Polymer Testing最新文献

{"title":"Impact of resin density and short-chain branching distribution on structural evolution and enhancement of tensile modulus of MDO-PE films","authors":"Dixit Guleria ,&nbsp;Shouren Ge ,&nbsp;Ludwig Cardon ,&nbsp;Sylvie Vervoort ,&nbsp;Jaap den Doelder","doi":"10.1016/j.polymertesting.2024.108560","DOIUrl":"10.1016/j.polymertesting.2024.108560","url":null,"abstract":"<div><p>This research explores the potential of PE-based mono-material flexible packaging as a sustainable alternative to traditional designs, emphasizing its efficient mechanical recyclability. Typically, non-PE materials are used in the outer layers of multilayer flexible packaging to ensure adequate stiffness and barrier properties. The stiffness of PE films can be significantly improved through the machine direction orientation (MDO) process. Our study investigates the influence of key polyethylene (PE) resin parameters, specifically, resin density and short-chain branching (SCB) distribution, with indications of molecular weight on lab-scale MDO film stretching and its subsequent effects on mechanical properties. We processed 5 distinct PE resins and blends in a lab-scale setup to produce compression molded base sheets and further MDO-PE films, characterizing them using shear rheology, GPC, DSC, and iCCD analyses. Tensile testing provided insights into the mechanical characteristics, while X-ray scattering (SAXS and WAXS) and AFM studies analysed structural evolution and morphology. Uniaxial stretching notably enhanced the tensile modulus of MDO-PE films along the machine direction, particularly in higher density blends, comparable to conventionally used polymers. Challenges related to extremely high-density base sheets led to localized stretching and breakage. Certain resin compositions exhibited unique molecular architecture, facilitating enhanced tensile modulus and axial stiffness. Our study offers insights into the microstructural changes and surface morphology of MDO-PE films, underscoring the potential use of stiffness-enhanced MDO-PE films as outer layers in PE-based flexible packaging designs.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"139 ","pages":"Article 108560"},"PeriodicalIF":5.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S014294182400237X/pdfft?md5=e23f458dd18538df89cf111d33e19825&pid=1-s2.0-S014294182400237X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of nano-hBN/ natural fibers reinforced epoxy composites for thermal and electrical applications using GRA and ANFIS optimization methods","authors":"Ramraji Kirubakaran ,&nbsp;Dinesh Ramesh Salunke ,&nbsp;Shenbaga Velu Pitchumani ,&nbsp;Venkatachalam Gopalan ,&nbsp;Aravindh Sampath","doi":"10.1016/j.polymertesting.2024.108561","DOIUrl":"10.1016/j.polymertesting.2024.108561","url":null,"abstract":"<div><p>Polymer composites reinforced with natural fibers have made great strides in industrial appliance use owing to the fibers exceptional composite properties, low environmental impact, and long lifespan. Five natural fibers-banana, sugar cane, coir, wood, and rice husk—are employed as short fibers in this experiment. The electrical and thermal properties of hybrid filler polymer (HFP) composites are also examined in relation to the thermal conductivity nano hBN filler weight ratio. HFP composites are prepared using the Taguchi design to select nano filler ratios and fifteen tests. Experimental results demonstrate that HFP composites with the maximum h-BN content are the most electrically and thermally robust. HFP composite material has the highest thermal conductivity and electrical resistance of 1.01 W/m-K and 346.91 Giga-Ohms respectively, with 5 % nano hBN and 2 % RH (sample 6). Nano h-BN fillers positively increase the thermal conductivity and electrical resistance of the composite structures. An improvement in thermal conductivity and electrical resistance is evident for the sample 6 composite, which increased by 16.09 % and 154.05 %, respectively, compared to the S1 interlaced multiphase hybrid polymer composite. Sample 4, containing rice husk fiber, achieves the minimal dielectric constant of 0.94, whereas sample 12, containing banana fiber, achieves a dielectric constant of 0.98. ANOVA is used to determine how such variables affect output variables. Performance measures are determined using the adaptive neuro-fuzzy inference system model with a hybrid grey base. Using the adaptive network-based fuzzy inference system, the input-output relation is modeled. After comparing experimental and ANFIS-anticipated data, the latter accurately predicted HFP composite behaviour. The combination of h-BN and natural fiber composites holds significant potential for various electrical and thermal applications due to their exceptional overall properties.