An excellent polymer electrolyte composition has excellent chemical stability of being resistant to strong oxidizing atmosphere during operation of fuel cell, and achieves excellent proton conductivity under low-humidification conditions, excellent mechanical strength and physical durability. A polymer electrolyte membrane, a membrane electrode assembly, and a polymer electrolyte fuel cell each use the same. The polymer electrolyte composition contains an ionic group-containing polymer (A), a phosphorus-containing additive (B), and a nitrogen-containing aromatic additive (C), the phosphorus-containing additive (B) and the nitrogen-containing aromatic additive (C) being a compound represented by specific structural formulae.

The present invention relates to a sealing element and/or a support ring, in particular for a reciprocating compressor, manufactured by compression molding of a mixture of chips of carbon fiber-reinforced composite material, wherein at least part of the chips contains carbon fibers having a length of 3 to 20 mm, and wherein the carbon fibers in the sealing element and/or support ring have a random fiber orientation.

Novel ultra-thin unidirectional pre-preg tapes are disclosed. They can be used to produce ultra-thin woven, bias, multiaxial, chopped-oriented etc. types of pre-pregs. These ultra-thin pre-pregs enable production of composite material products with well-controlled dimensional tolerances and smooth/even surfaces. Further, they render the production of composite material products relatively simpler, tidier, quicker, and economical. The obtained composite material products are relatively thinner, lighter, and mechanically higher-performing.

The following is provided as a member for a composite material that has excellent stiffness, heat resistance, and productivity. A member for a composite material containing resin component that contains polyaryletherketone as a main component. The resin component has a molecular weight distribution of 3.8 or more and 8 or less and a mass average molecular weight of 86000 or less. The member for a composite material has a thickness more than 15 m. The composite material contains a resin and reinforcing fibers having a number average fiber length of 5 mm or more.