Assessment of the chemical degradation of PFPE lubricants and greases for space applications: implications for long-term on-ground storage

2021 ◽  
Author(s):  
Archim Wolfberger ◽  
Andreas Hausberger ◽  
Sandra Schlögl ◽  
Małgorzata Hołyńska
Keyword(s):  
Chemical Degradation ◽  
Space Applications ◽  
Pfpe Lubricants

Mechanical Properties of Epoxy Adhesive Under Thermal Aging and Their Chemical Degradation Behavior

2021 ◽  
Vol 21 (8) ◽  
pp. 4444-4449
Author(s):  
Bongjin Chung ◽  
Shin Sungchul ◽  
Jaeho Shim ◽  
Seongwoo Ryu
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Photoelectron Spectroscopy ◽  
Thermal Exposure ◽  
Chain Scission ◽  
Epoxy Adhesive ◽  
Chemical Degradation ◽  
Adhesive Properties ◽  
Noticeable Reduction

Epoxy adhesive was analyzed under long term thermal aging and mechanical properties and chemical degradation were observed by X-ray photoelectron spectroscopy (XPS). Long term thermal exposure of epoxy causes a noticeable reduction in adhesive properties. We developed a predictive model of temperature and time dependent aging. The temperature dependent aging behavior of epoxy adhesive shows good agreement with conventional Arrhenius equations. Using XPS analysis, we also discovered a correlation between chemical degradation and the adhesive properties. Decay of C–C bonding ratio induced chain-scission of epoxy adhesive; increase of total numbers of C–O and C═O induced oxidation of epoxy adhesive during thermal exposure.

Thermoelectric Applications as Related to Biomedical Engineering for Nasa Johnson Space Center

1997 ◽  
Vol 478 ◽  
Author(s):  
C. D. Kramer ◽  
P.E.
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Space Environment ◽  
Space Applications ◽  
International Space ◽  
Future Technology ◽  
Technological Developments ◽  
Environment Noise ◽  
Scientific Value

AbstractThis paper presents current NASA biomedical developments and applications using thermoelectrics. Discussion will include future technology enhancements that would be most beneficial to the application of thermoelectric technology.A great deal of thermoelectric applications have focused on electronic cooling. As with all technological developments within NASA, if the application cannot be related to the average consumer, the technology will not be mass-produced and widely available to the public (a key to research and development expenditures and thermoelectric companies). Included are discussions of thermoelectric applications to cool astronauts during launch and reentry. The earth-based applications, or spin-offs, include such innovations as tank and race car driver cooling, to cooling infants with high temperatures, as well as, the prevention of hair loss during chemotherapy. In order to preserve the scientific value of metabolic samples during long-term space missions, cooling is required to enable scientific studies. Results of one such study should provide a better understanding of osteoporosis and may lead to a possible cure for the disease.In the space environment, noise has to be kept to a minimum. In long-term space applications such as the International Space Station, thermoelectric technology provides the acoustic relief and the reliability for food, as well as, scientific refrigeration/freezers. Applications and future needs are discussed as NASA moves closer to a continued space presence in Mir, International Space Station, and Lunar-Mars Exploration.

scholarly journals CREATION OF SPECIAL BATCHES OF DEVICES TO IMPROVE RELIABILITY OF ELECTRONIC COMPONENTS FOR SPACE APPLICATIONS

2020 ◽  
Vol 258 (3) ◽  
pp. 65-71
Author(s):  
V.I. Kuklin ◽  
V.I. Orlov ◽  
V.V. Fedosov
Keyword(s):  
Historical Background ◽  
Quality Level ◽  
Electronic Components ◽  
Joint Work ◽  
Space Applications ◽  
Manufacturing Plants ◽  
Term Operation ◽  
Optimal Approach ◽  
Improve Reliability

In this paper we give a brief historical background of the stages of work carried out by “ITC – NPO PM” JSC aimed at ensuring the long-term operation of electronic components for space applications. It is shown that the creation of specialized testing facilities is the optimal approach to make batches of electronic components of the Space quality level. We propose a further scenario to improve reliability of electronic components for space applications, involving the joint work of specialized testing facilities and manufacturing plants to make special batches of devices.

