CN114527234A - Method for testing carboxyl content in nylon 66 polymer - Google Patents
Method for testing carboxyl content in nylon 66 polymer Download PDFInfo
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- CN114527234A CN114527234A CN202210040369.XA CN202210040369A CN114527234A CN 114527234 A CN114527234 A CN 114527234A CN 202210040369 A CN202210040369 A CN 202210040369A CN 114527234 A CN114527234 A CN 114527234A
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- Prior art keywords
- polymer
- nylon
- sodium hydroxide
- glycol solution
- carboxyl
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- 229920000642 polymer Polymers 0.000 title claims abstract description 65
- 229920002302 Nylon 6,6 Polymers 0.000 title claims abstract description 50
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000012360 testing method Methods 0.000 title claims abstract description 23
- WVDDGKGOMKODPV-UHFFFAOYSA-N Benzyl alcohol Chemical compound OCC1=CC=CC=C1 WVDDGKGOMKODPV-UHFFFAOYSA-N 0.000 claims abstract description 36
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 18
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 claims abstract description 18
- KJFMBFZCATUALV-UHFFFAOYSA-N phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 claims abstract description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 17
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 12
- 235000019445 benzyl alcohol Nutrition 0.000 claims abstract description 12
- 238000010438 heat treatment Methods 0.000 claims abstract description 11
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 8
- 238000004448 titration Methods 0.000 claims abstract description 7
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000012760 heat stabilizer Substances 0.000 claims abstract description 4
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 3
- JTTXECQCCPZGII-UHFFFAOYSA-M sodium;ethane-1,2-diol;hydroxide Chemical compound [OH-].[Na+].OCCO JTTXECQCCPZGII-UHFFFAOYSA-M 0.000 claims description 12
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 9
- 229910052708 sodium Inorganic materials 0.000 claims description 9
- 239000011734 sodium Substances 0.000 claims description 9
- 239000003381 stabilizer Substances 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 239000007789 gas Substances 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- 229910001873 dinitrogen Inorganic materials 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 9
- 238000005979 thermal decomposition reaction Methods 0.000 abstract description 4
- 230000000295 complement effect Effects 0.000 abstract description 2
- WVDDGKGOMKODPV-ZQBYOMGUSA-N phenyl(114C)methanol Chemical compound O[14CH2]C1=CC=CC=C1 WVDDGKGOMKODPV-ZQBYOMGUSA-N 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 3
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000003017 thermal stabilizer Substances 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229940059082 douche Drugs 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
- G01N31/162—Determining the equivalent point by means of a discontinuity
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Molecular Biology (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention belongs to the technical field of nylon 66 polymer testing, and particularly relates to a method for testing carboxyl content in a nylon 66 polymer. Under the protection of nitrogen flow, dissolving a nylon 66 polymer tow sample in hot benzyl alcohol under the condition of adding copper acetate as a heat stabilizer; and (3) taking phenolphthalein as an indicator, carrying out neutralization titration by using a sodium hydroxide glycol solution, and calculating the content of the terminal carboxyl according to the consumption of the sodium hydroxide glycol solution. The method has the advantages that the benzyl alcohol is used for quickly dissolving the nylon 66 polymer under the heating condition, the content of carboxyl in the polymer can be quickly obtained, and the test result is stable. According to the invention, a certain amount of copper acetate solution is added in the process of dissolving the nylon 66 polymer, so that the thermal decomposition of the nylon 66 polymer can be prevented, the detection result of the carboxyl content in the nylon 66 polymer is ensured to be consistent with the actual result, and the detection result is complementary with the molecular weight result of the polymer characterized by a viscosity method.
Description
Technical Field
The invention belongs to the technical field of nylon 66 polymer testing, and particularly relates to a method for testing carboxyl content in a nylon 66 polymer.
Background
The carboxyl content in the nylon 66 polymer is directly in great relation with the viscosity and molecular weight of the polymer, and the properties such as strength of subsequent spinning samples are directly influenced, so that the measurement of the carboxyl content is an important detection item in the production process of the nylon 66.
However, when determining the carboxyl content of the nylon 66 polymer, the thermal stability of the nylon 66 polymer generally affects the accuracy of the determination result.
The method for testing the terminal carboxyl group in the polymer in the prior art comprises the following steps: dissolving a certain amount of nylon 66 tows in benzyl alcohol, using phenol as an indicator without adding a thermal stabilizer of copper acetate, titrating with a sodium hydroxide-ethylene glycol solution until the solution turns reddish, and calculating to obtain the content of terminal carboxyl in the polymer. Because no heat stabilizer is added in the prior art, the test result of the terminal carboxyl group is unstable, and the subsequent process adjustment cannot be guided.
