Abstract: An improved membrane electrode assembly (“MEA”) for an electrochemical fuel cell comprises coextensive ion exchange membrane and electrode layers and a rigid fluid impermeable integral seal comprising a sealant material impregnated into the porous electrode layers in sealing regions of the MEA. The integral seal envelops the peripheral region including the side edge of the MEA. The integral seal can circumscribe the electrochemically active area of the MEA and can also extend laterally beyond the edge of the MEA. An integral seal can also be provided around any openings, such as manifold openings, that are formed inside or outside the MEA. The seal has sealing features formed therein, such as raised ribs. Sealing features can be formed from the rigid sealant material or from resilient sealant material applied to the surface of the integral seal.

Abstract: Acrylic ester phosphonic acids of general formula (I), stereoisomers thereof and mixtures of these, wherein n is 1 or 2, on the condition that for n=1 R1 has the meaning and for n=2 R1 has the meaning R2 is a C1 to C12 alkylene radical, C4-C8 cycloalkylene radical or C7 to C15 alkylene phenylene radical; R3 is hydrogen, a C1 to C5 alkyl radical or a C1 to C5 O-alkyl radical; and R4, R5, independently of each other, each stand for a C1 to C5 alkyl radical or a C1 to C5 O-alkyl radical.

Abstract: Electrochemically inactive separators may be employed at the periphery of membrane electrode assemblies in fuel cells (such as solid polymer electrolyte fuel cells) to separate the various fluids within (for example, reactants, coolant). Complex fluid distribution features may be incorporated into these separators, thereby desirably simplifying the design and manufacture of other fuel cell components, such as the flow field plates employed to distribute fluids to the cell electrodes. This is particularly advantageous in fuel cells comprising thin, corrugated flow field plates. The separators may be bonded to the membrane electrode assemblies to form convenient, unitary structures.

Abstract: In a liquid feed fuel cell system, substantially pure fuel needs to be added to a dilute mixture of fuel in water so as to maintain the fuel concentration at an appropriate level for use with the fuel cell system. Under passive control of the fuel concentration, a first equilibrium concentration is established between the substantially pure fuel and a fuel transfer medium. A second equilibrium concentration is then established between the fuel transfer medium and the dilute mixture for use with the fuel cell system. The system is “passive” as it does not rely on the measurement of the fuel concentration and direct injection of fuel. The fuel transfer medium can be solid, liquid or gas.

Abstract: A method of controlling the temperature within an electrochemical fuel cell stack comprises introducing a reactant fluid stream comprising both a heat transfer liquid and a reactant into a fuel cell assembly such that the reactant fluid stream contacts an electrode. The heat transfer liquid is other than water. Preferably, the method further comprises recirculating heat transfer liquid which is in the reactant exhaust stream, typically via a heat exchanger, and re-introducing it into the fuel cell assembly in the reactant fluid stream. The recirculated heat transfer liquid may be directed to a reservoir which in turn supplies heat transfer liquid to the reactant fluid stream as it is needed. In a further embodiment, the method may comprise using the heat transfer liquid to heat a fuel cell stack to a desired operating temperature rather than cooling the stack.

Abstract: A method and apparatus are described for imaging wet samples with an Environmental Scanning Electron Microscope (ESEM). In particular, a carrier gas is humidified such that the water vapor in the carrier gas in the sample chamber of the ESEM has a partial pressure equal to the saturated vapor pressure of water. Thus, the sample can be imaged without observing any evaporation or condensation thereon. Both the carrier gas and the water vapor may act as the imaging gas within the ESEM. The apparatus is an imaging gas delivery system for the ESEM wherein the carrier gas may be appropriately humidified.

Abstract: Electrochemically inactive separators may be employed at the periphery of membrane electrode assemblies in fuel cells (such as solid polymer electrolyte fuel cells) to separate the various fluids within (for example, reactants, coolant). Complex fluid distribution features may be incorporated into these separators, thereby desirably simplifying the design and manufacture of other fuel cell components, such as the flow field plates employed to distribute fluids to the cell electrodes. This is particularly advantageous in fuel cells comprising thin, corrugated flow field plates. The separators may be bonded to the membrane electrode assemblies to form convenient, unitary structures.

Abstract: A method of controlling the temperature within an electrochemical fuel cell stack comprises introducing a reactant fluid stream comprising both a heat transfer liquid and a reactant into a fuel cell assembly such that the reactant fluid stream contacts an electrode. The heat transfer liquid is other than water. Preferably, the method further comprises recirculating heat transfer liquid which is in the reactant exhaust stream, typically via a heat exchanger, and re-introducing it into the fuel cell assembly in the reactant fluid stream. The recirculated heat transfer liquid may be directed to a reservoir which in turn supplies heat transfer liquid to the reactant fluid stream as it is needed. In a further embodiment, the method may comprise using the heat transfer liquid to heat a fuel cell stack to a desired operating temperature rather than cooling the stack.

Abstract: Tris-(cyanato)-s-triazines having the formula: ##STR1## wherein R.sub.1 and R.sub.2 independently of one another, represent halogen, in particular, chlorine, bromine and fluorine, hydrogen or a methyl group or ethyl group. The monomers disclosed always provide an anisotropic network. Methods for the polycyclotrimerization of polycyanates to obtain the inventive compounds are also disclosed.