CN114656765A - Full-bio-based heat-resistant polylactic acid composite material and preparation method and application thereof - Google Patents
Full-bio-based heat-resistant polylactic acid composite material and preparation method and application thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
- B29C48/50—Details of extruders
- B29C48/505—Screws
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- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
- C08L3/02—Starch; Degradation products thereof, e.g. dextrin
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- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
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- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
- C08K3/26—Carbonates; Bicarbonates
- C08K2003/265—Calcium, strontium or barium carbonate
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- C08L2201/08—Stabilised against heat, light or radiation or oxydation
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
- Y02W90/10—Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics
Abstract
The invention discloses a full-bio-based heat-resistant polylactic acid composite material and a preparation method and application thereof. The preparation method comprises the following steps: plasticizing starch to obtain plasticized modified starch; mixing the plasticized modified starch with epoxy soybean oil for pre-gelatinization to prepare pre-treated plasticized modified starch; and uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to obtain the full-bio-based heat-resistant polylactic acid composite material. The full-bio-based heat-resistant polylactic acid composite material provided by the invention has the advantages of simple process, low cost and suitability for large-scale production, the full-bio-based heat-resistant polylactic acid composite material can be prepared by adopting a special double-screw combination, a special raw material composition and a pre-gelatinization process, and the prepared full-bio-based heat-resistant polylactic acid composite material has excellent heat resistance and mechanical property.
Description
Technical Field
The invention belongs to the technical field of polylactic acid composite materials, and particularly relates to a full-bio-based heat-resistant polylactic acid composite material as well as a preparation method and application thereof.
Background
In recent years, as the application range of PLA is more and more extensive, many properties of PLA materials are also more and more required. But the heat distortion temperature of PLA is low (55-60 ℃), the heat resistance is poor, and the application range of PLA is greatly limited. Therefore, it is very critical to improve the heat resistance thereof. At present, in the research on the improvement of the thermal properties of PLA-based composite materials, the heat resistance of polymers is mainly improved by improving the self-crystallinity of PLA, blending with other materials with better heat resistance, crosslinking with other monomers or macromolecules, reinforcing fibers and other methods.
Starch is a low-cost, degradable, environmentally friendly material, however starch and PLA are thermodynamically incompatible, and their crystalline properties and hydrogen bonding between starch particles lead to poor thermal processability of starch, which is difficult to disperse in PLA matrix. Starch is usually modified, and the common method is to plasticize and modify the starch by adopting polyhydric alcohols (glycerol, sorbitol and the like); or adding reactive compatibilizer or coupling agent, such as maleic anhydride, methylene diphenyl diisocyanate, acrylic acid, methacrylic acid glyceride and the like, to improve the compatibility of the starch and the PLA matrix; or the starch is subjected to graft modification, in patents CN102604349A and CN111234484A, maleic anhydride and furfuryl glycidyl ether are used for graft modification of the starch to form a hydrophobic interface layer, so as to improve the compatibility of the starch and PLA, but the starch and PLA form a composite material in the form of granular filler, and the starch has no significant improvement effect on the toughness and heat resistance of PLA. A mature PLA-based heat-resistant straw material in the market is prepared by blending PLA with PBS (poly (butylene succinate)) with good heat resistance of more than 25%, and blending other degradable materials with good heat resistance, such as CN 110564121A, by melt blending 30-50% of polyhydroxyalkanoate with PLA, and by performing three-layer co-extrusion on 10-20% of aromatic polyester and 10-20% of aliphatic polyester in patent CN 112521735A. In patent CN110885542A, modified plant fiber is melt blended with PLA. The existing heat-resistant PLA-based composite material has higher price and does not have the advantage of daily use, and the cost can be obviously reduced by using fillers such as starch and the like to modify PLA. Patent CN101343406A discloses a preparation method of a temperature-resistant starch/polylactic acid alloy, wherein 10-20% of graft modified starch and 5-20% of natural fibrilia are used, and various chain extenders and coupling agents are added to increase the temperature resistance to 85 ℃. In patent CN102268144A, the heat distortion temperature of PLA-based composite material containing 20-80% of starch can reach 90-120 ℃ by gamma ray radiation treatment. The main disadvantage of the above existing polylactic acid heat-resistant modification technology is high cost, which is caused by the characteristics of polylactic acid materials. The polylactic acid has the heat distortion temperature of 55-60 ℃, is hard and brittle, has slow crystallization rate, and is mainly blended by degradable materials with better heat resistance, toughness and the like in the prior art, so the material price is higher. And the use of cheap fillers such as starch and the like is obviously beneficial to reducing the material cost. However, because starch has poor hot-working performance and poor compatibility with PLA, starch needs to be modified, and the effect of starch on improving the heat resistance and toughness of the composite material is not obvious, for example, in patent CN101343406A, natural fiber and a large amount of auxiliaries such as chain extender and coupling agent are also needed to increase the heat resistance to 85 ℃, while in patent CN102268144A, gamma-ray radiation treatment is needed to crosslink PLA so as to improve the heat resistance, but radiation treatment has high requirements on equipment and is not suitable for the food contact field, and high degree of crosslinking also has an adverse effect on the degradability of the material. Therefore, it is a problem to be solved to provide a low-cost all-bio-based heat-resistant polylactic acid composite material.
