CN113150521B

CN113150521B - High-toughness biodegradable composite material, and preparation device and method thereof

Info

Publication number: CN113150521B
Application number: CN202110500711.5A
Authority: CN
Inventors: 蔡少扬; 蔡贻琳
Original assignee: Jiangxi Xinhe Ecological Technology Co ltd
Current assignee: Jiangxi Xinhe Ecological Technology Co.,Ltd.
Priority date: 2021-05-08
Filing date: 2021-05-08
Publication date: 2022-01-25
Anticipated expiration: 2041-05-08
Also published as: CN113150521A

Abstract

The invention discloses a high-toughness biodegradable composite material, a preparation device and a preparation method thereof, wherein the high-toughness biodegradable composite material comprises the following raw materials in percentage by mass: 40-70% of biodegradable resin, 20-40% of modified straw fiber, 1-5% of fumed silica, 0.5-3% of silane coupling agent, 0.5-3% of compatilizer, 1-5% of plasticizer, 0.5-5% of lubricant, 0.1-0.5% of antioxidant and 0.1-0.5% of bacteriostatic agent. The invention adopts biodegradable resin and modified straw fiber as main raw materials, is assisted by an auxiliary agent, and fully mixes and mixes the components by a high-pressure internal mixer, so that the prepared composite material has good biodegradability, good strength and toughness, and greatly reduced material cost.

Description

High-toughness biodegradable composite material, and preparation device and method thereof

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a high-toughness biodegradable composite material, and a preparation device and method thereof.

Background

China is a large country for planting grain crops, mainly wheat, rice and corn, and can generate a large amount of crop straws every year. For the treatment of the straws, severe air pollution such as haze and the like can be caused by burning, if the straws are directly returned to the field, the straws contain a large amount of lignin and cellulose, so that the straws are not easy to decay, if the straws are not fully crushed or the ploughing depth is not enough, the germination rate of the next crop seeds is low, and if the straws are not treated and directly returned to the field, the crop diseases can be propagated through the soil. The effective treatment and utilization of the straws become a difficult problem in agricultural production in China.

The application of the high polymer material in our production and life is ubiquitous, but the high polymer material brings convenience, and simultaneously, due to the characteristic of difficult decomposition, the high polymer material also brings the problem of white pollution worldwide and continuously destroys our living environment. With the increasing awareness of environmental protection, the preparation of biodegradable materials is receiving more and more attention. However, most of the biodegradable materials in the prior art have the problems of high material cost, incapability of meeting the requirements and the like, and become an obstacle to further popularization of the biodegradable materials. Therefore, the biodegradable composite material which fully utilizes the cellulose rich in the crop straws, reduces the development cost and can strengthen and toughen has great significance.

In addition, when producing this biodegradable material, need earlier carry out the preliminary treatment with various raw materials after, carry out intensive mixing, common mixing means is to use high-pressure banbury mixer, but common banbury mixer need be before production begin with be about to in whole materials once only dropping into the machine, make the raw materials harden easily and cause subsequent not even mixing, or in the machine use, after will providing the high-pressure ram and mention, carry out follow-up feeding process after releasing the inside high pressure of banbury mixer, high pressure release not only can cause the influence to the inside material of mixing of banbury mixer, and simultaneously because the banbury mixer is at feed inlet department pressure imbalance, lead to the material of sending into easily to be extruded, cause the feeding process to go on many times.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-toughness biodegradable composite material and a preparation process thereof. The invention adopts biodegradable resin and modified straw fiber as main raw materials, is assisted by an auxiliary agent, and fully mixes and mixes the components by a high-pressure internal mixer, so that the prepared composite material has good biodegradability, good strength and toughness, and greatly reduced material cost.

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

a high-toughness biodegradable composite material comprises the following raw materials in percentage by mass: 40-70% of biodegradable resin, 20-40% of modified straw fiber, 1-5% of fumed silica, 0.5-3% of silane coupling agent, 0.5-3% of compatilizer, 1-5% of plasticizer, 0.5-5% of lubricant, 0.1-0.5% of antioxidant and 0.1-0.5% of bacteriostatic agent;

the biodegradable resin is a mixture of PBAT and PLA;

in the mixture of PBAT and PLA, the PBAT accounts for 20 to 40 percent of the total amount of the mixture of PBAT and PLA;

preferably, the high-toughness biodegradable composite material comprises the following raw materials in percentage by mass: 45-60% of biodegradable resin, 25-35% of modified straw fiber, 2-4% of fumed silica, 1-2% of silane coupling agent, 1-2% of compatilizer, 2-4% of plasticizer, 1-3% of lubricant, 0.2-0.4% of antioxidant and 0.2-0.4% of bacteriostatic agent;

in the mixture of PBAT and PLA, the PBAT accounts for 25 to 35 percent of the total amount of the mixture of PBAT and PLA.

