01984nas a2200253   4500008004100000022001400041245006900055210006800124260009900192300001400291490000700305520111100312653000901423653001801432653002401450653001801474100002901492700002201521700002301543700002001566700001801586700002401604856010201628       2006                        eng d  a0141-391000aPhotooxidation of vulcanized EPDM/montmorillonite nanocomposites0 aPhotooxidation of vulcanized EPDMmontmorillonite nanocomposites  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcDEC  a3033-30390 v913 a<p>The photooxidation of a vulcanized ethylene-propylene-diene monomer (EPDM)/montmorillonite nanocomposite as well as EPDM/nanocomposite with stabilizers was studied under accelerated UV-light irradiation (lambda &gt;= 300 nm, 60 degrees C) for different times. The development of functional groups during oxidation was monitored by infrared spectroscopy. Photodegradation of the neat polymer and composites took place and the increases of absorbance in hydroxyl and carbonyl groups with irradiation times and also the decreases of the EPDM unsaturations were measured. The data indicated that the photooxidation products were not changed in the presence of the nanofiller. However, the presence of MMt was observed to dramatically enhance the rate of photooxidation of EPDM with a shortening of the oxidation induction time, leading to a decrease of the durability of the nanocomposites. On the other hand, it was observed that addition of stabilizers, either Tinuvin P or 2-mercaptobenzimidazole, was efficient in inhibiting the degradative effect of MMt. (c) 2006 Elsevier Ltd. All rights reserved.</p>10aEPDM10aNanocomposite10aphotooxidation rate10astabilization1 aMorlat-Therias, Sandrine1 aFanton, Elisabeth1 aTomer, Namrata, S.1 aRana, Sravendra1 aSingh, R., P.1 aGardette, Jean, Luc  uhttps://library.ncl.res.in/content/photooxidation-vulcanized-epdmmontmorillonite-nanocomposites-002592nas 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