CN110408039B - Preparation method of high-strength high-toughness polylactic acid miniature product - Google Patents
Preparation method of high-strength high-toughness polylactic acid miniature product Download PDFInfo
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- 229920000747 poly(lactic acid) Polymers 0.000 title claims abstract description 75
- 239000004626 polylactic acid Substances 0.000 title claims abstract description 75
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- 238000002347 injection Methods 0.000 claims abstract description 32
- 239000007924 injection Substances 0.000 claims abstract description 32
- 238000000520 microinjection Methods 0.000 claims abstract description 30
- 238000000465 moulding Methods 0.000 claims abstract description 30
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 20
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 19
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 19
- 238000002156 mixing Methods 0.000 claims abstract description 16
- 125000004386 diacrylate group Chemical group 0.000 claims abstract description 14
- 239000002994 raw material Substances 0.000 claims abstract description 9
- 238000002844 melting Methods 0.000 claims abstract description 7
- 230000008018 melting Effects 0.000 claims abstract description 7
- AUZONCFQVSMFAP-UHFFFAOYSA-N disulfiram Chemical compound CCN(CC)C(=S)SSC(=S)N(CC)CC AUZONCFQVSMFAP-UHFFFAOYSA-N 0.000 claims description 26
- 238000001035 drying Methods 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 238000001291 vacuum drying Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 239000002861 polymer material Substances 0.000 abstract description 2
- 238000012545 processing Methods 0.000 description 29
- 238000001746 injection moulding Methods 0.000 description 28
- 238000002425 crystallisation Methods 0.000 description 16
- 230000008025 crystallization Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 11
- 238000001816 cooling Methods 0.000 description 9
- 238000002474 experimental method Methods 0.000 description 8
- 239000000155 melt Substances 0.000 description 8
- 238000012986 modification Methods 0.000 description 8
- 230000004048 modification Effects 0.000 description 8
- 229920000671 polyethylene glycol diacrylate Polymers 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 7
- 229920003023 plastic Polymers 0.000 description 7
- 239000004033 plastic Substances 0.000 description 7
- 239000008187 granular material Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000000178 monomer Substances 0.000 description 5
- 238000007385 chemical modification Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 208000034530 PLAA-associated neurodevelopmental disease Diseases 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 150000001723 carbon free-radicals Chemical group 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- OUPZKGBUJRBPGC-UHFFFAOYSA-N 1,3,5-tris(oxiran-2-ylmethyl)-1,3,5-triazinane-2,4,6-trione Chemical compound O=C1N(CC2OC2)C(=O)N(CC2OC2)C(=O)N1CC1CO1 OUPZKGBUJRBPGC-UHFFFAOYSA-N 0.000 description 1
- VLDPXPPHXDGHEW-UHFFFAOYSA-N 1-chloro-2-dichlorophosphoryloxybenzene Chemical compound ClC1=CC=CC=C1OP(Cl)(Cl)=O VLDPXPPHXDGHEW-UHFFFAOYSA-N 0.000 description 1
- HVVWZTWDBSEWIH-UHFFFAOYSA-N [2-(hydroxymethyl)-3-prop-2-enoyloxy-2-(prop-2-enoyloxymethyl)propyl] prop-2-enoate Chemical compound C=CC(=O)OCC(CO)(COC(=O)C=C)COC(=O)C=C HVVWZTWDBSEWIH-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 229920000704 biodegradable plastic Polymers 0.000 description 1
- 229920006237 degradable polymer Polymers 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000010096 film blowing Methods 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000011081 inoculation Methods 0.000 description 1
- 235000014655 lactic acid Nutrition 0.000 description 1
- 239000004310 lactic acid Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000005809 transesterification reaction Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- 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
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/76—Measuring, controlling or regulating
-
- 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
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/76—Measuring, controlling or regulating
- B29C45/77—Measuring, controlling or regulating of velocity or pressure of moulding material
-
- 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
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/76—Measuring, controlling or regulating
- B29C45/78—Measuring, controlling or regulating of temperature
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G81/00—Macromolecular compounds obtained by interreacting polymers in the absence of monomers, e.g. block polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
- C08K5/39—Thiocarbamic acids; Derivatives thereof, e.g. dithiocarbamates
- C08K5/40—Thiurams, i.e. compounds containing groups
-
- 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
-
- 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
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76494—Controlled parameter
- B29C2945/76498—Pressure
-
- 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
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76494—Controlled parameter
- B29C2945/76531—Temperature
-
- 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
- B29C2945/00—Indexing scheme relating to injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould
- B29C2945/76—Measuring, controlling or regulating
- B29C2945/76494—Controlled parameter
- B29C2945/76595—Velocity
- B29C2945/76598—Velocity linear movement
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Biological Depolymerization Polymers (AREA)
Abstract
The invention relates to the technical field of high polymer materials, in particular to a preparation method of a high-toughness high-strength polylactic acid miniature product. The invention provides a preparation method of a high-strength and high-toughness polylactic acid miniature product, which comprises the following steps: melting and blending polylactic acid, dicumyl peroxide and polyethylene glycol diacrylate at 170-190 ℃ for 1-6 min, and then preparing a polylactic acid miniature product by a micro injection molding method; the proportion of each raw material is as follows: 100 parts of polylactic acid, 0.3 part of dicumyl peroxide and 0.1-0.5 part of polyethylene glycol diacrylate; the micro injection molding process conditions are as follows: the injection speed is 200-500 mm/s, the injection temperature is 170-190 ℃, the injection pressure is 500-1200 bar, and the mold temperature is 50-100 ℃. The polylactic acid product prepared by the method has high strength and high toughness.
