聚酰胺酸湿法纺丝凝固过程三元相图的初步构建

The Construction of Phase Diagrams for Coagulation Formation of the Wet Spinning of Polyimide Fibers

利用浊点滴定法构建了聚酰胺酸(PAA)/N,N-二甲基乙酰胺(DMAc)/水(H2O)体系的三元相图.研究了PAA的特性黏数和分子结构变化对三元相图的影响.结果表明,PAA/DMAc/H2O三元体系只发生液-液相分离;相转变时体系的组成配比存在线性关系.在一定范围内,PAA特性黏数的变化基本不影响体系三元相图的构成.不同分子结构PAA的三元体系,其相分离过程对温度的敏感程度不同.

Based on the theory of membrane forming systems,the phase separation of polyimide wet spinning has been investigated. Poly （ amic acid） （PAA） fibers were prepared by the wet spinning way. The structure and properties of fibers were characterized by Fourier transform infrared spectroscopy （FTIR） and scanning electron microscopy （SEM）. Experimental cloudpoints of PAA/N, N-dimethylacetamide （DMAc）/H20 systems could be achieved in the accessible low polymer content range by cloud-point titration. Linearized cloudpoint （LCP） curve correlations for ternary systems were used to extrapolate to higher polymer concentrations to produce a full-phase diagram at different temperatures. The effect of changing the monomers of PAA was discussed in detail. The results suggested that a linearized cloudpoint curve correlation held for the ternary systems undergoing liquid/liquid demixing. The fact that the intrinsic viscosity of the ternary system within a certain range had little effect on the phase diagram was discussed. By changing the monomers of PAA, the phase separation of the system showed different sensitivities to temperature.