Development of thermally stable phosphonitrile elastomers for advanced aerospace structures

Attempts to prepare low molecular weight, curable poly-(fluoroalkoxyphosphazenes) have been successful. Derivatization of /Cl2PN/n polymer with alkoxides gave functionally reactive terpolymers. These terpolymers could be crosslinked with polyisocyanates at room temperature. Attempts to control molecular weight have not been as successful. The effects of (Cl2PN)3 monomer purity, use of (Cl2PN)3,4 mixture, and early termination of the bulk polymerization of (Cl2PN)3 were studied briefly. Both low and high molecular weight polymers were obtained. Reaction of NH4Cl with PCl5 with subsequent heating to give chain extension gave either gels of oils with molecular weights of several thousand. The stabilization of poly-(fluoroalkoxyphosphazene) was investigated. The results generally were inconclusive, but acids were found to be deleterious while bases had little discernible effect. Improvements in stability by modification of end groups was inconclusive

Development of thermally stable phosphonitrile elastomers for advanced aerospace structures

Both high and low molecular weight, curable poly(fluoroalkoxy phosphazene) terpolymers were prepared. These terpolymers resulted from reaction of (Cl2PNn) polymer with alkoxides derived from CF3CH2OH and C3F7CH2OH, and an alkoxide derived from CH3CH(OH)C2H4OH. The terpolymers were crosslinked with polyisocyanates at room temperature. High molecular weight materials were converted into isocyanate prepolymers which as films underwent moisture cures at room temperature. Prepolymer solutions were stable for several days, and showed good adhesion. Also the effects of polymerization of (Cl2PN)3 were studied. Purified octachlorophosphazene, thiocyanate salts, or hydrogen chloride were employed in attempts to decrease molecular weight. Hydrogen chloride was found to be a good agent for preparation of low molecular weight poly(dichloro phosphazene)

The evolution of climate change guidance for fluvial flood risk management in England

Floods are one of the biggest natural hazards to society, and there is increasing concern about the potential impacts of climate change on flood occurrence and magnitude. Furthermore, flood risk is likely to increase in the future not just through increased flood occurrence, but also through socio-economic changes, such as increasing population. The extent to which adaptation measures can offset this increased risk will depend on the level of future climate change, but there exists an urgent need for information on the potential impacts of climate change on floods, so that these can be accounted for by flood management authorities and local planners aiming to reduce flood risk. Agencies across the UK have been pro-active in providing such guidance for many years and in refining it as the science of climate change and hydrological impacts has developed. The history of this guidance for fluvial flood risk in England is presented and discussed here, including the recent adoption of a regional risk-based approach. Such an approach could be developed and applied to flood risk management in other countries, and to other sectors affected by climate change

MontanAqua : Wasserbewirtschaftung in Zeiten von Knappheit und globalem Wandel. Wasserbewirtschaftungsoptionen für die Region Crans-Montana-Sierre im Wallis

Das nationale Forschungsprogramm NFP 61 «Nachhaltige Wassernutzung » des Schweizerischen Nationalfonds hat sich zum Ziel gesetzt, wissenschaftliche Grundlagen zur nachhaltigen Wasserbewirtschaftung in der Schweiz zu liefern. Als Teil dieses Forschungsvorhabens wurde im Rahmen des Projektes MontanAqua die Wasserbewirtschaftung der Region Crans-Montana-Sierre (Wallis) untersucht. Es ging dabei darum, in enger Zusammenarbeit mit den in der Region betroffenen Akteuren nachhaltige Wassernutzungsstrategien für die Zukunft zu entwickeln. MontanAqua hat sich vertieft mit den bestehenden Systemen der Wasserbewirtschaftung auf der regionalen Skala (11 Gemeinden) auseinandergesetzt. Dazu wurden die zukünftigen Auswirkungen der klimatischen und sozioökonomischen Veränderungen einbezogen. Das Forschungsteam analysierte die aktuelle Situation anhand von quantitativen, qualitativen sowie kartografischen Methoden und kombinierte diese mit Modellberechnungen. Für die Modellierung der Zukunft wurden regionale Klimaszenarien und vier mit lokalen Akteuren entwickelte sozioökonomische Szenarien verwendet. Dieser Überblick fasst die Resultate des Projektes MontanAqua zusammen. Fünf wesentliche Fragen werden beantwortet und fünf Kernbotschaften erläutert. Zudem sind Empfehlungen für die Verantwortlichen der regionalen und kantonalen Wasserbewirtschaftung formuliert