CN110591003A - Preparation method of starch and polylactic acid graft copolymer - Google Patents
Preparation method of starch and polylactic acid graft copolymer Download PDFInfo
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- CN110591003A CN110591003A CN201910721009.4A CN201910721009A CN110591003A CN 110591003 A CN110591003 A CN 110591003A CN 201910721009 A CN201910721009 A CN 201910721009A CN 110591003 A CN110591003 A CN 110591003A
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Abstract
The invention is applicable to the technical field of materials, and provides a preparation method of a starch and oligolactic acid graft copolymer, which comprises the steps of putting a starch reaction product, an oligolactic acid reaction product and polybasic organic acid into a high-speed mixer for uniformly mixing to obtain a first mixture, adding a grafting monomer and an initiator into the first mixture, reacting and mixing at 100 ~ 200 ℃ to obtain a second mixture, adding a biological lubricant and a biological reinforcing agent into the second mixture, uniformly mixing, and adding the mixture into a parallel in-phase double-screw extruder for plasticizing and granulating to obtain the starch and oligolactic acid graft copolymer.
Description
Technical Field
The invention belongs to the technical field of materials, and particularly relates to a preparation method of a starch and polylactic acid copolymer.
Background
In the modern society developing at a high speed, especially today that the problem of environmental pollution is increasingly serious and resources are increasingly exhausted, the problem of 'white pollution' caused by pollution sources such as foamed packing materials, lunch boxes, petroleum-based plastic bags, some electronic buffer packages, agricultural mulching films and the like is increasingly paid attention by people.
Starch is a degradable natural high polymer material with wide sources, but the application of the starch as a thermoplastic material is influenced by the high water absorption of the starch; meanwhile, the thermal deformation temperature of the polylactic acid is generally within 55 ℃, the pressure maintaining time in the industrial production process is long, the rapid popularization of industrial application is not facilitated, the performance of the product is influenced due to the change of the temperature in the transportation process of the product, defective products in the transportation process are easy to generate, the compatibility and degradability of the polylactic acid material with other high polymers are influenced due to the high crystallinity of the polylactic acid material as plastic, the cost of the polylactic acid product is relatively high, and in addition, the problems of poor compatibility and ductility exist if the polylactic acid oligomer is combined with starch.
Therefore, the starch-based materials in the prior art have the problems of easy water absorption and low strength, the polylactic acid materials have the problems of high crystallinity and high product cost, and the combination of the two materials also has the problems of poor compatibility and poor ductility.
Disclosure of Invention
The embodiment of the invention provides a preparation method of a starch and polylactic acid graft copolymer, aiming at solving the problems that a starch-based material in the prior art is easy to absorb water and low in strength, a polylactic acid material is high in crystallinity and high in product cost, and the combination of the starch-polylactic acid material and the polylactic acid material is poor in compatibility and ductility.
The embodiment of the invention is realized in such a way that the preparation method of the starch and polylactic acid oligomer graft copolymer comprises the following steps:
putting 50-100 parts by weight of starch reaction products, 50-100 parts by weight of oligolactic acid reaction products and 1-5 parts by weight of polybasic organic acid into a high-speed mixer, and uniformly mixing for 5-30 min to obtain a first mixture;
adding 0.5-2 parts by weight of grafting monomer and 0.1-1 part by weight of initiator into the first mixture, and reacting and mixing at 100-200 ℃ for 30-150 min to obtain a second mixture;
and adding 0.5-2 parts by weight of a biological lubricant and 0.2-2 parts by weight of a biological reinforcing agent into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 90-200 ℃ to obtain the composite material.
Another object of an embodiment of the present invention is to provide a starch and polylactic acid oligomer graft copolymer, which is prepared by the above method.
