Thermal Aging Behavior Research Articles

Molecular dynamics study on the influence of thermal aging on the mechanical properties of epoxy resins for high voltage bushing.

Thermal aging significantly deteriorates the mechanical properties and service performance of epoxy resins used for the high-voltage bushing. Current studies on the thermal aging behavior of epoxy resins mainly focus on experimental observations. However, an in-depth understanding of the mechanism of thermal aging of epoxy resins requires the monitoring of structural evolution of epoxy resins during thermal aging at the molecular level. To thoroughly analyze the intrinsic factors affecting structural evolution and the effect of thermal aging on the mechanical properties of epoxy resin for high-voltage bushing, epoxy resin models with different crosslinking degrees were established and thermal aging treatments at various temperatures and time periods were carried out by molecular dynamics simulation. It was found that the tensile strength of the epoxy resin was enhanced with the increase of the crosslinking degree, which was related to the elevation of the proportion of C-N and O-H bonds in its structure. With the increase of thermal aging temperature, the tensile strength of the epoxy resin decreased, which was related to the formation of weak bonds. At the early stage of thermal aging and after a period of high-temperature thermal aging, the strength of epoxy resin significantly decreases. The thermal aging of the epoxy resin is accelerated under external loading. In addition, the crosslinking degree and curing agent also affect the thermal aging resistance of epoxy resins. The results of this study can provide guidance for predicting and improving the thermal aging resistance of epoxy resins. Materials Studio was used to construct molecular models and complete crosslinking reactions. DGEBA and 44DDS (or 33DDS) were mixed at a ratio of 2:1, followed by crosslinking reaction. During this process, the Nose method was used to control temperature, the Berendsen method was used to control pressure, and the polymer consistent force field (PCFF) was used to control the motion and force of atoms. Isobaric-isothermal ensemble (NPT ensemble) was used to heat up epoxy resin models to various thermal aging temperatures of 400K, 500K, 600K and 700K. The models were maintained at these temperatures for different thermal aging times of 100ps, 200ps, 300ps, 400ps, 500ps, 600ps, 700ps and 800ps. Afterwards, the models were cooled down to 300K and subjected to uniaxial tensile testing at this temperature with a strain rate of 1 × 109s-1. The structural configurations and stress-strain data during the tensile process were recorded. The flow stress of the material was derived by counting the average stress in the 20-50% strain interval.

Thermal aging behavior and heat resistance mechanism of ultraviolet crosslinked ultra‐high molecular weight polyethylene fiber

AbstractAs advances in heat resistant ultrahigh molecular weight polyethylene (UHMWPE) fiber via ultraviolet (UV) crosslinking, it is worth paying attention to its thermal aging behavior and heat resistance mechanism. UHMWPE fibers in different forms, the fully drawn yarn (FDY) and the UV crosslinked FDY (UVFDY), are subjected to isothermal aging at 135°C. The effects of thermal aging on their surface morphology and mechanical properties are studied and compared initially. The results demonstrate that UVFDY is a kind of a heat‐resistant fiber. Subsequently, to reveal the heat resistance mechanism of UVFDY, its crystalline and orientation structure evolution during thermal aging are further studied. It is indicated that the formation of dense‐packing crystals and disorientation behavior lead to fiber shrink, so that a number of grooves appear on the fiber surface. Since the crosslinked stucture of UVFDY hinders its molecules movement, the crystallization and disorientation behavior of UVFDY are weaker than those of FDY, resulting in UVFDY possesses slighter thermal shrinkage (Ts), fewer grooves and better mechanical properties than those of FDY. Therefore, the heat resistance of the fiber improves effectively after UV crosslinking. This work provides insights into the structure–property relationship of UVFDY during thermal aging, and offers basis data for its application in specific conditions.

