Oxidation profiles of thermally aged nitrile rubber

Celina, Mathias C.; Wise, Jonathan; Ottesen, David K.; Gillen, K.T.; Clough, R.L.

doi:10.1016/s0141-3910(97)00113-4

Cited by 112 publications

(62 citation statements)

References 20 publications

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“…A comparable result can be obtained from the fatigue tests with an activation energy of 95kJ/mol [4]. Both values are very close to other values found in the bibliography for various ageing indicators [16], [17], [29], [30]. …”

Section: Thermo-oxidative Ageingsupporting

confidence: 89%

Investigation of thermo-oxidative ageing effects on the fatigue design of automotive anti-vibration parts

et al. 2018

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Abstract. Elastomeric parts found in automotive anti-vibration systems are usually massive. Ageing therefore leads to heterogeneous properties, usually induced by several mechanisms due to the availability, or not, of oxygen in the part's bulk. To better understand the effects of oxygen in the degradation process and on the fatigue properties, this paper aims at studying the ageing of a rubber material (semi-efficient vulcanization system) in aerobic (with oxygen) and anaerobic (without oxygen) conditions for a wide range of temperatures, relevant for under hood applications. The material studied here is a fully formulated compound NR/IR blend reinforced with carbon black. A specific protocol to perform ageing under anaerobic conditions was set up and validated. Numerous tests have been carried out to evaluate the consequences of ageing on monotonic tension and fatigue properties. A comparison of these consequences and of their kinetics is finally presented for ageing with or without oxygen.

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Section: Thermo-oxidative Ageingsupporting

confidence: 89%

Investigation of thermo-oxidative ageing effects on the fatigue design of automotive anti-vibration parts

et al. 2018

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“…Special care was taken on homogeneity of the degradation through sample thickness in order to avoid diffusion limited oxidation (DLO). This latter aspect has been studied previously for oxidation of CR [25] and PU-PB [30]. The films were cut from bulk samples, cooled by liquid nitrogen, with a Leica microtome.…”

Section: Ageingmentioning

confidence: 99%

“…Oxidation leads to carbonecarbon double bond consumption, this consumption is mainly due to radical additions to double bonds. According to Celina [25], in CR, certain macro-radical additions to double bonds create new crosslinks and changes in the crosslink density. The change in crosslink density can be directly calculated from tensile modulus using the basic theory of rubber elasticity [29].…”

Section: Network Modification Induced By Oxidationmentioning

confidence: 99%

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Role of strain induced crystallization and oxidative crosslinking in fracture properties of rubbers

Gac

Broudin

Roux

et al. 2014

Polymer

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. a b s t r a c tTensile properties and crack propagation properties, especially critical strain energy release rate in mode I, G IC , have been used to investigate fracture properties of elastomers and their relationships with microstructure. These investigations were mainly based on a series of comparisons: first, the behaviour of polychloroprene rubber (CR), undergoing stress hardening due to strain induced crystallization (SIC) and oxidative crosslinking (OCL) was compared with that of chlorinated polyethylene (CPE), which undergoes SIC but not OCL, and with a polyurethane based on hydroxyl terminated polybutadiene (PU) which undergoes OCL but not SIC. Comparisons were also made on CR between fracture behaviour at ambient temperature, where SIC occurs and at 100 C where there is no SIC. Finally, oxidative crosslinking was used to vary in a continuous way the crosslink density in CR and PU, in order to evaluate the role of crosslinking in fracture behaviour. The results reveal the strong contribution of SIC to fracture strength. Crosslinking, even at low conversion, inhibits SIC which explains the sharp decrease of CR toughness in the early period of exposure to oxidation. When SIC has disappeared, it is possible to appreciate the effect of crosslinking on fracture behaviour. This effect, as evaluated from the density of deformation energy at rupture in tension or from G IC value, is almost negligible while the sample modulus increases regularly as a consequence of crosslinking. It appears that the toughness remains almost constant because it is under the influence of two contradictory phenomena: the negative effect of a reduction of ultimate elongation and the positive effect of a modulus increase. Such behaviour can be explained in terms of heterogeneous distribution of the lengths of elastically active chains. After long exposure, the sample behaviour becomes brittle, very high modulus values indicate that the samples approach, presumably in a heterogeneous way, the glassy state.