According to the preparation method of the starch and oligolactic acid graft copolymer provided by the embodiment of the invention, on one hand, the modified starch and the modified oligolactic acid are subjected to graft copolymerization, so that the compatibility is higher, hydrophilic groups of the modified starch and the modified oligolactic acid are shielded, the hydrophobic effect is achieved, the grafting efficiency is high, the production is easy, the organic combination of the starch and the oligolactic acid is realized, and the advantages of the starch and the oligolactic acid are fully exerted; on the other hand, the prepared starch and polylactic acid graft copolymer is smooth and fine, is easy to process and form, and has excellent degradation performance and cost obviously lower than that of the traditional high molecular weight polylactic acid.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Starch is a degradable natural high polymer material with wide sources, but the application of the starch as a thermoplastic material is influenced by the high water absorption of the starch, so the starch must be modified; polylactic acid as a high molecular material synthesized by natural materials has good biocompatibility and biodegradability, but the high crystallinity of the polylactic acid hinders the degradability and the compatibility with soft tissues and also hinders the application of the polylactic acid in soft plastics; in order to make two valuable degradable materials have good advantages and good disadvantages, the invention focuses on researching a method for producing a novel high polymer by combining polylactic acid oligomer and starch.
According to the preparation method of the starch and polylactic acid graft copolymer provided by the embodiment of the invention, the starch is activated by using the activating auxiliary agent, and then starch molecules are rearranged through the plasticizer so as to modify the starch; and carrying out preliminary polymerization on the polylactic acid oligomer in a molten state, and further carrying out polycondensation under the conditions of vacuum and high temperature; initiating the ring opening of the polylactic acid oligomer by an initiator, carrying out anionic polymerization on the modified polylactic acid oligomer and the modified polylactic acid oligomer, carrying out graft copolymerization reaction, and then carrying out melt extrusion under specific conditions to obtain a graft copolymer of starch and the polylactic acid oligomer; on one hand, the modified starch and the modified polylactic acid are subjected to graft copolymerization, so that the compatibility is higher, hydrophilic groups of the modified starch and the modified polylactic acid are shielded, the hydrophobic effect is achieved, the grafting efficiency is high, the production is easy, the organic combination of the starch and the polylactic acid is realized, and the advantages of the starch and the polylactic acid are fully exerted; on the other hand, the prepared starch and polylactic acid graft copolymer is smooth and fine, is easy to process and form, and has excellent degradation performance and cost obviously lower than that of the traditional high molecular weight polylactic acid.
Specifically, the preparation method of the starch and polylactic acid oligomer graft copolymer comprises the following steps:
putting 50-100 parts by weight of starch reaction products, 50-100 parts by weight of oligolactic acid reaction products and 1-5 parts by weight of polybasic organic acid into a high-speed mixer, and uniformly mixing for 5-30 min to obtain a first mixture;
adding 0.5-2 parts by weight of grafting monomer and 0.1-1 part by weight of initiator into the first mixture, and reacting and mixing at 100-200 ℃ for 30-150 min to obtain a second mixture;
and adding 0.5-2 parts by weight of a biological lubricant and 0.2-2 parts by weight of a biological reinforcing agent into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 90-200 ℃ to obtain the composite material.
In the embodiment of the invention, the starch reaction product is a modified starch product, and the specific modification method comprises the steps of mixing 100 parts by weight of plant starch, 10-50 parts by weight of water and 0.5-2 parts by weight of an activation aid for 10-60 min at the rotating speed of 1000-2000 r/min and the temperature of 0-30 ℃ to obtain activated starch; adding 0.5-5 parts by weight of a first catalyst and 10-50 parts by weight of a plasticizing auxiliary agent into the activated starch, heating to 70-160 ℃, pressurizing for 0.1-1 mpa, and treating for 5-30 minutes to obtain the starch.
Wherein the plant starch can be one or more of tapioca starch, potato starch, corn starch, wheat starch, pea starch and waxy corn starch, and is commercially available common starch.
Wherein the activating auxiliary agent is one or more of sodium hydroxide, urea, potassium hydroxide, calcium hydroxide and zinc oxide.
Wherein the first catalyst is one or more of vinyl acetate, hydrochloric acid, sodium trimetaphosphate, sodium tripolyphosphate, phosphoric acid and hydrogen peroxide.