Wherein, the PLA is polylactic acid, has the advantages that the material has excellent biodegradability and the defects of hard and brittle material and poor toughness;

the PBAT is a copolymer of butanediol adipate and butanediol terephthalate, has excellent biodegradability, better ductility and elongation at break, and better heat resistance and impact performance;

the modified straw fiber is prepared by taking any one of wheat straws, corn stalks and rice straws as a raw material;

the fumed silica is hydrophobic fumed silica with surface grafting modification;

the plasticizer is any one of epoxidized soybean oil, glycerol and polyethylene glycol;

the silane coupling agent is any one of KH550 or KH 560;

the compatilizer is maleic anhydride grafted compatilizer;

the lubricant is palm oil;

the antioxidant is phosphite ester;

the bacteriostatic agent is sodium dehydroacetate.

Preferably, the preparation method of the high-toughness biodegradable composite material comprises the following steps:

s1, grinding biodegradable resin into tiny particles, wherein the particle size of the particles is 100-200 meshes;

s2, grinding the modified straw fibers into nanoscale modified straw fibers;

s3, weighing the raw materials according to the proportion, and fully and uniformly mixing the raw materials in a high-pressure internal mixer;

and S4, placing the mixture obtained in the step S3 in a double-screw extruder for extrusion granulation to obtain the high-toughness biodegradable composite material.

Preferably, the preparation of the modified straw fiber comprises the following steps:

(1) pretreatment: removing leaves of the straws, cleaning, drying and crushing to obtain straw powder;

after being crushed, the straws are sieved by a 40-60-mesh sieve, and the particle size of the obtained straw powder is 40-60 meshes;

(2) physical modification: putting the straw powder into an ultrasonic oscillator, and adding pure water for oscillation treatment;

the amount of the added pure water is required to be capable of completely submerging the straw powder; the ultrasonic oscillation time is 45-60 minutes, so that the cell wall of the wood fiber is broken, the lignin is softened and partially degraded, and the hemicellulose is hydrolyzed;

(3) chemical modification: the method comprises the steps of placing a mixture of straw powder subjected to ultrasonic treatment and pure water into a reaction kettle, adding sodium hydroxide into the reaction kettle, enabling the straw powder to react with alkali liquor under the conditions of high temperature and high pressure, enabling components such as lignin and hemicellulose to flow out along with the alkali liquor, improving the content of cellulose, and enabling the surface of the straw to be rougher after the straw is treated with the alkali liquor, generating gully, increasing the contact area and strengthening the bonding capacity between fiber and a polymer interface.

The mass fraction of the sodium hydroxide in the alkali liquor formed by adding the sodium hydroxide is 8-16%; the high temperature and high pressure conditions are that the pressure is between 0.5 and 0.9M, the reaction temperature is between 130 and 170 ℃, and the reaction time is between 20 and 50 minutes;

(4) and (3) post-treatment: after the chemical modification is finished, adjusting the pH value to be neutral, filtering and collecting fibers, washing and drying to obtain modified straw fibers;

the pH is adjusted to be neutral, and the reaction is carried out when the temperature of a reaction system is reduced to be below 70 ℃; the raw material used for adjusting the pH is 36 percent acetic acid; the fiber washing process is to wash the fiber for 3 to 5 times by pure water; the drying temperature after washing is about 100 ℃.

Preferably, the specific operation of step S3 is as follows:

1) weighing PLA, PBAT, fumed silica, a silane coupling agent, a compatilizer, a plasticizer and a lubricant according to a ratio, feeding the mixture into a mixing chamber of a high-pressure mixer through a feeding mechanism of the high-pressure mixer, closing the feeding mechanism and providing continuous high pressure into the mixing chamber through a pressurizing assembly;

2) uniformly mixing the raw materials added into the mixing chamber under the action of two stirring rollers rotating in opposite directions to obtain a primary mixture;

3) weighing modified straw fibers, an antioxidant and a bacteriostatic agent according to a ratio, adding the modified straw fibers, the antioxidant and the bacteriostatic agent into a feeding mechanism through a feeding sealing assembly, pressurizing the inside of the feeding mechanism through a pressure balancing assembly to ensure that the pressure in the feeding mechanism is equal to the pressure in the mixing chamber, and removing the isolation between the feeding mechanism and the mixing chamber through a separating sealing assembly to ensure that the raw materials fall into the mixing chamber;

4) and (3) adding the raw materials in the mixing chamber again, and fully rolling and mixing the raw materials and the primary mixture in the mixing chamber in a high-pressure environment to obtain a mixture.

