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排序方式: 共有56条查询结果,搜索用时 15 毫秒
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Norman S. Allen Alfonso Chirinos-Padron John H. Appleyard Terence J. Henman 《Polymer Degradation and Stability》1983,5(2):105-112
The effect of calcium and nickel stearates on the photo-stabilising action and photo-decomposition of one calcium and two nickel metal chelates in polypropylene has been examined using infra-red and ultraviolet derivative spectroscopy. Whereas the presence of calcium stearate antagonises the photo-stabilising action of one nickel chelate, Irgastab 2002, it strongly synergises with the other, Cyasorb UV 1084. The presence of nickel stearate synergises with the calcium chelate, Irganox 1425, in unprocessed polymer whereas, in processed polymer, it exhibits antagonism. Rates of photo-decomposition of the metal chelates are also affected by metal stearates. The data suggests that, with these nickel chelates, there might be some degree of metal exchange with certain metal stearates. 相似文献
3.
Norman S. Allen Alfonso Chirinos-Padron John H. Appleyard 《Polymer Degradation and Stability》1982,4(3):223-237
The photo-stabilising action of three metal chelates—nickel (II) 2,2′ thiobis (4-tert-octylphenylato) n-butylamine and the nickel and calcium derivatives of bis (ethyl-3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate, in polypropylene—is examined using normal and second order derivative ultraviolet, infra-red and phosphorescence spectroscopic techniques and hydroperoxide analysis. Whilst all three stabilisers quenched the phosphorescence emission of a powerful photo-sensitiser, benzophenone, there was no protective action during photo-sensitised oxidation of the polymer. In the case of anthraquinone, there was no quenching and no protection. Processing history plays a dominant rôle in controlling the photo-stabilising performance of the chelates. Each stabiliser operates differently, being dependent on its relative stability during processing and photo-oxidation and on the formation and destruction of polymeric and antioxidant hydroperoxides during processing. Metal chelates operate by inhibiting polymer hydroperoxide formation during processing and acting as ultraviolet stable chain terminators or by giving products during the early stages of photo-oxidation which are themselves effective stabilisers. 相似文献
4.
Norman S. Allen Alfonso Chirinos-Padron John H. Appleyard 《Polymer Degradation and Stability》1984,6(3):149-176
The interactions of three metal chelates (nickel (II) 2,2′-thiobis (4-tertoctyl-phenolato), n-butylamine (Cyasorb UV 1084) and the nickel and calcium derivatives of bis(ethyl-3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate (Irgastab 2002 and Irganox 1425)) with other commercial additives, in the stabilisation of polypropylene film, are examined using normal and second-order derivative ultraviolet and infra-red spectroscopic techniques. It is shown that the observed behaviour is dependent on the particular additive, the processing history of the polymer and the metal chelate concerned, and is therefore highly complex. All three chelates show antagonism with a hindered piperidine, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770), in unprocessed polymer, whereas one of the chelates behaves synergistically with this additive in processed samples. The chelates also show antagonism with a primary antioxidant, tris((3-(3′,5′-di-tert-butyl-4-hydroxybenzyl)-2′'-aceto-ethyl)) isocyanurate (Goodrite 3125), whereas, with a secondary antioxidant, distearyl pent-aerithrityl diphosphite (Weston 618), their behaviour is synergistic in both unprocessed and processed polymer. Two of the chelates show synergism with 2-hydroxy-4-n-octoxybenzophenone (Cyasorb UV 531), the remaining chelate showing antagonism. Mixtures containing a three-additive system show a more complex behaviour. The results are explained in terms of hydroperoxide decomposition, inhibition, stabiliser dispersion, ultraviolet stability and additive compatibility. 相似文献
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Le Faou JH Suomijärvi T Blumenfeld Y Piattelli P Agodi C Alamanos N Alba R Auger F Bellia G Chomaz P Coniglione R Del Zoppo A Finocchiaro P Frascaria N Gaardhoje JJ Garron JP Gillibert A Lamehi-Rachti M Liguori-Neto R Maiolino C Migneco E Russo G Roynette JC Santonocito D Sapienza P Scarpaci JA Smerzi A 《Physical review letters》1994,72(21):3321-3324
7.
Akiba Y Beavis D Beery P Britt HC Budick B Chasman C Chen Z Chi CY Chu YY Cianciolo V Cole BA Costales JB Crawford HJ Cumming JB Debbe R Engelage J Fung SY Gonin M Gushue S Hamagaki H Hansen O Hayano RS Hayashi S Homma S Kaneko H Kang J Kaufman S Kehoe WL Kurita K Ledoux RJ Levine MJ Miake Y Morrison DP Morse RJ Moskowitz B Nagamiya S Namboodiri MN Nayak TK Olness J Parsons CG Remsberg LP Roehrich D Rothschild P Sakurai H Sangster TC Seto R Soltz R Stankus P Steadman SG Stephans GS Sung T 《Physical review letters》1996,76(12):2021-2024
8.
Lenhart JL van Zanten JH Dunkers JP Zimba CG James CA Pollack SK Parnas RS 《Journal of colloid and interface science》2000,221(1):75-86
Silane coupling agents are commonly applied to glass fibers to promote fiber/resin adhesion and enhance durability in composite parts. In this study, a coupling agent multilayer on glass was doped with trace levels of the dimethylaminonitrostilbene (DMANS) fluorophore. The fluorophore was immobilized on the glass surface by tethering the molecule to a triethoxy silane coupling agent, creating the DMANS/silane coupling agent molecule (DMSCA). DMSCA was then diluted with commonly used coupling agents and grafted to a glass microscope coverslip to create a model composite interface. A 53-nm blue shift in fluorescence from the immobilized DMSCA can be followed during cure of an epoxy resin overlayer, giving this technique potential to monitor the properties of the fiber/resin interface during composite processing. Contact angle measurements on these coupling agent layers were similar in the presence or absence of the DMSCA molecule, suggesting that trace levels of the fluorescent probe did not affect the structure of the layer. The immobilized DMSCA molecule behaved similarly to the DMANS precursor in solution. Both showed longer wavelength fluorescence in more polar environments. Copyright 2000 Academic Press. 相似文献
9.
Garcia Ruano JL Alemparte C Martin Castro AM Adams H Rodriguez Ramos JH 《The Journal of organic chemistry》2000,65(23):7938-7943
The behavior of (Z)-3-p-tolylsulfinylacrylonitrile (1) as a chiral dienophile has been evaluated from its reactions with furan and acyclic dienes. Electrostatic interactions of the cyano group with the sulfinyl one restrict the conformational mobility around the C-S bond, thus controlling the pi-facial selectivity, which is almost complete in all cases, the approach of the diene from the less-hindered face of the dienophile (that bearing the lone electron pair) in the predominant rotamer being the favored one. The regioselectivity is also completely controlled by the cyano group. Additionally, the reactivity of compound 1 as well as its endo-selectivity are both higher than those observed for the corresponding (Z)-3-sulfinylacrylates, thus proving the potential of sulfinylnitriles as chiral dienophiles. 相似文献
10.