Thermal aging of high‐performance fabrics used in the outer shell of firefighters' protective clothing

AbstractHigh‐performance fibers are known for their exceptional specific strength and resistance to various hazardous conditions, including fire. However, the long‐term performance of these fibers when exposed to convective heat has rarely been reported. This study investigated the accelerated thermal aging behavior of three high‐performance fabrics of different blends of inherently flame‐resistant high‐performance fibers: copolymer of aramids (Technora®)/polybenzoxazole (PBO); para‐aramid/meta‐aramid; and para‐aramid/polybenzimidazole (PBI). Fabric specimens were thermally aged for up to 1200 h at temperatures ranging from 90 to 320°C. While all three fabrics experienced losses in the breaking force, the Technora®/PBO fabric displayed the best strength retention, despite the complete disappearance of the Technora® fiber crystallinity after aging at 320°C for 1200 h. The para‐aramid/PBI blended fabric showed signs of competing aging processes at high temperatures. An increase in the fabrics' crystallinity and evidence of chain scission were observed after thermal aging. Additionally, degradation in the fabric's water‐repellent finish was observed. The findings of this study will contribute to the development of more durable and safer protective gear, particularly for high‐risk activities like firefighting.

Thermal Oxidative Aging Effect on Chemo-Rheological and Morphological Evolution of Crumb Rubber Modified Asphalt Binders with Wax-Based Warm Mix Additives

Wax-based warm mix additives can decrease the viscosity and improve the workability of crumb rubber (CR)-modified asphalt, but the mechanism of influence on the aging performance of CR-modified asphalt is not clear. To investigate the thermal aging behavior and mechanism of wax-based warm mix CR-modified asphalt, polyethylene wax (PEW) and polyamide wax (PAW) were mixed to prepare warm mix CR-modified asphalt. The effect of thermal aging on the rheological and mechanical properties was characterized by a basic property test, frequency sweep test, and multiple stress creep recovery test. The chemical composition changes during aging were then analyzed by Fourier transform infrared spectroscopy and gel permeation chromatography. Finally, the phase morphology during thermal aging was observed by fluorescence microscopy. The results showed that compared with the degradation of CR, the oxidative aging of the asphalt binder played a dominant role in the process. Not only did PEW and PAW attach to the asphalt surface in the form of crystallization to prevent its reaction with oxygen but they also promoted the dissolution of CR, and released polymerization chains, thereby enhancing the antiaging properties of CR-modified asphalt. Furthermore, the antiaging of PAW/CR-modified asphalt was better than that of PEW/CR-modified asphalt, because the amide group of PAW reacted with CR-modified asphalt to form a polymer structure.

Systematic methodologies to surveil and evaluate the early imperceptible thermal degradation of EPDM composite

Without knowledge and resultful surveillance of the early degradation of polymers, it is challenging to realize the high reliability of high-end equipment and the screening and grading of waste plastics. Their reliability evaluation and lifetime prediction are also unfulfillable for a lack of sensitive characterization techniques. This work, taking commercial ethylene propylene diene monomer (EPDM) composite as an example, explores a variety of multi-scale evaluation methods to identify its early thermal aging behaviors and molecular mechanisms, including various spectroscopic technology, swelling-equilibrium tests, scanning electron microscope (SEM), thermal analysis, contact angle tests and mechanical properties. Only some methods can give the perceptible indicators of the slight thermal degraded EPDM, namely fluorescent probe technology, infrared spectroscopy for gas mixtures, swelling-equilibrium tests and specific mechanical properties. Other methods are inferior in early aging identification. Both fluorescent probe technology and infrared spectroscopy for gas mixtures can recognize the thermal degradation induced products within 5 h at a temperature lower than 120 °C, while elongation at break can reflect the damage of EPDM within 5 h at 60 °C. Based on the time-temperature superposition principle, the master curve of the thermal aged EPDM is constructed using the data of elongation at break, which predicts that 50% retention of elongation at break occurs after 10.5 years at 30 °C. We further propose a new aging evaluation methodology to reflect the aging degree comprehensively, which is based on the standardized sequence numbers obtained from the above sensitive characterization methods.

