Topic:Preferential Orientation of Molecular Planes of Rigid-Rod Polymers along the Radial Direction Normal to the Fiber Axis
Speaker:Dr. T. Kitagawa(Toyobo Co.)
Time:15:30, Mar 12th, 2018
Venue:Room 604, Building 28
Abstract:Fibers made of rigid-rod polymers have been developed to utilize the mechanical properties of the molecules to the utmost; the rigidity gives straightness and toughness in the chemical bonds along the molecular axis aligned along the fiber axis. We have previously proposed an estimation method to predict the preferential orientation of the () crystal planes of PBO (poly-p-phenylenebenzobisoxazole) crystals normal to the fiber axis from the diffraction X-ray intensities in diffraction patterns obtained by a micro-focus X-ray diffraction method. Because the PBO molecule have a thin-planar structure with rigidity, it can rotate freely around the molecular axis in the solution state. It is found that the alignment of the (0) planes of the crystals was determined in fibers prepared by coagulation during the fiber spinning process. In this presentation a calculation method to predict the intensities of the (0) reflections of PBO fibers as a function of the distance from the center of the fiber to the center of the focus point of a micro X-ray beam on the fiber is proposed. The method can estimate the degree of preferential orientation of thealong the radial direction of the fiber. The process of preferential orientations of the PBO crystals forming in the fiber structure induced by coagulation was revealed.