Preferably, the preparation device for the high-toughness biodegradable composite material is a high-pressure internal mixer, and the high-pressure internal mixer comprises:

a support assembly;

the banburying chamber is arranged at the top end of the supporting component and is used for receiving the raw materials fed by the feeding mechanism and stirring and mixing the raw materials;

the pressurizing assembly is arranged at the top end of the mixing chamber and is used for providing a high-pressure environment for the interior of the mixing chamber;

and the feeding mechanism is arranged on one side of the top end of the mixing chamber and used for feeding the raw materials into the mixing chamber for multiple times and keeping the pressure of the feeding mechanism consistent with that of the mixing chamber when the raw materials are fed.

Preferably, the feed mechanism comprises a pressure balancing assembly, a feed seal assembly and a separation seal assembly;

the pressure balancing component is used for keeping the internal pressure of the feeding mechanism consistent with the internal pressure of the mixing chamber;

the feeding sealing assembly is used for inputting raw materials into the feeding mechanism and ensuring the isolation between the feeding mechanism and the outside when the feeding sealing assembly is closed;

the separation sealing component is used for opening or blocking the communication between the feeding mechanism and the mixing chamber.

Preferably, a discharging assembly is arranged on one side of the bottom end of the mixing chamber, which is far away from the feeding mechanism, two stirring rollers are arranged inside the mixing chamber, and the stirring rollers are driven by a motor arranged outside the mixing chamber;

the discharging component is used for discharging the raw materials which are stirred in the mixing chamber out of the mixing chamber;

the stirring roller is used for stirring the raw materials in the internal mixing chamber.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, PLA (polylactic acid) and PBAT (poly (butylene adipate/terephthalate)) and modified straw fiber are used as main raw materials to prepare the biodegradable composite material, the PLA (polylactic acid) and the PBAT (poly (butylene adipate/terephthalate)) can be completely degraded by microorganisms in the nature under specific conditions, the PLA belongs to hard plastic, the PBAT belongs to soft plastic, the PLA and the PBAT are combined to ensure that the material has good strength and toughness, and the straw fiber has very good mechanical property and higher toughness, so that after being doped into biodegradable resin, the degradation speed of the composite material can be accelerated, the strength and toughness of the material can be enhanced, the cost of the material can be greatly reduced, and the promotion of plastic-limiting work is facilitated.

2. According to the invention, the crop straws are subjected to multiple processes of pretreatment, physical modification, chemical modification and post-treatment, so that the cellulose content is greatly improved, and the mechanical strength is improved accordingly; hemicellulose, lignin, crude protein and the like which have the effect of hindering interface adhesion are effectively removed, the combination with biodegradable resin is facilitated, and the adhesion effect is better.

3. The main raw materials of the biodegradable resin and the modified straw fiber are ground, so that the particle size of the raw materials is smaller, the materials are uniformly mixed during banburying and mixing, the materials are firmly combined with each other, and the composite material has higher strength and toughness.

4. The surface graft modified hydrophobic fumed silica is added in the invention, so that the strength, toughness, wear resistance, waterproofness and aging resistance of the material can be improved, the dispersibility of the material can be improved, and high-content modified straw fibers can be prevented from being agglomerated.

5. The sodium dehydroacetate is used as the bacteriostatic agent, so that the bacteriostatic effect is good, and the sodium dehydroacetate is a food-grade bacteriostatic agent, so that toxic substances cannot migrate into food when the biodegradable composite material prepared by the method is used for preparing edible products such as food, beverage and the like, and the method is safe and reliable.

Drawings

FIG. 1 is a flow diagram of a manufacturing process of the present invention;

FIG. 2 is a schematic perspective view of a high pressure internal mixer according to the present invention;

FIG. 3 is a schematic cross-sectional view of a high pressure internal mixer according to the present invention;

FIG. 4 is a schematic perspective view of a stirring roller of the high pressure internal mixer of the present invention;

FIG. 5 is a schematic perspective view of a feeding mechanism of the high pressure internal mixer of the present invention;

FIG. 6 is a schematic sectional view of the feeding mechanism of the high-pressure internal mixer of the present invention;

FIG. 7 is a schematic perspective view of the open state of the sealing assembly of the feeding mechanism of the high pressure internal mixer of the present invention;

FIG. 8 is a schematic sectional view showing an opened state of a feed seal assembly of the feeding mechanism of the high pressure internal mixer according to the present invention;

FIG. 9 is a second schematic perspective view of the high pressure internal mixer of the present invention;

FIG. 10 is a second schematic cross-sectional view of a high pressure internal mixer of the present invention.