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"139 ","pages":"Article 108561"},"PeriodicalIF":5.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002381/pdfft?md5=f1cd18b818134fed1d25dd54a9aafcb7&pid=1-s2.0-S0142941824002381-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water transport mechanism and performance evaluation in polyurethane materials: A state-of-the-art review","authors":"Cuixia Wang ,&nbsp;Zihan Xu ,&nbsp;Yangyang Xia ,&nbsp;Chao Zhang ,&nbsp;Hongyuan Fang ,&nbsp;Kangyan Sun","doi":"10.1016/j.polymertesting.2024.108554","DOIUrl":"10.1016/j.polymertesting.2024.108554","url":null,"abstract":"<div><p>In environments with high humidity or water exposure, the performance of polyurethane materials could be adversely affected by water and its penetration, which could compromise their long-term utility. The influence of water on polyurethane materials is affected by water transport and various factors. This article summarizes the factors affecting the water absorption of polyurethane, introduces research methods for water transport in polyurethane, analyzes the pathways of water transport, and reviews the influence of water on the mechanical properties of polyurethane and its composite materials. The ultimate goal of this paper is to furnish a comprehensive theoretical foundation and a valuable reference for the research and practical application of polyurethane materials in water environments.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108554"},"PeriodicalIF":5.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002319/pdfft?md5=5f35be3954146bbd88fbe8b336ca3954&pid=1-s2.0-S0142941824002319-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design of interpenetration network in light-based 3D printing for robust and sustainable dielectric insulators","authors":"Yingfan Zhang,&nbsp;Zhengyong Huang,&nbsp;Run He,&nbsp;Teng Zhao,&nbsp;Chenxin Li,&nbsp;Jian Li","doi":"10.1016/j.polymertesting.2024.108558","DOIUrl":"10.1016/j.polymertesting.2024.108558","url":null,"abstract":"<div><p>The sustainability and additive manufacturing of dielectric insulators are the development direction of the power system. Introducing dynamic covalent bonds in light-based 3D printing have attracted considerable attention as the reversible crosslinks allow for the reprocessing of printed objects. However, there generally exists a trade-off between mechanical strength, glass transition temperature (T_g), and reconfigurability for dynamic covalent networks. The reconfiguring process of the dynamic covalent network often requires high mobility of molecular chains and large free volumes, which in turn decreases the mechanical strength, T_g, and electrical insulating performance. Herein, we demonstrate a novel strategy for developing a kind of mechanically robust and sustainable vitrimer by building a rigid-flexible coupling inter-penetration network (IPN). Specifically, a two-stage curing approach was used to prepare high-performance 3D-printing vitrimers by using the plant oil-epoxy hybrid resin, which brings a lot of ester bonds and <em>β</em>-hydroxyl ester for the crosslinking network. Computational techniques with molecular dynamics calculation are used for the design and optimization of the crosslinking network, and then the optimized IPN is prepared by digital light processing 3D printing and subsequent heat curing. In the IPN, the epoxy backbone is rigid to enhance the T_g and tensile strength, while the plant-based methacrylate is flexible to guarantee topological rearrangement at elevated temperatures. Compared to reported epoxy vitrimers, the resultant IPN exhibits simultaneous high T_g (111 °C), outstanding tensile strength and toughness (tensile strength of 70 MPa, elongation at break of 17.58 %), good topological rearrangement, and excellent dielectric properties (permittivity less than 4, breakdown strength of 49.3 kV/mm). This work provides a new strategy for balancing the strength, toughness, electrical insulating and sustainability of 3D-printed thermosets.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108558"},"PeriodicalIF":5.