Fluorescence visualization method for predicting service life of cultural relic bonding polymer material

Abstract

The invention discloses a fluorescence visualization method for predicting the service life of a cultural relic bonding polymer material, and belongs to the technical field of cultural relic protection and analysis. Through a three-dimensional fluorescence imaging method, fluorescence visual monitoring of the early aging behavior of the polymer material bonded with the cultural relics is realized. And establishing an internal relation between the three-dimensional fluorescence volume of polymer aging and mechanical properties, establishing a quantitative equation, and predicting the service life of the cultural relic bonding polymer material through the fluorescence volume generated by aging. The method realizes the qualitative and quantitative analysis of the aging behavior of the bonding polymer at the degradation gap of the cultural relic, realizes the life prediction of the bonding polymer material of the cultural relic in combination with the performance change, and provides a theoretical basis for the protection of the cultural relic and the use management of the polymer material.

Description

Technical Field

[0001] The present invention belongs to the technical field of cultural relic protection and analysis, and specifically relates to a fluorescent identification method for the aging behavior of polymer materials at the bonding interface of cultural relics, as well as the prediction of their service life. The method not only studies the aging behavior of polymers at the bonding interface, but also establishes a service life prediction equation, which can provide a theoretical basis for the use and management of materials. Background Art

[0002] Cultural relics are important witnesses of human civilization. Scientific and effective restoration and protection measures are of vital importance to the protection of cultural relics. Organic polymer materials, such as acrylic resins (B72, B66, etc.), silicone resins, and epoxy resins, have been widely used in the protection and restoration of stone and earthen cultural relics in the past few decades due to their excellent properties. However, polymers are prone to aging under conditions such as temperature, water vapor, oxygen, and light, causing the structure and performance of the polymers used in cultural relics to deteriorate, reducing their service life, and leading to yellowing, brittleness, cracking, and even peeling of the cultural relic matrix. Therefore, accurately evaluating the aging behavior of polymer protective materials and establishing a scientific life prediction model are crucial for optimizing material selection and formulating protection strategies.

[0003] Currently, researchers are applying methods such as Fourier transform infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), and differential scanning calorimetry (DSC) to the study of the aging of polymers used in cultural relic protection. However, these techniques all use destructive sampling methods, requiring the polymer to be peeled off from the carrier. This has limitations for polymer aging studies applied to real cultural relics. These techniques cannot reveal the aging behavior of polymers used in real cultural relic restoration, nor can they intuitively present the aging behavior at the cultural relic-polymer interface, limiting the lifespan prediction of polymer materials. Therefore, there is an urgent need for a monitoring method for the aging of cultural relic adhesive materials that can non-destructively and highly sensitively monitor the aging behavior of polymers at the cultural relic bonding interface, intuitively analyze changes in the interface between cultural relic and polymer, and thus make accurate lifespan predictions for polymer materials used in cultural relic restoration.

[0004] Based on the intrinsic fluorescence generated by polymer aging, this study used confocal laser fluorescence microscopy to perform three-dimensional fluorescence imaging of polymers at the bonding interface of cultural relics, measuring the complex thermal-oxidative aging pathways of polymers. By combining the changes in mechanical properties during aging with the volume of intrinsic fluorescence generated by aging, it was possible to predict the ultimate service life of the adhesive material. These findings can inspire researchers in the field of cultural heritage to consider the compatibility of adhesive materials with cultural relic materials when putting them into use. They can also provide valuable information for relevant material developers, contributing to the protection of cultural relics. Summary of the Invention

[0005] The present invention provides a method for predicting the service life of an adhesive polymer based on fluorescence analysis of the identification of the aging behavior of the polymer material at the adhesive position of cultural relics.

[0006] The technical solution of the present invention is to test and study polymer materials used to bond cultural relics. First, a three-dimensional imaging analysis of the aging sites produced by the polymer at the edge of the mold sample is performed using a laser scanning confocal microscope, and the aging fluorescence volume is further quantitatively counted and the kinetic curve is fitted. Second, the fluorescence imaging strategy is applied to the aging monitoring of the polymer at the bonding interface of cultural relics, and the aging sites produced by the polymer are subjected to three-dimensional imaging analysis. A control experiment and quantitative analysis are used to explore the influence of adhesive materials of different materials on the aging behavior of the polymer. Third, an atomic force microscope is used to test the mechanical properties of the aged polymer to explore the influence of aging on the polymer properties. At the same time, an intrinsic connection is established between the aging fluorescence volume and the performance changes, realizing the prediction of the service life of the polymer material at the bonding interface of cultural relics. This method studies the aging behavior of the masonry-polymer interface through a highly sensitive three-dimensional imaging method, and at the same time, combines the changes in polymer properties to achieve the prediction of the service life of the polymer material used to bond cultural relics. This can provide an important reference for material researchers and developers, and facilitate the innovative development of cultural relic protection technology.