Description
Technical Field
The invention relates to the technical field of high polymer materials, in particular to a preparation method of a high-toughness high-strength polylactic acid miniature product.
Background
With the development of science and technology, environmental pollution is becoming more and more serious. How to effectively expand the use field of biodegradable plastics has become a hot point of research. The polylactic acid is a degradable polymer obtained by polymerizing lactic acid serving as a main raw material, and has a wide application prospect, but when the polylactic acid is used as a material, the wide application of the polylactic acid is limited by the brittleness of the PLA, and the improvement of the toughness of the PLA becomes an important research direction for P LA modification. However, the current polylactic acid resin is mainly linear in structure, is limited in application due to its own defects (low melt strength and crystallization properties), such as film blowing, foaming, etc., and is difficult to be made into products for popularization and application.
Through the search of the existing documents, some researchers modify polylactic acid to improve the physical properties of the polylactic acid, and polyethylene glycol (PEG) and the polylactic acid have good compatibility and are excellent plasticizers of the polylactic acid; by blending with PEG, the flexibility of polylactic acid can be greatly improved, and the elongation at break is improved but the tensile strength is reduced. Another common method is chemical modification, in which a long-chain branched structure is introduced into linear polylactic acid to improve its crystallization performance, for example, polylactic acid is blended with pyromellitic dianhydride and triglycidyl isocyanurate to perform chemical modification, so that the crystallization performance is improved, but the melt strength is not significantly improved. And the reaction rate of the chemical modification used at present is too slow, so that large-scale expanded production cannot be carried out, the utilization rate of the monomer is too low, and the waste of the monomer is caused to a certain extent. It has been found through previous studies that the formation of a long-chain structure or the addition of a second part can improve the crystallization promoting property, toughness or strength of PLA, but cannot improve both the strength and toughness of PLA articles.
Disclosure of Invention
Aiming at the defects, the invention provides a preparation method of a polylactic acid miniature product, and the polylactic acid product prepared by the method has high strength and high toughness; the experimental method is simple and different, can obviously improve the effective utilization rate of the monomer, is convenient for industrial production, and expands the application field of the monomer.
The technical scheme of the invention is as follows:
the first technical problem to be solved by the invention is to provide a preparation method of a high-strength high-toughness polylactic acid miniature product, which comprises the following steps: melting and blending polylactic acid, dicumyl peroxide (DCP) and polyethylene glycol diacrylate (PEGDA) at 170-190 ℃ for 1-6 min, and then preparing a polylactic acid miniature product by a micro injection molding method; wherein the proportion of each raw material is as follows: 100 parts of polylactic acid, 0.3 part of dicumyl peroxide (DCP) and 0.1-0.5 part of polyethylene glycol diacrylate (PEGDA); the micro injection molding process conditions are as follows: the injection speed is 200-500 mm/s, the injection temperature is 170-190 ℃, the injection pressure is 500-1200 bar, and the mold temperature is 50-100 ℃.
Further, in the method, the raw material also comprises 0.05-0.12 weight part of tetraethylthiuram disulfide (TETDS).
Further, the preparation method of the high-strength and high-toughness polylactic acid miniature product comprises the following steps:
1) melting and blending the dried polylactic acid, dicumyl peroxide, polyethylene glycol diacrylate and tetraethylthiuram disulfide in an internal mixer at 170-190 ℃ for 5-8 min to obtain a blend;
2) the resulting blend was subjected to micro injection molding: the injection speed is 200-500 mm/s (preferably 300mm/s), the mold temperature is 50-100 ℃, the injection temperature is 170-190 ℃, and the injection pressure is 500-1200 bar (preferably 450 bar).