In the figure: 1. a support assembly; 2. an internal mixing chamber; 3. a pressurizing assembly; 4. a feeding mechanism; 41. a pressure balancing assembly; 411. an auxiliary hydraulic press; 412. a hydraulic telescopic rod; 413. a pressurizing plate; 414. a pressure sensor; 42. a feed seal assembly; 421. a feeding box; 422. a locking bolt; 423. a leak-proof plate; 43. a separation seal assembly; 431. a partition plate; 432. a lateral driver; 5. a discharge assembly; 51. a discharge baffle; 52. an electric telescopic rod; 6. stirring rollers; 61. and (4) spiral ribs.

Detailed Description

For further understanding of the present invention, the high toughness biodegradable composite material provided by the present invention, and the apparatus and method for preparing the same are described below with reference to the following examples, and the scope of the present invention is not limited by the following examples.

Example 1

A high-toughness biodegradable composite material comprises the following raw materials in percentage by mass: 40.8% of PLA, 17.6% of PBAT, 30% of modified straw fiber, 3% of fumed silica, 1.5% of silane coupling agent, 1.5% of compatilizer, 3% of plasticizer, 2% of lubricant, 0.3% of antioxidant and 0.3% of bacteriostatic agent;

PBAT accounts for 30% of the total mixture of PBAT and PLA;

the modified straw fiber is prepared by taking wheat straws as raw materials, and the preparation steps are as follows:

(1) pretreatment: removing leaves of wheat straws, cleaning, drying, crushing, and sieving with a 50-mesh sieve to obtain straw powder with the particle size of 50 meshes;

(2) physical modification: putting the straw powder into an ultrasonic oscillator, adding pure water for oscillation treatment, wherein the ultrasonic oscillation time is 50 minutes;

(3) chemical modification: placing the mixture of the ultrasonically treated straw powder and pure water into a reaction kettle, adding sodium hydroxide into the reaction kettle to form an alkali liquor, wherein the mass fraction of the sodium hydroxide in the alkali liquor is 10%, controlling the pressure in the reaction kettle to be about 0.8M, the reaction temperature to be about 150 ℃ and the reaction time to be 30 minutes;

(4) and (3) post-treatment: after the chemical modification is finished, adjusting the pH value of the solution to be neutral by using 36% acetic acid, filtering and collecting fibers, cleaning the fibers for 4 times by using pure water, and finally drying at about 100 ℃ to obtain the wheat modified straw fibers.

The preparation method of the high-toughness biodegradable composite material comprises the following steps:

s1, grinding PBAT and PLA into fine particles of 200 meshes;

s2, grinding the modified straw fibers into nanoscale modified straw fibers:

s3, weighing the raw materials according to the proportion, and fully and uniformly mixing in a high-pressure internal mixer:

1) weighing PBAT, PLA, fumed silica, a silane coupling agent, a compatilizer, a plasticizer and a lubricant according to the proportion, feeding the mixture into an internal mixing chamber 2 of a high-pressure internal mixer through a feeding mechanism 4 of the high-pressure internal mixer, sealing the feeding mechanism 4 and providing continuous high pressure into the internal mixing chamber 2 through a pressurizing assembly 3;

2) adding PBAT, PLA, fumed silica, a silane coupling agent, a compatilizer, a plasticizer and a lubricant in the banburying chamber 2, and uniformly mixing under the action of two stirring rollers 6 rotating in opposite directions to obtain a primary mixture;

3) weighing modified straw fibers, an antioxidant and a bacteriostatic agent according to a ratio, adding the modified straw fibers, the antioxidant and the bacteriostatic agent into the feeding mechanism 4 through the feeding sealing component 42, pressurizing the inside of the feeding mechanism 4 through the pressure balancing component 41 to ensure that the pressure in the feeding mechanism 4 is equal to the pressure in the banburying chamber 2, and releasing the isolation between the feeding mechanism 4 and the banburying chamber 2 through the separating sealing component 43 to ensure that the modified straw fibers, the antioxidant and the bacteriostatic agent fall into the banburying chamber 2;

4) adding the modified straw fiber, the antioxidant and the bacteriostatic agent in the banburying chamber 2 into the banburying chamber 2 again, and fully rolling and mixing the mixture and the primary mixture in the banburying chamber 2 in a high-pressure environment to obtain a mixture;

Comparative example 1

Based on embodiment 1, the difference from embodiment 1 is that: the content of PBAT in the raw materials is adjusted to be 40 percent of the total amount of the mixture of PBAT and PLA, namely 35 percent of PLA and 23.4 percent of PBAT, and the content of other raw materials is not changed.