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002356/pdfft?md5=2e0501658765056e37daa2629e57051c&pid=1-s2.0-S0142941824002356-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Melamine formaldehyde resin adhesive toughened with graphene oxide: Structures and properties","authors":"Xiaoxue Xu ,&nbsp;Bengang Zhang ,&nbsp;Liping Yu ,&nbsp;De Li ,&nbsp;Zhigang Wu ,&nbsp;Jiankun Liang ,&nbsp;Hong Lei","doi":"10.1016/j.polymertesting.2024.108557","DOIUrl":"10.1016/j.polymertesting.2024.108557","url":null,"abstract":"<div><p>The melamine-formaldehyde (MF) resin adhesive was modified by graphene oxide (GO), the chemical structure, wettability, bonding performance, tensile properties, curing performance and thermal properties of the modified resin were analyzed, and the toughening mechanism was also discussed in this study. The results showed that: (1) The MF resin with a high molar ratio possessed stable methylene ether bonds, which could easily generate parallel folding in space to form a π-π stacking supramolecular self-assembly special structure, with the potential of enhancing the toughness of molecular structures. (2) GO contained a large number of oxygen-containing reactive functional groups, which could further lower the curing temperature of the MF resin. A dense cross-linked network structure improved the thermal stability of the resin. (3) The bonding strength and toughness of the resin were significantly improved when the content of GO was 0.1 wt%. However, due to the large specific surface area and the intense π-π interaction between sheets, GO was easy to agglomerate, and the properties of the resin with GO content of 0.4 wt% degraded sharply. (4) The crystallinity of the MF resin modified by GO decreased, and the surface energy and plastic deformation energy increased due to the increased fracture crack path and fracture surface of the resin, which was the macro-reason for the improvement of toughness. (5) The strong π-π interaction between GO sheets and π-π accumulation between triazine rings were like parallel “springs” in the molecular structure of the resin, which might be the internal reason for the improvement of toughness. In addition, it was also proved that this special structure could limit the activity of hydroxymethyl and the release of free formaldehyde in the resin.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108557"},"PeriodicalIF":5.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002344/pdfft?md5=ffcbf4b59c1821ffa8b4e6669b029e5d&pid=1-s2.0-S0142941824002344-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142117358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of biological environment on bending fatigue lifetime in additive-manufactured polylactic acid fabricated by 3D-printing","authors":"Fatemeh Zahra Hosseini,&nbsp;Morteza Kianifar,&nbsp;Mohammad Azadi","doi":"10.1016/j.polymertesting.2024.108562","DOIUrl":"10.1016/j.polymertesting.2024.108562","url":null,"abstract":"<div><p>Polylactic acid (PLA) has become desirable for biomedical applications, particularly implantable devices. However, the degradation of PLA in biological environments under mechanical stress remains incompletely understood and requires further investigation. This study compared the plain fatigue (PF) and the biodegraded fatigue (BDF) behavior of 3D-printed PLA. For this purpose, two sets of standard fatigue specimens were additively manufactured by the fused filament fabrication (FFF) method. One set was used for plain fatigue testing, and the other was immersed for 330 days in simulated body fluid (SBF). After immersion, the samples were dried and weighed before fatigue testing. The fully reversed rotary bending fatigue tests were conducted on both sets of specimens, and the stress-lifetime (S-N) curves were obtained. Additionally, the fatigue properties of PF and BDF specimens were evaluated. Moreover, the fracture behaviors of the materials were studied using field emission scanning electron microscopy (FESEM). The outcomes implied that the weight of the samples extended during the immersion period, primarily due to water absorption by the PLA. However, after drying, the final weights did not change compared to the weights before immersion. The SBF immersion significantly reduced the fatigue performance of the biodegraded samples comparing the PF result.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108562"},"PeriodicalIF":5.