Further, in the preparation method of the polylactic acid miniature product with high strength and high toughness, the raw material in the step 1) is dried until the water content is lower than 250 ppm; specifically, vacuum drying is adopted, the drying time is 8-48 h, and the drying temperature is 60-80 ℃.
The second technical problem to be solved by the invention is to provide a high-strength high-toughness polylactic acid miniature product which is prepared by adopting the method.
The invention has the beneficial effects that:
1) in the invention, the DCP is added to promote the linear polylactic acid to be decomposed to generate unstable tertiary carbon free radicals, and the unstable tertiary carbon free radicals can generate long-chain branching reaction with polyethylene glycol diacrylate under the action of TETDS or the DCP per se to form highly branched long-chain branched polylactic acid, and meanwhile, the occurrence of crosslinking can be avoided.
2) The addition of TETDS can promote the inoculation rate of the monomer and improve the reaction degree.
3) In the invention, dicumyl peroxide and polyethylene glycol diacrylate are added into polylactic acid, and a micro injection molding process is adopted to obtain a polylactic acid micro-product with high strength and high toughness; because the polyethylene glycol diacrylate (PEGDA) is added, the in-situ self-crosslinking and the interfacial transesterification reaction are carried out to form a binary system with uniform dispersion and strong interfacial acting force, the unique molecular chain structure of the system and the synergistic effect of the long branched chain after the grafting reaction are fully utilized, the strength and the toughness of the miniature product are improved simultaneously, and a foundation is laid for further expanding the application field of the miniature product.
The specific implementation mode is as follows:
the first technical problem to be solved by the invention is to provide a preparation method of a high-strength high-toughness polylactic acid miniature product, which comprises the following steps: melting and blending polylactic acid, dicumyl peroxide (DCP) and polyethylene glycol diacrylate (PEGDA) at 170-190 ℃ for 1-6 min, and then preparing a polylactic acid miniature product by a micro injection molding method; wherein the proportion of each raw material is as follows: 100 parts of polylactic acid, 0.3 part of dicumyl peroxide (DCP) and 0.1-0.5 part of polyethylene glycol diacrylate (PEGDA); the micro injection molding process conditions are as follows: the injection speed is 200-500 mm/s, the injection temperature is 170-190 ℃, the injection pressure is 500-1200 bar, and the mold temperature is 50-100 ℃.
The second technical problem to be solved by the invention is to provide a high-strength high-toughness polylactic acid miniature product which is prepared by adopting the method.
The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.
Example 1
1) Drying PLA granules at 70 ℃ in vacuum for 24 hours; placing 100 parts by weight of PLA into an internal mixer for blending, wherein the blending time is 5min, the rotating speed is 50rpm, and the processing temperature is 180 ℃;
2) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
3) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 1) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; the samples were subjected to mechanical property tests, and the results are shown in table 2.
Example 2
1) Drying PLA granules at 70 ℃ in vacuum for 24 hours; mixing 100 parts by weight of PLA, 0.06 part by weight of TETDS and 0.3 part by weight of DCP in an internal mixer for 5min at the rotation speed of 50rpm and the processing temperature of 180 ℃;
2) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
3) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 1) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; all samples were tested for mechanical properties and the results are shown in table 2.
Example 3
1) Drying PLA granules at 70 ℃ in vacuum for 24 hours; 100 parts by weight of PLA, 0.06 part by weight of TETDS, 0.3 part by weight of DCP and 0.2 part by weight of PEGDA are put into an internal mixer for blending, the blending time is 5min, the rotating speed is 50rpm, and the processing temperature is 180 ℃;
2) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
3) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 1) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; all samples were tested for mechanical properties and the results are shown in table 2.
Example 4
1) Drying PLA granules at 70 ℃ in vacuum for 24 hours; 100 parts by weight of PLA, 0.06 part by weight of TETDS, 0.3 part by weight of DCP and 0.4 part by weight of PEGDA are put into an internal mixer for blending, the blending time is 5min, the rotating speed is 50rpm, and the processing temperature is 180 ℃;
2) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
3) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 1) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; all samples were tested for mechanical properties and the results are shown in table 2.
