CN111732727B - Preparation method of self-repairing crosslinked polyamide - Google Patents
Preparation method of self-repairing crosslinked polyamide Download PDFInfo
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- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
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- C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
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Abstract
A preparation method of self-repairing cross-linked polyamide belongs to the field of polyamide. Firstly, reacting acrylic ester with furan methylamine to obtain furan methylamine diester, and then polycondensing with polyether diamine to synthesize a linear amide prepolymer with furan side groups; in addition, piperazine and butenedioic acid diester are subjected to bulk Michael addition to obtain piperazine tetraester, and the piperazine tetraester is reacted with furan methylamine to obtain furan ring-terminated star-shaped tetraamide; and performing DA reaction on the two and bismaleimide to obtain the self-repairing polyamide. The method is simple and convenient to operate, is green and environment-friendly, can obtain the self-repairing crosslinked polyamide with excellent mechanical property, and has the self-repairing efficiency of more than 85%.
Description
Technical Field
The invention belongs to the field of polyamide, and particularly relates to a preparation method of crosslinked polyamide with a self-repairing function.
Technical Field
The polyamide is a kind of mixed chain polymer containing amide group (-CONH-) repeat unit in the main chain, mainly formed by self-polymerization of amino acid or polycondensation of diamine and dibasic acid, called PA for short, has the characteristics of excellent mechanical property, strong temperature resistance, oil resistance, wear resistance and the like, is widely used in the fields of fiber, engineering plastics, membrane materials, hot melt adhesive, anticorrosion coatings and the like, and is a common engineering plastic variety with the largest consumption at present. The thermal stability and mechanical properties of the crosslinked polyamides are likewise superior compared to those of linear polyamides. The current synthesis of crosslinked polyamides is dominated by the ring-opening polymerization-crosslinking process and the polyamine-acid chloride process. The crosslinked polyamide can generate defects such as cracks and the like during the use process, so that the performance of the material is reduced. The self-repairing structure is introduced into the cross-linked polyamide material, so that the service life of the cross-linked polyamide material can be prolonged, and the excellent mechanical property of the cross-linked polyamide material can be maintained.
The self-repairing material can be classified into an external type and an intrinsic type according to whether a repairing agent is implanted in the repairing process. The research of the externally-applied self-repairing material mainly comprises a chemical healing mechanism, a design and preparation technology of a microcapsule/micro-vessel network, micro-crack response kinetics of a repairing agent and the like. 201811456305.8 discloses a scratch self-repairing nylon composite material and a preparation method thereof, wherein the scratch self-repairing nylon composite material comprises the following raw materials in parts by mass: 6.70-95% of polyamide, 0.5-4% of self-repairing microcapsule, 0-8% of toughening agent, 0.2-2% of nucleating agent, 2-20% of inorganic filler, 0.2-0.8% of antioxidant and 0.5-2% of other auxiliary agents, and can solve the problem that the common nylon composite material cannot be repaired after being scratched. Although the method has application prospect, the supply mode of the repairing agent is limited, and multiple repairing can not be realized. The intrinsic self-repairing material utilizes the chemical structure characteristics of the material, and realizes multiple self-repairing through the chemical actions of reversible covalent bonds and non-covalent bonds (including Diels-Alder reaction, dynamic covalent chemistry, disulfide bonds, hydrogen bond self-repairing, pi-pi stacking, ionic polymer and the like). The Diels-Alder reaction is frequently adopted in self-repairing epoxy resin, self-repairing polyurethane and self-repairing polyester due to excellent thermal reversibility, mild reaction conditions, high yield, few side reactions and particular suitability for preparing thermal stimulation self-repairing polymer materials, but the application in self-repairing polyamide is still few at present.
Therefore, there is a need to develop a self-repairing polyamide material based on the Diels-Alder reaction, and the polyamide material has good mechanical properties and self-repairing efficiency.
Disclosure of Invention
The invention provides a preparation method of self-repairing crosslinked polyamide, aiming at solving the problems of shortened service life and the like caused by cracks in the use process of a polyamide material. The method has the advantages of easily obtained raw materials, mild reaction conditions, no need of any catalyst, high efficiency and environmental protection; and the obtained self-repairing crosslinked polyamide has good mechanical property and self-repairing efficiency.
