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CN-121978066-A - Method and device for testing crosslinking density of crosslinked polymer

CN121978066ACN 121978066 ACN121978066 ACN 121978066ACN-121978066-A

Abstract

The invention relates to the technical field of polymer crosslinking density testing, and discloses a method and a device for testing crosslinking density of a crosslinked polymer; the test method comprises the steps of S1, mixing an initial polymer, aggregation-induced emission molecules and a crosslinking initiator for treatment to prepare a crosslinked polymer doped with the aggregation-induced emission molecules, S2, carrying out ultraviolet irradiation on the crosslinked polymer, heating and photographing to obtain a fluorescence photo of the crosslinked polymer, S3, measuring the fluorescence intensity of the fluorescence photo, and S4, carrying the fluorescence intensity obtained by measurement into a mathematical model constructed according to a fitting standard curve to obtain the crosslinking density of the crosslinked polymer. The test method tests the fluorescence intensity of the crosslinked polymers doped with aggregation-induced emission molecules at high temperature, so that the nondestructive, small-error, low-cost, simple and rapid detection of the crosslinked densities of different crosslinked polymers is realized.

Inventors

  • Tian Mingce
  • ZHANG YONGJIE
  • YANG WEI
  • Dai Xiying
  • LUO KAIQIANG
  • SUN KAIYUE
  • LI WEIKANG

Assignees

  • 北京怀柔实验室

Dates

Publication Date
20260505
Application Date
20260107

Claims (10)

  1. 1. A method for testing the crosslink density of a crosslinked polymer, said method comprising: S1, mixing an initial polymer, aggregation-induced emission molecules and a crosslinking initiator for treatment to prepare a crosslinked polymer doped with the aggregation-induced emission molecules; S2, carrying out ultraviolet irradiation on the crosslinked polymer, heating and photographing to obtain a fluorescence photograph of the crosslinked polymer; s3, measuring the fluorescence intensity of the fluorescence photo, and S4, carrying the measured fluorescence intensity into a mathematical model constructed according to a fitting standard curve to obtain the crosslinking density of the crosslinked polymer.
  2. 2. The test method of claim 1, wherein the aggregation-induced emission molecules are selected from one or more of tetraphenyl ethylene, phenyl-substituted silole, phenyl vinyl anthracene, and phenyl-substituted pyrrole; And/or the weight ratio of the aggregation-induced emission molecules to the amount of the initial polymer is (0.1-5): 100.
  3. 3. The test method according to claim 2, wherein the initial polymer is polyethylene for cables, the aggregation-induced emission molecules are tetraphenyl ethylene, and the crosslink density of the crosslinked polymer is calculated according to a mathematical model represented by formula (I): X XLD = (G/G 0 + 6.878)/1.383×10 -4 mol/mL, formula (I); wherein G is the fluorescence intensity of the crosslinked polymer added with the crosslinking initiator with different contents; Wherein G 0 is the fluorescence intensity of the crosslinked polymer when the content of the crosslinking initiator is 0; Wherein X XLD is the crosslink density, mol/mL.
  4. 4. The test method according to claim 1, wherein in step S1, the treatment comprises an open mill, wherein the conditions of the open mill include a temperature of the open mill lower than a melting temperature of the initial polymer by 2-7 ℃ and a mixing time of 3-10min.
  5. 5. The test method according to claim 1, wherein in step S1, the treatment comprises hot pressing, wherein the hot pressing conditions include a temperature of the hot pressing of first a melting temperature + -3 ℃ of the initial polymer, a pressure of 10-20MPa, a hot pressing time of 10-30min, and then a temperature of rising to an initiation temperature + -3 ℃ of the crosslinking initiator, a pressure of 10-20MPa, and a crosslinking time of 15-40min; And/or hot-pressed into a film.
  6. 6. The test method according to claim 1, wherein in step S2, the heating conditions include that the heating temperature is 20-40 ℃ higher than the melting temperature of the initial polymer, and the constant temperature time is 5-10min.
  7. 7. The test method according to claim 1, wherein in step S3, the method for measuring fluorescence intensity comprises: (S3-1) first randomly selecting n square regions of the same area on the fluoroscope; (S3-2) then calculating the average gray value of each of the n regions; And (S3-3) finally, averaging the average gray values of n areas to obtain the fluorescence intensity of the crosslinked polymer, wherein n is more than or equal to 5.
  8. 8. The test method according to any one of claims 1 to 7, wherein the error of the test method is 0.05 to 0.5%, and the test detection limit of the crosslink density is 0.011X 10 -4 mol/mL.
  9. 9. An apparatus for testing the crosslink density of a crosslinked polymer, the apparatus comprising: a heater (2) for heating a sample, wherein the sample is a crosslinked polymer doped with aggregation-inducing luminescent molecules; An ultraviolet lamp (3) for irradiating the sample with ultraviolet light; a photographing device (4) for photographing the sample to obtain a fluorescence photograph, and And the analyzer is used for acquiring the fluorescence intensity of the fluorescence photo, and bringing the measured fluorescence intensity into a mathematical model constructed according to a fitting standard curve to obtain the crosslinking density of the crosslinked polymer.
  10. 10. The apparatus of claim 9, wherein the initial polymer is polyethylene for a cable, the aggregation-induced emission molecules are tetraphenyl ethylene, and the analyzer is configured to calculate a crosslink density of the crosslinked polymer according to a mathematical model of formula (I): X XLD = (G/G 0 + 6.878)/1.383×10 -4 mol/mL, formula (I); wherein G is the fluorescence intensity of the crosslinked polymer added with the crosslinking initiator with different contents; Wherein G 0 is the fluorescence intensity of the crosslinked polymer when the content of the crosslinking initiator is 0; Wherein X XLD is the crosslink density, mol/mL.