Comparative example 2

Based on embodiment 1, the difference from embodiment 1 is that: the content of the modified straw fiber in the raw material is improved and adjusted from 30% to 35%, the content of the biodegradable resin is reduced and adjusted from 58.4% to 53.4%, the proportion of PBAT in the biodegradable resin to the total amount of the mixture of PBAT and PLA is unchanged, namely 30%, namely 37.4% of PLA, 16% of PBAT, and the content of other raw materials is unchanged.

Comparative example 3

Based on embodiment 1, the difference from embodiment 1 is that: the added modified straw fiber and the biodegradable resin are not ground.

Comparative example 4

Based on embodiment 1, the difference from embodiment 1 is that: the modified straw fibers are not added, the difference is complemented by PLA and PBAT, the PBAT accounts for the total amount of the mixture of the PBAT and the PLA and is the same as that in the embodiment 1, namely, the PLA is 61.9 percent, the PBAT is 26.5 percent, and the contents of other raw materials are not changed.

Example 2

Referring to fig. 2-10, the high pressure internal mixer provided by the invention is shown in a schematic structural diagram.

As shown in fig. 2, a high pressure internal mixer comprising:

a support assembly 1;

the banburying chamber 2 is arranged at the top end of the support component 1 and is used for receiving the raw materials fed by the feeding mechanism 4 and stirring and mixing the raw materials;

the pressurizing assembly 3 is arranged at the top end of the mixing chamber 2 and is used for providing a high-pressure environment for the interior of the mixing chamber 2;

and the feeding mechanism 4 is arranged on one side of the top end of the mixing chamber 2 and used for feeding the raw materials into the mixing chamber 2 for multiple times and keeping the pressure of the feeding mechanism 4 consistent with that of the mixing chamber 2 when the raw materials are fed.

With reference to fig. 3 and 4, in this embodiment, one or more raw materials to be mixed are firstly fed into the mixing chamber 2 through the feeding mechanism 4, after the raw materials enter the mixing chamber 2, the feeding mechanism 4 is closed and continuous high pressure is provided to the inside of the mixing chamber 2 through the pressurizing assembly 3, so that the raw materials inside the mixing chamber 2 are continuously kneaded under the action of the helical ribs 61 on the two stirring rollers 6 rotating in opposite directions, and the raw materials inside the mixing chamber 2 are uniformly mixed.

As shown in fig. 4, the two stirring rollers 6 rotate in opposite directions, the stirring rollers 6 are provided with a plurality of spiral ribs 61, the spiral directions of the spiral ribs 61 on the two stirring rollers 6 are opposite, and the density of the spiral ribs 61 in the center of the stirring rollers 6 is greater than that of the spiral ribs 61 at the two ends of the stirring rollers 6.

In this embodiment, in the process of mixing and stirring inside the mixing chamber 2, the two stirring rollers 6 are constantly rotated under the action of the external motor, so that the raw materials inside the mixing chamber 2 are constantly kneaded between the spiral ribs 61 on the stirring rollers 6 and inside the mixing chamber 2, and thus the raw materials are sufficiently mixed under the high-pressure environment provided by the pressurizing assembly 3 and the constantly kneading and stirring action, and because the density of the spiral rib 61 in the center of the stirring roller 6 is greater than the density of the spiral ribs 61 at the two ends of the stirring roller 6, when the raw materials are located at the center of the stirring roller 6, the kneading and stirring effects are stronger, and in use, by controlling the rotation direction of the stirring roller 6, the conveying direction of the raw materials passing through the spiral ribs 61 is controlled, so that the materials can be collected, and the raw materials inside the mixing chamber 2 can be sufficiently mixed, the mixing effect of the internal mixer is ensured.

As shown in fig. 5-8, the feed mechanism 4 includes a pressure balancing assembly 41, a feed seal assembly 42, and a separation seal assembly 43; the pressure balancing component 41 is used for keeping the internal pressure of the feeding mechanism 4 consistent with the internal pressure of the mixing chamber 2; the feeding sealing assembly 42 is used for inputting raw materials into the feeding mechanism 4, and the feeding sealing assembly 42 ensures the isolation between the feeding mechanism 4 and the outside when closed; the separating seal 43 serves to open or block the communication of the feed mechanism 4 with the mixing chamber 2.

The pressure balancing assembly 41 comprises an auxiliary hydraulic machine 411, a hydraulic telescopic rod 412, a pressurizing plate 413 and a pressure sensor 414, the auxiliary hydraulic machine 411 drives the pressurizing plate 413 to move inside the feeding mechanism 4 through the hydraulic telescopic rod 412, the pressure sensor 414 is used for detecting the internal pressure of the feeding mechanism 4, and the auxiliary hydraulic machine 411 adjusts the position of the pressurizing plate 413 according to the internal pressure of the feeding mechanism 4 until the internal pressures of the feeding mechanism 4 and the internal mixing chamber 2 are equal.