Wherein the plasticizing adjuvant is one or more of ethylene glycol, glycerol, erythritol, pentanol, sorbitol, and 1, 4-butanediol.
In the embodiment of the invention, the reaction product of the oligomeric lactic acid is a product obtained by modifying a polylactic acid oligomer, and is generated by a one-step method, wherein the specific modification method comprises the steps of melting 100 parts by weight of the polylactic acid oligomer, 0.1-1 part by weight of a second catalyst and 0.5-2 parts by weight of a modification auxiliary agent in a reaction kettle at a high temperature of 80-200 ℃, vacuumizing, and reacting for 30-90 minutes, so as to obtain the oligomeric lactic acid.
Wherein, the second catalyst is one or more of organic guanidine, stannous octoate, zinc oxide, tin oxide, aluminum oxide and zinc chloride.
Wherein, the modifying auxiliary agent is one or more of polyethylene glycol, polycaprolactone, polyacrylate, polyvinyl acetate, starch and polyethylene.
In the embodiment of the invention, the polybasic organic acid is one or more of itaconic acid, tartaric acid, oxalic acid, malic acid, citric acid and terephthalic acid.
In the embodiment of the invention, the grafting monomer is one or more of acrylic acid, maleic anhydride, isoprene, styrene, vinyl acetate and acrylamide.
In the embodiment of the invention, the initiator is one or more of cerium ammonium nitrate, potassium permanganate, ammonium persulfate, potassium persulfate, hydrogen peroxide and copper peroxide.
In the embodiment of the invention, the biological lubricant is one or more of stearic acid, stearamide, adipic acid, catechol, epoxidized soybean oil and polyethylene wax.
In the embodiment of the invention, the biological enhancer is one or more of butyl acrylate, butyl methacrylate, dodecyl methacrylate, methyl methacrylate and methyl acrylate.
The technical effects of the starch and polylactic acid-grafted copolymer of the present invention will be further described below with reference to specific examples.
Example 1
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 100 parts by weight of starch reaction product, 100 parts by weight of oligolactic acid reaction product and 5 parts by weight of itaconic acid into a high-speed mixer, and uniformly mixing for 30min to obtain a first mixture;
adding 2 parts by weight of acrylic acid and 1 part by weight of ammonium ceric nitrate into the first mixture, and reacting and mixing for 150min at 200 ℃ to obtain a second mixture;
and adding 2 parts by weight of stearic acid and 2 parts by weight of butyl acrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 200 ℃ to obtain the composite material.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of cassava starch, 50 parts by weight of water and 2 parts by weight of sodium hydroxide for 60min at the rotating speed of 2000r/min and the temperature of 30 ℃ to obtain activated starch;
adding 5 parts by weight of vinyl acetate and 50 parts by weight of ethylene glycol into the activated starch, heating to 160 ℃, pressurizing to 1mpa, and treating for 30 minutes to obtain the activated starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 1 part by weight of organic guanidine and 2 parts by weight of polyethylene glycol are melted at high temperature in a reaction kettle, the temperature is set at 200 ℃, the reaction kettle is vacuumized, the vacuum degree is 1 atmosphere, and the polylactic acid oligomer is obtained after reaction for 90 minutes.
Example 2
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 60 parts by weight of starch reaction product, 60 parts by weight of low-polymer lactic acid reaction product and 2 parts by weight of tartaric acid into a high-speed mixer, and uniformly mixing for 8min to obtain a first mixture;
adding 0.8 part by weight of maleic anhydride and 0.3 part by weight of potassium permanganate into the first mixture, and reacting and mixing for 50min at 120 ℃ to obtain a second mixture;
and adding 0.8 part by weight of stearamide and 0.8 part by weight of butyl methacrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 120 ℃ to obtain the composite material.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of potato starch, 20 parts by weight of water and 0.9 part by weight of urea at the rotation speed of 1300r/min and the temperature of 5 ℃ for 15min to obtain activated starch;
adding 1 part by weight of sodium trimetaphosphate and 15 parts by weight of glycerol into the activated starch, heating to 85 ℃, pressurizing for 0.3mpa, and treating for 10 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 0.3 part by weight of stannous octoate and 0.8 part by weight of polycaprolactone are melted in a reaction kettle at high temperature of 120 ℃, and the mixture is vacuumized, the vacuum degree is 0.5 atmospheric pressure, and the polylactic acid oligomer, the stannous octoate and the polycaprolactone are reacted for 50 minutes to obtain the polylactic acid.