Disclosure of Invention
The invention mainly aims to provide a full-bio-based heat-resistant polylactic acid composite material, and a preparation method and application thereof, so as to overcome the defects of the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a preparation method of a full-bio-based heat-resistant polylactic acid composite material, which comprises the following steps:
plasticizing starch to obtain plasticized modified starch;
mixing the plasticized modified starch with epoxy soybean oil for pre-gelatinization to prepare pre-treated plasticized modified starch;
uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material;
the double-screw extruder comprises a first shearing group, a second shearing group, a third shearing group, a fourth shearing group and a fifth shearing group, wherein the first shearing group comprises 3 shearing blocks, and the shearing angles of the 3 shearing blocks are 45 degrees, 45 degrees and 45 degrees respectively; the second shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 45 degrees and 90 degrees respectively; the third shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 60 degrees and 45 degrees respectively; the fourth shearing group comprises 3 shearing blocks, and the shearing angles of the 3 shearing blocks are respectively 45 degrees, 60 degrees and 90 degrees; the fifth shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 45 degrees and 60 degrees respectively.
The embodiment of the invention also provides the full-bio-based heat-resistant polylactic acid composite material prepared by the method, wherein starch in the full-bio-based heat-resistant polylactic acid composite material is gelatinized and crosslinked; the heat distortion temperature of the full-bio-based heat-resistant polylactic acid composite material is 80-94 ℃.
The embodiment of the invention also provides application of the total bio-based heat-resistant polylactic acid composite material in preparation of a degradable straw.
The embodiment of the invention also provides a degradable straw which is prepared from the full-bio-based heat-resistant polylactic acid composite material.
Compared with the prior art, the invention has the beneficial effects that: the full-bio-based heat-resistant polylactic acid composite material provided by the invention has the advantages of simple process, low cost and suitability for large-scale production, the full-bio-based heat-resistant polylactic acid composite material can be prepared by adopting a special double-screw combination, a special raw material composition and a pre-gelatinization process, and the prepared full-bio-based heat-resistant polylactic acid composite material has excellent heat resistance and mechanical property.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic view of the screw combination of a twin-screw extruder employed in an exemplary embodiment of the present invention.
Description of the drawings: 1-a feeding port, 2-a first liquid injection port, 3-a first natural exhaust port, 4-a first side feeding port, 5-a second liquid injection port, 6-a second natural exhaust port, 7-a second side feeding port and 8-a vacuum exhaust port; 9-first cutting group, 10-second cutting group, 11-third cutting group, 12-fourth cutting group, and 13-fifth cutting group.