The feeding sealing assembly 42 includes a feeding box 421 and at least one locking bolt 422, the locking bolt 422 locks or unlocks the feeding box 421 by rotating, and a leakage-proof plate 423 is disposed on one side of the feeding box 421 located inside the feeding mechanism 4.

The partition sealing assembly 43 includes a partition plate 431 and a lateral driver 432, and the lateral driver 432 drives the partition plate 431 to move laterally.

According to the present invention, a sealing ring is provided on the side of the material inlet box 421 contacting the material inlet mechanism 4, and a sealing ring of the same material is provided on the portion of the partition plate 431 contacting the interior of the material inlet mechanism 4.

In this embodiment, when other raw materials need to be fed into the mixing chamber 2, first, the raw materials are fed into the upper portion of the separation sealing assembly 43 inside the feeding mechanism 4 through the feeding sealing assembly 42 of the feeding mechanism 4, then the feeding mechanism 4 is sealed through the feeding sealing assembly 42, so that the feeding mechanism 4 is isolated from the outside, then the pressure balancing assembly 41 pressurizes the inside of the feeding mechanism 4, so that the pressure inside the feeding mechanism 4 is equal to the pressure inside the mixing chamber 2, at this time, the isolation between the feeding mechanism 4 and the mixing chamber 2 is released through the separation sealing assembly 43, so that the raw materials inside the feeding mechanism 4 fall into the mixing chamber 2 under the action of gravity, and are fully kneaded and mixed with the previously added raw materials in the high-pressure environment in the mixing chamber 2. After the feeding is accomplished, it is isolated once more between with mixing chamber 2 and feed mechanism 4 to reset through making to separate seal assembly 43, later can open again feeding seal assembly 42 and send into other raw materials once more, so circulate and to add the raw materials many times, make under the prerequisite that does not influence mixing operation is kneaded to the inside high pressure of mixing chamber 2, to the inside feeding many times of mixing chamber 2, so that divide into the misce bene many times between multiple raw materials, prevent that all raw materials once only from getting into mixing chamber 2 inside and causing the raw materials scheduling problem that hardens, influence the mixed effect of raw materials.

When the raw materials get into mixing chamber 2 from feed mechanism 4 inside, pressure between feed mechanism 4 and the mixing chamber 2 equals, effectively prevent the condition of the feeding difficulty because of the inside high pressure of mixing chamber 2 leads to and appear, and through pressure balance, make and need not to relieve the high pressure to mixing chamber 2 inside and can smoothly to mixing chamber 2 inside feeding, when reducing the feeding hindrance, mixing chamber 2 inside need not to carry out the pressure release operation, when guaranteeing mixing chamber 2 inside to remain the high pressure throughout and knead the mixing, reduce the energy resource consumption because the pressure release brings, energy saving cost when promoting the mixing effect.

In this embodiment, a pressure sensor is also disposed inside the mixing chamber 2 for detecting the pressure inside the mixing chamber 2, when the material is fed through the feeding mechanism 4, the hydraulic telescopic rod 412 is driven by the auxiliary hydraulic press 411 to continuously extend, the hydraulic telescopic rod 412 drives the pressurizing plate 413 to move downward inside the feeding mechanism 4, so as to pressurize the material, and the pressure inside the feeding mechanism 4 is measured in real time through the pressure sensor 414, when the pressure inside the feeding mechanism 4 is equal to the pressure inside the mixing chamber 2, the auxiliary hydraulic press 411 stops operating, so that the hydraulic telescopic rod 412 and the pressurizing plate 413 stop moving, thereby maintaining the pressure inside the feeding mechanism 4, ensuring that the pressure inside the feeding mechanism 4 is always the same as the pressure inside the mixing chamber 2 in the feeding process to the inside of the mixing chamber 2, so that the material inside the feeding mechanism 4 can naturally enter the mixing chamber 2 under the action of gravity, so that the raw materials inside the feeding mechanism 4 can completely enter the inside of the mixing chamber 2 without being influenced by the high pressure inside the mixing chamber 2.

When feeding to the internal mixer, rotate earlier locking bolt 422 and remove the locking to feeding box 421, then open feeding box 421, under the common restriction effect through feeding box 421 and leak protection plate 423, feed into feeding mechanism 4 inside with the raw materials that need to add, send into the completion back, it is closed between feeding box 421 and the feeding mechanism 4, then lock between feeding box 421 and the feeding mechanism 4 through rotatory locking bolt 422, and the effect through the sealing washer that sets up on feeding box 421 is isolated between feeding mechanism 4 and the external world, guarantee not revealed at the pressure to the inside pressurization in-process of feeding mechanism 4, when guaranteeing that the raw materials that add can get into feeding mechanism 4 inside completely, effectively guarantee feeding mechanism 4's sealed.