[0007] A fluorescence visualization method for predicting the service life of a polymer material for bonding cultural relics, characterized by comprising the following steps:

[0008] (1) Preparation of polymer samples

[0009] Using room temperature curing, the polymer and curing agent are combined and transferred to the mold. The mold sample of pure polymer and the sample of the object to be tested are bonded by polymer and curing agent between the simulated cultural relics to be tested. The thickness of the adhesive can be adjusted by changing the amount of polymer used.

[0010] (2) Polymer sample aging test

[0011] The polymer mold sample and the test object sample prepared in step (1) are placed in a thermal oxygen aging test chamber for accelerated aging treatment; the thermal aging temperature range is 20-400° C. (the aging temperature is optimized according to the actual environment of the cultural relics), the aging treatment time is 0-10 days, and the polymer material is aged for different time periods;

[0012] (3) Fluorescence imaging and quantitative analysis of adhesive polymers

[0013] A laser scanning confocal microscope was used to observe and image the polymers used to simulate the bonding of cultural relics. Different lasers were used to excite the polymers according to the emission light corresponding to different aging groups. The emission wavelength range was adjusted to capture the emission wavelength signals of different aging groups for imaging. The scanning range of the Z axis (the Z axis is consistent with the thickness direction) was appropriately adjusted according to the thickness of the polymer bond.

[0014] Visual quantitative information (including the volume and location of aging fluorescent spots) is obtained from the results of three-dimensional imaging for analysis. The aging process of the polymer and the aging sites at the polymer-artifact bonding interface are studied. The volume changes of aging fluorescent spots are analyzed and compared. If the aging of the polymer at the interface of the mold sample and the simulated artifact bonding sample are consistent, the next step is carried out. At the same time, quantitative data on the volume of aging fluorescent spots corresponding to different polymer aging times are obtained.

[0015] (4) Study the changes in mechanical properties of mold samples before and after aging for different times, and then establish the intrinsic relationship between the three-dimensional fluorescence volume of polymer aging and mechanical properties, and predict the life of the bonding polymer through the aging volume;

[0016] (a) comparing the growth and volume change of the fluorescent spots at the edge of the mold sample and at the interface of the simulated cultural relic bonding sample to determine whether the polymer aging at the interface of the simulated cultural relic bonding sample is consistent with the polymer aging change at the mold edge, and if so, proceeding to the next step; (b) performing mechanical property tests on the mold samples at different aging times to obtain the relationship between different times and mechanical properties, such as Young's modulus; (c) combining the quantitative data of polymer aging obtained in step (3) with step (b) to obtain a relationship between the volume of the polymer aging fluorescent spots and the change in mechanical properties;

[0017] (5) Perform three-dimensional imaging of the adhesive in the artifact to be tested, and bring the visualized quantitative information obtained from the three-dimensional imaging into the relationship in step (4) to obtain the true mechanical properties, which are compared with the volume of the fluorescent spot when the material decays to 50%, and then combined with the relationship between different times and mechanical properties such as Young's modulus in step (b) to obtain the corresponding lifespan.

[0018] It is further preferred that the volume of the aged fluorescent spot is the sum of the volumes of all aged fluorescent spots within the imaging range; the imaging range is 1.16 mm*1.16 mm*Z-axis depth, and the Z-axis depth is between 0 and 200 microns.

[0019] Exploring the aging process and service life prediction of polymer materials used in cultural relic protection is essential for cultural relic protection. By predicting the service life of polymer materials used to bond different cultural relic materials, suitable bonding materials for cultural relics of different materials can be screened (a relatively high accelerated aging temperature can be used in step 2) (e.g., in step 4, dense materials have no effect on the aging of polymer bonding materials), thus achieving long-term and safe protection for cultural relics. At the same time, the degree of polymer aging directly determines the performance of the polymer; exploring the service life of the polymer can predict the critical time when the polymer's performance fails, so that the deteriorated polymer can be replaced before the polymer fails, achieving long-term protection for cultural relics.

