Some Physical and Mechanical Properties of Some High-Modulus Fibers Prepared from All-Para Aromatic Polyamide-Hydrazides

Abstract

Abstract The tensile and physical properties of some high-modulus X-500 class fibers prepared from certain polyamide-hydrazides are described and the tensile properties, in particular, are compared with those of glass, steel, graphite, and several of the organic fibers. As a consequence of the wide range of densities of these fibers (glass, 2.6 g/cm3; steel, 7.8 g/cm3; and X-500 class fibers, ∼1.45 g/cm3), the tensile property comparisons are made in both textile and engineering units, grams/ denier and pounds/ inch2, respectively. The amide-hydrazide polymers from which fibers of the X-500 class are obtained are typical fiber-forming organic polymers in the sense that fibers with a wide range of stress-strain properties can be spun from them. Fibers were made with elongations-to-break as high as 60% and as low as 2-3%. For any given elongation-to-break, the modulus is much higher than that of conventional fibers. The initial moduli characteristically are greater than described by the expression, initial modulus-1000Eb. −0.38, where Eb is the elongation-to-break. Typical values for initial moduli are 600-750 g/den at 3-4% elongation, 210-230 g/den at 15-20%, and 100 g/den at 40%. The thermal properties such as melting point and glass transition temperature and the thermooxidative stability of these polyamide-hydrazide fibers place them in the heat resistant class. They are hydrolytically stable. Their electrical properties make them superior to glass for use in composites for certain electrical applications.