Horizontal driver 432 includes but not limited to screw drive, drive methods such as telescopic link drive, removal through separating seal assembly 43 is to feed mechanism 4 and banburying chamber 2 inside isolated or intercommunication, thereby control the inside raw materials of feed mechanism 4 and get into the process of banburying chamber 2, and the effect of the sealing washer that sets up through division board 431 outer lane, guarantee to open when external to feed mechanism 4 feeding at sealed feeding box 421, feed mechanism 4 and banburying chamber 2 in isolated completely, guarantee that the inside raw materials of banburying chamber 2 can not be because of high pressure rush out to feed mechanism 4, make the high pressure in the banburying chamber 2 keep, prevent that the raw materials in the banburying chamber 2 from rushing out at reinforced in-process, guarantee the security of banbury mixer.

As shown in fig. 9-10, a discharging assembly 5 is arranged at one side of the bottom end of the mixing chamber 2 far away from the feeding mechanism 4, two stirring rollers 6 are arranged inside the mixing chamber 2, and the stirring rollers 6 are driven by a motor arranged outside the mixing chamber; the discharging component 5 is used for discharging the raw materials stirred in the mixing chamber 2 out of the mixing chamber 2; the stirring roller 6 is used for stirring the raw materials in the internal mixing chamber 2.

The discharging assembly 5 comprises a discharging baffle 51 and at least one electric telescopic rod 52, wherein the electric telescopic rod 52 is used for controlling the opening and closing of the discharging baffle 51.

In this embodiment, be provided with sealing device between discharge baffle 51 and the mixing chamber 2 and be used for guaranteeing the internal mixer during operation mixing chamber 2 and external between sealed, discharge assembly 5 still includes the guard plate of setting in discharge baffle 51 both sides, and the raw materials after the mixing drops from discharge baffle 51 both sides when the guard plate is used for preventing the ejection of compact.

In the inside stirring mixing in-process of banbury mixer, electric telescopic handle 52

control discharge baffle

51 and 2 bottoms of mixing chamber are closed completely to 2 bottoms of mixing chamber are sealed, accomplish the back at the mixing, through electric telescopic handle 52's effect, discharge baffle 51 opens, the raw materials behind the mixing of mixing chamber 2 inside are carried to 5 one sides of ejection of compact subassembly through the effect of two stirring running rollers 6, make and locate the roll-off from discharge baffle 51 through gravity, accomplish ejection of compact step.

According to the invention, the interior of the housing of the mixing chamber 2, close to the inner wall of the mixing chamber 2, is also provided with heating pipes which are used to provide the temperature required for the mixing in the mixing chamber 2.

Effect evaluation and Performance detection

Experiment one: physical and chemical property detection

The biodegradable composite materials of example 1, comparative example 2, comparative example 3 and comparative example 4 were respectively put into an injection molding machine to be made into sample bars to be measured, and the performance test was performed, and the test results are shown in table 1.

TABLE 1 results of physical and chemical Properties measurements

As can be seen from the results of the performance tests of example 1 and comparative examples 1, 2, 3 and 4 in Table 1, the biodegradable composite prepared by grinding the modified straw fibers into nano-sized particles and blending the nano-sized particles with the biodegradable resin ground into fine particles has good mechanical properties, strength and toughness as compared with the biodegradable composite prepared by adding no modified straw fibers, and also as compared with the biodegradable composite prepared by adding no ground modified straw fibers and no ground biodegradable resin.

Experiment two: degradation Performance detection

The biodegradable composite materials of example 1, comparative example 2, comparative example 3 and comparative example 4 were subjected to degradation performance test.

The evaluation of the degradation performance of the composite material adopts the measurement of the final aerobic biological decomposition capacity of the material under the controlled composting condition, and a method for measuring the released carbon dioxide is adopted, according to the standard: GB/T19277.1-2011 (IDT ISO14855-1:2005), the reference material is cellulose, the compost age is 3 months, the test volume is 3L, and the method for measuring carbon dioxide comprises the following steps: the mixed gas at the outlet of the test container is continuously measured by an infrared carbon dioxide analyzer, the amount of the released carbon dioxide is collected and calculated, and the basic characteristics and the detection results of the sample are respectively shown in tables 2 and 3.

TABLE 2 basic characteristics of the samples

TABLE 3 degradation Performance test

As can be seen from the degradation performance test results of example 1 and comparative examples 1, 2, 3 and 4, the high-toughness biodegradable composite material prepared by using the modified straw fibers has obviously excellent degradation performance compared with the composite material prepared without using the modified straw fibers, and the degradation performance is better when the amount of the modified straw fibers is larger.

