M5 fiber (polyhydroquinone-diimidazopyridine orPIPD) is a high-strengthsynthetic fiber first developed by the Dutch chemical firmAkzoNobel.[1] It is produced in the United States by the Magellan Systems International, which became a division ofDuPont.
M5 fiber is prepared by acondensation polymerization betweentetraaminopyridine anddihydroxyterephthalic acid usingdiphosphorus pentoxide as a dehydrating agent. The polymer mixture is then heated and extruded to form brightly blue polymer fibers. The fibers are then washed extensively with water and base in order to remove thephosphoric acid generated by the hydration of diphosphorus pentoxide from the polymer.
Next the fiber is heated, to remove water, and exposed to controlled stress, enabling the intermolecularhydrogen bonds to be created, thus increasing the strength of the polymer by aligning the molecular structure of the fiber in a better configuration for tensile and compressive strength.
M5 has atensile strength of 4 GPa[1] to 9.5GPa.[2] Otheraramids- (such asKevlar andTwaron) orUHMWPE-fibres (such asDyneema andSpectra) range from 2.2 to 3.9 GPa.[3]
M5 has "very high levels" of fire resistance, flame retardancy, and chemical resistance, especially high for an organic fiber.[citation needed] It is less brittle than carbon fiber and will yield when stretched.