Disclosure of Invention
The invention provides a method for testing the content of carboxyl in a nylon 66 polymer in order to improve the accuracy of the content determination of the carboxyl in the nylon 66 polymer, and the method adds a certain amount of copper acetate in the process of dissolving the nylon 66 polymer by benzyl alcohol, thereby preventing the thermal decomposition of the polymer and ensuring that the detection result is consistent with the actual result; and then titrating by adopting a sodium hydroxide-ethylene glycol solution, reading the volume of the consumed sodium hydroxide-ethylene glycol, and calculating the content of carboxyl in the polymer.
The invention relates to a method for testing carboxyl content in a nylon 66 polymer, which adopts the following technical scheme:
under the protection of nitrogen flow, a nylon 66 polymer tow sample is dissolved in hot benzyl alcohol under the condition of adding copper acetate as a heat stabilizer to prevent the nylon 66 polymer from thermal decomposition, phenolphthalein is used as an indicator, a sodium hydroxide glycol solution is used for neutralization titration, and the content of the terminal carboxyl groups is calculated according to the consumption of the sodium hydroxide glycol solution.
The invention relates to a method for testing carboxyl content in a nylon 66 polymer, which comprises the following steps:
a. adding benzyl alcohol into the container, introducing nitrogen, and heating; wherein the gas flow of the nitrogen is adjusted to be 0.6L/min;
b. after the benzyl alcohol is heated to 178-182 ℃, a stabilizer and a phenolphthalein indicator are added while stirring, and the purpose of adding the stabilizer is to prevent the polymer from decomposing at high temperature and influencing the test result of the carboxyl content. The stabilizer is a copper acetate solution;
then titrating with sodium hydroxide-glycol solution from colorless to reddish, adding the nylon 66 polymer sample after blank is eliminated, and continuing heating;
the dosage ratio of the nylon 66 polymer to the benzyl alcohol is 2-4 g:25 mL; the mass ratio of the nylon 66 polymer to the copper acetate is 80-160: 1.
c. After the nylon 66 polymer sample is completely dissolved, titrating with a sodium hydroxide-glycol solution, and recording the consumption volume of the sodium hydroxide-glycol solution when the titration is finished and the titration is carried out from colorless to reddish; the concentration of the sodium hydroxide-glycol solution is 0.05-0.15M;
d. the carboxyl content of the nylon 66 polymer was calculated according to the formula shown in formula (1):
in the formula:
v: volume consumed (mL) of sodium hydroxide-ethylene glycol solution;
w: weight of sample (g);
100: and (4) a conversion coefficient.
The invention has the beneficial effects that:
the method comprises the steps of dissolving a nylon 66 polymer by using benzyl alcohol, adding a phenolphthalein indicator, titrating by using a sodium hydroxide-ethylene glycol solution, reading the volume of the consumed sodium hydroxide-ethylene glycol, and calculating the content of carboxyl in the polymer. The invention uses benzyl alcohol to dissolve nylon 66 polymer quickly under heating condition, and can obtain carboxyl content in polymer quickly, and the test result is stable.
According to the invention, a certain amount of copper acetate solution is added in the process of dissolving the nylon 66 polymer, so that the thermal decomposition of the nylon 66 polymer can be prevented, the detection result of the carboxyl content in the nylon 66 polymer is ensured to be consistent with the actual result, and the detection result is complementary with the molecular weight result of the polymer characterized by a viscosity method.
Detailed Description
The present invention will be described in more detail with reference to the following embodiments for understanding the technical solutions of the present invention, but the present invention is not limited to the scope of the present invention.
Example 1
1. Using an instrument: magnetic stirrer, straight pipe cold douche, N2A flowmeter, a thermometer, a 250-300 ml three-neck flask, a rotor, a burette and a cover heater.
2. Using the following reagents: 0.1M sodium hydroxide-ethylene glycol solution, 0.05 Wt% copper acetate reagent, 1 Vol% phenolphthalein indicator.
3. The determination method comprises the following steps:
a. half an hour before the measurement, a cover type heater switch is turned on, and the gas flow of the nitrogen is adjusted to be 0.6L/min;
b. accurately weighing 6g of a nylon 66 polymer tow sample and placing the sample in a beaker; 50mL of benzyl alcohol is put into a three-neck flask from a dispenser, a rotor is put into the three-neck flask, a nitrogen pipe, a condenser pipe and a thermometer are respectively inserted into three mouths of the three-neck flask, and the three-neck flask is placed in a heating cover for heating;
c. after the internal temperature of the three-necked flask was raised to 180 ℃, 1ml of 0.05Wt% copper acetate and 0.3ml of vo 1% phenolphthalein indicator were added while stirring, and the purpose of adding copper acetate was to prevent the polymer from decomposing at high temperature and affecting the test result of the carboxyl group content. Then titrated with 0.1M sodium hydroxide-ethylene glycol solution from colorless to reddish, after the blank is eliminated, a sample of nylon 66 polymer strand is added and heating is continued to maintain the temperature at 180 ℃.
d. After complete dissolution, titrating with 0.1M sodium hydroxide-glycol solution from colorless to reddish, namely the end point, and recording the volume consumed by the sodium hydroxide-glycol solution.