Example 5
1) Drying PLA granules at 70 ℃ in vacuum for 24 hours; mixing 100 parts by weight of PLA, 0.3 part by weight of DCP and 0.4 part by weight of PEGDA in an internal mixer for 5min at the rotation speed of 50rpm and the processing temperature of 180 ℃;
2) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
3) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 1) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; all samples were tested for mechanical properties and the results are shown in table 2.
Comparative example 1
1) Drying PLA granules at 70 ℃ in vacuum for 24 hours; mixing 100 parts by weight of PLA and 0.4 part by weight of polyethylene glycol (PEG) in an internal mixer for 5min at the rotation speed of 50rpm and the processing temperature of 180 ℃;
2) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
3) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 1) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; all samples were tested for mechanical properties and the results are shown in tables 2 and 3.
Comparative example 2
1) Drying PLA in vacuum at 80 ℃ for 12 h;
2) dissolving 100 parts of PLA and 0.6 part of DCP, 0.12 part of TETDS and 0.4 part of PETA which are subjected to drying treatment in acetone to ensure that the DCP and the TETDS are fully and uniformly coated on the surfaces of PLA particles, and then carrying out solvent volatilization;
3) putting the blended materials into a vacuum oven at 50 ℃ and drying for 36 hours; finally, putting the blend into an internal mixer for reaction, wherein the reaction time is 6min, the rotating speed is 60rpm, and the temperature is 180 ℃;
4) and (3) carrying out micro injection molding processing on the blend by adopting a micro injection molding machine with the model of micropower5, wherein the processing parameters are as follows: the injection speed is 300 mm/s; the temperatures from the barrel to the nozzles were set at 185, 180, 175 ℃; the mold temperature was 100 deg.C, the shape of the sample was dumbbell-shaped, and the dimensions were 15X 3X 0.3mm3；
5) In order to verify the influence on the crystallization behavior of polylactic acid after processing modification, the obtained samples were subjected to DSC test by first heating at 10 ℃/min from 40 ℃ to 200 ℃ and isothermally maintaining for 5min, and then cooling at 10 ℃/min from 200 ℃ to 40 ℃, the results of which are shown in Table 1.
In the experiment, still carried out traditional injection moulding simultaneously and processed, conveniently with miniature injection moulding carry out the contrast in the performance, use the mini injection moulding equipment of HAAKE MiniJet Pro to the product that step 3) gained to mould plastics: the injection pressure is 450bar, the melt temperature is 180 ℃, and the mold temperature is 100 ℃; all samples were tested for mechanical properties and the results are shown in tables 2 and 3.
TABLE 1 parameters obtained from DSC melting curves of samples obtained in examples 1 to 5 and comparative examples 1 to 2
| Temperature for onset of crystallization (. degree. C.) | Crystallization temperature of maximum peak (. degree. C.) | Semi-crystallization time (min) | |
| Example 1 | ----- | ----- | ------ |
| Example 2 | 119.3 | 102.4 | 4.2 |
| Example 3 | 139.5 | 123.9 | 1.6 |
| Example 4 | 141.7 | 132.2 | 1.1 |
| Example 5 | 123.7 | 114.2 | 1.8 |
| Comparative example 1 | 127.7 | 112.2 | 4.7 |
| Comparative example 2 | 143.7 | 130.2 | 0.8 |
TABLE 2 comparison of tensile Properties of general injection Molding and micro injection Molding of samples obtained in examples 1 to 5 and comparative examples 1 to 2
| Common injection molding (MPa) | Minitype injection molding (MPa) | |
| Example 1 | 66.8 | 69.7 |
| Example 2 | 62.4 | 70.1 |
| Example 3 | 74.5 | 80.3 |
| Example 4 | 72.4 | 86.7 |
| Example 5 | 69.8 | 78.2 |
| Comparative example 1 | 48.2 | 53.1 |
| Comparative example 2 | 73.4 | 98.4 |
TABLE 3 comparison of elongation at break by ordinary injection molding and by micro injection molding of samples obtained in examples 1 to 5 and comparative examples 1 to 2
| General injection Molding (%) | Mini injection molding (%) | |
| Example 1 | 20.5 | 13.3 |
| Example 2 | 17.5 | 11.4 |
| Example 3 | 27.4 | 21.3 |
| Example 4 | 32.6 | 28.1 |
| Example 5 | 29.4 | 26.5 |
| Comparative example 1 | 33.7 | 24.2 |
| Comparative example 2 | 10.1 | 7.8 |
As can be seen from the comparison of tables 1, 2 and 3, the formation of long branched chain structure can significantly improve the crystallization property of polylactic acid, and as can be seen from the comparison of table 1, the introduction of TETDS can further improve the crystallization property thereof, and the semicrystallization time is significantly shortened from 2.8min to 1.8 min. In addition, compared with the traditional injection molding, the mechanical property of the micro injection molding sample is obviously improved by 24.3 MPa. However, the elongation at break is reduced and then increased, and finally the toughness is improved. Compared with a PLA miniature sample, the tensile strength is improved to 86.7MPa from 69.7MPa, the elongation at break is improved to 28.1% from 13.3%, the aim of simultaneously strengthening and toughening is fulfilled, and a good space is provided for popularization and application of the miniature product in the future. The method mainly comprises the following steps that the micro injection molding processing has higher shearing force and cooling speed, the characteristic is fully utilized, the cooling speed is accelerated while the micro injection molding processing is carried out, the retention of a highly oriented molecular chain is promoted, the addition of the polyethylene glycol diacrylate plays a toughening role to a certain extent, and the retention of the oriented molecular chain can improve the mechanical property to a great extent.