[0020] The present invention provides a non-destructive, three-dimensional, quantitative analysis method to detect the aging of polymers at the bonding interface of masonry cultural relics. Based on the obtained results, it can be analyzed whether the different materials of cultural relics affect the aging process of polymers during the aging process. At the same time, the service life of polymer materials can be predicted based on the changes in aging performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Fluorescence 3D imaging of the conjugated part of the epoxy resin mold sample after thermal oxidation aging for 0min, 45min, and 75min

[0022] Figure (excitation wavelength is 405 nm, emission collection range is 415-490 nm).

[0023] Figure 2 Kinetic fitting curve of fluorescence volume of sample conjugated structure and aging time

[0024] Figure 3 A is a schematic diagram of the bonding interface of masonry artifacts, and 3B is a three-dimensional fluorescence imaging of the polymer at the bonding interface of masonry artifacts.

[0025] 3C is a top view of the three-dimensional fluorescence imaging at the bonding interface of the masonry cultural relic, and 3D is a side view of the three-dimensional fluorescence imaging at different distances from the masonry cultural relic.

[0026] Figure 4 A is a side view of three-dimensional fluorescence imaging at the edge of the mold sample, and 4B is a side view of three-dimensional fluorescence imaging at the bonding interface of the quartz sample.

[0027] 4C is a statistical graph of the polymer aging fluorescence volume at the interface of different bonding materials.

[0028] Figure 5 Young's modulus attenuation curve of mold samples under different aging time treatments.

[0029] Figure 6 Fitting the life prediction curve of the correlation between the fluorescence volume and Young's modulus of the adhesive polymer for masonry artifacts. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the examples, but the present invention is not limited to the following examples.

[0031] Example 1:

[0032] (1) Preparation of epoxy resin samples

[0033] Take 10.0g of bisphenol A epoxy resin and 0.91g of diethylenetriamine and stir them magnetically for 20min until they are evenly mixed. Then take 2.0g of the mixture and inject it into a 10×10×20mm 3 The 1×10×20 mm silica gel mold was naturally cured at room temperature for 48 hours. 3 Take epoxy resin film mixed with curing agent and place it on a plate with size of 1×4×20mm. 3 The two masonry samples and the quartz sample were placed between them, and the bonded samples were then placed on a 10×10×20mm 3 Masonry artifact bonding samples and quartz bonding samples were prepared in a silicone mold for 48 hours.

[0034] (2) Thermal oxidative aging of epoxy resin samples

[0035] The cured epoxy resin mold samples, masonry cultural relics bonding samples and quartz sheet bonding samples were placed in a thermal oxidative aging box for accelerated thermal oxidative aging treatment. The temperature was set to 120°C and sampling was performed every 15 minutes.

[0036] (3) Fluorescence imaging and quantitative analysis of epoxy resin samples

[0037] Laser scanning confocal fluorescence microscopy was used to record changes in the intrinsic fluorescence of epoxy resin samples during aging. The excitation wavelength was set to 405 nm, and fluorescence emission was collected in the range of 415-490 nm. Three-dimensional fluorescence imaging was performed using an X- and Y-axis range of 1.16 mm, a Z-axis depth of 100 μm based on the epoxy resin film thickness, and a step size of 1 μm.

[0038] like Figure 1 As shown in A, only a small amount of fluorescence signal appears when the epoxy resin mold sample is not aged, but after aging for 45 minutes ( Figure 1 B) and an obvious fluorescence signal appeared. The aging time was extended to 75 min ( Figure 1 C), the fluorescence signal increased significantly, which indicates that the aging degree of epoxy resin deepened with the extension of aging treatment time.

[0039] The fluorescence signal generated by epoxy resin aging was further quantitatively counted. The results show that the volume of the fluorescence spot generated by aging is 509.91μm 3 Increased to 24859.69μm 3 In addition, if Figure 2 As shown in the figure, the change of volume (V) with time (t) conforms to the first-order kinetic reaction law, and there is a good linear relationship between lnV and time t: lnV = 3.71×10 -4 t-15.91 (R=0.9886) (T=120°C, t>0).