Claims

1. The preparation method of the high-toughness biodegradable composite material is characterized by being used for preparing the high-toughness biodegradable composite material, wherein the high-toughness biodegradable composite material comprises the following raw materials in percentage by mass: 40-70% of biodegradable resin, 20-40% of modified straw fiber, 1-5% of fumed silica, 0.5-3% of silane coupling agent, 0.5-3% of compatilizer, 1-5% of plasticizer, 0.5-5% of lubricant, 0.1-0.5% of antioxidant and 0.1-0.5% of bacteriostatic agent; the biodegradable resin is a mixture of PBAT and PLA; in the mixture of the PBAT and the PLA, the PBAT accounts for 20-40% of the total amount of the mixture of the PBAT and the PLA; the preparation method comprises the following steps:

s1, grinding biodegradable resin into tiny particles;

s2, grinding the modified straw fibers into nanoscale modified straw fibers;

the preparation of the modified straw fiber comprises the following steps:

(3) chemical modification: placing the straw powder solution subjected to ultrasonic treatment in a reaction kettle, and adding sodium hydroxide into the reaction kettle to enable the straw powder to react with alkali liquor under the conditions of high temperature and high pressure;

2. The method for preparing a high-toughness biodegradable composite material as claimed in claim 1, wherein said step S3 is specifically performed by:

1) weighing biodegradable resin, fumed silica, a silane coupling agent, a compatilizer, a plasticizer and a lubricant according to a ratio, feeding the mixture into an internal mixing chamber (2) of a high-pressure internal mixer through a feeding mechanism (4) of the high-pressure internal mixer, sealing the feeding mechanism (4) and providing continuous high pressure into the internal mixing chamber (2) through a pressurizing assembly (3);

2) the raw materials added into the banburying chamber (2) are uniformly mixed under the action of two stirring rollers (6) rotating in opposite directions to obtain a primary mixture;

3) weighing modified straw fibers, an antioxidant and a bacteriostatic agent according to a ratio, adding the modified straw fibers, the antioxidant and the bacteriostatic agent into a feeding mechanism (4) through a feeding sealing component (42), pressurizing the inside of the feeding mechanism (4) through a pressure balancing component (41) to ensure that the pressure in the feeding mechanism (4) is equal to the pressure in an internal mixing chamber (2), and releasing the isolation between the feeding mechanism (4) and the internal mixing chamber (2) through a separating sealing component (43) to ensure that the raw materials fall into the internal mixing chamber (2);

4) and (3) adding the raw materials in the mixing chamber (2) again and fully kneading and mixing the raw materials and the primary mixture in the mixing chamber (2) in a high-pressure environment to obtain a mixture.

3. A manufacturing apparatus for the high tenacity biodegradable composite material as set forth in any one of claims 1 to 2, wherein said manufacturing apparatus is a high pressure internal mixer, said high pressure internal mixer comprising:

a support assembly (1);

the banburying chamber (2) is arranged at the top end of the support component (1) and is used for receiving the raw materials fed by the feeding mechanism (4) and stirring and mixing the raw materials;

the pressurizing assembly (3) is arranged at the top end of the mixing chamber (2) and is used for providing a high-pressure environment for the interior of the mixing chamber (2);

the feeding mechanism (4) is arranged on one side of the top end of the mixing chamber (2) and used for feeding raw materials into the mixing chamber (2) for multiple times, the feeding mechanism (4) comprises a pressure balance component (41), and when the raw materials are fed, the pressure balance component (41) is used for keeping the internal pressure of the feeding mechanism (4) consistent with the internal pressure of the mixing chamber (2).

4. The apparatus for preparing a high toughness biodegradable composite material as claimed in claim 3, wherein: the feeding mechanism (4) further comprises a feeding sealing assembly (42) and a separating sealing assembly (43);

the feeding sealing assembly (42) is used for inputting raw materials into the feeding mechanism (4), and the feeding mechanism (4) is isolated from the outside when the feeding sealing assembly (42) is closed;

the separation sealing component (43) is used for opening or blocking the communication between the feeding mechanism (4) and the mixing chamber (2).

5. The device for preparing the high-toughness biodegradable composite material according to claim 4, wherein: a discharging assembly (5) is arranged on one side of the bottom end of the mixing chamber (2) far away from the feeding mechanism (4), two stirring rollers (6) are arranged inside the mixing chamber (2), and the stirring rollers (6) are driven by a motor arranged outside the mixing chamber;

the discharging assembly (5) is used for discharging the raw materials which are stirred in the mixing chamber (2) out of the mixing chamber (2);

the stirring roller (6) is used for stirring the raw materials in the internal mixing chamber (2).