For protection of elastomeric materials against ageing, antioxidants such as UV-stabilizers and antiozonants are used. Although historically N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD) was the only approved antiozonant in Germany, a range of other phenylene diamine antiozonants (excluding 6PPD) are permitted for use in rubber articles intended for repeat food-contact use in the US (FDA regulations chapter 21 Part 177.2600). The biggest disadvantage of 6PPD is its partial decomposition during the vulcanization leading to the formation of toxic primary aromatic amines (PAA), such as aniline and secondary aromatic amines (SAA). A number of new PPDs have been developed and patented, that due to their chemical structures, are far less soluble in aqueous solutions but a lot more soluble within the rubber matrix. They therefore show significantly less migration of PAA and SAA. These new antiozonants were investigated and compared to 6PPD using commercial rubber materials with a certain content of antiozonant with regard to their migration of PAA and SAA into three different food simulants. The lowest concentration of PAA and SAA in all food simulants was measured in the RU 997 stabilized elastomer. Due to this fact RU 997 was permitted as a new antiozonant for commodities based on rubber according to the Recommendation XXI 'Articles based on natural and synthetic rubber' of the Federal Institute for Risk Assessment (BfR). RU 997 therefore represents an alternative for 6PPD with less migration of aromatic amines.

The paper deals with the appraisal and applicaiion detayed. lnjectivity and produtivity of the welis of waxer control technologies for gas wells and were improved by a rcduction in friction Ioss m gas storage welis. A laboratory evaluation of the vicrnity of the well bore, presumably due to different polymer products for a variety of polymer adsorption. reservoir conditions -temperaxure, salinity of reseoir brine, rock peeability was performed. For the numencal characterization of polymers, the performance factor, which is the residual resistance factor for water divided by the resistance factor of the polymer solution, was used to select the best suited products for 4 caiididate welis. The investigations were performed by 3 mdependent laboratones DBI-GUT m Freiberg, IFP m Paris and ITE in Clausthal. Twa examples of field application are presented:The high temperature gas well Salzwedel 85, which suffered from secondary water migration through a depletcd gas layer and the gas storage well Buchholz P 17 with moderate depth and temperaxure, in which water production penodicily occurred at the end of theproduction period. Successful treatments could be performed in both cases and the results have shown that secondary water influx could be stopped and water break-through in a storage welt couid be 48 IiictionWater influx m production wells is a generaf problem whîch dominates the cost side of production. Exccssive water production can resuk in reduced well productivity, extra corrosion sand production and increased envîronmental protection costs. On the other side, water injection and aquifer expansion are vital mechanisms for oil production and pressure maintin2nce in reservoiis. Measurcs to separate the formation water from oil and gas m the reservoir have been tried for many years at dîfl'erent reservoir conditions, with different methods and products, J. Morgan /1/ from BP Exptoration concludes from an analysis of various interventions m existing wells to slow the passage of water, that ,,there is no cure -alt proccss at present and what is successful in one field, may be inappropriaxe elsewhere". Y. Guerrini, N. Kohler and A. Zaitoun /2/ classify the water control methods, depending on the structure of the reservoir rock into -permanent barner methods -selective barner methods lf waler and hydrocarbon zones are clearly separated, processes using permanent barners which can be ptaced m the water bearing zones, generaily give good results. They can be formed by injection of cements, resins or silicate gels. However, when oil, gas and water are fiowing simultaneously, potymer solutions and/or getants are injected which can biock the water phase, but remain permeabte to oil and gas, Depending on the type of reservoir rock, reservoir temperature and salinity of the reservoir brine, different potymer substances can be used for biocking the water. For Iow salinity conditions and moderate telnperatures, polyacrylaniides have been often used together with crosslinking agents to fonn gels whereas for higher sairn...

The optical transmission loss behavior was investigated for commercially available poly(methyl methacrylate) (PMMA) based polymer optical fibers (POFs). POFs were exposed to various climates of temperature and humidity. Optical transmission measurements using multiplexer (a prototype device) reveal that POFs exhibited an early drop-off followed by a slow decline of transmission at 1008C with low humidity and nearly 100% loss of transmission at the early stages of exposure at 928C with 95% relative humidity (RH) and at 1208C with low humidity. Fourier transform infrared (FTIR) and gel permeation chromatography (GPC) analysis data show no significant molecular changes in the PMMA core after climatic exposures. However, the attenuated total reflection (ATR)-FTIR data shows a few molecular changes in claddings due to degradation. Scanning electron microscopy (SEM) data illustrate the shrinkage and folding structure in claddings. The loss of the optical transmission at the early (initial) stages of exposure is attributed to the physical changes (like thermal expansion), and the same at the later stages mainly to chemical changes (e.g., oxidative degradation). The experiments conducted here show that the POFs optical transmission stability is strongly dependent on the chemical composition of claddings.

No abstract

ZUSAMMENFASSUNG:Durch Addition von Aziridin an Mono-und Divinyl-p-chinone unterschiedlichen Redoxpotentials werden N-substituierte Aziridinverbindungen dargestellt. Die Redoxpotentiale der Monomeren, ihr Polymerisationsverhalten und die Eigenschaften der Redoxpolymeren werden untersucht. SUMMARY:N-substituted aziridinyl compounds were prepared by the addition of aziridine to monoand divinyl-substituted p-quinones with different redox potentials. The redox potentials of the monomers, their polymerization behaviour and the properties of redox polymers were investigated.Die auf Grund der Inhibitorwirkung des Chinonsystems teilweise schlechte radikalische Polymerisierbarkeit von Vinylchinonen veranlaate uns, die kationisch leicht polymerisierbare Aziridinylgruppe durch Addition an die Vinylgruppelf2) von Vinylchinonen in Chiononsysteme einzufuhren. Dabei konnte angenommen werden, daB die durch Polymerisation der Aziridinylgruppe erhaltenen Redoxpolymeren infolge ihrer tertiaren Aminogruppen in der Polymerenkette im waBrig-sauren Medium uber eine ausreichende Quellbarkeit verfugen wurden, so daB hier auf eine sonst ubliche Modifizierung der Redoxpolymeren durch Einfuhrung hydrophiler Gruppen verzichtet werden konnte.