A Method for Assessing the Degradation of PVC-Insulated Low-Voltage Distribution Cables Exposed to Short-Term Cyclic Aging

The distribution grid comprises cables with diverse constructions. The insulating material used in low-voltage (LV) distribution cables is predominantly PVC. Furthermore, the presence of cables with different structures in the grid poses challenges in detecting the aging of the cable network. Finding a universal and dependable condition-monitoring technique that can be applied to various types of cables is indeed a challenge. The diverse construction and materials used in different cables make it difficult to identify a single monitoring approach that can effectively assess the condition of all cables. To address this issue, this study aims to compare the thermal aging behavior of different LV distribution cables with various structures, i.e., one cable contains a PVC belting layer, while the other contains filler material. The growing adoption of distributed generation sources, electric vehicles, and new consumer appliances in low-voltage distribution grids can lead to short, repetitive overloads on the low-voltage cable network. Hence, these cable samples were exposed to short-term cyclic accelerated aging in the climate chamber at 110 °C. The cable’s overall behavior under thermal stress was evaluated through frequency and time domain electrical measurements (including tan δ and extended voltage response) and a mechanical measurement (Shore D). The tan δ was measured in the frequency range of 20 Hz–500 kHz by using the Wayne-Kerr impedance analyzer. The extended voltage response measurement was conducted using a C# application developed in-house specifically for laboratory measurements in the .NET environment. The study observed a strong correlation between the different measurement methods used, indicating that electrical methods have the potential to be adopted as a non-destructive condition-monitoring technique.

10000 hours thermal aging behavior and supercritical CO2 corrosion performance of candidate cladding AFA alloys for novel gas - cooled reactors

This study investigated the thermal aging (10,000 h at 650 °C) and corrosion performance (3000 h at 650 °C/15 MPa under sCO2) of two AFA alloys (AFA-20 and AFA-14), featuring 20 wt.% and 14 wt.% Cr. The increase in Cr content elevated the thermodynamically stable σ content and promoted its precipitation. The σ precipitation within the matrix significantly decelerated the coarsening kinetics of the Laves phase in AFA-20 over 5000 h aging. The intergranular σ phase facilitated crack formation, potentially increasing elongation, while the intragranular σ phase mitigated stress concentration at grain boundaries, making AFAs more brittle. AFA-20 developed a continuous protective Al2O3 oxide layer, whereas AFA-14, lacking this shielding, experienced increased internal oxidation. M23C6 carbides formed in the internal reaction zone, yet notably enriched in Mo rather than Cr.

Constrained sintering and thermal ageing behaviour of electrophoretically deposited Yb2Si2O7 environmental barrier coating

The oxidation of SiC and the formation of a thermally grown oxide layer (TGO) limit the lifetime of environmental barrier coatings. Thus, this paper focuses on the deposition of denser Yb2Si2O7 coatings using electrophoretic deposition to reduce the TGO growth rate. The findings show densification for Yb2Si2O7 can be achieved with an optimized sintering profile (heating/cooling rate, temperature, and time). However, the addition of 1.5 wt. % of Al2O3 to Yb2Si2O7 promoted densification and lowered the required sintering temperature, at 1380 °C using 2 °C/min heating/cooling rate for 10 hours provided efficient coating density. Moreover, adding Al2O3 reduced the TGO growth rate by more than 70% compared to the Al2O3-free coatings, without cracking in TGO after 150 hours of thermal ageing at 1350 °C. Results within this study suggest electrophoretic deposition with Al2O3 addition produces promising Yb2Si2O7 environmental barrier coatings on SiC substrate with low oxidation rates and increased lifetime.