The purpose of the invention is realized by the following technical scheme:
firstly, furan methylamine diester obtained by reacting acrylic ester with furan methylamine is used for synthesizing a linear amide prepolymer with furan side groups through polycondensation with polyether diamine; in addition, piperazine and butenedioic acid diester are subjected to bulk Michael addition to obtain piperazine tetraester, and the piperazine tetraester is reacted with furan methylamine to obtain furan ring-terminated star-shaped tetraamide; and performing DA reaction on the two and bismaleimide to obtain the self-repairing polyamide. The method comprises the following specific steps:
1) preparation of Linear Polyamide oligomers with pendant Furan groups: performing Michael addition reaction on furan methylamine and acrylic ester at a molar ratio of 1:2 at 40-100 ℃ to obtain furan methylamine diester, and performing melt polycondensation on furan methylamine diester and polyether diamine at 120-200 ℃ without any catalyst to obtain a linear polyamide prepolymer with furan ring side groups;
2) preparation of furan ring-terminated star-shaped tetra-amide: feeding piperazine and butenedioic acid diester at a molar ratio of 1:2, carrying out Michael addition reaction at 25-90 ℃ to obtain oxazine tetraester, and reacting the oxazine tetraester with furan methylamine at a molar ratio of 1:4 at 150-200 ℃ to obtain terminal furyl star-shaped tetraamide;
3) preparation of self-repairing crosslinked polyamide: uniformly mixing the linear polyamide prepolymer containing the furan side group obtained in the step 1) and the terminal furyl star-shaped tetra-amide obtained in the step 2) with bismaleimide according to different proportions at 110-150 ℃, pouring the mixture into a mould, and reacting in a vacuum oven at 60 ℃ for 20-40h to obtain the crosslinked polyamide with the self-repairing function.
The acrylate used in the step 1) comprises methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate and the like; the structure of the synthesized furan methylamine diester is shown as (I):
wherein R is1Methyl, ethyl, propyl, butyl, and the like.
The structure of the polyether diamine used in the step 1) is shown as (II), and the structure comprises one or two of D230, D400 and D2000.
Wherein x is 1-20, preferably D230, D400;
the molar ratio of the furan methylamine diester to the polyether diamine in the step 1) is (m +1) to m, wherein m is a natural number, and m is preferably 3-5; the structure of the obtained linear polyamide prepolymer is shown as (III):
wherein R is1Methyl, ethyl, propyl, butyl, etc.; r2Wherein x is 1-20.
The diester of butenedioic acid used in the above step 2) includes dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate and the like. The structural formula of the piperazine tetraester is shown as (IV):
wherein R is3Methyl, ethyl, etc.
The structure of the terminal furyl star-shaped tetra-amide obtained in the step 2) is shown as (V):
the structure of the bismaleimide in the step 3) is shown as (VI):
the preferred bismaleimide is 1, 5-bis (maleimido) -2-methylpentane;
the dosage relationship of the linear polyamide prepolymer containing the furan side group, the terminal furyl star-shaped tetra-amide and the bismaleimide in the step 3) can be adjusted according to requirements, wherein the weight part ratio of the linear polyamide prepolymer containing the furan side group to the terminal furyl star-shaped tetra-amide is 6: (0.1-1), and the ratio of the content of furyl groups in the mixture to the content of imide groups in the bismaleimide is 1:1 (molar ratio).
The structural formula of the self-repairing crosslinked polyamide obtained in the step 3) is shown as (VII):
the invention has the following effects:
the raw materials used in the invention are easy to obtain, and the preparation method is simple and environment-friendly. The self-repairing polyamide obtained by adopting the optimized technical scheme has the best performance, the tensile strength can reach 30MPa, and the self-repairing efficiency can reach more than 86%; and the self-repairing cross-linked polyamide material with different mechanical properties and excellent self-repairing efficiency can be obtained by changing the proportion of the furan methylamine diester to the polyether diamine and the proportion of the linear polyamide prepolymer to the star-shaped tetra-amide.
Detailed Description
According to the GB/T1040-2006 standard, the product is made into a standard dumbbell type sample, the stretching speed is 5mm/min, and the tensile strength and the elongation at break are measured by an INSTRON-1185 universal tensile machine.
And (3) cutting the dumbbell-shaped sample strip from the middle, aligning fractures, heating in an oven at 130 ℃ for 2h for repairing, and then putting the dumbbell-shaped sample strip into a vacuum oven at 60 ℃ for curing for 30 h. And finally, testing the mechanical property of the sample by using a universal testing machine at a stretching speed of 5mm/min, and calculating the self-repairing efficiency by using the ratio of the repaired tensile strength to the original sample strip tensile strength before repairing.
The technical solution of the present invention is further explained by the following embodiments. The examples are only for the purpose of facilitating understanding of the present invention and should not be construed as specifically limiting the present invention.
Example 1:
1) preparation of Linear Polyamide oligomers with pendant Furan groups: weighing 26 parts by weight of methyl acrylate and 14 parts by weight of furanmethanamine, reacting for 3 hours at 50 ℃, refluxing for 2 hours at 80 ℃, and cooling to room temperature to obtain furanmethanamine diester;
weighing 10 parts of furan methylamine diester and 6.4 parts of D230 polyether diamine in parts by weight, reacting for 10 hours at 190 ℃ in nitrogen atmosphere, reducing pressure for 1 hour, and cooling to room temperature to obtain the linear polyamide prepolymer with furan side groups.
