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

1.对铸态聚酰亚胺（PAA）薄膜进行冷拔，然后进行热亚胺化和拉伸退火，可以有效地提高刚性和线性聚酰亚胺（pi）薄膜的拉伸力学性能，因为亚胺化过程中形成的有序相保留了主链的取向。肿胀法也是一种很好的方法。如果选择合适的混合溶胀溶剂和温度，胀膜拉伸比冷拔法具有更高的拉伸率。热拉伸法适用于柔性主链聚酰亚胺。特别是对于具有扩展构象的线性主链的柔性PI（PMDA/3.4′-ODA）最有效。利用聚苯二胺染料的吸收二色性评价了PAA和PI的单轴分子取向对PAA薄膜拉伸率的影响。二向色光谱表明，对于刚性PI (BPDA/PDA)，微拉伸PAA（BPDA/PDA）薄膜在热亚酰化过程中发生自发分子取向。研制了一种新型聚丙烯酸纤维纺丝装置。芳香族PI分子纤维和分子丝的研制正在利用该装置和PI薄膜的拉伸技术进行。

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.