Determination of anisotropic diamagnetic susceptibility of polymeric fibers suspended in liquid

Anisotropic diamagnetic susceptibilities of polymeric fibers in liquid susp ensions determined by means of the method proposed recently by us were comp ared with those obtained by other methods including superconducting quantum interference device (SQUID) and magnetic torque meter. Poly(p-phenylene-2, 6-benzobisoxazole) (PBO) fibers and carbon fibers (CF) were used for the me asurements. Both fibers exhibited positive diamagnetic anisotropy, i.e., ch i (a) = chi (parallel to) - chi (perpendicular to) > 0, where the parallel direction is taken as the fiber axis. The values of anisotropic susceptibil ities determined by these three different methods were in good agreement wi th each other, demonstrating the usefulness of the proposed method for the measurement of a single fiber.