2) Preparation of furan ring-terminated star-shaped tetra-amide: weighing 8.6 parts of anhydrous piperazine by weight, and dissolving the piperazine by 10 parts of anhydrous ethanol; dissolving 28.8 parts of dimethyl maleate in 20 parts of absolute ethyl alcohol, slowly adding the dimethyl maleate into the absolute piperazineethyl solution, reacting for 2 hours at room temperature, filtering the solid product, washing for 1-2 times by using the absolute ethyl alcohol, and drying to obtain piperazinetexilate;
weighing 5 parts of piperazine tetraester and 7.2 parts of furan methylamine in parts by weight, reacting for 10 hours at 190 ℃ in nitrogen atmosphere, decompressing for 1 hour, and cooling to room temperature to obtain furan ring-terminated star-shaped tetraamide.
3) Preparation of self-repairing crosslinked polyamide: weighing 6 parts by weight of the linear polyamide oligomer obtained in the step 1) and 0.24 part by weight of the star-shaped tetraamide obtained in the step 2), adding 2.38 parts by weight of 1, 5-bismaleimide-2-methylpentane, heating and mixing uniformly at 130 ℃, pouring into a dumbbell-shaped mold, decompressing and removing bubbles in a vacuum oven at 150 ℃, and curing at 60 ℃ for about 30 hours to obtain the self-repairing crosslinked polyamide. The tensile strength of the composite material is 12MPa, the elongation at break is 84%, and the first self-repairing efficiency is 84%.
Example 2:
1) preparation of linear polyamide oligomers with pendant Furan groups: 10 parts of furan methylamine diester prepared in the step 1) in the embodiment 1 and 7.2 parts of D230 polyether diamine are weighed according to parts by weight, reacted for 10 hours at 190 ℃ in nitrogen atmosphere, decompressed for 1 hour, and cooled to room temperature to obtain the linear polyamide prepolymer with furan ring side groups.
2) Preparation of self-repairing crosslinked polyamide: weighing 6 parts by weight of the linear polyamide prepolymer prepared in the step 1) in the embodiment 2, 0.22 part by weight of furan ring-terminated star-shaped tetraamide prepared in the step 2) in the embodiment 1 and 2.28 parts by weight of 1, 5-bismaleimide-2-methylpentane, heating and mixing uniformly at 130 ℃, pouring into a dumbbell-shaped mold, decompressing and removing bubbles in a vacuum oven at 150 ℃, and curing for about 30 hours at 60 ℃ to obtain the self-repairing crosslinked polyamide. The tensile strength of the composite material is 16MPa, the elongation at break is 5%, and the first self-repairing efficiency is 87%.
Example 3:
weighing 6 parts by weight of the linear polyamide prepolymer prepared in the step 1) in the embodiment 2, 0.88 part by weight of the furan ring-terminated star-shaped tetraamide prepared in the step 2) in the embodiment 1, and 2.93 parts by weight of 1, 5-bismaleimide-2-methylpentane, heating and mixing uniformly at 130 ℃, pouring into a dumbbell-shaped mold, decompressing and removing bubbles in a vacuum oven at 150 ℃, and curing at 60 ℃ for about 30 hours to obtain the self-repairing crosslinked polyamide. The tensile strength of the composite material is 30MPa, the elongation at break is 6%, and the first self-repairing efficiency is 90%.
Example 4
1) Preparation of Linear Polyamide oligomers with pendant Furan groups: 10 parts of furan methylamine diester prepared in the step 1) in the embodiment 1 and 12.56 parts of D400 polyether diamine are weighed according to the parts by weight, reacted for 10 hours at 190 ℃ in nitrogen atmosphere, then decompressed for 1 hour, and cooled to room temperature to obtain the linear polyamide prepolymer with furan side groups.
2) Preparation of self-repairing crosslinked polyamide: weighing 6 parts by weight of the linear polyamide prepolymer prepared in the step 1) in the embodiment 4, 0.64 part by weight of the furan ring-terminated star-shaped tetraamide prepared in the step 2) in the embodiment 1 and 2.17 parts by weight of 1, 5-bismaleimide-2-methylpentane, heating and mixing uniformly at 130 ℃, pouring into a dumbbell-shaped mold, decompressing and removing bubbles in a vacuum oven at 150 ℃, and curing for about 30 hours at 60 ℃ to obtain the self-repairing crosslinked polyamide. The tensile strength of the composite material is 4MPa, the elongation at break is 269%, and the initial self-repairing efficiency is 96%.
