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)/H2O 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.