Example 3
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 70 parts by weight of starch reaction product, 70 parts by weight of low-polymer lactic acid reaction product and 3 parts by weight of oxalic acid into a high-speed mixer, and uniformly mixing for 15min to obtain a first mixture;
adding 1 weight part of isoprene and 0.7 weight part of ammonium persulfate into the first mixture, and reacting and mixing at 150 ℃ for 100min to obtain a second mixture;
and adding 0.9 part by weight of adipic acid and 0.9 part by weight of dodecyl methacrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 150 ℃ to obtain the high-performance polyester prepolymer.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of corn starch, 30 parts by weight of water and 1.5 parts by weight of calcium hydroxide for 30min at the rotating speed of 1500r/min and the temperature of 15 ℃ to obtain activated starch;
adding 1.5 parts by weight of sodium tripolyphosphate and 30 parts by weight of pentadiol into the activated starch, heating to 100 ℃, pressurizing for 0.5mpa, and treating for 25 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 0.8 part by weight of alumina and 0.8 part by weight of polyethylene are melted at high temperature in a reaction kettle, the temperature is set at 200 ℃, and the reaction kettle is vacuumized, the vacuum degree is 0.5 atmospheric pressure, and the polylactic acid oligomer is obtained after 60 minutes of reaction.
Example 4
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 50 parts by weight of starch reaction product, 50 parts by weight of oligolactic acid reaction product and 1 part by weight of terephthalic acid into a high-speed mixer, and uniformly mixing for 5min to obtain a first mixture;
adding 0.5 part by weight of vinyl acetate and 0.1 part by weight of hydrogen peroxide into the first mixture, and reacting and mixing at 100 ℃ for 30min to obtain a second mixture;
and adding 0.5 part by weight of epoxidized soybean oil and 0.2 part by weight of methyl acrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 90 ℃ to obtain the epoxy soybean oil-methyl acrylate copolymer.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of wheat starch, 10 parts by weight of water and 0.5 part by weight of zinc oxide at the rotation speed of 1000r/min and the temperature of 2 ℃ for 10min to obtain activated starch;
adding 0.5 weight part of hydrogen peroxide and 10 weight parts of 1, 4-butanediol into the activated starch, heating to 70 ℃, pressurizing for 0.1mpa, and treating for 5 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 0.1 part by weight of zinc chloride and 0.5 part by weight of polyethylene are melted at high temperature in a reaction kettle, the temperature is set at 80 ℃, and the reaction kettle is vacuumized, the vacuum degree is 0.1 atmosphere, and the polylactic acid oligomer is obtained after 30 minutes of reaction.
Example 5
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 80 parts by weight of starch reaction product, 80 parts by weight of oligolactic acid reaction product and 4 parts by weight of itaconic acid into a high-speed mixer, and uniformly mixing for 25min to obtain a first mixture;
adding 1.5 parts by weight of acrylic acid and 0.7 part by weight of ammonium ceric nitrate into the first mixture, and reacting and mixing at 150 ℃ for 120min to obtain a second mixture;
and adding 1.5 parts by weight of adipic acid and 0.8 part by weight of dodecyl methacrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 150 ℃ to obtain the high-performance polyester prepolymer.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of pea starch, 40 parts by weight of water and 1.5 parts by weight of urea at the rotating speed of 1600r/min and the temperature of 25 ℃ for 50min to obtain activated starch;
adding 4 parts by weight of sodium trimetaphosphate and 30 parts by weight of sorbitol into the activated starch, heating to 140 ℃, pressurizing to 0.8mpa, and treating for 25 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 0.6 part by weight of tin oxide and 1.6 parts by weight of polyvinyl acetate are melted at high temperature in a reaction kettle, the temperature is set at 170 ℃, the vacuum degree is 0.6 atmospheric pressure, and the polylactic acid oligomer is obtained after reaction for 40 minutes.
