阅读说明：本技术 生物基聚乳酸复合材料 (Bio-based polylactic acid composite material ) 是由 戴玲 于 2021-01-13 设计创作，主要内容包括：本发明公开了一种生物基聚乳酸复合材料,其按重量份计,由以下组分制备而来：接枝改性聚乳酸81.0－92.0份,生物基填料34.0份－55.0份,改性纳米纤维素12.0－16.0份,碳酸钙2.0－5.0份。本发明的接枝改性聚乳酸由衣康酸酯与聚乳酸按质量比为1－1.5：3－5按如下方法接枝制备而来：将衣康酸酯与聚乳酸分散于2－3倍的去离子水中,加入聚乳酸重量0.05－0.1倍的引发剂,于20－35℃下反应10～20小时。将得到的反应物于35％的乙醇溶液中浸泡处理10－15h后,于50℃鼓风烘箱中干燥24小时,即得到本发明的衣康酸酯与聚乳酸的共聚物。(The invention discloses a bio-based polylactic acid composite material which is prepared from the following components in parts by weight: 81.0-92.0 parts of graft modified polylactic acid, 34.0-55.0 parts of bio-based filler, 12.0-16.0 parts of modified nano-cellulose and 2.0-5.0 parts of calcium carbonate. The graft modified polylactic acid is prepared from itaconic acid ester and polylactic acid according to the mass ratio of 1-1.5: 3-5 is prepared by grafting according to the following method: dispersing itaconate and polylactic acid in deionized water of 2-3 times, adding an initiator of 0.05-0.1 time of the weight of the polylactic acid, and reacting at 20-35 ℃ for 10-20 hours. Soaking the obtained reactant in 35% ethanol solution for 10-15 h, and drying in a forced air oven at 50 ℃ for 24 h to obtain the copolymer of itaconate and polylactic acid.)

1. The bio-based polylactic acid composite material is characterized by being prepared from the following components in parts by weight:

81.0 to 92.0 portions of graft modified polylactic acid,

34.0 to 55.0 portions of bio-based filler,

12.0 to 16.0 portions of modified nano-cellulose,

2.0-5.0 parts of calcium carbonate.

2. The bio-based polylactic acid composite material according to claim 1, wherein the modified nanocellulose is prepared by the following method: mixing microcrystalline cellulose in a ratio of 1: 5, soaking in 5 percent NaOH solution at 60-80 ℃ for 3-5 h, homogenizing at 1000-5000 rpm for 10-30 min, centrifuging, repeatedly centrifuging and washing for 2-3 times, adding deionized water for dispersing, and homogenizing at 4000-7000 rpm for 20-40 min to obtain the modified nano-cellulose.

3. The bio-based polylactic acid composite material according to claim 1, wherein the bio-based filler comprises 22.0 to 35.0 parts of tapioca flour and 12.0 to 20.0 parts of corn straw powder.

4. The bio-based polylactic acid composite material according to any one of claims 1 to 3, wherein the polylactic acid is itaconic ester graft-modified polylactic acid, and the mass ratio of itaconic ester to polylactic acid is 1-1.5: 3-5, and connecting according to the following method: dispersing itaconate and polylactic acid in deionized water of 2-3 times, adding an initiator of 0.05-0.1 time of the weight of the polylactic acid, and reacting at 20-35 ℃ for 10-20 hours.

5. The bio-based polylactic acid composite material according to claim 4, wherein the obtained reactant is soaked in 35% ethanol solution for 10-15 h, and then dried in a 50 ℃ forced air oven for 24 h to obtain the copolymer of itaconate and polylactic acid.

6. The bio-based polylactic acid composite material according to claim 5, which is prepared by the following method:

pretreatment of bio-based filler: and (3) cooking the cassava powder and the corn straw powder for 2-4 h, leaching in a 50% ethanol solution for 1-2 d, filtering, drying, crushing, and sieving with a 40-100-mesh sieve to obtain the cassava starch.

And secondly, uniformly mixing the pretreated bio-based filler, the copolymer of the itaconate and the polylactic acid, the modified nano-cellulose and the calcium carbonate.

Melting, extruding, bracing, air cooling and granulating by using a double-screw extruder to obtain the bio-based polylactic acid composite material, wherein the length-diameter ratio of screws of the double-screw extruder is 29: 1-35: 1, the melting temperature of the double-screw extruder is 180-230 ℃.

Technical Field

The invention relates to the technical field of bio-based composite materials, in particular to a bio-based polylactic acid composite material.

Background

Polylactic acid is a thermoplastic polyester with good biocompatibility, biodegradability and processability, is greatly researched and developed due to the fact that the polylactic acid is derived from biomass and degradation products are non-toxic and harmless, and is used as an environment-friendly material to replace a traditional petroleum-based material.