Description

Method and device for testing crosslinking density of crosslinked polymer Technical Field The invention relates to the technical field of polymer crosslinking density testing, in particular to a method and a device for testing the crosslinking density of a crosslinked polymer. Background Crosslinked polymers are important in the field of modern material application, and the key properties of mechanical properties, thermal properties, chemical resistance and the like are closely related to the crosslinking density. The method can accurately measure the crosslinking density of the material, intuitively understand the crosslinking state inside the material, evaluate whether the material can meet the performance requirements of practical application, and help to understand the influence of different formulas and process conditions on the crosslinking reaction, so that the formulas and the process are optimized, and new materials with more excellent performance are developed. Various methods of testing crosslink density have been established, including swelling, nuclear Magnetic Resonance (NMR), and dynamic thermo-mechanical analysis (DMA). However, these methods have disadvantages such as long test period, large influence of factors such as solvent and temperature, large measurement error, and inability to obtain the crosslink density by nondestructive test, and high cost of instruments and equipment, relatively complex test process and data analysis, and certain requirements on the shape and size of the sample. Therefore, there is an urgent need to develop a method that has small errors, low cost, is simple and rapid, and can nondestructively and accurately detect the crosslink density. Disclosure of Invention The invention aims to overcome the defects of larger testing error and complex testing process of the crosslinking density of the crosslinking polymer in the prior art, and provides a method and a device for testing the crosslinking density of the crosslinking polymer, the testing method tests the fluorescence intensity of the crosslinked polymers doped with the aggregation-induced emission (AIE) molecules at high temperature, so that the nondestructive, small-error, low-cost, simple and rapid detection of the crosslinking density of different crosslinked polymers is realized. In order to achieve the above object, a first aspect of the present invention provides a method for testing a crosslink density of a crosslinked polymer, wherein the method comprises: S1, mixing an initial polymer, aggregation-induced emission molecules and a crosslinking initiator for treatment to prepare a crosslinked polymer doped with the aggregation-induced emission molecules; S2, carrying out ultraviolet irradiation on the crosslinked polymer, heating and photographing to obtain a fluorescence photograph of the crosslinked polymer; s3, measuring the fluorescence intensity of the fluorescence photo, and S4, carrying the measured fluorescence intensity into a mathematical model constructed according to a fitting standard curve to obtain the crosslinking density of the crosslinked polymer. In a second aspect, the present invention provides an apparatus for testing the crosslink density of a crosslinked polymer, wherein the apparatus comprises: A heater 2 for heating a sample, wherein the sample is a crosslinked polymer doped with aggregation-inducing luminescent molecules; an ultraviolet lamp 3 for irradiating ultraviolet to the sample; A photographing device 4 for photographing the sample to obtain a fluorescence photograph, and And the analyzer is used for acquiring the fluorescence intensity of the fluorescence photo, and bringing the measured fluorescence intensity into a mathematical model constructed according to a fitting standard curve to obtain the crosslinking density of the crosslinked polymer. Through the technical scheme, the beneficial effects of the invention include: (1) The aggregation-induced emission molecules are uniformly doped in the crosslinked polymer, and the fluorescence intensity of the crosslinked polymer doped with the aggregation-induced emission molecules at high temperature is tested, so that the change of the crosslinking density is tested, and the nondestructive, small-error, low-cost, simple, convenient and rapid detection of the crosslinking density of different polymers is realized. (2) The aggregation-induced emission molecules have wide range, cheap and easily available raw materials and low cost, and are suitable for large-scale popularization and application. (3) The method can be suitable for cross-linked polymers with wide types, has good universality, is simple to operate and does not need chemical modification. Drawings FIG. 1 shows the zero shear viscosity η 0 of different crosslinked polymers at 150 ℃; FIG. 2 is a schematic diagram of an apparatus for testing the crosslink density of crosslinked polymers provided by the present invention; FIG. 3 is a photograph taken of fluorescence