Effects of Ageing in Marine Environment on Glass Fibre/Unsaturated Polyester Composite

2011 ◽  
Vol 146 ◽  
pp. 51-63 ◽  
Author(s):  
Khedoudja Laoubi ◽  
Nabila Belloul ◽  
Ali Ahmed Benyahia ◽  
Aîcha Sérier ◽  
Nourdine Ouali
Keyword(s):  
Unsaturated Polyester ◽  
Laminated Composite ◽  
Chemical Degradation ◽  
Polyester Composite ◽  
Fibre Degradation ◽  
Hydrolysis Of ◽  
Fibre Matrix ◽  
Strength And Ductility ◽  
Made In

The aim of this work is the study of the long term behaviour of a laminated composite made in glass/polyester and aged in seawater at various temperatures. The results obtained show that the immersion in seawater causes ageing of the composite material. This was reflected first by a change in color of the material depending on the temperature of the immersion and the gel-coat loses its brightness. The infrared spectroscopy has confirmed activation of chemical degradation (hydrolysis of the resin and of the fibre/matrix interface, fibre degradation). This chemical degradation could be the cause of decrease in strength and ductility detected by analysing the behaviour of immersed testing specimens. It could also be the cause of the increase of absorption rate recorded for immersions exceeding 22 days.

scholarly journals Long-Term Biostability of Pet Vascular Prostheses

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Florence Dieval ◽  
Foued Khoffi ◽  
Riaz Mir ◽  
Walid Chaouch ◽  
Didier Le Nouen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Manufacturing Process ◽  
Vascular Prosthesis ◽  
Chemical Degradation ◽  
Medical Complications ◽  
Human Metabolism ◽  
Vascular Prostheses ◽  
In Vivo Degradation

PET Vascular prostheses are susceptible to physical modification and chemical degradation leading sometimes to global deterioration and rupture of the product. To understand the mechanisms of degradation, we studied 6 vascular prostheses that were explanted due to medical complications. We characterized their level of degradation by comparing them with a virgin prosthesis and carried out physicochemical and mechanical analyses. Results showed an important reduction of the fabric’s mechanical properties in specific areas. Moreover, PET taken from these areas exhibited structural anomalies and was highly degraded even in virgin prostheses. These results suggest that vascular prostheses have weak areas prior to implantation and that these areas are much more prone to in vivo degradation by human metabolism. Manufacturing process could be responsible for these weaknesses as well as designing of the compound. Therefore, we suggest that a more controlled manufacturing process could lead to a vascular prosthesis with enhanced lifespan.

scholarly journals Flexible Electronics: 3D Graphene-Infused Polyimide with Enhanced Electrothermal Performance for Long-Term Flexible Space Applications (Small 48/2015)

Small ◽  
2015 ◽  
Vol 11 (48) ◽  
pp. 6369-6369
Author(s):  
Manuela Loeblein ◽  
Asaf Bolker ◽  
Siu Hon Tsang ◽  
Nurit Atar ◽  
Cecile Uzan-Saguy ◽  
...  
Keyword(s):  
Flexible Electronics ◽  
Space Applications ◽  
3D Graphene

scholarly journals Using the concepts of homogeneity in additional tests of electronic components for space applications

2020 ◽  
Vol 4 (4) ◽  
pp. 209-218
Author(s):  
S. M. Golovanov ◽  
V. I. Orlov ◽  
V. V. Fedosov
Keyword(s):  
High Reliability ◽  
Outer Space ◽  
Physical Analysis ◽  
Electronic Components ◽  
Space Applications ◽  
Term Operation ◽  
Specialized Production ◽  
The Russian Federation ◽  
Further Development