However, the tensile property test and the impact resistance of the existing polylactic acid-based composite material are mostly not ideal, and therefore, the application range of the composite material is greatly limited. At present, the mechanical property of the polylactic acid-based composite material is improved mostly by compounding organic high molecular polymers, however, the degradation property and the use safety performance of the material are adversely affected.

Disclosure of Invention

In order to overcome the defects, the invention aims to provide a bio-based polylactic acid composite material which is prepared from the following components in parts by weight:

81.0 to 92.0 portions of graft modified polylactic acid,

34.0 to 55.0 portions of bio-based filler,

12.0 to 16.0 portions of modified nano-cellulose,

2.0-5.0 parts of calcium carbonate.

Further, the modified nanocellulose is prepared according to the following method: mixing microcrystalline cellulose in a ratio of 1: 5, soaking in 5 percent NaOH solution at 60-80 ℃ for 3-5 h, homogenizing at 1000-5000 rpm for 10-30 min, centrifuging, repeatedly centrifuging and washing for 2-3 times, adding deionized water for dispersing, and homogenizing at 4000-7000 rpm for 20-40 min to obtain the modified nano-cellulose.

Further, the bio-based filler comprises 22.0-35.0 parts of cassava flour and 12.0-20.0 parts of corn straw powder.

Furthermore, the polylactic acid is itaconic ester graft modified polylactic acid, and the mass ratio of the itaconic ester to the polylactic acid is 1-1.5: 3-5, and connecting according to the following method: dispersing itaconate and polylactic acid in deionized water of 2-3 times, adding an initiator of 0.05-0.1 time of the weight of the polylactic acid, and reacting at 20-35 ℃ for 10-20 hours.

Further, the obtained reactant is soaked in 35% ethanol solution for 10-15 h, and then dried in a forced air oven at 50 ℃ for 24 h to obtain the copolymer of the itaconate and the polylactic acid.

Further, the preparation method comprises the following steps:

pretreatment of bio-based filler: and (3) cooking the cassava powder and the corn straw powder for 2-4 h, leaching in a 50% ethanol solution for 1-2 d, filtering, drying, crushing, and sieving with a 40-100-mesh sieve to obtain the cassava starch.

And secondly, uniformly mixing the pretreated bio-based filler, the copolymer of the itaconate and the polylactic acid, the modified nano-cellulose and the calcium carbonate.

Melting, extruding, bracing, air cooling and granulating by using a double-screw extruder to obtain the bio-based polylactic acid composite material, wherein the length-diameter ratio of screws of the double-screw extruder is 29: 1-35: 1, the melting temperature of the double-screw extruder is 180-230 ℃.

The invention has the following beneficial effects: the bio-based polylactic acid composite material is prepared from bio-based raw materials, is environment-friendly, high in use safety, good in tensile property and impact resistance, and high in tensile toughness up to 80MJ/m³Above, the notch impact strength is as high as 81kJ/m²The above.

Detailed Description

The present invention is described in detail below with reference to examples so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and thus the scope of the present invention can be clearly and clearly defined.

The bio-based polylactic acid composite material is prepared from the following components in parts by weight:

81.0 to 92.0 portions of graft modified polylactic acid,

34.0 to 55.0 portions of bio-based filler,

12.0 to 16.0 portions of modified nano-cellulose,

2.0 to 5.0 portions of calcium carbonate,

the graft modified polylactic acid is prepared from itaconic acid ester and polylactic acid according to the mass ratio of 1-1.5: 3-5 is prepared by grafting according to the following method: dispersing itaconate and polylactic acid in deionized water of 2-3 times, adding an initiator of 0.05-0.1 time of the weight of the polylactic acid, and reacting at 20-35 ℃ for 10-20 hours. Soaking the obtained reactant in 35% ethanol solution for 10-15 h, and drying in a forced air oven at 50 ℃ for 24 h to obtain the copolymer of itaconate and polylactic acid.

The modified nanocellulose is prepared according to the following method: mixing microcrystalline cellulose in a ratio of 1: 5, soaking in 5 percent NaOH solution at 60-80 ℃ for 3-5 h, homogenizing at 1000-5000 rpm for 10-30 min, centrifuging, repeatedly centrifuging and washing for 2-3 times, adding deionized water for dispersing, and homogenizing at 4000-7000 rpm for 20-40 min to obtain the modified nano-cellulose.

The bio-based filler comprises 22.0-35.0 parts of cassava flour and 12.0-20.0 parts of corn straw powder.