[0040] (4) Epoxy resin fluorescence imaging at the bonding interface of cultural relics

[0041] In order to monitor the aging of epoxy resin closer to the actual usage, the fluorescence imaging strategy was applied to the aging monitoring of epoxy resin at the bonding interface of masonry cultural relics ( Figure 3 A). According to the three-dimensional fluorescence imaging of epoxy resin, a large amount of fluorescence signals also appeared on the right side of the white dotted line ( Figure 3 B). Comparing with the bright field of 3D fluorescence imaging, it can be determined that the right side of the white dotted line is the epoxy resin part, and the left side of the yellow line is the masonry part ( Figure 3 C). Observing the three-dimensional fluorescence imaging of the epoxy resin at the bonding interface reveals that there are significantly more fluorescent spots on the side close to the masonry. To observe this phenomenon more clearly, the three-dimensional fluorescence imaging was divided into regions along the x-axis with the masonry as the boundary and a unit length of 0.2 mm. From the xz side view of the divided regions, it can be observed that the aging behavior of the epoxy resin occurs in two directions: the surface and the side close to the masonry, and the number of fluorescent spots gradually decreases as the x-axis coordinate axis increases ( Figure 3 D) The above results prove that the oxygen in the voids of non-dense masonry artifacts affects the aging reaction process of epoxy resin, accelerates the aging degradation of epoxy resin, and produces more conjugated structures, which shortens the service life of epoxy resin.

[0042] (5) Comparative study of masonry artifact bonding samples, mold samples, and quartz bonding samples

[0043] As a reference, the epoxy resin mold sample and the dense structure quartz bonding sample prepared in the same way and subjected to accelerated aging treatment were subjected to fluorescence imaging analysis.

[0044] like Figure 4As shown in Figure A, the cross-sectional view of the fluorescence 3D imaging shows that the left side of the white dotted line is air and the right side is epoxy resin. It can be found that the fluorescence points gather from the surface and edge of the sample, and the number of fluorescence points increases as the sample approaches the edge, showing the same pattern as the aging of epoxy resin at the bonding of masonry artifacts. Compare the side view of the 3D fluorescence imaging of epoxy resin at the dense structure of quartz bonding interface ( Figure 4 B), the left side of the white dotted line is quartz glass, and the right side is epoxy resin. It can be found that the growth of the fluorescent spots is irregular. The above results can prove that oxygen plays a key role in the thermal oxidation aging of epoxy resin. In order to further explore the aging of aged epoxy resin at different bonding materials, quantitative statistics of its three-dimensional fluorescence imaging ( Figure 4 C), it can be found that V 砖石 ≈V 模具 >V 石英 This further demonstrates that the mold sample and the epoxy resin bonded to the masonry artifact exhibit the same aging process. Therefore, the aging behavior of the mold sample can be used to predict the service life of the epoxy resin bonded to the artifact.

[0045] (6) Life prediction of epoxy resin at the bonding interface of masonry cultural relics

[0046] In order to explore the influence of the thermo-oxidative aging behavior of epoxy resin on its performance, the interaction force between the measuring probe of the atomic force microscope and the epoxy resin was used to test the Young's modulus of its surface, so as to measure the changes in the mechanical properties of the epoxy resin before and after aging. The Young's modulus of a series of epoxy resin samples treated with thermo-oxidative aging was tested, and it was found that the Young's modulus of the epoxy resin gradually decreased with the extension of the aging time. From no aging to thermo-oxidative aging for 75 minutes, the Young's modulus of the epoxy resin slowly decreased from 3.70GPa to 2.34GPa. The decrease in Young's modulus on the surface of the epoxy resin is related to the oxidation reaction that occurs during the aging process. The oxidation reaction generates a large number of carbonyl groups and other groups, which reduces the integrity of the three-dimensional network structure of the resin. In addition, the relationship between the Young's modulus and the aging time follows an exponential decay function model, and its change law is fitted ( Figure 5 ), we can get the function: (T=120°C, the temperature is chosen to speed up the experimental process).

[0047] The relationship between the aging fluorescence volume (V) and Young's modulus (M) of the conjugated structure of epoxy resin is established ( Figure 6 ), we can get the relationship: (R 2 =0.9882)(T=120°C).