Claims (6)
1. A preparation method of a high-strength high-toughness polylactic acid miniature product is characterized by comprising the following steps: melting and blending polylactic acid, dicumyl peroxide and polyethylene glycol diacrylate at 170-190 ℃ for 1-6 min, and then preparing a polylactic acid miniature product by a micro injection molding method; wherein the proportion of each raw material is as follows: 100 parts of polylactic acid, 0.3 part of dicumyl peroxide and 0.1-0.5 part of polyethylene glycol diacrylate; the micro injection molding process conditions are as follows: the injection speed is 200-500 mm/s, the injection temperature is 170-190 ℃, the injection pressure is 500-1200 bar, and the mold temperature is 50-100 ℃.
2. The method for preparing a high-strength and high-toughness polylactic acid micro-product according to claim 1, wherein the raw material further comprises 0.05 to 0.12 weight part of tetraethylthiuram disulfide.
3. The method of claim 2, wherein the method of manufacturing the high-strength high-toughness polylactic acid micro-product comprises the steps of:
1) melting and blending the dried polylactic acid, dicumyl peroxide, polyethylene glycol diacrylate and tetraethylthiuram disulfide in an internal mixer at 170-190 ℃ for 5-8 min to obtain a blend;
2) the resulting blend was subjected to micro injection molding: the injection speed is 200-500 mm/s, the mold temperature is 50-100 ℃, the injection temperature is 170-190 ℃, and the injection pressure is 500-1200 bar.
4. The method for preparing a high-strength and high-toughness polylactic acid micro-product according to claim 3, wherein the raw material in the step 1) is dried to a water content of less than 250 ppm.
5. The method for preparing the high-strength and high-toughness polylactic acid miniature product according to claim 4, characterized in that vacuum drying is adopted, the drying time is 8-48 h, and the drying temperature is 60-80 ℃.
6. A high-strength high-toughness polylactic acid miniature product is prepared by the preparation method of any one of claims 1 to 5.
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| CN103965598A (en) * | 2014-05-19 | 2014-08-06 | 中国科学技术大学 | Modified polylactic acid and preparation method thereof |
| CN107903596A (en) * | 2017-11-30 | 2018-04-13 | 四川力智久创知识产权运营有限公司 | A kind of high temperature resistant lactic acid composite material and preparation method thereof |
| WO2018117885A1 (en) * | 2016-12-21 | 2018-06-28 | S.C. Institutul De Cercetari Produse Auxiliare Organice S.A. | Pla - based active and degradable biocomposites for food packaging |
| CN108570145A (en) * | 2018-04-11 | 2018-09-25 | 四川大学 | A kind of preparation method of the miniature product of highly -branched high intensity polylactic acid |
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| CN103965598A (en) * | 2014-05-19 | 2014-08-06 | 中国科学技术大学 | Modified polylactic acid and preparation method thereof |
| WO2018117885A1 (en) * | 2016-12-21 | 2018-06-28 | S.C. Institutul De Cercetari Produse Auxiliare Organice S.A. | Pla - based active and degradable biocomposites for food packaging |
| CN107903596A (en) * | 2017-11-30 | 2018-04-13 | 四川力智久创知识产权运营有限公司 | A kind of high temperature resistant lactic acid composite material and preparation method thereof |
| CN108570145A (en) * | 2018-04-11 | 2018-09-25 | 四川大学 | A kind of preparation method of the miniature product of highly -branched high intensity polylactic acid |
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