Detailed Description
Aiming at the defect that the starch is only dispersed in a base material as a filler and does not fully play the role of the starch in the existing PLA-starch composite material, the invention adopts a scheme of starch pre-gelatinization and combines a proper screw combination design to ensure that the starch is gelatinized and crosslinked to a certain degree, thereby being beneficial to improving the toughness of the PLA material and also improving the heat resistance of the material. The method mainly comprises the steps of plasticizing and modifying starch, baking at high temperature for pre-gelatinization, blending polylactic acid, the plasticized and modified starch and an inorganic filler according to a certain proportion, and then carrying out melt blending processing by adopting a double-screw extruder with strong shearing screw combination, thereby preparing the full-bio-based heat-resistant polylactic acid composite material.
The technical solutions of the present invention will be described clearly and completely below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
One aspect of the embodiment of the invention provides a preparation method of a full-bio-based heat-resistant polylactic acid composite material, which comprises the following steps:
plasticizing starch to obtain plasticized modified starch;
mixing the plasticized modified starch with epoxy soybean oil for pre-gelatinization to prepare pre-treated plasticized modified starch;
uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material;
the double-screw extruder comprises a first shearing group, a second shearing group, a third shearing group, a fourth shearing group and a fifth shearing group, wherein the first shearing group comprises 3 shearing blocks, and the shearing angles of the 3 shearing blocks are 45 degrees, 45 degrees and 45 degrees respectively; the second shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 45 degrees and 90 degrees respectively; the third shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 60 degrees and 45 degrees respectively; the fourth shearing group comprises 3 shearing blocks, and the shearing angles of the 3 shearing blocks are respectively 45 degrees, 60 degrees and 90 degrees; the fifth shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 45 degrees and 60 degrees respectively.
In some more specific embodiments, the screw combination of the twin screw extruder is as shown in fig. 1, with 12 shear blocks, 5 shear groups, and shear angles of 45 °, 90 °, 60 °, 45 °, 60 °, 90 °, 45 °, and 60 °, respectively. The double-screw extruder comprises a feeding port 1, a first liquid injection port 2, a first natural exhaust port 3, a first side feeding port 4, a second liquid injection port 5, a second natural exhaust port 6, a second side feeding port 7 and a vacuum exhaust port 8; 9-a first shearing group (45 ° ), 10-a second shearing group (45 °, 90 °), 11-a third shearing group (60 °, 45 °), 12-a fourth shearing group (45 °, 60 °, 90 °), 13-a fifth shearing group (45 °, 60 °).
In some more specific embodiments, the mass ratio of the polylactic acid to the plasticized modified starch to the inorganic filler is 40-80: 10-40: 10 to 20.
In some more specific embodiments, the inorganic filler includes any one or a combination of two or more of calcium carbonate, talc, silica, montmorillonite, and alumina, and is not limited thereto.
In some more specific embodiments, the plasticizing process comprises: and (3) mixing starch and a liquid plasticizer at a high speed for 5-10 min to obtain the plasticized modified starch, wherein the rotating speed of the high-speed mixing is 700-1000 r/m.
Further, the starch includes any one or a combination of two or more of corn starch, tapioca starch, and oxidized starch, and is not limited thereto.
Further, the liquid plasticizer includes any one or a combination of two or more of glycerin, sorbitol, PEG400, triethyl citrate, and is not limited thereto.
Further, the mass ratio of the starch to the liquid plasticizer is 6: 4-8: 2.
In some more specific embodiments, the preparation method specifically comprises: and mixing the plasticized modified starch with epoxy soybean oil, and performing pre-gelatinization treatment for 1-5 hours at 110-150 ℃ to obtain the pre-treated plasticized modified starch.
In some more specific embodiments, the pre-gelatinization process comprises: and mixing the plasticized modified starch with epoxy soybean oil, and baking and pre-gelatinizing at 110-150 ℃ for 1-5 hours to obtain the pretreated plasticized modified starch.
Further, the mass ratio of the plasticized modified starch to the epoxidized soybean oil is 7: 3-9: 1.
in some more specific embodiments, the melt blending temperature is 165-180 ℃.
The embodiment of the invention also provides the total bio-based heat-resistant polylactic acid composite material prepared by the method, wherein starch in the total bio-based heat-resistant polylactic acid composite material is gelatinized and crosslinked; the heat distortion temperature of the full-bio-based heat-resistant polylactic acid composite material is 80-94 ℃.
