Potential systems, high temperature

Although they are not elastomers, other phosphazenes also offer potential In areas requiring heat and fire resistance. Mixed fluoroalkoxy - aryloxy substituted cyclic phosphazenes are currently attracting Interest for fire resistant fluid applications (46). In other studies, cyclophosphazene matrix resins have been prepared which have potential for high temperature adhesive applications (47) and as composite matrix materials (48). These studies serve to further demonstrate the enhanced thermal stability and fire resistance which can be achieved with these phosphorus - nitrogen systems. 

Fig. 2.8 a A schematic of a double welled potential. At high temperatures both wells can be sampled. As the temperature reduces the deeper, low density well becomes the preferentially filled, resulting in a LDL. As the pressure is increased the system becomes situated in the less deep well, corresponding to a higher density liquid, b The proposed position in TP space of the liquid-liquid phase transition in water, reproduced from Mishima and Stanley (Reprinted by permission from Macmillan Publishers Ltd [48], 1998). Th is the homogenous nuclea-tion temperature line for supercooled water, while Tx is the temperature at which amorphous ice spontaneously crystallizes upon heating... 

Temperature is handled the same way in Langevin dynamics as it its in molecular dynamics. High temperature runs may be used to overcome potential energy barriers. Cooling a system to a low temperature in steps may result in a different stable conformation than would be found by direct geometry optimization. 

Acrylonitrile has contributed the desirable properties of rigidity, high temperature resistance, clarity, solvent resistance, and gas impermeabiUty to many polymeric systems. Its availabiUty, reactivity, and low cost ensure a continuing market presence and provide potential for many new appHcations. 

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