PLGA10/90, the molecular weight is 10000-30000, and the median diameter D50 is less than or equal to 0.113 mu m;

the molecular weight of the polydioxanone (PPDO) is 10000-30000, and the median diameter D50 is less than or equal to 0.125 mu m;

2. The multi-element combined synergistic refined biodegradable straw according to claim 1, wherein the rice flour is one or a mixture of two of early indica rice flour, chen Mifen and crushed rice flour, and the median diameter D50 is less than or equal to 0.442 μm.

3. The multi-component synergistic refined biodegradable straw according to claim 1, wherein the high amylose starch is one or a mixture of two of high amylose corn starch and high amylose epidermoid pleated pea starch, the amylose content of the high amylose starch is 90-95%, and the median diameter D50 is less than or equal to 0.320 μm.

4. The multi-element combined synergistic refined biodegradable straw according to claim 1, wherein the plant fiber is sugar cane fiber with a median particle diameter D50 less than or equal to 0.261 μm and a median particle diameter D50 less than or equal to 0.316

Bamboo fiber with a diameter of mu m and lotus leaf fiber with a median diameter D50 of less than or equal to 0.230 mu m.

5. The multicomponent synergistic refined biodegradable plastic suction tube as claimed in claim 1, wherein said compatibilizer is any one of PLGA-b-PPDO block copolymer and PGA-b-PPDO block copolymer;

the ratio of PLGA to PPDO in the PLGA-b-PPDO block copolymer is 2:1, a step of;

the PGA-b-PPDOS block copolymer has a PGA and PPDOS ratio of 2:1.

6. the multi-component synergistic refined biodegradable straw of claim 1, wherein the compound plasticizer is a mixture of two or more of polyethylene caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer, 1-ethyl-3 methylimidazole acetate, isosorbide, acetyl tributyl citrate, polyethylene glycol stearate, acetylated monoglyceride, propylene glycol, glycerol, poloxamer.

7. The multi-component synergistic refined biodegradable plastic suction tube as claimed in claim 1, wherein said natural antioxidant is one or two of vitamin E, tea polyphenols, soybean polyphenols.

8. The multi-component synergistic refined biodegradable straw according to claim 1, characterized in that the preparation method thereof comprises the following steps:

(2) weighing according to the weight portion: 3 to 8 parts of plant fiber, 0.3 to 1.2 parts of modifier, 3 to 8 parts of eggshell calcium carbonate, 0.02 to 0.05 part of natural antioxidant and 0.06 to 0.1 part of antibacterial agent are added into a mixer, stirred for 5 minutes at the rotating speed of 300 to 500rpm, and then dried until the water content is less than or equal to 1 percent, and sealed for standby;

(3) weighing according to the weight portion: 5 to 50 Parts of Polydioxanone (PPDO), 5 to 50 parts of polylactic acid-glycolic acid copolymer (PLGA) and 0.8 to 4.4 parts of compatibilizer are added into a mixer, and the mixture is stirred for 10 minutes at the speed of 800 to 1000rpm and then sealed for standby;

9. The multi-element combined synergistic refined biodegradable suction tube and its preparation method as claimed in claim 8, wherein the various tubular objects are produced in large scale by changing the forming die and the cutting knife in the production line.