Claims (11)
1. A preparation method of self-repairing crosslinked polyamide based on DA reaction is characterized in that firstly, acrylic ester reacts with furan methylamine to obtain furan methylamine diester, and the furan methylamine diester is condensed with polyether amine to synthesize a linear amide prepolymer with furan side groups; in addition, piperazine and butenedioic acid diester are subjected to bulk Michael addition to obtain piperazine tetraester, and the piperazine tetraester is reacted with furan methylamine to obtain furan ring-terminated star-shaped tetraamide; performing DA reaction on the two and bismaleimide to obtain self-repairing polyamide; the specific steps are as follows:
1) preparation of linear polyamide oligomers with pendant Furan groups: carrying out Michael addition reaction on the furan methylamine and the acrylic ester at the temperature of 40-100 ℃ to obtain furan methylamine diester; carrying out melt polycondensation with polyether diamine at 120-200 ℃ under the condition of no catalyst to obtain a linear polyamide prepolymer with furan side groups;
2) preparation of furan ring-terminated star-shaped tetra-amide: feeding piperazine and butenedioic acid diester at a molar ratio of 1:2, and carrying out Michael addition reaction at 25-90 ℃ to obtain piperazine tetraester; reacting the intermediate with furan methylamine at a molar ratio of 1:4 at 150-200 ℃ to obtain a star-shaped tetra-amide with furan ring terminal group;
3) and (2) preparing self-repairing crosslinked polyamide, namely uniformly mixing the linear polyamide prepolymer containing the furan side group synthesized in the step 1) and the terminal furyl star-shaped tetra-amide synthesized in the step 2) with bismaleimide according to different proportions at 110-150 ℃, pouring the mixture into a mold, and reacting in a vacuum oven at 60 ℃ for 20-40h to obtain the crosslinked polyamide with the self-repairing function.
2. The preparation method of claim 1, wherein the acrylate used in step 1) comprises methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate, and the synthesized furan methylamine diester has a structure shown in (I):
wherein R is1Methyl, ethyl, propyl and butyl.
3. The preparation method according to claim 1, wherein the polyether diamine used in step 1) has a structure shown as (II) and comprises one or two of D230, D400 and D2000;
wherein x is 1-20.
4. The preparation method of claim 1, wherein the molar ratio of the furan methylamine diester to the polyether diamine in the step 1) is (m +1): m, m is a natural number, and the structure of the linear polyamide prepolymer obtained is shown as (III):
wherein R is1Is methyl, ethyl, propyl or butyl; r2Wherein x is 1-20.
5. The method according to claim 4, wherein m is 3 to 5.
6. The method according to claim 1, wherein the diester of butene diacid used in step 2) comprises one of dimethyl maleate, diethyl maleate, dimethyl fumarate and diethyl fumarate; the structural formula of the piperazine tetraester is shown as (IV):
wherein R is3Is methyl or ethyl.
7. The method according to claim 1, wherein the terminal furyl star-shaped tetra-amide obtained in step 2) has the structure shown in (V):
8. the method according to claim 1, wherein the bismaleimide in step 3) has the structure shown in (VI):
9. the process according to claim 8, wherein the bismaleimide is 1, 5-bis (maleimido) -2-methylpentane.
10. The method according to claim 1, wherein the amount of the furan side group-containing linear polyamide prepolymer, the furan-terminated star-shaped tetra-amide and the bismaleimide in the step 3) can be adjusted according to requirements, wherein the weight ratio of the furan side group-containing linear polyamide prepolymer to the furan-terminated star-shaped tetra-amide is 6: (0.1-1), wherein the molar ratio of the content of furyl in the mixture to the content of imide in the bismaleimide is 1: 1.
11. The preparation method of claim 1, wherein the self-healing crosslinked polyamide obtained in step 3) has a structural formula shown in (VII):
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109796589A (en) * | 2019-01-08 | 2019-05-24 | 北京化工大学 | The preparation method of selfreparing crosslinked polyamide |
| CN110156987A (en) * | 2019-05-22 | 2019-08-23 | 北京化工大学 | The preparation method of selfreparing non-isocyanate polyurethane |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109796589A (en) * | 2019-01-08 | 2019-05-24 | 北京化工大学 | The preparation method of selfreparing crosslinked polyamide |
| CN110156987A (en) * | 2019-05-22 | 2019-08-23 | 北京化工大学 | The preparation method of selfreparing non-isocyanate polyurethane |
Non-Patent Citations (1)
| Title |
|---|
| 《Cross-Linked Polyamides Synthesized through a Michael Addition Reaction Coupled with Bulk Polycondensation》;Chenfeng Yi et al.;《Industrial & Engineering Chemistry Research》;20171031;第56卷;第13743-13750页 * |
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