The bio-based polylactic acid composite material is prepared by the following method:

step one, pretreatment of bio-based filler: steaming cassava powder and corn stalk powder for 2-4 h, leaching in 50% ethanol solution for 1-2 d, filtering, oven drying, pulverizing, and sieving with 40-100 mesh sieve.

Step two, uniformly mixing the pretreated bio-based filler, the copolymer of itaconate and polylactic acid, the modified nano-cellulose and calcium carbonate;

and step three, carrying out melt extrusion, bracing, air cooling and granulation by using a double-screw extruder to prepare the bio-based polylactic acid composite material, wherein the length-diameter ratio of screws of the double-screw extruder is 29: 1-35: 1, the melting temperature of the double-screw extruder is 180-230 ℃.

The following will explain the preparation process of the bio-based polylactic acid composite material of the present invention with reference to the specific examples:

the first embodiment is as follows:

preparing graft modified polylactic acid: the mass ratio of the itaconate to the polylactic acid is 1: 3 was prepared according to the method described previously.

Preparing modified nano-cellulose: mixing microcrystalline cellulose in a ratio of 1: 5, soaking in 5 percent NaOH solution at 60-80 ℃ for 3-5 h, homogenizing at 1000-5000 rpm for 10-30 min, centrifuging, repeatedly centrifuging and washing for 2-3 times, adding deionized water for dispersing, and homogenizing at 4000-7000 rpm for 20-40 min to obtain the modified nano-cellulose.

Thirdly, after cooking 22.0 parts of cassava powder and 12.0 parts of corn straw powder for 2-4 hours, leaching in 50% ethanol solution for 1-2 days, filtering, drying and crushing, and sieving with a 40-100 mesh sieve.

81 parts of copolymer of the itaconate and the polylactic acid in the step I, 12 parts of the modified nano-cellulose in the step II, and 2 parts of the pretreated bio-based filler and the calcium carbonate in the step III are uniformly mixed;

utilizing a double-screw extruder to perform melt extrusion, bracing, air cooling and granulation to prepare the bio-based polylactic acid composite material, wherein the length-diameter ratio of screws of the double-screw extruder is 29: 1-35: 1, the melting temperature of the double-screw extruder is 180-230 ℃.

The bio-based polylactic acid composite material of the present example was subjected to a tensile property test and an impact resistance test.

And (3) testing tensile property:

first, the sample was hot-pressed at 200 ℃ into a sheet of 0.5mm thickness and cut into a specific shape as a test sample, and a tensile test was conducted at a tensile rate of 5 mm/min.

And (3) testing the impact resistance:

the composite material of this example was hot-pressed into a 5mm x 8mm x 50mm sample strip, and a V-shaped notch was made in the middle of the sample strip as a test sample. An impact force was applied to the V-notch region of each sample strip at 25 ℃, and the magnitude of the impact force at which the sample was crushed was recorded.

Example two:

preparing graft modified polylactic acid: the mass ratio of the itaconate to the polylactic acid is 1: 4 prepared according to the method described previously.

Preparing modified nano-cellulose: mixing microcrystalline cellulose in a ratio of 1: 5, soaking in 5 percent NaOH solution at 60-80 ℃ for 3-5 h, homogenizing at 1000-5000 rpm for 10-30 min, centrifuging, repeatedly centrifuging and washing for 2-3 times, adding deionized water for dispersing, and homogenizing at 4000-7000 rpm for 20-40 min to obtain the modified nano-cellulose.

Thirdly, 28 parts of the cassava powder and 15 parts of the corn straw powder are steamed and boiled for 2 to 4 hours, then are leached in 50 percent ethanol solution for 1 to 2 days, and are filtered, dried and crushed, and then are sieved by a sieve with 40 to 100 meshes.

Fourthly, uniformly mixing 88 parts of copolymer of the itaconate and the polylactic acid in the first step, 15 parts of modified nano-cellulose in the second step, and 5 parts of pretreated bio-based filler and calcium carbonate in the third step;

utilizing a double-screw extruder to perform melt extrusion, bracing, air cooling and granulation to prepare the bio-based polylactic acid composite material, wherein the length-diameter ratio of screws of the double-screw extruder is 29: 1-35: 1, the melting temperature of the double-screw extruder is 180-230 ℃.

The bio-based polylactic acid composite material of the present example was subjected to tensile property test and impact resistance test, and the test methods were performed with reference to example one.

The results of the performance test on the bio-based polylactic acid composite materials D of the first embodiment and the second embodiment are as follows:

	tensile toughness (MJ/m)3)	Notched impact strength (kJ/m)2)
			Example one	82.3	81.0
Example two	85.6	86.3

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the present invention is not limited thereto, and any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.