4. And (4) calculating a result:
in the formula:
v: sodium hydroxide-ethylene glycol solution consumption volume (mL);
w: weight of sample (g);
100: and (4) a conversion coefficient.
5. Test results
The pre-polymerization carboxyl and the post-polymerization carboxyl are both nylon 66 polymer carboxyl, and the molecular weights of the two polymers are different.
Pre-polymerized carboxyl group: when the nylon 66 polymer tow is prepared, the polymer in the pre-polymerizer has relatively low molecular weight and higher carboxyl content; post-polymerization of carboxyl group: the polymer in the postpolymerizer has a relatively large molecular weight and a low carboxyl content.
TABLE 1 detection results of carboxyl content under different detection methods
Example 2
The method for testing the terminal carboxyl in the polymer in the prior art comprises the following steps: dissolving 5.8-6.2 g of nylon 66 tows in hot 50ml of benzyl alcohol, adding 0.3ml of 1 Vol% phenolphthalein without adding a thermal stabilizer of copper acetate as an indicator, titrating with 0.1mol/L sodium hydroxide-ethylene glycol solution until the solution turns reddish, and calculating to obtain the content of terminal carboxyl groups in the polymer. The results are shown in Table 1.
The test result after adding copper acetate is lower than that of the copper acetate, which shows that the polymer molecules are decomposed in the heating process of the copper acetate, so that the carboxyl end group content is increased, and further shows that the detection result of the carboxyl group content in the nylon 66 polymer is closer to the actual situation.
The above-described embodiments are merely preferred embodiments of the present invention, and not intended to limit the scope of the invention, so that equivalent changes or modifications in the structure, features and principles described in the present invention should be included in the claims of the present invention.
Claims (5)
1. A method for testing the carboxyl content in a nylon 66 polymer is characterized in that,
under the protection of nitrogen flow, dissolving a nylon 66 polymer tow sample in hot benzyl alcohol under the condition of adding copper acetate as a heat stabilizer; and (3) taking phenolphthalein as an indicator, carrying out neutralization titration by using a sodium hydroxide glycol solution, and calculating the content of the terminal carboxyl according to the consumption of the sodium hydroxide glycol solution.
2. The method for testing the carboxyl content of the nylon 66 polymer as claimed in claim 1, which comprises the following steps:
a. adding benzyl alcohol into the container, introducing nitrogen, and heating;
b. heating benzyl alcohol to 178-182 ℃, and adding a stabilizer and a phenolphthalein indicator while stirring, wherein the stabilizer is a copper acetate solution;
then titrating with sodium hydroxide-glycol solution from colorless to reddish, adding the nylon 66 polymer tow sample after blank is eliminated, and continuously heating;
c. after the nylon 66 polymer sample is completely dissolved, titrating with a sodium hydroxide-glycol solution, and recording the consumption volume of the sodium hydroxide-glycol solution when the titration is finished and the titration is carried out from colorless to reddish;
d. the carboxyl content of the nylon 66 polymer was calculated according to the formula shown in formula (1):
in the formula:
v: volume consumed (mL) of sodium hydroxide-ethylene glycol solution;
w: weight of sample (g);
100: and (4) a conversion coefficient.
3. The method for testing the carboxyl content in the nylon 66 polymer as claimed in claim 2, wherein the gas flow of the nitrogen gas in the step a is adjusted to be 0.6L/min.
4. The method for testing the carboxyl content in the nylon 66 polymer as claimed in claim 2, wherein the dosage ratio of the nylon 66 polymer to the benzyl alcohol is 2-4 g:25 mL; the mass ratio of the nylon 66 polymer to the copper acetate is 80-160: 1.
5. The method for testing the carboxyl content in the nylon 66 polymer as claimed in claim 2, wherein the concentration of the sodium hydroxide-ethylene glycol solution is 0.05-0.15M.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210040369.XA CN114527234B (en) | 2022-01-14 | 2022-01-14 | Method for testing carboxyl content in nylon 66 polymer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210040369.XA CN114527234B (en) | 2022-01-14 | 2022-01-14 | Method for testing carboxyl content in nylon 66 polymer |
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| CN114527234B CN114527234B (en) | 2024-08-23 |
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|---|---|---|---|---|
| CN102181052A (en) * | 2011-04-14 | 2011-09-14 | 杭州师范大学 | Nylon 66 resin, nylon 66 filament and preparation method thereof |
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| CN111905755A (en) * | 2020-07-16 | 2020-11-10 | 浙江恒澜科技有限公司 | Catalyst for hydrogenation of 2,2,4, 4-tetramethyl-1, 3-cyclobutanedione and preparation method and application thereof |
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2022
- 2022-01-14 CN CN202210040369.XA patent/CN114527234B/en active Active
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