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“…For materials influenced by DLO effects, the air-exposed outside surfaces will age at the same rate as they would have in the absence of DLO effects (the interior regions will age at a slower rate). Since cracks originating at the air-exposed surfaces often propagate rapidly through the material leading to tensile failure, elongation measurements are often unaffected by DLO effects [3][4]32,[52][53][54][55][56] Since this is the case for the Okonite neoprene material, both the homogeneous and the non-homogeneous data are analyzed using the DED method. Since we found above that the E a values appropriate to this material were 89 kJ/mol above 70C and 71 kJ/mol below this temperature, these values are used for the t-T-DR superposition procedure with the results at a temperature of 50C shown in Figure 40.…”

Section: Chloroprene (Neoprene) Cable Jacketing Materialsmentioning

confidence: 99%

Review of nuclear power plant safety cable aging studies with recommendations for improved approaches and for future work.

Gillen¹,

Bernstein²

2010

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Many U. S. nuclear power plants are approaching 40 years of age and there is a desire to extend their life for up to 100 total years. Safety-related cables were originally qualified for nuclear power plant applications based on IEEE Standards that were published in 1974. The qualifications involved procedures to simulate 40 years of life under ambient power plant aging conditions followed by simulated loss of coolant accident (LOCA). Over the past 35 years or so, substantial efforts were devoted to determining whether the aging assumptions allowed by the original IEEE Standards could be improved upon. These studies led to better accelerated aging methods so that more confident 40-year lifetime predictions became available.Since there is now a desire to potentially extend the life of nuclear power plants way beyond the original 40 year life, there is an interest in reviewing and critiquing the current state-of-the-art in simulating cable aging. These are two of the goals of this report where the discussion is concentrated on the progress made over the past 15 years or so and highlights the most thorough and careful published studies. An additional goal of the report is to suggest work that might prove helpful in answering some of the questions and dealing with some of the issues that still remain with respect to simulating the aging and predicting the lifetimes of safety-related cable materials. EXECUTIVE SUMMARYMany U. S. nuclear power plants are approaching 40 years of age and there is a desire to extend their life for up to 100 total years. Safety-related cables were originally qualified for nuclear power plant applications based on IEEE Standards that were published in 1974. The qualifications involved procedures to simulate 40 years of life under ambient power plant aging conditions followed by simulated loss of coolant accident (LOCA). Over the past 35 years or so, substantial efforts were devoted to determining whether the aging assumptions allowed by the original IEEE Standards could be improved upon. These studies led to better accelerated aging methods so that more confident 40-year lifetime predictions became available.In particular, three of the aging assumptions used were found to be overly simplistic. Thermal aging was typically carried out at a few high temperatures, then they were modeled with an Arrhenius function to derive an Arrhenius activation energy E a and finally the results were extrapolated to ambient conditions assuming no change in E a . Recent studies show that E a often drops at low temperatures, reducing the extrapolated lifetime. For radiation aging, an equal damage, equal dose assumption (e.g., no dose rate effects) was used. Careful studies have now shown that dose rate effects that reduce extrapolated material lifetime are both common and expected and come from several different mechanisms. Finally, for simulating combined radiation plus thermal environments, sequential aging (usually thermal aging followed by room temperature radiation aging) was allowed whereas rece...

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Oxidation profiles of thermally aged nitrile rubber

Cited by 112 publications

References 20 publications

Investigation of thermo-oxidative ageing effects on the fatigue design of automotive anti-vibration parts

Investigation of thermo-oxidative ageing effects on the fatigue design of automotive anti-vibration parts

Role of strain induced crystallization and oxidative crosslinking in fracture properties of rubbers

Review of nuclear power plant safety cable aging studies with recommendations for improved approaches and for future work.

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