Thermal aging and CMAS corrosion behaviors of Y2SiO5 ceramic for environmental barrier coatings

Yttrium silicate (Y2SiO5) is considered as one of the most promising candidate materials for environmental barrier coatings. In this paper, Y2SiO5 powder with a single phase were successfully prepared by high-temperature solid phase reaction method. The influence of sintering behavior on the microstructure, phase composition and mechanical properties of Y2SiO5 ceramics was studied at 1400 °C. In addition, the corrosion behavior and mechanism of Y2SiO5 against CMAS at 1250 °C and 1350 °C were also investigated. The results showed that the grain size of the prepared Y2SiO5 ceramic was about 1.28 µm with relatively uniform, and there were many pore structures. Although Y2SiO5 was still the main phase, a new small amount of Y4.67(SiO4)3O phase was formed in Y2SiO5 ceramics after sintering at 1400 °C for 25 h. The sintering phenomenon of Y2SiO5 ceramics occurred at 1400 °C: the porosity decreased and the grain size grew. With the increase of sintering time, fracture toughness first increased and then decreased. The maximum fracture toughness was 4.84 MPa m1/2 after 50 h sintering. Part of Y2SiO5 was dissolved in CMAS melt and Ca4Y6(SiO4)6O rare-earth oxyapatite phase was generated after CMAS corrosion for 24 h. The corrosion zone could be divided into loose corrosion area (about 93 µm thickness) and dense reaction layer with Ca4Y6(SiO4)6O phase (about 16 µm thickness) at 1250 °C for 24 h. With the increase of corrosion time and corrosion temperature, both the corrosion depth of CMAS and the thickness of dense reaction layer increases. The dense Ca4Y6(SiO4)6O layer can effectively resist the further corrosion of CMAS melt.

Effects of under‐clothing airflow on thermal protective performance and thermal aging behaviors of flame‐retardant fabric

AbstractTo investigate the effects of under‐clothing airflows on the thermal protection performance (TPP) and thermal aging of flame‐retardant fabrics, we constructed an under‐clothing air‐gap ventilation device based on the TPP tester. This device can generate different levels of airflow velocities such as 0.17, 1.0, and 2.0 m/s. The flame‐retardant fabrics were exposed to a heat flux of 30 kW/m2 to simulate an indoor fire scene. The impacts of under‐clothing airflows on the heat transfer behaviors of fabrics were analyzed with the temperature rise measured by thermocouples. The thermal aging behavior of the fabric was investigated based on the outer‐shell morphology, mass loss, and residual tensile strength. The results of this study indicated that the under‐clothing airflow enhanced the TPP of flame‐retardant fabric and the best TPP was achieved under the airflow of 1.0 m/s. Under‐clothing airflow increased the post‐thermal‐exposure mass loss of the fabric but did not further decrease the tensile strength. Higher severity thermal aging occurred for 2.0 m/s airflow than for 1.0 m/s airflow. The findings of this study are important for TPP prediction for firefighters' clothing and will help optimize firefighters' clothing design.

High temperature shear and thermal aging behavior of dissimilar transient liquid phase bonded Hastelloy X to Ni3Al intermetallic compound

Nickel super alloys and intermetallic compounds (IMCs) are candidate as strategic materials for turbine industry, because of its excellent high temperature properties. In this study, mechanical properties and thermal aging behavior (post thermal exposure) of the transient liquid phase (TLP) bonds between Hastelloy X to Ni3Al IMC at temperature range of 800–900 °C were investigated. The microstructure and fracture surfaces of the joints were examined by optical and scanning electron microscopes as well as XRD analysis. The optimum joint bonding strength was achieved for the sample treated at 1100 °C–180 min equaling to 355 ± 4.5 MPa. XRD patterns of semi-cleavage fracture surfaces revealed nickel solid solution matrix containing BNi3 and Ni3Si compounds generated at ASZ/ISA interface. The ultimate tensile strength reaches 36.5 ± 1 and 20.5 ± 1 MPa at temperatures of 800 °C and 900 °C, respectively. Fracture occurred in the IMC substrates for both temperatures were due to shrinkage porosity during solidification of IMC and mismatch of crystal lattice constants with the matrix. The thermal aging process at 900 °C for 50–500 h had a minor effect on the joint microstructure but generated TCP phases in the Hastelloy X.