Example 6
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 90 parts by weight of starch reaction product, 90 parts by weight of oligolactic acid reaction product and 4 parts by weight of terephthalic acid into a high-speed mixer, and uniformly mixing for 25min to obtain a first mixture;
adding 1.5 parts by weight of acrylamide and 0.8 part by weight of potassium persulfate into the first mixture, and reacting and mixing at 180 ℃ for 120min to obtain a second mixture;
and adding 1.5 parts by weight of catechol and 1.5 parts by weight of methyl methacrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 180 ℃ to obtain the compound material.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of waxy corn starch, 40 parts by weight of water and 2 parts by weight of zinc oxide at the rotation speed of 1800r/min and the temperature of 25 ℃ for 50min to obtain activated starch;
adding 4.5 parts by weight of phosphoric acid and 45 parts by weight of pentadiol into the activated starch, heating to 150 ℃, pressurizing for 0.7mpa, and treating for 25 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 1.7 parts by weight of alumina and 1.7 parts by weight of polyacrylate are subjected to high-temperature melting in a reaction kettle, the temperature is set at 180 ℃, the vacuum degree is 0.5 atmospheric pressure, and the polylactic acid oligomer is obtained after reaction for 60 minutes.
Example 7
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 100 parts by weight of starch reaction product, 100 parts by weight of oligolactic acid reaction product and 4 parts by weight of citric acid into a high-speed mixer, and uniformly mixing for 25min to obtain a first mixture;
adding 2 parts by weight of styrene and 1 part by weight of copper peroxide into the first mixture, and reacting and mixing for 130min at 200 ℃ to obtain a second mixture;
and adding 1.5 parts by weight of stearic acid and 1.5 parts by weight of butyl acrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 150 ℃ to obtain the composite material.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing wheat starch 100 weight parts, water 30 weight parts and sodium hydroxide 1.5 weight parts at rotation speed of 1800r/min and temperature of 25 deg.C for 60min to obtain activated starch;
adding 5 parts by weight of hydrochloric acid and 50 parts by weight of erythritol into the activated starch, heating to 160 ℃, pressurizing to 1mpa, and treating for 30 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
melting 100 parts by weight of polylactic acid oligomer, 1 part by weight of alumina and 2 parts by weight of polyethylene glycol in a reaction kettle at high temperature of 200 ℃, vacuumizing to 1 atmosphere, and reacting for 90 minutes to obtain the polylactic acid-based resin.
Example 8
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 50 parts by weight of starch reaction product, 50 parts by weight of oligolactic acid reaction product and 1 part by weight of malic acid into a high-speed mixer, and uniformly mixing for 5min to obtain a first mixture;
adding 0.5 part by weight of styrene and 0.1 part by weight of hydrogen peroxide into the first mixture, and reacting and mixing for 30min at 100 ℃ to obtain a second mixture;
and adding 0.5 part by weight of epoxidized soybean oil and 0.2 part by weight of dodecyl methacrylate into the second mixture, uniformly mixing, and adding the mixture into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 90 ℃ to obtain the epoxy soybean oil/dodecyl methacrylate copolymer.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of corn starch, 10 parts by weight of water and 0.5 part by weight of potassium hydroxide for 10min at the rotating speed of 1000r/min and the temperature of 5 ℃ to obtain activated starch;
adding 0.5 part by weight of sodium trimetaphosphate and 10 parts by weight of sorbitol into the activated starch, heating to 70 ℃, pressurizing for 0.1mpa, and treating for 5 minutes to obtain the starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 0.1 part by weight of zinc chloride and 0.5 part by weight of polycaprolactone are melted at high temperature in a reaction kettle, the temperature is set at 80 ℃, the vacuum degree is pumped, the vacuum degree is 0.1 atmosphere, and the polylactic acid oligomer is obtained after reaction for 30 minutes.
