Characteristics of C4F7N/Epoxy Resin Insulation System Affected by Long-Term Electro-Thermal Accelerated Aging

2021 ◽  
Vol 28 (6) ◽  
pp. 1973-1979
Cong Wang ◽  
Renjie Cao ◽  
Youping Tu ◽  
Xin Ai ◽  
Ying Zhang ◽  
2012 ◽  
Vol 182-183 ◽  
pp. 76-79 ◽  
Lei Lei Song ◽  
Quan Rong Liu ◽  
Jia Lu Li

In this paper, carbon fiber reinforced resin matrix composites were produced by stacking eight pieces of carbon fiber woven plain fabric and subjected to accelerated ageing. Accelerated ageing was carried out in oven at 180°C for three different time intervals (60 hours, 120 hours and 180 hours). The influence of different ageing time intervals at 180°C on tensile properties of laminated composites was examined, compared with the composites without aging. The appearance and damage forms of these laminated composites were investigated. The results revealed that the tensile strength of the laminates declined significantly after long term accelerated aging at 180°C. The average tensile strengths of composite samples aged 60 hours, 120 hours, and 180 hours period of time at 180°C are 80.36%, 79.82%, 76.57% of average tensile strength of composite samples without aging, respectively. The high temperature accelerated aging makes the resin macromolecular structure in the composites changed, and then the adhesive force between fiber bundles and resin declines rapidly which result in the tensile strength of composites aged decrease. This research provides a useful reference for long term durability of laminated/epoxy resin composites.

2013 ◽  
Vol 1518 ◽  
pp. 73-78 ◽  
Shirley K. Fong ◽  
Brian L. Metcalfe ◽  
Randall D. Scheele ◽  
Denis M. Strachan

ABSTRACTA calcium phosphate ceramic waste-form has been developed at AWE for the immobilisation of chloride containing wastes arising from the pyrochemical reprocessing of plutonium. In order to determine the long term durability of the waste-form, aging trials have been carried out at PNNL. Ceramics were prepared using Pu-239 and -238, these were characterised by PXRD at regular intervals and Single Pass Flow Through (SPFT) tests after approximately 5 yrs.While XRD indicated some loss of crystallinity in the Pu-238 samples after exposure to 2.8 x 1018 α decays, SPFT tests indicated that accelerated aging had not had a detrimental effect on the durability of Pu-238 samples compared to Pu-239 waste-forms.

2019 ◽  
Vol 14 (2) ◽  
pp. 45-59 ◽  
Halet Almila Arda Buyuktaskin ◽  
Mehmet Serkan Yatagan ◽  
Gulseren Erol Soyoz ◽  
Leyla Tanacan ◽  
Morvarid Dilmaghani

Although timber was used extensively as a structural material for traditional buildings in Turkey in the past, usage of structural timber decreased significantly over time and timber has been largely replaced by other materials. As timber is a natural, durable and sustainable material, it would be desirable to re-introduce timber structural elements to contemporary construction in a form that is appealing to industry. Timber-glass composite structural elements are potentially a good candidate for this purpose. To that end, a series of tests were conducted on load-bearing timber-glass composites in order to understand the long–term structural performance of the composite material under atmospheric conditions; to decrease the recurring cost of repair and maintenance; and to minimize the exhaustion of raw materials and energy. In this paper, the first part of this experimental work is presented, which focuses on the durability of timber-glass composite under the effects of accelerated aging, carried out on small-sized timber-glass composite specimens. Accelerated aging effects were observed under wetting-drying, freezing-thawing, UV effects, resistance to acids and high temperature. The mechanical strength of the timber-glass composite specimens before and after the effect of accelerated aging was measured by adhesion and shear strength tests and a comparative analysis of the results was carried out. The results of the experiments indicate that timber-glass composite is suitable to be used under protection from environmental conditions.

2020 ◽  
Vol 29 (1) ◽  
pp. 40-56 ◽  
Arooj Rashid ◽  
Jawad Saleem ◽  
Muhammad Amin ◽  
Sahibzada Muhammad Ali

Multiple environmental stresses produce complex phenomena of aging in polymeric insulators. The main aim of this research is to investigate the improved aging characteristics of silica (SiO2)/alumina trihydrate (ATH) hybrid samples (HSs) in high-temperature vulcanized rubber. For this purpose, three HSs comprising 20% micro-ATH with 2% nano-SiO2 (S2), 4% nano-SiO2 (S4), 6% nano-SiO2 (S6) along with sample-virgin (SV) are subjected to long-term accelerated aging of 9000 h. A special aging chamber is fabricated for the aging process of samples. The aging characteristics of these samples are investigated by measuring leakage current (LC) and hydrophobicity classification (HC) after every weathering cycle. Similarly, Fourier transform infrared (FTIR) spectroscopy is performed to observe the important structural changes over the entire aging time. The dielectric strength of AC is also performed after every 1000 h of aging. Tracking and erosion resistance and mechanical properties are also investigated before and after aging. From the critical investigation, it is observed that HSs possess improved results in all the conducted tests. S2 has the lowest LC and HC values throughout the aging time. Similarly, S6 described the highest breakdown strength at the end of the accelerated aging. In the case of FTIR, it is analyzed that the important wave numbers remain intact for all the HSs in the accelerated aging environment. The loss percentage in the wave number for SV is higher, compared to the HSs. After performing the tracking and erosion resistance test, HSs have superior performance. For some of the mechanical properties, HSs showed improved values. Thus, from the experimental analysis, it is deducted that the sample S2 offers the highest resistance to the aging conditions, compared to the SV and other HSs.