In modern conditions in the Russian Federation the equipment of spacecraft with a highly reliable electronic components is possible only through testing technical centers which act as a link between manufacturers of electronic components and their consumers. Given the lack of specialized production of electronic components of the «Space» category in our country, this is the only alternative way. Testing technical centers carry out the formation of batches of electronics for space applications by conducting additional tests of electronic components for general industrial use allowing the rejection of elements containing defects that can manifest themselves during long-term operation in outer space. A modern spacecraft contains about 100–200 thousand electronic components. Taking into account the fact that the on-board equipment of the spacecraft during its operation cannot be repaired, it is obvious that extremely high reliability requirements are imposed on the electronic components of space applications. In this regard the improvement of the methodology for increasing the reliability of the electronic components of space applications is of paramount importance for the further development of the space industry. This article outlines an approach to improving the technology of additional tests in testing technical centers, based on the use of the concepts of homogeneity of the tested batch of electronic components which makes it possible to meaningfully generate samples for destructive physical analysis and radiation resistance tests, as well as to additionally identify emission elements that are potentially unreliable elements.

scholarly journals Effect of formaldehyde exposure on bacterial communities in simulating indoor environments

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianguo Guo ◽  
Yi Xiong ◽  
Taisheng Kang ◽  
Hua Zhu ◽  
Qiwen Yang ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Human Health ◽  
Bacterial Communities ◽  
Shannon Index ◽  
Chemical Degradation ◽  
Indoor Environments ◽  
Operational Taxonomic Units ◽  
Formaldehyde Exposure ◽  
Recommended Level

AbstractIndoor formaldehyde (CH2O) exceeding the recommended level is a severe threat to human health. Few studies have investigated its effect on indoor surface bacterial communities, affecting habitants' health. This study used 20-L glass containers to mimic the indoor environment with bacterial inputs from human oral respiration. The behavior of bacterial communities responding to CH2O varied among the different CH2O levels. The bacterial community structure significantly changed over time in the 0.054 mg·m−3 CH2O group, which varied from the 0.1 mg·m−3 and 0.25 mg·m−3 CH2O groups. The Chao1 and Shannon index significantly increased in the 0.054 mg·m−3 CH2O group at 6 week, while they remained unchanged in the 0.25 mg·m−3 CH2O group. At 12 week, the Chao1 significantly increased in the 0.25 mg·m−3 CH2O group, while it remained unchanged in the 0.054 mg·m−3 CH2O group. Only a few Operational Taxonomic Units (OTUs) significantly correlated with the CH2O concentration. CH2O-induced OTUs mainly belong to the Proteobacteria and Firmicutes. Furthermore, bacterial communities formed at 6 or 12 weeks differed significantly among different CH2O levels. Functional analysis of bacterial communities showed that inferred genes related to chemical degradation and diseases were the highest in the 0.25 mg·m−3 CH2O group at 12 weeks. The development of nematodes fed with bacteria collected at 12 weeks was applied to evaluate the bacterial community's hazards. This showed significantly impaired growth in the 0.1 mg·m−3 and 0.25 mg·m−3 CH2O groups. These findings confirmed that CH2O concentration and exposure time could affect the indoor bacterial community and formed bacterial communities with a possibly more significant hazard to human health after long-term exposure to high CH2O levels.

scholarly journals Causes of mountain meadow soil chemical degradation in long-term fertiliser experiment

2011 ◽  
Vol 48 (No. 4) ◽  
pp. 159-166
Author(s):  
M. Kopeć
Keyword(s):  
Chemical Degradation ◽  
Yield Potential ◽  
Meadow Soil ◽  
Botanical Composition ◽  
Nitrogen Forms ◽  
Production Risk ◽  
Mountain Meadow ◽  
Long Period ◽  
Set Up

The fertilising experiment was set up in 1968 on the mountain meadow (720 m a.s.l.) in Czarny Potok near Krynica (20&deg;8&rsquo; E, 49&deg;4&rsquo; N). The experiment was conducted on the acid Cambi soil and comprised objects fertilised with two nitrogen forms and two doses against the background of PK fertilisation, the untreated object, and plots with unilateral P and N fertilisation. The paper concerns 30 years of investigations (1968&ndash;1997) of the effect of different NPK fertilisation on the dynamic of yields and the meadow sward quality against a&nbsp;background of the same treatments. The dynamic of the botanical composition was presented as well as the dynamic of the grassland yield potential with systematic mineral fertilisation and liming. The application of nitrogen fertilisation with the rate of 90 N.ha<sup>&ndash;1</sup> + PK under mountain conditions and systematic liming of the meadow enables to maintain or increase production over the long period, to decrease the production risk and to prevent degradation of the environment and natural resources.

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