Example 9
A preparation method of a starch and polylactic acid graft copolymer comprises the following steps:
putting 75 parts by weight of starch reaction product, 75 parts by weight of oligolactic acid reaction product and 2.5 parts by weight of citric acid into a high-speed mixer, and uniformly mixing for 20min to obtain a first mixture;
adding 1.5 parts by weight of acrylic acid and 0.5 part by weight of ammonium ceric nitrate into the first mixture, and reacting and mixing at 150 ℃ for 90min to obtain a second mixture;
and adding 1.5 parts by weight of stearic acid and 1.5 parts by weight of butyl acrylate into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 150 ℃ to obtain the composite material.
Wherein the preparation method of the starch reaction product comprises the following steps:
mixing 100 parts by weight of cassava starch, 35 parts by weight of water and 1.5 parts by weight of potassium hydroxide for 45min at the rotating speed of 1500r/min and the temperature of 15 ℃ to obtain activated starch;
adding 2.5 parts by weight of vinyl acetate and 35 parts by weight of glycerol into the activated starch, heating to 120 ℃, pressurizing for 0.5mpa, and treating for 15 minutes to obtain the starch-based activated starch;
wherein the preparation method of the reaction product of the low-polymer lactic acid comprises the following steps:
100 parts by weight of polylactic acid oligomer, 0.5 part by weight of stannous octoate and 1.5 parts by weight of polyacrylate are melted at high temperature in a reaction kettle, the temperature is set at 130 ℃, the vacuum degree is vacuumized, the vacuum degree is 0.5 atmospheric pressure, and the polylactic acid oligomer is obtained after reaction for 60 minutes.
The preparation methods of the starch and polylactic acid graft copolymer of the embodiments 1 to 9 of the invention successfully nest the starch on the polylactic acid oligomer, so that the combination of the starch and the lactic acid oligomer is more compact and the compatibility is higher; the prepared starch and polylactic acid graft copolymer is subjected to water absorption and mechanical property tests, and the test results are shown in the following table 1.
Wherein, the water absorption test method comprises weighing 200mg of starch and polylactic acid graft copolymer of each example and common starch sold in the market, respectively placing into 500mL beakers, adding a certain amount of deionized water (or a liquid absorption medium of 0.9% NaCl solution prepared in advance), changing different liquid absorption conditions, standing for liquid absorption for a period of time, filtering out excessive water by a natural filtration method, and obtaining the formula Y (m ═ m)2-m1)/m0Calculating the water absorption multiplying power Y, wherein m1The total mass (g) of the filter screen and the dry sample; m is2The total mass (g) of the filtered sample and the filter screen; m is0Dry sample mass (g).
The mechanical property test method comprises preparing dumbbell-shaped tensile sample strip and impact sample strip by using HAAKE MiniJet micro injection molding machine, wherein the effective part of the tensile sample strip has a size of 20 × 4 × 2mm3The specification of the impact specimen is 80X 10X 4mm3. Tensile testing was carried out using a Zwick/Roell Z020 universal tester at a tensile rate of 10 mm/min. A CE Λ ST pendulum material impact instrument is used for carrying out a notched cantilever beam impact test, and the energy of an impact hammer is 4J. Impact splines were notched beforehand with a 2mm deep V-notch on a CE Λ ST notching machine. Five bars were tested in parallel for each sample of the tensile and impact tests, the average was used as the calculation result and the standard deviation was calculated.
TABLE 1
In summary, as can be seen from table 1, in examples 1 to 9 of the present invention, the water absorption of the starch and polylactic acid graft copolymer prepared from one of the commercially available common starch is far lower than that of the commercially available common starch, and the strength is also significantly improved, so as to solve the problems of easy water absorption and low strength of the starch-based material in the prior art, and the problems of high crystallinity and high product cost of the polylactic acid material.
