Assessment of compressive properties of high performance organic fibers

The compressive properties of five high performance organic fibers with varying degrees of lateral molecular interactions have been analyzed. A novel micro-mechanical technique applies an axial compressive load on a segment of free fiber in order to quantify the axial compressive modulus of single filaments. The data reduction methodology used in the analysis accounts for fiber deviations from a perfectly vertical column through the use of Southwell plots. The resulting ratios of axial compressive to tensile modulus show values ranging between 0.3 and 1.0, depending on the type and degree of intermolecular interactions present in the fiber. Heat treatment of M5 fiber provides enhanced lateral interactions and improved molecular alignment that maintain molecular orientation during compressive deformation, resulting in the compressive modulus of M5 heat treated being statistically equal to its tensile modulus. Fibers lacking strong lateral interactions show considerable damage resulting from axial compressive deformations.