[0048] According to the national standard GB / T9344-1998 for polymers, the service life can be determined when the performance of the material decays to 50% of its original value. According to the formula, when the Young's modulus decays to 50% of its initial value, the fluorescent volume at this time is 3.19×10 4 μm 3 , the usage time is 7.08×10 4 Therefore, based on this relationship, a simple visualization experiment of the aging fluorescence volume of epoxy resin at the bonding position can be used to predict the mechanical properties of epoxy resin, and further infer the usage limit of epoxy resin at the bonding interface of cultural relics, thereby achieving the purpose of protecting cultural relics.

Claims

1. A fluorescence visualization method for predicting the service life of polymer materials used in bonding cultural relics, characterized in that: The following steps are involved: (1) Preparation of polymer samples Using room temperature curing, the polymer and curing agent are combined and transferred to the mold. The mold sample of pure polymer and the sample of the object to be tested are bonded by polymer and curing agent between the simulated cultural relics to be tested. The thickness of the adhesive can be adjusted by changing the amount of polymer used. (2) Polymer sample aging test The polymer mold sample and the test sample prepared in step (1) are placed in a thermal oxygen aging test chamber for accelerated aging treatment; the thermal aging setting temperature range is 20-400° C., the aging treatment time is 0-10 days, and the polymer material is aged for different time periods; (3) Fluorescence imaging and quantitative analysis of adhesive polymers A laser scanning confocal microscope was used to observe and image the polymers used to simulate the bonding of cultural relics. Different lasers were used to excite the polymers according to the emission light corresponding to different aging groups. The emission wavelength range was adjusted to capture the emission wavelength signals of different aging groups for imaging. The scanning range of the Z axis (the Z axis is consistent with the thickness direction) was appropriately adjusted according to the thickness of the polymer bond. Visual quantitative information (including the volume and location of aging fluorescent spots) is obtained from the results of three-dimensional imaging for analysis. The aging process of the polymer and the aging sites at the polymer-artifact bonding interface are studied. The volume changes of aging fluorescent spots are analyzed and compared. If the aging of the polymer at the interface of the mold sample and the simulated artifact bonding sample are consistent, the next step is carried out. At the same time, quantitative data on the volume of aging fluorescent spots corresponding to different polymer aging times are obtained. (4) Study the changes in mechanical properties of mold samples before and after aging for different times, and then establish the intrinsic relationship between the three-dimensional fluorescence volume of polymer aging and mechanical properties, and predict the life of the bonding polymer through the aging volume; (a) Comparing the growth and volume changes of the fluorescent spots at the edge of the mold sample and at the interface of the simulated artifact bonding sample to determine whether the aging of the polymer at the interface of the simulated artifact bonding sample is consistent with the aging of the polymer at the mold edge. If so, proceed to the next step; (b) Performing mechanical property tests on the mold samples after aging for different times to obtain the relationship between different times and mechanical properties, such as Young's modulus; (c) combining the quantitative data of polymer aging obtained in step (3) with the data from step (b) to obtain a relationship between the volume of polymer aging fluorescent dots and changes in mechanical properties; (5) Perform three-dimensional imaging of the adhesive in the artifact to be tested, and bring the visualized quantitative information obtained from the three-dimensional imaging into the relationship in step (4) to obtain the true mechanical properties, which are compared with the volume of the fluorescent spot when the material decays to 50%, and then combined with the relationship between different times and mechanical properties such as Young's modulus in step (b) to obtain the corresponding lifespan.

2. The method according to claim 1, characterized in that The volume of the aged fluorescent spot is the sum of the volumes of all aged fluorescent spots within the imaging range; the imaging range is 1.16 mm*1.16 mm*Z-axis depth, and the Z-axis depth is between 0 and 200 microns.

3. The method according to claim 1, characterized in that Step (2) optimizes the aging temperature according to the actual environment in which the cultural relics are located.

4. The method according to claim 1, characterized in that Further application of the above method is to study the service life prediction equations of different polymer materials to screen out polymer protective materials that have good chemical stability for specific cultural relics and can safely protect cultural relics, so as to achieve long-term and safe protection of cultural relics.

5. The method according to claim 1, characterized in that The degree of polymer aging directly determines the performance of the polymer. Further application of the method to explore the service life of the polymer can predict the critical time of polymer performance failure, so as to replace the deteriorated polymer before the polymer fails and achieve long-term protection of cultural relics.

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