Tungsten-based bcc-superalloys: Thermal stability and ageing behaviour

Tungsten is considered as a primary material for the divertor and first wall in many fusion reactor designs. There has been further interest in nano-structured multi-phase tungsten alloys and composites, such as oxide dispersion strengthened alloys, where interfaces may be harnessed as defect sinks to improve irradiation resilience, whilst also improving base mechanical strength, and potentially ductility. Here we further investigate the concept of tungsten-based ‘bcc-superalloys’ within the W-Ti-Fe ternary system, comprising W-TiFe, A2-B2, β-β’ nanostructures. Alloys were produced by arc melting and the microstructure controlled via thermal heat treatments, by solutionising at 1250 °C, followed by 750 °C ageing.The alloys were characterised using electron microscopy, including composition measurements, alongside hardness measurements. Building on our previous work, we have demonstrated that nano-scale B2 TiFe(W) forms within A2(W,Ti,Fe) in the W-Ti-Fe alloys, creating localised regions of the targeted A2-B2 (β-β’) precipitate reinforced structure. Further, here we evaluated ageing at 750 °C, where within the interdendritic domains decomposition consistent with B2TiFe(W) -> B2 + A2 and A2(Ti,Fe,W) -> A2 + A3 is proposed. An experimentally validated preliminary W-Ti-Fe ternary phase diagram has been produced, helping to understand the stable phases present and instructing onward optimisation of W-superalloys as a candidate material for fusion energy.

Rapid evaluation of UV and thermal aging of boiled tung oil by micro-UV/Py-GC/MS system

Boiled tung oil is the commonly used drying oil in Chinese cultural relics, and light radiation, temperature are the important factors leading to its aging. In order to investigate the photo and thermal aging behavior of boiled tung oil and determine the characteristic parameters to evaluate its aging degree, micro-UV/Py-GC/MS system has been applied in the present work to monitor the volatile aging products released by boiled tung oil film, to obtain high aging degree boiled tung oil film in short time and to investigate its composition change in different aging degree.Research results showed that volatile products released by boiled tung oil film during UV irradiation and 60 ℃ were mainly series of aldehydes, ketones, carboxylic acids and hydrocarbons with small molecule. With increase of aging time, the type of volatile products remain unchanged, but their amount gradually decreases until cannot be detected. Pyrolytical products of unaged and aged boiled tung oil is the same, but with the increase of aging degree, relative content of glycerol, dicarboxylic acids and azelaic acid in boiled tung oil film gradually increased, while the relative content of oleic, linoleic and eleostearic acid, as well as the content ratio of mono-carboxylic acids to di-carboxylic acids gradually decreased.Changes of volatile and pyrolytical products during aging process were summarized to evaluate the aging degree of boiled tung oil used in cultural relics. Boiled tung oil used in two lacquerware samples collected from the same carved lacquer panel from Fuwang Ge in the Forbidden City, and two polychrome samples separately collected from the inner and outer eave of Yanxi Tang in the Forbidden City were investigated, the aging degree evaluation results of boiled tung oil in historical samples have further confirm the reliability of summarized parameters. Research results of the present work can provide scientific support for the conservation and restoration of related cultural relics, and also lay a foundation for the in-depth study of the photo and thermal aging mechanism of boiled tung oil.