Winnie M.C. van den Boogaard ◽  
Marry M. van den Heuvel-Eibrink ◽  
Jan H.J. Hoeijmakers ◽  
Wilbert P. Vermeij

Dietary restriction (DR) is the most successful nutritional intervention for extending life span and preserving health in numerous species. Reducing food intake triggers a protective response that shifts energy resources from growth to maintenance and resilience mechanisms. This so-called survival response has been shown to particularly increase life and health span and decrease DNA damage in DNA repair–deficient mice exhibiting accelerated aging. Accumulation of DNA damage is the main cause of aging, but also of cancer. Moreover, radiotherapies and most chemotherapies are based on damaging DNA, consistent with their ability to induce toxicity and accelerate aging. Since fasting and DR decrease DNA damage and its effects, nutritional preconditioning holds promise for improving (cancer) therapy and preventing short- and long-term side effects of anticancer treatments. This review provides an overview of the link between aging and cancer, highlights important preclinical studies applying such nutritional preconditioning, and summarizes the first clinical trials implementing nutritional preconditioning in cancer treatment. Expected final online publication date for the Annual Review of Cancer Biology, Volume 5 is March 4, 2021. Please see for revised estimates.

1989 ◽  
Vol 16 (1) ◽  
pp. 72-81 ◽  
Brahim Benmokrane ◽  
Gérard Ballivy

Estimation of loss of prestress is an essential part of the design of permanent or temporary prstressed anchors since stability of the retained structure must not be compromised. Findings of a field study on long-term behaviour of prestressed anchors are presented herein: different lengths of anchors in solid rock were injected with cement grout or epoxy resin. Load variation in the anchors with time indicated two distinct stages of loss of prestress: an initial stage of rapid loss of prestress and a second stage of very minor and uniform loss ending about 6 months after prestressing. Our study also showed that restressing anchors after a period of time reduces subsequent prestress loss and that overdimensioning of the injected length does not. Key words: rock, prestressed injected anchor, grout, loss of prestress, creep, relaxation.

2012 ◽  
Vol 1466 ◽  
Juan S. Ordonez ◽  
Christian Boehler ◽  
Martin Schuettler ◽  
Thomas Stieglitz

ABSTRACTDelamination between thin-film metal and substrate is a major cause of failure in polyimide based neural microelectrode arrays. Chemical adhesion is the only way to establish a long-term bond that will allow two materials to stick to each other even in a wet environment, given that the materials do not deteriorate in the presence of water. This study assesses, by means of peel and shear tests, a long-term quantitative and comparative study of the adhesion of polyimide to various metallic and other inorganic layers of interest. Polyimide (BPDA-PPD) was cured on the layers, which involve platinum, gold and tungsten-titanium as commonly used implant metals and diamond-like carbon (DLC), silicon carbide (SiC), silicon dioxide (SiO2) and silicone nitride (SiN) as potential adhesion promoters to be used later as intermediate layers between metal and polyimide. The adhesion was observed over one year under accelerated-aging conditions by storing the specimens in 60°C saline (corresponding to 40000 hrs at 37°C). Only silicon carbide and amorphous carbon showed almost unaffected adhesion to polyimide over the testing period. No water intrusion at the interface was observed and the strong bond is almost fully maintained.

2011 ◽  
Vol 399-401 ◽  
pp. 461-464
Wei Geng ◽  
Lei Lei Song ◽  
Jia Lu Li

In this paper, the tensile strength of 3-dimension-4-direction braided/epoxy resin composites after accelerated aging for different period of time at 150°C was investigated. The tensile tests of 3-dimension-4-direction braided/epoxy resin composite samples without aging and aged 60 hours, 120 hours, 180 hours, at 150°C were carried out. The damage forms of braided composite samples tested were investigated. The experiment result indicates that the accelerated aging process at 150°C has some effect on the tensile strength of braided composite samples. The average tensile strengths of composite samples aged 60 hours, 120 hours, and 180 hours period of time at 150°C are 92.44%, 91.62% and 84.91% of average tensile strength of braided composite samples without aging, respectively. This means that the tensile strength will be decreased when the aging period of time increases at 150°C. The damage form of samples tested shows that when accelerated aging, the resin in the composite samples is damaged, which makes the adhesive force between fiber bundles and epoxy resin decline, so that the ability of fiber and resin bearing the tensile load together decreases.

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