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002393/pdfft?md5=0a8a6f268fe57555c8dcf9a7e747cc21&pid=1-s2.0-S0142941824002393-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142163754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compressive behavior and visco-hyperelastic constitutive of polyurethane elastomer over a wide range of strain rates","authors":"Guanxia Yang,&nbsp;Haijun Wu,&nbsp;Heng Dong,&nbsp;Fenglei Huang","doi":"10.1016/j.polymertesting.2024.108553","DOIUrl":"10.1016/j.polymertesting.2024.108553","url":null,"abstract":"<div><p>Polyurethane elastomers (PUEs) will experience different strain rates in different application scenarios. Therefore, it is of great significance to study the mechanical properties of PUE under a wide range of strain rates and establish a constitutive model that considers strain rates with high accuracy and few parameters. In this study, the quasi-static and dynamic compression tests of two types of PUEs (PUE55 and PUE85) were carried out, and investigated the strain rate effect of the materials. Based on the Mooney-Rivlin hyperelastic model and the Prony series, a compressible visco-hyperelastic constitutive model for PUE was established. Different from the conventional constant relaxation time in Prony series, two relaxation times that vary exponentially with principal stretch were proposed based on the relaxation test to describe the strain rate effect of the material at low and high strain rate respectively. In addition, using the visco-hyperelastic constitutive model to obtain the model inputs of the Simplified rubber/foam model in LS-DYNA, the impact process of the Metal/PUE composite projectile was reproduced under different impact conditions through the finite element simulation. Simulation results verified the visco-hyperelastic model in generating numerical model material parameters and the rationality of the Simplified rubber/foam model in describing PUEs.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108553"},"PeriodicalIF":5.0,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002307/pdfft?md5=b254f8eece2788ecff5959a601521ba3&pid=1-s2.0-S0142941824002307-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142095351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation on mechanical and tribological properties of PTFE nanocomposites reinforced by surface-modified graphene using molecular dynamics simulations","authors":"Yadi Yang ,&nbsp;Jing Zhao ,&nbsp;Jianzheng Cui ,&nbsp;Yunlong Li ,&nbsp;Bowen Jiang","doi":"10.1016/j.polymertesting.2024.108555","DOIUrl":"10.1016/j.polymertesting.2024.108555","url":null,"abstract":"<div><p>Surface-modified nanoparticles are commonly used to improve the mechanical properties and wear resistance of polytetrafluoroethylene (PTFE). However, fewer studies have been devoted to quantitatively revealing the action mechanism of graphene (Gr) modified with different functional groups on the mechanical and tribological properties of PTFE. Herein, the effects of four functional groups (−OH, −NH₂, −COOH, and −COOCH₃ functional groups) on the surface of Gr nanosheets on the mechanical and tribological properties of PTFE nanocomposites are studied using molecular dynamics simulations. The results indicate that the incorporation of functional groups to the Gr surface is able to significantly improve the mechanical properties and wear resistance of the nanocomposites, and the COOH-functionalized Gr nanosheet shows the best reinforcing effect due to the synergistic effect of its own high surface roughness and strong interfacial interaction between itself and the matrix. It is also found that the friction coefficient of the nanocomposites is obviously increased by the inclusion of functionalized Gr nanosheets, and the greater the surface roughness of the functionalized Gr nanosheet, the more significant the growth of the friction coefficient of the nanocomposites. The pull-out test and confined shear simulation reveal that due to the increased interfacial shear strength and the isolation of functional groups, an inhomogeneous transfer film is formed at the friction interface, leading to a decreased anti-friction property. This study provides some guidance for the future design and development of polymer nanocomposites with excellent mechanical and tribological performance for use in extreme service conditions.