The embodiment of the invention also provides application of the total bio-based heat-resistant polylactic acid composite material in preparation of a degradable straw.
In another aspect of the embodiment of the invention, the degradable straw is made of the total bio-based heat-resistant polylactic acid composite material.
The preparation method of the full-bio-based heat-resistant polylactic acid composite material provided by the invention has the following advantages: (1) the cost is low, the mature PLA-based heat-resistant straw material in the market is usually prepared by blending high-price degradable materials such as PBS and the like, and the price of the PLA material is higher, so that the market popularization is not facilitated. The invention adopts starch and inorganic filler with the price of only one tenth of that of PBS and the like to replace PBS and PLA in large quantity, so that the cost is greatly reduced; (2) the invention combines the screw combination design and the formula design, only needs to adjust the screw combination of the existing double-screw extruder, adopts the corresponding formula, well controls the pre-gelatinization process of the starch, can carry out production, has small equipment change, and is suitable for large-scale production and popularization.
The technical solution of the present invention is further described in detail with reference to several preferred embodiments, which are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the following embodiments.
The experimental materials used in the examples used below were all available from conventional biochemical reagents companies, unless otherwise specified.
Example 1
(1) Mixing corn starch and glycerol at high speed for 10min at the rotating speed of 1000r/r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerin is 7: 3;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 5 hours at 110 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 9: 1;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material; wherein the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are respectively 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees and 60 degrees.
In this example, the amounts of the plasticized modified starch, the inorganic filler, and the polylactic acid and the conditions of the pre-gelatinization are shown in table 1, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 2.
Example 2
(1) Mixing corn starch and glycerol at high speed for 8min at the rotation speed of 900r/r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerin is 7: 3;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 2 hours at 120 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 9: 1;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In this example, the amounts of the plasticized modified starch, the inorganic filler, the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 1, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 2.
Example 3
(1) Mixing corn starch and glycerol at high speed for 8min at the rotation speed of 1000r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerol is 8: 2;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 2 hours at 130 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 8: 2;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In this example, the amounts of the plasticized modified starch, the inorganic filler, the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 1, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 2.
Example 4
(1) Mixing corn starch and glycerol at high speed for 5min at the rotating speed of 800r/r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerin is 6: 4;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 1h at 140 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 8: 2;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In this example, the amounts of the plasticized modified starch, the inorganic filler, the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 1, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 2.
Example 5
(1) Mixing corn starch and glycerol at high speed for 6min at the rotating speed of 700r/m to prepare plasticized modified starch; wherein the ratio of corn starch to glycerin is 6: 4;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 1h at 150 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 7: 3;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In this example, the amounts of the plasticized modified starch, the inorganic filler, and the polylactic acid and the conditions of the pre-gelatinization are shown in table 1, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 2.
TABLE 1 amounts of plasticized modified starch, inorganic filler, polylactic acid and conditions of pregelatinization in examples 1-5
| Name(s) | Polylactic acid | Plasticized modified starch | Conditions of pregelatinization | Inorganic filler |
| Example 1 | 40 portions of | 40 portions of | 110℃5h | 20 portions of |
| Example 2 | 50 portions of | 30 portions of | 120℃2h | 20 portions of |
| Example 3 | 60 portions of | 20 portions of | 130℃2h | 20 portions of |
| Example 4 | 70 portions of | 15 portions of | 140℃1h | 15 portions of |
| Example 5 | 80 portions of | 10 portions of | 150℃1h | 10 portions of |
TABLE 2 Properties of Total Bio-based Heat resistant polylactic acid composites prepared in examples 1-5
| Test item | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 |
| Tensile strength MPa | 28.4 | 30.6 | 32.9 | 35.6 | 38.8 |
| Elongation at break% | 78 | 63 | 55 | 34 | 17 |
| Bending strength MPa | 39.4 | 42.1 | 49.0 | 51.6 | 53.3 |
| Flexural modulus MPa | 2977 | 3332 | 3866 | 4407 | 4823 |
| Impact strength kJ/m2 | 9.8 | 7.2 | 5.8 | 4.8 | 4.4 |
| Heat distortion temperature DEG C | 94 | 91 | 85 | 84 | 80 |
Comparative example 1
(1) Mixing corn starch and glycerol at high speed for 10min at the rotating speed of 1000r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerol is 7: 3;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 2 hours at 130 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 9: 1;
(3) uniformly mixing the pretreated plasticized modified starch with polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare a full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In the comparative example, the amounts of the plasticized modified starch and the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 3, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 4.
