DEVELOPMENT OF QUASI-MICROSCOPIC TECHNIQUES FOR MOLECULAR FIBER/WIRE OF AROMATIC POLYIMIDES

点击翻译按钮获取中文摘要

1.The cold drawing of as-cast polyamic acid (PAA) film followed by thermal imidization and annealing under tension was very effective for improving the tensile mechanical properties of films of rigid and linear polyimides (PIs) because the orientation of the main chains is retained by the formation of ordered phases during imidization.The swelling method was also an excellent technique. The drawing of swollen polyamic acid films can provide more draw ratio than the cold drawing method if mixed swelling solvents and temperatures are chosen properly.The hot drawing methed was appropriate for polyimides of flexible main chains. Especially it was most effective for flexible PI(PMDA/3.4'-ODA) with a linear main chain in an extended conformation.2.The absorption dichroism of perylenebisimide dye was applied to evaluate the monoaxial molecular orientation of PAA and PI as function of draw ratio of PAA films. The dichroic spectra showed that for rigid PI (BPDA/PDA) spontaneous molecular orientation occurs during thermal imidization of slightly drawn PAA(BPDA/PDA) filsm.3.A new apparatue was prepared for spinning PAA fibers. The devel opment of molecular fiber and molecular wire of aromatic PIs are in progress using this apparatus and the drawing techniques for PI films.