01873nas a2200169 4500008004100000022001400041245012700055210006900182260008900251300002000340520113000360100002701490700001801517700001801535700002101553856012901574 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

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.

1 aDelor-Jestin, Florence1 aTomer, N., S.1 aSingh, R., P.1 aLacoste, Jacques uhttp://library.ncl.res.in/content/characterization-polydimethylsiloxane-rubber-upon-photochemical-thermal-salt-fog-ageings-101620nas a2200241 4500008004100000022001400041245009700055210006900152260009900221300001200320490000700332520075000339653001101089653000901100653001401109653002101123653002201144100001801166700002701184700001801211700002101229856012801250 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

The ageing of filled and cross-linked ethylene propylene diene elastomer (EPDM) has been studied under accelerated UV irradiation (lambda >= 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.

10aageing10aEPDM10aOxidation10athermal analysis10athermoporosimetry1 aTomer, N., S.1 aDelor-Jestin, Florence1 aSingh, R., P.1 aLacoste, Jacques uhttp://library.ncl.res.in/content/cross-linking-assessment-after-accelerated-ageing-ethylene-propylene-diene-monomer-rubber02066nas a2200277 4500008004100000022001400041245017900055210006900234260006700303300001400370490000800384520105500392653001101447653001501458653001601473653001301489100001601502700002601518700001801544700002101562700001801583700001701601700002101618700002301639856012601662 2013 eng d a0021-899500aCopolymerization of ethylene with unsaturated alcohols and methylmethacrylate using a silylated alpha-diimine nickel catalyst: molecular modeling and photodegradation studies0 aCopolymerization of ethylene with unsaturated alcohols and methy a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcAUG a1820-18320 v1293 a

In this article, the experimental results obtained in the copolymerization of ethylene with polar monomers using a silylated -diimine nickel catalyst are described and compared with those obtained with a non-silylate similar one. The results show that the introduction of a siliyl group in the para-position of the imine moiety turns the catalyst less sensitive toward polar functionalities. However, the reactivity observed in copolymerization reactions was found to be reduced both the global polymerization and incorporation rates. Molecular modeling calculation allowed us to understand both the preferred insertion mode and the intermediate product structures for E/MMA copolymerization. Photodegradation studies showed that the presence of polar groups in the copolymers increases their rate of oxidation and turn them more easily degradable. The stabilization performed by Tinuvin 770 showed that for long-exposure times, it is not very effective regardless it is only mixed or grafted to the copolymer. (c) 2012 Wiley Periodicals, Inc.

10aageing10acopolymers10aDegradation10agrafting1 aMatos, Ines1 aFernandes, Susete, N.1 aLiu, Hua-Rong1 aTevtia, Amit, K.1 aSingh, R., P.1 aManda, Lemos1 aLemos, Francisco1 aMarques, Maria, M. uhttp://library.ncl.res.in/content/copolymerization-ethylene-unsaturated-alcohols-and-methylmethacrylate-using-silylated-0