Comparative example 2
(1) Uniformly mixing an inorganic filler and polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare a full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In the comparative example, the amounts of the plasticized modified starch, the inorganic filler and the polylactic acid and the conditions of the pre-gelatinization are shown in table 3, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 4.
Comparative example 3
(1) Mixing corn starch and glycerol at high speed for 10min at the rotation speed of 1000r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerin is 7: 3;
(2) mixing the plasticized modified starch and epoxidized soybean oil, and performing pre-gelatinization treatment for 2 hours at 130 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 9: 1;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to prepare the full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 11 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 60 degrees, 90 degrees, 45 degrees and 45 degrees respectively.
In the comparative example, the amounts of the plasticized modified starch, the inorganic filler and the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 3, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 4.
Comparative example 4
(1) Mixing corn starch and glycerol at high speed for 10min at the rotation speed of 1000r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerin is 7: 3;
(2) mixing the plasticized modified starch with epoxidized soybean oil, and performing pre-gelatinization treatment for 2 hours at 130 ℃ to prepare pre-treated plasticized modified starch, wherein the ratio of the plasticized modified starch to the epoxidized soybean oil is 9: 1;
(3) uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to obtain a full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 11 shearing blocks (two of the two reverse shearing blocks) of the 4 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 45 degrees and 45 degrees respectively.
In the comparative example, the amounts of the plasticized modified starch, the inorganic filler and the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 3, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 4.
Comparative example 5
(1) Mixing corn starch and glycerol at high speed for 10min at the rotation speed of 1000r/m to obtain plasticized modified starch; wherein the ratio of corn starch to glycerin is 7: 3;
(2) uniformly mixing plasticized modified starch, epoxidized soybean oil, an inorganic filler and polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to obtain a full-bio-based heat-resistant polylactic acid composite material; the shearing angles of the 12 shearing blocks of the 5 shearing groups of the screw combination of the double-screw extruder are 45 degrees, 90 degrees, 60 degrees, 45 degrees, 60 degrees, 90 degrees, 45 degrees, 60 degrees and 60 degrees respectively.
In the comparative example, the amounts of the plasticized modified starch, the inorganic filler and the polylactic acid and the conditions of the pre-gelatinization treatment are shown in table 3, and the properties of the prepared all-bio-based heat-resistant polylactic acid composite material are shown in table 4.
TABLE 3 amounts of plasticized modified starch, inorganic filler, polylactic acid and conditions of the pregelatinization in comparative examples 1 to 5
| Name(s) | Polylactic acid | Plasticized modified starch | Conditions of pregelatinization | Inorganic filler | Screw combination |
| Comparative example 1 | 60 portions of | 40 portions of | 130℃2h | 0 portion of | Book combination |
| Comparative example 2 | 60 portions of | 0 portion of | 130℃2h | 40 portions of | The combination |
| Comparative example 3 | 60 portions of | 20 portions of | 130℃2h | 20 portions of | Weak shear |
| Comparative example 4 | 60 portions of | 20 portions of | 130℃2h | 20 portions of | High shear |
| Comparative example 5 | 60 portions of | 20 portions of | Without gelatinization | 20 portions of | The combination |
TABLE 4 Properties of all-bio-based heat-resistant polylactic acid composite materials prepared in comparative examples 1 to 5
In addition, the inventors of the present invention have also made experiments with other materials, process operations, and process conditions described in the present specification with reference to the above examples, and have obtained preferable results.
It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific embodiments, and all technical modifications made according to the technical solution of the present invention fall within the protection scope of the present invention without departing from the spirit of the present invention and the protection scope of the claims.