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108555"},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002320/pdfft?md5=c81892e61704b4e48147d4871e6d61ff&pid=1-s2.0-S0142941824002320-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Upgrading properties and circularity of the recycled flexible polypropylene by developing composites with an optimal combination of a fumed silica and maleated polypropylene copolymer: Influence of the addition of copolymer, type of fumed silica and the silica/copolymer ratio on packaging properties","authors":"Eliezer Velásquez ,&nbsp;Carol López-de-Dicastillo ,&nbsp;Cristian Patiño Vidal ,&nbsp;Guillermo Copello ,&nbsp;C.J. Pérez ,&nbsp;Abel Guarda ,&nbsp;María José Galotto","doi":"10.1016/j.polymertesting.2024.108556","DOIUrl":"10.1016/j.polymertesting.2024.108556","url":null,"abstract":"<div><p>Rigid polypropylene is mechanically recycled but flexible polypropylene is mostly used in energetic valorization because of the poor properties of the recycled polymer. A recycled polypropylene-based composite with outstanding properties for flexible food packaging was developed. For the first time, the influence of maleated polypropylene copolymer addition and the fumed silica/copolymer ratio on the packaging properties of recycled flexible polypropylene under the effects of silica hydrophilicity was investigated. The structural, morphological, thermal, mechanical, melt flow, overall migration, water vapor barrier and sealing properties of the developed nanocomposites were analyzed. Prominently, the addition of 1:1 maleated polypropylene and hydrophobic nanosilica improved the global performance of all tested methods. The recycled polypropylene had an overall migration to olive oil of 17 mg dm⁻², exceeding the limit allowed for food packaging, but the developed added-value composite reduced it to the tolerance limit according EU legislation. The seal strength was drastically increased by 50 % with adhesive peeling, high thermal stability, and well-dispersed particles without affecting the ductility.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108556"},"PeriodicalIF":5.0,"publicationDate":"2024-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002332/pdfft?md5=dbfdcae2c059dbbdf93ddf8c48193b26&pid=1-s2.0-S0142941824002332-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrical breakdown mechanism and life prediction of thermal-aged epoxy/glass fibre composites","authors":"Pengfei Wang,&nbsp;Ji Liu,&nbsp;Zhen Li,&nbsp;Chao Zhang,&nbsp;Longfei Zhang,&nbsp;Shouming Wang,&nbsp;Mingze Zhang","doi":"10.1016/j.polymertesting.2024.108552","DOIUrl":"10.1016/j.polymertesting.2024.108552","url":null,"abstract":"<div><p>Epoxy/glass fibre composites possess excellent mechanical and electrical properties and are widely utilised in electrical and electronic power equipment. However, the composites exhibit relatively poor thermal conductivity, causing the temperature of the composites to increase during the operation of power equipment, resulting in a significant reduction in the electrical breakdown strength. Although the effects of thermal aging on polymeric materials have been widely studied, its influence on electrical strength mechanisms has not been investigated at the molecular level. In this study, epoxy/glass fibre composite specimens were subjected to accelerated thermal aging treatment for 360 h at 180 °C. Functional groups, molecular chain dynamics, and electrical breakdown are characterised using infrared spectroscopy, dielectric spectroscopy, and breakdown measurement. Subsequently, electrical breakdown mechanism and life prediction of the thermally aged composites are discussed. During thermal aging, the epoxy resin molecular chains undergo continuous oxidation and chain scission, which generate numerous polar functional groups and short chains and an increase in the free volume. This triggers an enhancement in the chain segmental dynamics, thereby significantly reducing the activation energy of the epoxy resin. After 360 h, activation energy decreased from 0.78 eV to 0.67 eV. The DC breakdown voltages of the specimens decreased from 168.28 kV/mm to 134.91 kV/mm. An insulation life prediction model for thermally aged epoxy/glass fibre composites is established based on the time-temperature equivalence theory. The prediction results indicate that the service life of the operational composites is approximately 11.2 years at 353 K, which is consistent with engineering experience.</p></div>","PeriodicalId":20628,"journal":{"name":"Polymer Testing","volume":"138 ","pages":"Article 108552"},"PeriodicalIF":5.0,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0142941824002290/pdfft?md5=c51d0874b6acc480b432c30fb9876a33&pid=1-s2.0-S0142941824002290-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}