01874nas a2200169   4500008004100000022001400041245012700055210006900182260008900251300002000340520113000360100002701490700001801517700001801535700002101553856013001574       2006                        eng d  a1618-722900aCharacterization of polydimethylsiloxane rubber upon photochemical, thermal, salt-fog ageings and exposure to acid vapours0 aCharacterization of polydimethylsiloxane rubber upon photochemic  a1, QUAI LEZAY-MARNESIA, F067000 STRASBOURG, FRANCEbEUROPEAN POLYMER FEDERATIONcMAY  aArticle No. 0133 a<p>The changes in the chemical structure and the physical properties of a filled crosslinked polydimethylsiloxane rubber were monitored as a function of various ageing factors. The variables included photochemical, thermal, salt-fog ageings and exposure to acid vapours. Unaged and aged samples were studied by IR spectroscopy, hardness measurements, Differential Scanning Calorimetry (DSC) and thermogravimetric analysis (TGA) coupled with IR spectroscopy. No significant oxidation was detected after all ageings, except for nitric acid treatment. The presence of aluminium trihydrate was clearly identified as responsible for the observed chemical changes. Then an important vulnerability of this filled silicone rubber towards the cross-linking reactions provoked by usual ageings was also detected. The DSC-thermoporosimetry measurements of the mesh size distribution gave a comparison of cross-linking densities for each ageing. The complementary analysis with TGA-IR allowed us to differenciate the thermal stability of the formulation after various ageings and to acquire new knowledge about thermal decomposition.</p>1 aDelor-Jestin, Florence1 aTomer, N., S.1 aSingh, R., P.1 aLacoste, Jacques  uhttps://library.ncl.res.in/content/characterization-polydimethylsiloxane-rubber-upon-photochemical-thermal-salt-fog-ageings-101621nas a2200241   4500008004100000022001400041245009700055210006900152260009900221300001200320490000700332520075000339653001101089653000901100653001401109653002101123653002201144100001801166700002701184700001801211700002101229856012901250       2007                        eng d  a0141-391000aCross-linking assessment after accelerated ageing of ethylene propylene diene monomer rubber0 aCrosslinking assessment after accelerated ageing of ethylene pro  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAR  a457-4630 v923 a<p>The ageing of filled and cross-linked ethylene propylene diene elastomer (EPDM) has been studied under accelerated UV irradiation (lambda &gt;= 290 nm) at 60 degrees C, thermal ageing at 100 degrees C and in nitric acid vapours for different time intervals. Hardness measurements were performed. DSC-thermoporosimetry was used to estimate the mesh size distribution and cross-linking densities for each ageing. The development of functional groups was monitored by ATR spectroscopy. An increase in oxidation with exposure time after the different types of ageing was observed. The thermal stability of EPDM was assessed by TGA and evolved volatile gases were identified using FTIR spectroscopy. (c) 2006 Elsevier Ltd. All rights reserved.</p>10aageing10aEPDM10aOxidation10athermal analysis10athermoporosimetry1 aTomer, N., S.1 aDelor-Jestin, Florence1 aSingh, R., P.1 aLacoste, Jacques  uhttps://library.ncl.res.in/content/cross-linking-assessment-after-accelerated-ageing-ethylene-propylene-diene-monomer-rubber02592nas a2200241   4500008004100000022001400041245008600055210006900141260012000210300001100330490000600341520171600347653002502063653001502088653000902103653002202112653001302134100002702147700002302174700002002197700002102217856011202238       2008                        eng d  a1468-699600aDurability of crosslinked polydimethylsyloxanes: the case of composite insulators0 aDurability of crosslinked polydimethylsyloxanes the case of comp  aNATL INST MATERIALS SCIENCE, 1-2-1 SENGEN, TSUKUBA-CITY, IBARAKI, 305-0047, JAPANbNATL INST MATERIALS SCIENCEcJUN  a0244060 v93 a<p>Most applications of silicones are linked to their hydrophobic properties and (or) their high resistance to ageing (e. g. thermal ageing and photoageing). However, when placed in extreme environments, these materials can fail as in the case of epoxy/fiber glass composite powerlines insulators, where crosslinked polymethylsyloxanes (PDMSs) are used as the protective envelope (housing) of the insulator. We report on the behavior of both pure/noncrosslinked PDMSs and typical formulations used in industrial insulators, i.e. containing peroxide crosslinked PDMS, alumina trioxide hydrated (ATH) and silica. Special attention is paid on both (i) the sources of potential degradation and (ii) the best analytical methods that can be applied to the study of very complex formulations. (i) Aside from conventional types of ageing such as photo-ageing and thermal, hydrolytic, and service life ageings, treatments with acidic vapors, plasma and ozone possibly generating species from the reaction of a high electric field with air were also performed, which allowed to accelerate electrical and out-door ageings and to obtain differently aged materials. (ii) Aside from conventional analytical methods of polymer degradation such as FTIR/ATR spectroscopy and SEC, TG, hardness measurements, more specific methods like photo/DSC, TG/IR, thermoporosimetry, resistivity and density measurements were also performed to characterize the chemical and physical evolutions of polymer materials. In particular, it was found that treatment with nitric acid vapor has detrimental effects on the properties of both fire retardants (e. g. ATH) and PDMSs, affecting the hardness and resistivity of the formulated material.</p>10acomposite insulators10adurability10aPDMS10apost-crosslinking10asilicone1 aDelor-Jestin, Florence1 aTomer, Namrata, S.1 aSingh, Raj, Pal1 aLacoste, Jacques  uhttps://library.ncl.res.in/content/durability-crosslinked-polydimethylsyloxanes-case-composite-insulators-0