Further, the starch and polylactic acid graft copolymer prepared in examples 1 to 9 of the present invention were tested for their degradation effect in soil, and the test results are shown in table 2 below:
TABLE 2
| The test was carried out for 30 days | The test was carried out for 45 days | The test was carried out for 90 days | The test was carried out for 120 days | |
| Example 1 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 2 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 3 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 4 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 5 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 6 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 7 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 8 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Example 9 | Mildew occurs | Occurrence of holes | Degradation is 95% | Complete degradation |
| Common plastic | Remain intact | Remain intact | Remain intact | Remain intact |
In conclusion, it can be seen from table 2 above that the starch and polylactic acid oligomer graft copolymer prepared by the present invention has good time-controlled degradability, the starch and polylactic acid oligomer graft copolymer starts to mildew after 30 days of the test, gradually degrades after 45 days of the test, and completely degrades after 120 days of the test, and the starch and polylactic acid oligomer graft copolymer has excellent degradability, is safe and environment-friendly, and has no pollution.
It is worth noting that after starch grafting, hydroxyl groups are shielded, and the water absorption is lower along with the increase of the grafting rate; in addition, the plasticizing processing can further improve the compatibility of the starch and the polylactic acid, reduce the crystallization strength of the polylactic acid and improve the ductility of the material. The prepared starch and polylactic acid graft copolymer has lower cost than the traditional high molecular weight polylactic acid due to the addition of starch materials, and the polymer can be independently processed due to the addition of the polylactic acid, so that the applicability of the graft copolymer in the degradable material industry is improved.
According to the preparation method of the starch and polylactic acid graft copolymer provided by the embodiment of the invention, the starch is activated by using the activating auxiliary agent, and then starch molecules are rearranged through the plasticizer so as to modify the starch; and carrying out preliminary polymerization on the polylactic acid oligomer in a molten state, and further carrying out polycondensation under the conditions of vacuum and high temperature; initiating the ring opening of the polylactic acid oligomer by an initiator, carrying out anionic polymerization on the modified polylactic acid oligomer and the modified polylactic acid oligomer, carrying out graft copolymerization reaction, and then carrying out melt extrusion under specific conditions to obtain a graft copolymer of starch and the polylactic acid oligomer; on one hand, the modified starch and the modified polylactic acid are subjected to graft copolymerization, so that the compatibility is higher, hydrophilic groups of the modified starch and the modified polylactic acid are shielded, the hydrophobic effect is achieved, the grafting efficiency is high, the production is easy, the organic combination of the starch and the polylactic acid is realized, and the advantages of the starch and the polylactic acid are fully exerted; on the other hand, the prepared starch and polylactic acid graft copolymer is smooth and fine, is easy to process and form, and has excellent degradation performance and cost obviously lower than that of the traditional high molecular weight polylactic acid.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A preparation method of a starch and polylactic acid graft copolymer is characterized by comprising the following steps:
putting 50 ~ 100 parts by weight of starch reaction product, 50 ~ 100 parts by weight of oligolactic acid reaction product and 1 ~ 5 parts by weight of polybasic organic acid into a high-speed mixer, and uniformly mixing for 5 ~ 30min to obtain a first mixture;
adding 0.5 ~ 2 parts by weight of grafting monomer and 0.1 ~ 1 parts by weight of initiator into the first mixture, and reacting and mixing at 100 ~ 200 ℃ for 30 ~ 150min to obtain a second mixture;
and adding 0.5 ~ 2 parts by weight of biological lubricant and 0.2 ~ 2 parts by weight of biological enhancer into the second mixture, uniformly mixing, and adding into a parallel in-phase double-screw extruder for plasticizing and granulating at the temperature of 90 ~ 200 ℃, thus obtaining the biological lubricant.