Microstructure, macro-, and nano-hardness assessment of AISI 302 steel aged at 1000°C

Changes in the microstructure of the AISI 302 steel must be analyzed in order to optimize its mechanical performance. In this paper, we studied the thermal aging behavior of the AISI 302 steel. The aging treatments of the steel were carried out at a fixed temperature of 1000°C and for durations between 0 and 6000 minutes. A metallographic microscope was used to see changes in the AISI 302 steel microstructure. In addition, the steel was mechanically characterized using the nano-indentation technique and macro-hardness tests. At the temperature investigated, the aging time increase caused a microstructure composed of large austenitic grains and a small area of grain boundaries per unit volume. For the mechanical characterization, the nano-indentation responses also showed a decrease in the nano-hardness and plasticity of the austenite as the aging time increased. The steel macro-hardness decreased significantly by incrementing the aging time.

Use of Multi-Scale Investigation to Evaluate Adhesion Performance of Warm-Mix Polymer-Modified Asphalt

Warm Mix Asphalt (WMA) technology can effectively reduce carbon emissions and energy consumption during road project construction. However, it may have a negative impact on the binding properties of asphalt mixtures. In order to effectively evaluate the adhesion performance of asphalt binders and aggregates under the combined influence of WMA and traditional polymer-modified asphalt, this paper provides a comprehensive evaluation at the micro and macro levels. The adhesion between three different modified asphalts (warm mix crumb rubber/ Styrene-Butadiene-Styrene (SBS) composite modified asphalt, warm mix crumb rubber asphalt, and warm mix SBS modified asphalt) and two different aggregates (limestone and granite) under both virgin and short-term aging conditions were analyzed. Regardless of the type of modified asphalt, the results showed that limestone aggregates have better adhesion properties with asphalt binders. In addition, the short-term thermal oxidation aging behavior is conducive to enhancing the asphalt-aggregate adhesion characteristics. Furthermore, WMA additives, crumb rubber, and SBS compound modification can improve the adhesion performance between asphalt and aggregate.

Effects of thermal aging on damage evolution behavior of glass fiber reinforced composites with multilayer graphene by acoustic emission

AbstractThe thermal aging behavior of glass fiber reinforced composites has attracted much attention because of its application in elevated temperatures environments. In this study, to improve the thermal aging resistance performance of composites, multilayer graphene was embedded in glass fiber reinforced composites and the damage evolution behaviors of the composites after thermal aging treatments were investigated. The mapping relationship between damage modes and acoustic emission parameters is established by principal component analysis and k‐means clustering methods, then the acoustic emission data were trained by K‐Nearest Neighbor algorithms to obtain a damage modes identification model with positive predictive values above 90%. The results showed that more matrix cracking signals are captured (or matrix cracking accumulation acoustic emission (AE) energy is abruptly raised) at the early stage of loading after 32 days of thermal aging. With the addition of multilayer graphene, the fiber/matrix debonding accumulation AE energy is significantly less than the matrix cracking accumulation AE energy, which is more obvious after thermal aging. Damage initiation and extension obtained by the acoustic emission events help to find the correlation between aging time and interior interface damage mechanism.

Research Progress of Steels for Nuclear Reactor Pressure Vessels.

The nuclear reactor pressure vessel is an important component of a nuclear power plant. It has been used in harsh environments such as high temperature, high pressure, neutron irradiation, thermal aging, corrosion and fatigue for a long time, which puts forward higher standards for the performance requirements for nuclear pressure vessel steel. Based on the characteristics of large size and wall thickness of the nuclear pressure vessel, combined with its performance requirements, this work studies the problems of forging technology, mechanical properties, irradiation damage, corrosion failure, thermal aging behavior and fatigue properties, and summarizes the research progress of nuclear pressure vessel materials. The influencing factors of microstructures evolution and mechanism of mechanical properties change of nuclear pressure vessel steel are analyzed in this work. The mechanical properties before and after irradiation are compared, and the influence mechanisms of irradiation hardening and embrittlement are also summarized. Although the stainless steel will be surfacing on the inner wall of nuclear pressure vessel to prevent corrosion, long-term operation may cause aging or deterioration of stainless steel, resulting in corrosion caused by the contact between the primary circuit water environment and the nuclear pressure vessel steel. Therefore, the corrosion behavior of nuclear pressure vessels materials is also summarized in detail. Meanwhile, the evolution mechanism of the microstructure of nuclear pressure vessel materials under thermal aging conditions is analyzed, and the mechanisms affecting the mechanical properties are also described. In addition, the influence mechanisms of internal and external factors on the fatigue properties, fatigue crack initiation and fatigue crack propagation of nuclear pressure vessel steel are analyzed in detail from different perspectives. Finally, the development direction and further research contents of nuclear pressure vessel materials are prospected in order to improve the service life and ensure safe service in harsh environment.

