The assumption of equal tensile and compressive modulus necessary to determine single fiber axial compressive strength from the elastica loop test is relaxed by deriving a compressive strength equation based on the analysis of the flexural response of a fiber with different modulus in tension and compression. Previously determined tensile (E1t) and compressive (E1c ) modulus values for different high performance organic fibers with varying degrees of lateral molecular interactions are used to determine fiber compressive strength. The importance of using the bi-moduli equation becomes evident in the case of fibers that lack strong intermolecular interactions, since calculations done with the original loop test equation can result in an overestimation of the compressive strength on the order of 80%, as seen for the poly-(p-phenylene benzobisoxazole) fiber PBO. Kink band angles measured from looped fiber specimens are documented and correlated to the calculated compressive strength values.

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We demonstrate the continuous production of liquid-filled polymeric fibers in a stable meltspinning process at the pilot plant scale. Different polymers and liquids could successfully be combined over a wide range of core-sheath dimensions. The ability to produce a continuous liquid-core fiber (LCF) is attractive since post-filling of a hollow fiber with similar dimensions is not practical. We characterized the mechanical properties of the LCF's with particular attention to their damping properties. A LCF can exhibit significantly enhanced

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The development of thermoplastic fibers containing a liquid core is described. Internal morphology analysis confirms that the liquid-containing core is composed of a continuous cylindrical microchannel of constant diameter. Microfluidic experiments on both liquid core and reference hollow fibers were conducted by pumping distilled water through several filaments simultaneously. The observed fluid motions are satisfactorily described by the Hagen-Poiseuille law, indicating that the hollow and liquid core fibers have internal diameters of 31.6 and 14.8 µm, respectively. Flushing the liquid core fibers with a surfactant solution efficiently removes the saturated ester initially used during the melt spinning of the fiber. GRAPHICAL ABSTRACT ARTICLE HISTORY