Claims (10)
1. A preparation method of a full-bio-based heat-resistant polylactic acid composite material is characterized by comprising the following steps:
plasticizing starch to obtain plasticized modified starch;
mixing the plasticized modified starch with epoxy soybean oil for pre-gelatinization to prepare pre-treated plasticized modified starch;
uniformly mixing the pretreated plasticized modified starch, the inorganic filler and the polylactic acid, and then adding the obtained mixed material into a double-screw extruder for melt blending to obtain a full-bio-based heat-resistant polylactic acid composite material;
the double-screw extruder comprises a first shearing group, a second shearing group, a third shearing group, a fourth shearing group and a fifth shearing group, wherein the first shearing group comprises 3 shearing blocks, and the shearing angles of the 3 shearing blocks are 45 degrees, 45 degrees and 45 degrees respectively; the second shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 45 degrees and 90 degrees respectively; the third shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are 60 degrees and 45 degrees respectively; the fourth shearing group comprises 3 shearing blocks, and the shearing angles of the 3 shearing blocks are respectively 45 degrees, 60 degrees and 90 degrees; the fifth shearing group comprises 2 shearing blocks, and the shearing angles of the 2 shearing blocks are respectively 45 degrees and 60 degrees.
2. The production method according to claim 1, characterized in that: the mass ratio of the polylactic acid to the plasticized modified starch to the inorganic filler is 40-80: 10-40: 10-20.
3. The method of claim 1, wherein: the inorganic filler comprises any one or the combination of more than two of calcium carbonate, talcum powder, silicon dioxide, montmorillonite and alumina.
4. The production method according to claim 1, wherein the plasticizing process includes: and (3) mixing starch and a liquid plasticizer at a high speed for 5-10 min to obtain the plasticized modified starch, wherein the rotating speed of the high-speed mixing is 700-1000 r/m.
5. The method of claim 4, wherein: the starch comprises any one or the combination of more than two of corn starch, cassava starch, starch and oxidized starch;
and/or the liquid plasticizer comprises any one or the combination of more than two of glycerol, sorbitol, PEG400 and triethyl citrate;
and/or the mass ratio of the starch to the liquid plasticizer is 6: 4-8: 2.
6. The method according to claim 1, comprising: mixing the plasticized modified starch with epoxy soybean oil, and performing pre-gelatinization treatment for 1-5 hours at 110-150 ℃ to prepare the pre-treated plasticized modified starch;
preferably, the mass ratio of the plasticized modified starch to the epoxidized soybean oil is 7: 3-9: 1.
7. The method of claim 1, wherein: the temperature of the melt blending is 165-180 ℃.
8. The fully bio-based heat-resistant polylactic acid composite material prepared by the method of any one of claims 1 to 7, wherein starch is gelatinized and crosslinked; the heat distortion temperature of the full-bio-based heat-resistant polylactic acid composite material is 80-94 ℃.
9. The use of the all-bio-based heat-resistant polylactic acid composite material according to claim 8 in the preparation of a degradable straw.
10. A degradable straw is characterized in that: the degradable straw is made of the full-bio-based heat-resistant polylactic acid composite material according to claim 8.
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| CN112778722A (en) * | 2020-12-31 | 2021-05-11 | 武汉华丽环保科技有限公司 | Heat-resistant full-biodegradable straw and preparation method thereof |
| CN113429635A (en) * | 2021-06-30 | 2021-09-24 | 扬州惠通新材料有限公司 | High-starch-content film-grade full-biodegradable masterbatch and preparation method thereof |
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| CN112778722A (en) * | 2020-12-31 | 2021-05-11 | 武汉华丽环保科技有限公司 | Heat-resistant full-biodegradable straw and preparation method thereof |
| CN113429635A (en) * | 2021-06-30 | 2021-09-24 | 扬州惠通新材料有限公司 | High-starch-content film-grade full-biodegradable masterbatch and preparation method thereof |
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| Title |
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| RAMZI BELHASSEN ET AL: "Thermoplasticized starch modified by reactive blending with epoxidized soybean oil" * |
| 颜斌玉等: "聚乳酸/醋酸淀粉共混物性能形态研究" * |
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