Monitoring and prediction of thermal failure of high-voltage switchgear insulation materials by studying the thermodynamic properties of FR-4 epoxy resin and the characteristic gas of thermal decomposition

FR-4 epoxy resin is a common material used as internal parts in high voltage switchgear. In this paper, we adopted the accelerated thermal aging method to explore the thermal aging behavior of FR-4 epoxy resin, simulating the practical application of this material in high voltage switch. The effects of thermal aging on the thermodynamic properties and thermal decomposition characteristic gases of FR-4 epoxy resin were characterized by FT-IR, DSC, TG and GC-MS analyses. The experiment results showed that thermal aging could destroy the internal crystal structure of FR-4 epoxy resin, which could lead to this material easier to be decomposed after heating. We also detected that the thermal decomposition rate of FR-4 epoxy resin aging was greatly accelerated compared with the materials that had not been aged. In addition, unaged FR-4 epoxy resin could release 9 main volatile gases under 120°C, and irreversible defects or structural damages occurred in the materials along with the volatilization of small organic molecules. Furthermore, after continuous thermal aging at 120 °C for 672 h, the molecules of FR-4 epoxy resin were more cracked and volatilized, we observed a more obvious phenomenon of thermal decomposition in this materials. In total, we compared the types of thermal decomposition gases and the decomposion mechanism of aged and unaged FR-4 epoxy resin. In application, our results can provide reference for condition monitoring and fault prediction for this material in high voltage switchgear in the future.

Research on Thermal Aging Behavior and Thermal Decomposition of Insulating Material XLPE

In this paper, accelerated thermal aging experiment was used to simulate the thermal aging behavior of XLPE, and FT-IR, DSC, TG and other test techniques were used to characterize the materials with different aging periods. The results show that with the aging time, the oxygen-containing groups in XLPE increase, and the crosslinking degree of molecular chains decreases. At the same time, the melting peak of the endothermic peak of the material shifts and the endothermic enthalpy decreases. After aging, the high temperature resistance of XLPE decreases and decomposition occurs more easily. The thermal decomposition of XLPE before and after thermal aging was carried out at different temperatures, and the corresponding thermal decomposition gases were collected. According to GC-MS analysis, the thermal decomposition gas products were all small molecule unsaturated olefin, small molecule containing oxygen and long carbon chain containing oxygen, and the content changed significantly before and after aging.

Research on Thermal Aging Behavior and Thermal Decomposition of Insulating Material XLPE

In this paper, accelerated thermal aging experiment was used to simulate the thermal aging behavior of XLPE, and FT-IR, DSC, TG and other test techniques were used to characterize the materials with different aging periods. The results show that with the aging time, the oxygen-containing groups in XLPE increase, and the crosslinking degree of molecular chains decreases. At the same time, the melting peak of the endothermic peak of the material shifts and the endothermic enthalpy decreases. After aging, the high temperature resistance of XLPE decreases and decomposition occurs more easily. The thermal decomposition of XLPE before and after thermal aging was carried out at different temperatures, and the corresponding thermal decomposition gases were collected. According to GC-MS analysis, the thermal decomposition gas products were all small molecule unsaturated olefin, small molecule containing oxygen and long carbon chain containing oxygen, and the content changed significantly before and after aging.