2. The method for preparing a starch and polylactic acid-grafted copolymer according to claim 1, wherein the starch reaction product is prepared by:
mixing 100 parts by weight of plant starch, 10 ~ 50 parts by weight of water and 0.5 ~ 2 parts by weight of an activating auxiliary agent for 10 ~ 60min at the rotating speed of 1000 ~ 2000r/min and the temperature of 0 ~ 30 ℃ to obtain activated starch;
adding 0.5 ~ 5 parts by weight of first catalyst and 10 ~ 50 parts by weight of plasticizing adjuvant into the activated starch, heating to 70 ~ 160 ℃, pressurizing to 0.1 ~ 1mpa, and treating for 5 ~ 30 minutes to obtain the starch.
3. The method for preparing the starch and polylactic acid-co-polymer according to claim 2, wherein the activating auxiliary agent is one or more of sodium hydroxide, urea, potassium hydroxide, calcium hydroxide and zinc oxide.
4. The method for preparing a graft copolymer of starch and lactic acid oligomer according to claim 2, wherein the first catalyst is one or more of vinyl acetate, hydrochloric acid, sodium trimetaphosphate, sodium tripolyphosphate, phosphoric acid and hydrogen peroxide.
5. The method for preparing a starch and polylactic acid-grafted copolymer according to claim 1, wherein the reaction product of the polylactic acid is prepared by:
100 parts by weight of polylactic acid oligomer, 0.1 part by weight of second catalyst 0.1 ~ 1 and 0.5 part by weight of modification auxiliary agent 0.5 ~ 2 are melted at high temperature of 80 ~ 200 ℃ in a reaction kettle, and then the mixture is vacuumized, the vacuum degree is 0.1 ~ 1 atmospheric pressures, and the mixture is reacted for 30 ~ 90 minutes, thus obtaining the polylactic acid/polylactic acid composite material.
6. The method for preparing the starch and polylactic acid-co-oligomer of claim 5, wherein the second catalyst is one or more of organic guanidine, stannous octoate, zinc oxide, tin oxide, aluminum oxide and zinc chloride.
7. The method for preparing the starch and polylactic acid-grafted copolymer according to claim 5, wherein the modifying assistant is one or more selected from polyethylene glycol, polycaprolactone, polyacrylate, polyvinyl acetate, starch and polyethylene.
8. The method for preparing the starch and polylactic acid-grafted copolymer according to claim 1, wherein the polybasic organic acid is one or more of itaconic acid, tartaric acid, oxalic acid, malic acid, citric acid and terephthalic acid.
9. The method for preparing the starch and polylactic acid-grafted copolymer according to claim 1, wherein the grafting monomer is one or more of acrylic acid, maleic anhydride, isoprene, styrene, vinyl acetate and acrylamide.
10. A starch and polylactic acid oligomer graft copolymer, wherein the starch and polylactic acid oligomer graft copolymer is prepared by the method of any one of claims 1 to 9.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112661911A (en) * | 2020-12-21 | 2021-04-16 | 深圳市裕同包装科技股份有限公司 | Multi-monomer grafted polylactic acid compatilizer and preparation method and application thereof |
| CN113512253A (en) * | 2021-07-13 | 2021-10-19 | 江苏昊晟塑业科技有限公司 | Biodegradable foamed polypropylene and preparation method thereof |
| CN114013128A (en) * | 2022-01-10 | 2022-02-08 | 江苏安普林新材料研究院有限公司 | High-barrier full-biodegradable composite film and preparation method thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112661911A (en) * | 2020-12-21 | 2021-04-16 | 深圳市裕同包装科技股份有限公司 | Multi-monomer grafted polylactic acid compatilizer and preparation method and application thereof |
| CN113512253A (en) * | 2021-07-13 | 2021-10-19 | 江苏昊晟塑业科技有限公司 | Biodegradable foamed polypropylene and preparation method thereof |
| CN114013128A (en) * | 2022-01-10 | 2022-02-08 | 江苏安普林新材料研究院有限公司 | High-barrier full-biodegradable composite film and preparation method thereof |
| CN114013128B (en) * | 2022-01-10 | 2022-03-25 | 江苏安普林新材料研究院有限公司 | High-barrier full-biodegradable composite film and preparation method thereof |
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